ORCID Profile
0000-0003-2164-7877
Current Organisations
University of Liverpool
,
University of Adelaide
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Animal Structure and Function | Palaeoecology | Zoology | Phylogeny and Comparative Analysis | Invasive Species Ecology | Evolutionary Biology | Biological Adaptation
Expanding Knowledge in the Biological Sciences | Medical Instruments | Climate Variability (excl. Social Impacts) | Flora, Fauna and Biodiversity at Regional or Larger Scales |
Publisher: Wiley
Date: 25-04-2014
DOI: 10.1111/JOA.12190
Publisher: Oxford University Press (OUP)
Date: 14-02-2019
Publisher: Springer Science and Business Media LLC
Date: 09-09-2022
DOI: 10.1007/S10914-022-09624-6
Abstract: Studies on the evolution of brain size variation usually focus on large clades encompassing broad phylogenetic groups. This risks introducing ‘noise’ in the results, often obscuring effects that might be detected in less inclusive clades. Here, we focus on a s le of endocranial volumes (endocasts) of 18 species of rabbits and hares (Lagomorpha: Leporidae), which are a discrete radiation of mammals with a suitably large range of body sizes. Using 60 in iduals, we test five popular hypotheses on brain size and olfactory bulb evolution in mammals. We also address the pervasive issue of missing data, using multiple phylogenetic imputations as to conserve the full s le size for all analyses. Our analyses show that home range and burrowing behaviour are the only predictors of leporid brain size variation. Litter size, which is one of the most widely reported constraints on brain size, was unexpectedly not associated with brain size. However, a constraining effect may be masked by a strong association of litter size with temperature seasonality, warranting further study. Lastly, we show that unreasonable estimations of phylogenetic signal (Pagel’s lamba) warrant additional caution when using small s le sizes, such as ours, in comparative studies.
Publisher: Cold Spring Harbor Laboratory
Date: 29-09-2023
Publisher: Public Library of Science (PLoS)
Date: 06-03-2013
Publisher: Wiley
Date: 31-03-2015
DOI: 10.1111/PALA.12159
Publisher: Wiley
Date: 21-02-2019
DOI: 10.1111/EDE.12284
Abstract: Snakes exhibit a erse array of body shapes despite their characteristically simplified morphology. The most extreme shape changes along the precloacal axis are seen in fully aquatic sea snakes (Hydrophiinae): "microcephalic" sea snakes have tiny heads and dramatically reduced forebody girths that can be less than a third of the hindbody girth. This morphology has evolved repeatedly in sea snakes that specialize in hunting eels in burrows, but its developmental basis has not previously been examined. Here, we infer the developmental mechanisms underlying body shape changes in sea snakes by examining evolutionary patterns of changes in vertebral number and postnatal ontogenetic growth. Our results show that microcephalic species develop their characteristic shape via changes in both the embryonic and postnatal stages. Ontogenetic changes cause the hindbodies of microcephalic species to reach greater sizes relative to their forebodies in adulthood, suggesting heterochronic shifts that may be linked to homeotic effects (axial regionalization). However, microcephalic species also have greater numbers of vertebrae, especially in their forebodies, indicating that somitogenetic effects also contribute to evolutionary changes in body shape. Our findings highlight sea snakes as an excellent system for studying the development of segment number and regional identity in the snake precloacal axial skeleton.
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.JHEVOL.2017.08.018
Abstract: If Wolff's law is valid, then quantifying the three-dimensional architecture of trabecular bone, specifically 3D principal trabecular orientation (3D-PTO), can reveal joint loading direction among different taxa. This study measured the architecture of trabecular bone in the 3rd metacarpal head of humans and chimpanzees, and then tested their association with expected joint loading direction. We postulate that since chimpanzees, unlike humans, directly load their metacarpal bones during knuckle-walking, trabecular structure in the dorsal aspect of the 3rd metacarpal head will be significantly more organized and robust in chimpanzees. To test this hypothesis, we micro-CT scanned the 3rd metacarpal from 11 chimpanzees and 12 humans. Three 6 mm volumes of interest (VOI palmar, center and dorsal) were selected and trabecular bone properties and 3D-PTO were measured. The results revealed many similarities between humans and chimpanzees: in both taxa the dorsal VOI demonstrated the lowest bone volume fraction (BV/TV), the most rod-like trabecular structure, the fewest and thinnest trabeculae, and low organization of the trabecular architecture (degree of anisotropy). Nevertheless, 3D-PTO in the dorsal VOI differed significantly between humans and chimpanzees. While 3D-PTO in humans was clustered together and aligned nearly along the bone long axis, in chimpanzees 3D-PTO was ided into two distinct groups and aligned with an angle toward either the medial or lateral orientations. Our results suggest that loading effects on trabecular bone properties such as BV/TV might be partially constrained by genetic factors. On the other hand, 3D-PTO is continually affected by active loading (i.e., modeling) and thus may serve as a useful tool to infer differences in joint loading directions.
Publisher: Springer Science and Business Media LLC
Date: 12-04-2023
DOI: 10.1186/S12862-023-02113-1
Abstract: The shape of the semicircular canals of the inner ear of living squamate reptiles has been used to infer phylogenetic relationships, body size, and life habits. Often these inferences are made without controlling for the effects of the other ones. Here we examine the semicircular canals of 94 species of extant limbed lepidosaurs using three-dimensional landmark-based geometric morphometrics, and analyze them in phylogenetic context to evaluate the relative contributions of life habit, size, and phylogeny on canal shape. Life habit is not a strong predictor of semicircular canal shape across this broad s le. Instead, phylogeny plays a major role in predicting shape, with strong phylogenetic signal in shape as well as size. Allometry has a limited role in canal shape, but inner ear size and body mass are strongly correlated. Our wide s ling across limbed squamates suggests that semicircular canal shape and size are predominantly a factor of phylogenetic relatedness. Given the small proportion of variance in semicircular canal shape explained by life habit, it is unlikely that unknown life habit could be deduced from semicircular canal shape alone. Overall, semicircular canal size is a good estimator of body length and even better for body mass in limbed squamates. Semiaquatic taxa tend to be larger and heavier than non-aquatic taxa, but once body size and phylogeny are accounted for, they are hard to distinguish from their non-aquatic relatives based on bony labyrinth shape and morphology.
Publisher: Public Library of Science (PLoS)
Date: 17-02-2016
Publisher: Cold Spring Harbor Laboratory
Date: 29-03-2017
DOI: 10.1101/121525
Abstract: Anolis lizards are a model system for the study of adaptive radiation and convergent evolution. Greater Antillean anoles have repeatedly evolved six similar forms or ecomorphs: crown-giant, grass-bush, twig, trunk, trunk-crown, and trunk-ground. Members of each ecomorph category possess a specific set of morphological, ecological and behavioural characteristics which have been acquired convergently. Here we test whether the semicircular canal system – the organ of balance – is also convergent among ecomorphs, reflecting the shared sensory requirements of their ecological niches. As semicircular canal shape has been shown to reflect different locomotor strategies, we hypothesised that each Anolis ecomorph would have a unique canal morphology. Using 3D semilandmarks and geometric morphometrics, semicircular canal shape was characterised in 41 Anolis species from the Greater Antilles and the relationship between canal shape and ecomorph grouping, phylogenetic history, size, and perch characteristics was assessed. Further, canal morphology of modern species was used to predict the ecomorph affinity of five fossil anoles from the Miocene of the Dominican Republic. Our study recovered ecomorph as the single-most important covariate of canal morphology in modern taxa although phylogenetic history and size also showed a small, yet significant correlation with shape. Surprisingly, perch characteristics were not found to be significant covariates of canal shape, even though they are important habitat variables. Using posterior probabilities, we found that the fossil anoles have different semicircular canals shapes to modern ecomorph groupings implying extinct anoles may have been interacting with their Miocene environment in different ways to modern Anolis species.
Publisher: Springer Science and Business Media LLC
Date: 05-11-2014
DOI: 10.1038/NATURE13819
Publisher: Oxford University Press (OUP)
Date: 04-08-2014
DOI: 10.1111/ZOJ.12159
Publisher: Springer Science and Business Media LLC
Date: 28-07-2022
Publisher: The Royal Society
Date: 22-02-2012
Abstract: The limbless, primarily soil-dwelling and tropical caecilian hibians (Gymnophiona) comprise the least known order of tetrapods. On the basis of unprecedented extensive fieldwork, we report the discovery of a previously overlooked, ancient lineage and radiation of caecilians from threatened habitats in the underexplored states of northeast India. Molecular phylogenetic analyses of mitogenomic and nuclear DNA sequences, and comparative cranial anatomy indicate an unexpected sister-group relationship with the exclusively African family Herpelidae. Relaxed molecular clock analyses indicate that these lineages erged in the Early Cretaceous, about 140 Ma. The discovery adds a major branch to the hibian tree of life and sheds light on both the evolution and biogeography of caecilians and the biotic history of northeast India—an area generally interpreted as a gateway between bio ersity hotspots rather than a distinct biogeographic unit with its own ancient endemics. Because of its distinctive morphology, inferred age and phylogenetic relationships, we recognize the newly discovered caecilian radiation as a new family of modern hibians.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-10-2012
Abstract: Fortey introduces readers to well-worn organisms that, having endured all of the difficulties thrown at them over the ages, he refers to as "messengers from deep geological time."
Publisher: Wiley
Date: 02-02-2021
DOI: 10.1111/EVO.14163
Publisher: Cold Spring Harbor Laboratory
Date: 04-07-2019
DOI: 10.1101/692632
Abstract: Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the in idual. In such cases, shape variation should not be dominated by allometry ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus) but this main variation should emerge from high in idual variability and thus have low eigenvalues. We assessed the evidence for high in idual variation through 3D geometric morphometric shape analysis of crania and mandibles of thre species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in in iduals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between in idual and ordinated shape variation was limited, indicating high levels of in idual variability in the masticatory apparatus. Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that in idual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraint act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.
Publisher: Wiley
Date: 15-11-2019
DOI: 10.1111/EDE.12328
Abstract: Sea snakes (Hydrophiinae) that specialize on burrowing eel prey have repeatedly evolved tiny heads and reduced forebody relative to hindbody girths. Previous research has found that these "microcephalic" forms have higher counts of precaudal vertebrae, and postnatal ontogenetic changes cause their hindbodies to reach greater girths relative to their forebodies. We examine variation in vertebral size along the precaudal axis of neonates and adults of three species. In the nonmicrocephalic Hydrophis curtus, these intracolumnar patterns take the form of symmetrical curved profiles, with longer vertebrae in the midbody (50% of body length) relative to distal regions. In contrast, intracolumnar profiles in the microcephalic H. macdowelli and H. obscurus are strongly asymmetrical curves (negative skewness) due to the presence of numerous, smaller-sized vertebrate in the forebody (anterior to the heart). Neonate and adult H. macdowelli and H. obscurus specimens all exhibit this pattern, implying an onset of fore- versus hindbody decoupling in the embryo stage. Based on this, we suggest plausible developmental mechanisms involving the presence and positioning of Hox boundaries and heterochronic changes in segmentation. Tests of our hypotheses would give new insights into the drivers of rapid convergent shifts in evolution, but will ultimately require studies of gene expression in the embryos of relevant taxa.
Publisher: Wiley
Date: 13-04-2013
DOI: 10.1111/EVO.12100
Abstract: Studies integrating evolutionary and developmental analyses of morphological variation are of growing interest to biologists as they promise to shed fresh light on the mechanisms of morphological ersification. Sexually dimorphic traits tend to be incredibly ergent across taxa. Such ersification must arise through evolutionary modifications to sex differences during development. Nevertheless, few studies of dimorphism have attempted to synthesize evolutionary and developmental perspectives. Using geometric morphometric analysis of head shape for 50 Anolis species, we show that two clades have converged on extreme levels of sexual dimorphism through similar, male-specific changes in facial morphology. In both clades, males have evolved highly elongate faces whereas females retain faces of more moderate proportion. This convergence is accomplished using distinct developmental mechanisms one clade evolved extreme dimorphism through the exaggeration of a widely shared, potentially ancestral, developmental strategy whereas the other clade evolved a novel developmental strategy not observed elsewhere in the genus. Together, our analyses indicate that both shared and derived features of development contribute to macroevolutionary patterns of morphological ersity among Anolis lizards.
Publisher: Cold Spring Harbor Laboratory
Date: 05-2020
DOI: 10.1101/2020.04.30.071308
Abstract: Among vertebrates, placental mammals are particularly variable in the covariance between their cranial shapes and body size (allometry), with the notable exception of rodents. Australian murid rodents present an opportunity to assess the cause of this anomaly because they radiated on an ecologically erse continent unique for lacking other terrestrial placentals. Here we used 3D geometric morphometrics to quantify species-level and evolutionary allometries in 38 species (317 crania) from all Australian murid genera. We ask if ecological opportunity resulted in greater allometric ersity conversely, we test if intrinsic constraints and/or stabilizing selection conserved allometry. To increase confidence in species-level allometric slopes, we introduce a new phylogeny-based method of bootstrapping and randomly res ling across the whole s le. We found exceedingly conserved allometry across the 10 million year split between Mus and the clade containing Australian murids. Cranial shapes followed craniofacial evolutionary allometry (CREA) patterns, with larger species having relatively longer snouts and smaller braincases. CREA is consistent with both intrinsic constraints and stabilizing selection hypotheses for conserved allometry. However, large-bodied frugivores evolved faster, while carnivorous specialists showed skull modifications known to conflict with masticatory efficiency. These results suggest a strong role of stabilizing selection on the masticatory apparatus of murid rodents.
Publisher: CSIRO Publishing
Date: 27-04-2023
DOI: 10.1071/ZO22044
Abstract: Among the many catastrophic introductions of exotic species to Australia, the Australian Dung Beetle Project stands apart as a success story. From 1965 dung beetles (Coleoptera: Scarabaeinae) were introduced for biological control purposes, and 23 species survived to become integrated into the environment with apparently little-to-no competition with native species. To understand this, we investigated ecomorphological ersity in the Australian dung beetle fauna, examining variation in functional traits among rolling and tunnelling species that are native to Australia and introduced. We found that introduced species are, on average, larger than native species of the same nidification strategy, but the size ranges overlap. Native and introduced tunnellers are convergent in body shape, whereas introduced rollers have distinct body shape compared with native species. Rollers and tunnellers also have distinct allometric patterns, where shape variation predicted by size aligns along two erging allometric trajectories between nidification strategies. Our results suggest that ecomorphological differences do not explain the apparent lack of competition between tunnellers, but this may be the factor for rollers. Also, these results indicate that body size and associated allometric scaling is an important aspect of the ecomorphology of dung beetles that should be considered in future studies.
Publisher: Springer Science and Business Media LLC
Date: 11-2019
DOI: 10.1186/S12983-019-0338-5
Abstract: Within-species skull shape variation of marsupial mammals is widely considered low and strongly size-dependent (allometric), possibly due to developmental constraints arising from the altricial birth of marsupials. However, species whose skulls are impacted by strong muscular stresses – particularly those produced through mastication of tough food items – may not display such intrinsic patterns very clearly because of the known plastic response of bone to muscle activity of the in idual. In such cases, allometry may not dominate within-species shape variation, even if it is a driver of evolutionary shape ergence ordination of shape in a geometric morphometric context through principal component analysis (PCA) should reveal main variation in areas under masticatory stress (incisor region/zygomatic arches/mandibular ramus) but this main variation should emerge from high in idual variability and thus have low eigenvalues. We assessed the evidence for high in idual variation through 3D geometric morphometric shape analysis of crania and mandibles of three species of grazing-specialized wombats, whose diet of tough grasses puts considerable strain on their masticatory system. As expected, we found little allometry and low Principal Component 1 (PC1) eigenvalues within crania and mandibles of all three species. Also as expected, the main variation was in the muzzle, zygomatic arches, and masticatory muscle attachments of the mandibular ramus. We then implemented a new test to ask if the landmark variation reflected on PC1 was reflected in in iduals with opposite PC1 scores and with opposite shapes in Procrustes space. This showed that correspondence between in idual and ordinated shape variation was limited, indicating high levels of in idual variability in the masticatory apparatus. Our results are inconsistent with hypotheses that skull shape variation within marsupial species reflects a constraint pattern. Rather, they support suggestions that in idual plasticity can be an important determinant of within-species shape variation in marsupials (and possibly other mammals) with high masticatory stresses, making it difficult to understand the degree to which intrinsic constraints act on shape variation at the within-species level. We conclude that studies that link micro- and macroevolutionary patterns of shape variation might benefit from a focus on species with low-impact mastication, such as carnivorous or frugivorous species.
Publisher: Oxford University Press (OUP)
Date: 07-05-2019
DOI: 10.1093/ICB/ICZ033
Abstract: Morphological variation among the viviparous sea snakes (Hydrophiinae), a clade of fully aquatic elapid snakes, includes an extreme “microcephalic” ecomorph that has a very small head atop a narrow forebody, while the hind body is much thicker (up to three times the forebody girth). Previous research has demonstrated that this morphology has evolved at least nine times as a consequence of dietary specialization on burrowing eels, and has also examined morphological changes to the vertebral column underlying this body shape. The question addressed in this study is what happens to the skull during this extreme evolutionary change? Here we use X-ray micro-computed tomography and geometric morphometric methods to characterize cranial shape variation in 30 species of sea snakes. We investigate ontogenetic and evolutionary patterns of cranial shape ersity to understand whether cranial shape is predicted by dietary specialization, and examine whether cranial shape of microcephalic species may be a result of heterochronic processes. We show that the diminutive cranial size of microcephalic species has a convergent shape that is correlated with trophic specialization to burrowing prey. Furthermore, their cranial shape is predictable for their size and very similar to that of juvenile in iduals of closely related but non-microcephalic sea snakes. Our findings suggest that heterochronic changes (resulting in pedomorphosis) have driven cranial shape convergence in response to dietary specializations in sea snakes.
Publisher: The Royal Society
Date: 03-2018
DOI: 10.1098/RSOS.172141
Abstract: Viviparous sea snakes are the most rapidly speciating reptiles known, yet the ecological factors underlying this radiation are poorly understood. Here, we reconstructed dated trees for 75% of sea snake species and quantified body shape (forebody relative to hindbody girth), maximum body length and trophic ersity to examine how dietary specialization has influenced morphological ersification in this rapid radiation. We show that sea snake body shape and size are strongly correlated with the proportion of burrowing prey in the diet. Specialist predators of burrowing eels have convergently evolved a ‘microcephalic’ morphotype with dramatically reduced forebody relative to hindbody girth and intermediate body length. By comparison, snakes that predominantly feed on burrowing gobies are generally short-bodied and small-headed, but there is no evidence of convergent evolution. The eel specialists also exhibit faster rates of size and shape evolution compared to all other sea snakes, including those that feed on gobies. Our results suggest that trophic specialization to particular burrowing prey (eels) has invoked strong selective pressures that manifest as predictable and rapid morphological changes. Further studies are needed to examine the genetic and developmental mechanisms underlying these dramatic morphological changes and assess their role in sea snake speciation.
Publisher: Springer Science and Business Media LLC
Date: 06-08-2008
DOI: 10.1038/HDY.2008.79
Abstract: Genomic imprinting refers to the pattern of monoallelic parent-of-origin-dependent gene expression where one of the two alleles at a locus is expressed and the other silenced. Although some genes in mice are known to be imprinted, the true scope of imprinting and its impact on the genetic architecture of a wide range of morphometric traits is mostly unknown. We therefore searched for quantitative trait loci (QTL) exhibiting imprinting effects on mandible size and shape traits in a large F(3) population of mice originating from an intercross of the LG/J (Large) and SM/J (Small) inbred strains. We discovered a total of 51 QTL affecting mandible size and shape, 6 of which exhibited differences between reciprocal heterozygotes, the usual signature of imprinting effects. However, our analysis showed that only one of these QTL (affecting mandible size) exhibited a pattern consistent with true imprinting effects, whereas reciprocal heterozygote differences in the other five all were due to maternal genetic effects. We concluded that genomic imprinting has a negligible effect on these specific morphometric traits, and that maternal genetic effects may account for many of the previously reported instances of apparent genomic imprinting.
Publisher: MDPI AG
Date: 11-02-2015
DOI: 10.3390/SYM7010146
Publisher: Oxford University Press (OUP)
Date: 13-02-2023
Abstract: Biological variation is often considered in a scalable hierarchy, e.g., within the in idual, within the populations, above the species level. Morphological integration, the concept of covariation among constituent parts of an organism, is also hierarchical the degree to which these “modules” covary is a matter of the scale of the study as well as underlying processes driving the covariation. Multilevel analyses of trait covariation are a valuable tool to infer the origins and historical persistence of morphological ersity. Here, we investigate concordance in patterns of integration and modularity across three biological levels of variation: within a species, within two genera-level radiations, and among species at the family level. We demonstrate this approach using the skull of mammalian family Leporidae (rabbits and hares), which is morphologically erse and has a rare-among-mammals functional signal of locomotion adaptation. We tested three alternative hypotheses of modularity from the most supported we investigated disparity and integration of each module to infer which is most responsible for patterns of cranial variation across these levels, and whether variation is partitioned consistently across levels. We found a common pattern of modularity underlies leporid cranial ersity, though there is inconsistency across levels in each module’s disparity and integration. The face module contributes the most to disparity at all levels, which we propose is facilitating evolutionary ersity in this clade. Therefore, the distinctive facial tilt of leporids is an adaptation to locomotory behavior facilitated by a modular system that allows lineages to respond differently to selection pressures.
Publisher: Springer Science and Business Media LLC
Date: 10-01-2023
Publisher: Springer Science and Business Media LLC
Date: 20-06-2014
Publisher: The Royal Society
Date: 10-2017
DOI: 10.1098/RSOS.170058
Abstract: Anoli s lizards are a model system for the study of adaptive radiation and convergent evolution. Greater Antillean anoles have repeatedly evolved six similar forms or ecomorphs: crown-giant, grass-bush, twig, trunk, trunk-crown and trunk-ground. Members of each ecomorph category possess a specific set of morphological, ecological and behavioural characteristics which have been acquired convergently. Here we test whether the semicircular canal system—the organ of balance during movement—is also convergent among ecomorphs, reflecting the shared sensory requirements of their ecological niches. As semicircular canal shape has been shown to reflect different locomotor strategies, we hypothesized that each Anolis ecomorph would have a unique canal morphology. Using three-dimensional semilandmarks and geometric morphometrics, semicircular canal shape was characterized in 41 Anolis species from the Greater Antilles and the relationship between canal shape and ecomorph grouping, phylogenetic history, size, head dimensions, and perch characteristics was assessed. Further, canal morphology of modern species was used to predict the ecomorph affinity of five fossil anoles from the Miocene of the Dominican Republic. Of the covariates tested, our study recovered ecomorph as the single-most important covariate of canal morphology in modern taxa although phylogenetic history, size, and head dimensions also showed a small, yet significant correlation with shape. Surprisingly, perch characteristics were not found to be significant covariates of canal shape, even though they are important habitat variables. Using posterior probabilities, we found that the fossil anoles have different semicircular canals shapes to modern ecomorph groupings implying extinct anoles may have been interacting with their Miocene environment in different ways to modern Anolis species.
Publisher: Springer Science and Business Media LLC
Date: 10-11-2022
DOI: 10.1007/S11692-022-09584-Y
Abstract: Highly cursorial animals are specialised for fast, sustained running via specific morphological adaptations, notably including changes in limb segment length and mechanical advantage. Members of the order Lagomorpha (hares, rabbits and pikas) vary in cursorial ability hares are generally highly cursorial, rabbits more frequently saltate, and pikas predominantly trot. Previous investigations of lagomorphs have identified anatomical trends correlated with this ‘cursoriality gradient’, however, the phylogenetic s ling of such investigations has been limited to three American species, namely the American pika ( Ochotona princeps ), brush rabbit ( Sylvilagus bachmani ), and black-tailed jackrabbit ( Lepus californicus ). Here, we expand the phylogenetic s le and body size range by including novel data from Australian s les of the European rabbit ( Oryctolagus cuniculus ) and European hare ( L. europaeus ), alongside unpublished data on the Eastern cottontail ( S. floridanus ). X-ray Computed Tomography and digital landmarking were used to capture proportions within the appendicular skeleton of ~ 40 specimens of each European species. In doubling the number of species studied, we find the previously-identified morphological gradients associated with cursorial behaviour are complicated when evaluated in the larger s le. The relative length and joint velocity of limbs was found to be lower than predicted in European rabbits and hares. Furthermore, we present a novel assessment of morphological integration in the lagomorph appendicular skeleton, finding between-limb covariation patterns that are generally similar to those of other mammals. Broadly, these results suggest cursoriality is only one of many selective forces driving lagomorph skeletal evolution, with variations in body size and fossoriality potentially having measurable impacts.
Publisher: Proceedings of the National Academy of Sciences
Date: 27-07-2015
Abstract: An unresolved question in ecology is whether the structure of ecological communities can be stable over very long timescales. Here we describe a wealth of new amber fossils for an ancient radiation of Hispaniolan lizards that, until now, has had a very poor fossil record. These fossils provide an important and previously unavailable perspective on an ecologically well-studied group and indicate that anole lizard communities occurring on Hispaniola 20 Mya were made up of the same types of habitat specialists present in this group today. These data indicate that the ecological processes important in extant anole communities have been operative over long periods of time.
Publisher: PeerJ
Date: 17-03-2015
DOI: 10.7717/PEERJ.844
Publisher: Wiley
Date: 22-10-2019
DOI: 10.1002/JMOR.21074
Abstract: The close association between muscle and bone is broadly intuitive however, details of the covariation between the two has not been comprehensively studied. Without quantitative understanding of how muscle anatomy influences bone shape, it is difficult to draw conclusions of the significance of many morphological traits of the skeleton. In this study, we investigated these relationships in the Quenda (Isoodon fusciventer), a scratch-digging marsupial. We quantified the relationships between forelimb muscle anatomy and bone shape for animals representing a range of body masses (124-1,952 g) using two-block partial least square analyses. Muscle anatomy was quantified as muscle mass and physiological cross-sectional area (PCSA), and we used two morphometric methods to characterize bone shape: seven indices of linear bone proportions, and landmarks analysis. Bone shape was significantly correlated with body mass, reflecting allometric bone growth. Of the seven bone indices, only shoulder moment index (SMI) and ulna robustness index (URI) showed a significant covariation with muscle anatomy. Stronger relationships between muscle anatomy and forelimb bone shape were found using the landmark coordinates: muscle mass and PCSA were correlated with the geometric shape of the scapula, humerus, and third metacarpal, but to a lesser extent with shape of the ulna. Overall, our data show that landmark coordinates are more sensitive than bone indices to capturing shape changes evident throughout ontogeny, and is therefore a more appropriate method to investigate covariation with forelimb muscle anatomy. Single-species studies investigating ontogeny require refined methods to accurately develop understanding of the important relationships between muscle force generation and bone shape remodeling. Landmark analyses provide such a method.
Publisher: Springer Science and Business Media LLC
Date: 09-10-2023
Publisher: The Royal Society
Date: 20-06-2018
Abstract: Increasing body size is accompanied by facial elongation across a number of mammalian taxa. This trend forms the basis of a proposed evolutionary rule, cranial evolutionary allometry (CREA). However, facial length has also been widely associated with the varying mechanical resistance of foods. Here, we combine geometric morphometrics and computational biomechanical analyses to determine whether evolutionary allometry or feeding ecology have been dominant influences on facial elongation across 16 species of kangaroos and relatives (Macropodiformes). We found no support for an allometric trend. Nor was craniofacial morphology strictly defined by dietary categories, but rather associated with a combination of the mechanical properties of vegetation types and cropping behaviours used to access them. Among species examined here, shorter muzzles coincided with known diets of tough, resistant plant tissues, accessed via active slicing by the anterior dentition. This morphology consistently resulted in increased mechanical efficiency and decreased bone deformation during incisor biting. Longer muzzles, by contrast, aligned with softer foods or feeding behaviours invoking cervical musculature that circumvent the need for hard biting. These findings point to a potential for craniofacial morphology to predict feeding ecology in macropodiforms, which may be useful for species management planning and for inferring palaeoecology.
Publisher: Wiley
Date: 26-03-2019
DOI: 10.1111/EVO.13722
Abstract: Grass leaf shape is a strong indicator of their habitat with linear leaves predominating in open areas and ovate leaves distinguishing forest-associated grasses. This pattern among extant species suggests that ancestral shifts between forest and open habitats may have coincided with changes in leaf shape or size. We tested relationships between habitat, climate, photosynthetic pathway, and leaf shape and size in a phylogenetic framework to evaluate drivers of leaf shape and size variation over the evolutionary history of the family. We also estimated the ancestral habitat of Poaceae and tested whether forest margins served as transitional zones for shifts between forests and grasslands. We found that grass leaf shape is converging toward different shape optima in the forest understory, forest margins, and open habitats. Leaf size also varies with habitat. Grasses have smaller leaves in open and drier areas, and in areas with high solar irradiance. Direct transitions between linear and ovate leaves are rare as are direct shifts between forest and open habitats. The most likely ancestral habitat of the family was the forest understory and forest margins along with an intermediate leaf shape served as important transitional habitat and morphology, respectively, for subsequent shifts across forest-grassland biome boundaries.
Publisher: Wiley
Date: 27-07-2016
DOI: 10.1111/EVO.12995
Abstract: Directional evolution is one of the most compelling evolutionary patterns observed in macroevolution. Yet, despite its importance, detecting such trends in multivariate data remains a challenge. In this study, we evaluate multivariate evolution of shell shape in 93 bivalved scallop species, combining geometric morphometrics and phylogenetic comparative methods. Phylomorphospace visualization described the history of morphological ersification in the group revealing that taxa with a recessing life habit were the most distinctive in shell shape, and appeared to display a directional trend. To evaluate this hypothesis empirically, we extended existing methods by characterizing the mean directional evolution in phylomorphospace for recessing scallops. We then compared this pattern to what was expected under several alternative evolutionary scenarios using phylogenetic simulations. The observed pattern did not fall within the distribution obtained under multivariate Brownian motion, enabling us to reject this evolutionary scenario. By contrast, the observed pattern was more similar to, and fell within, the distribution obtained from simulations using Brownian motion combined with a directional trend. Thus, the observed data are consistent with a pattern of directional evolution for this lineage of recessing scallops. We discuss this putative directional evolutionary trend in terms of its potential adaptive role in exploiting novel habitats.
Publisher: Springer Science and Business Media LLC
Date: 12-2017
Publisher: The Royal Society
Date: 07-2020
Abstract: Analyses of morphological disparity have been used to characterize and investigate the evolution of variation in the anatomy, function and ecology of organisms since the 1980s. While a ersity of methods have been employed, it is unclear whether they provide equivalent insights. Here, we review the most commonly used approaches for characterizing and analysing morphological disparity, all of which have associated limitations that, if ignored, can lead to misinterpretation. We propose best practice guidelines for disparity analyses, while noting that there can be no ‘one-size-fits-all’ approach. The available tools should always be used in the context of a specific biological question that will determine data and method selection at every stage of the analysis.
Publisher: Figshare
Date: 2018
Publisher: Frontiers Media SA
Date: 07-2021
Abstract: Due to their global distribution, invasive history, and unique characteristics, European rabbits are recognizable almost anywhere on our planet. Although they are members of a much larger group of living and extinct mammals [Mammalia, Lagomorpha (rabbits, hares, and pikas)], the group is often characterized by several well-known genera (e.g., Oryctolagus , Sylvilagus , Lepus , and Ochotona ). This representation does not capture the extraordinary ersity of behavior and form found throughout the order. Model organisms are commonly used as exemplars for biological research, but there are a limited number of model clades or lineages that have been used to study evolutionary morphology in a more explicitly comparative way. We present this review paper to show that lagomorphs are a strong system in which to study macro- and micro-scale patterns of morphological change within a clade that offers underappreciated levels of ersity. To this end, we offer a summary of the status of relevant aspects of lagomorph biology.
Publisher: Springer Science and Business Media LLC
Date: 27-04-2021
DOI: 10.1186/S12862-021-01808-7
Abstract: New Zealand’s diplodactylid geckos exhibit high species-level ersity, largely independent of discernible osteological changes. Consequently, systematic affinities of isolated skeletal elements (fossils) are primarily determined by comparisons of size, particularly in the identification of Hoplodactylus duvaucelii , New Zealand’s largest extant gecko species. Here, three-dimensional geometric morphometrics of maxillae (a common fossilized element) was used to determine whether consistent shape and size differences exist between genera, and if cryptic extinctions have occurred in subfossil ‘Hoplodactylus cf. duvaucelii’ . S ling included 13 diplodactylid species from five genera, and 11 Holocene subfossil ‘ H. cf. duvaucelii ’ in iduals. We found phylogenetic history was the most important predictor of maxilla morphology among extant diplodactylid genera. Size comparisons could only differentiate Hoplodactylus from other genera, with the remaining genera exhibiting variable degrees of overlap. Six subfossils were positively identified as H. duvaucelii , confirming their proposed Holocene distribution throughout New Zealand. Conversely, five subfossils showed no clear affinities with any modern diplodactylid genera, implying either increased morphological ersity in mainland ‘ H. cf. duvaucelii ’ or the presence of at least one extinct, large, broad-toed diplodactylid species.
Publisher: Oxford University Press (OUP)
Date: 19-10-2023
Publisher: Wiley
Date: 22-02-2017
DOI: 10.1111/EDE.12220
Abstract: Marsupials display far less forelimb ersity than placentals, possibly because of the laborious forelimb-powered climb to the pouch performed by most marsupial neonates. This is thought to result in stronger morphological integration (i.e., higher co-variance) within the marsupial forelimb skeleton, and lower integration between marsupial fore- and hind limbs, compared to other mammals. Possible mechanisms for this constraint are a fundamental developmental change in marsupial limb patterning, or alternatively more immediate perinatal biomechanical and metabolic requirements. In the latter case, peramelid marsupials (bandicoots), which have neonates that climb very little, should show lower within-limb and higher between-limb integration, compared to other marsupials. We tested this in four peramelid species and the related bilby, using partial correlation analyses of between-landmark linear measurements of limb bones, and Procrustes-based two-block partial least-squares analysis (2B-PLS) of limb bone shapes using the same landmarks. We find extensive between-limb integration in partial correlation analyses of only bone lengths, consistent with a reduction of a short-term biomechanical/allocation constraint in peramelid forelimbs. However, partial correlations of bone proportions and 2B-PLS reveal extensive shape ergence between correlated bone pairs. This result contradicts expectations of developmental constraints or serial homology, instead suggesting a function-driven integration pattern. Comparing visualizations from cross-species principal components analysis and 2B-PLS, we tentatively identify selection for digging and half-bounding as the main driver of bandicoot limb integration patterning. This calls for further assessments of functional versus developmental limb integration in marsupials with a more strenuous neonatal climb to the pouch.
Publisher: The Royal Society
Date: 12-2022
DOI: 10.1098/RSOS.221087
Abstract: Sea snakes in the Hydrophis-Microcephalophis clade (Elapidae) show exceptional body shape variation along a continuum from similar forebody and hindbody girths, to dramatically reduced girths of the forebody relative to hindbody. The latter is associated with specializations on burrowing prey. This variation underpins high sympatric ersity and species richness and is not shared by other marine (or terrestrial) snakes. Here, we examined a hypothesis that macroevolutionary changes in axial development contribute to the propensity, at clade level, for body shape change. We quantified variation in the number and size of vertebrae in two body regions (pre- and post-apex of the heart) for approximately 94 terrestrial and marine elapids. We found Hydrophis-Microcephalophis exhibit increased rates of vertebral evolution in the pre- versus post-apex regions compared to all other Australasian elapids. Unlike other marine and terrestrial elapids, axial elongation in Hydrophis-Microcephalophis occurs via the preferential addition of vertebrae pre-heart apex, which is the region that undergoes concomitant shifts in vertebral number and size during transitions along the relative fore- to hindbody girth axis. We suggest that this macroevolutionary developmental change has potentially acted as a key innovation in Hydrophis-Microcephalophis by facilitating novel (especially burrowing) prey specializations that are not shared with other marine snakes.
Publisher: Springer Science and Business Media LLC
Date: 14-11-2018
Publisher: Magnolia Press
Date: 02-04-2014
DOI: 10.11646/ZOOTAXA.3785.1.4
Abstract: A new species of striped ichthyophiid caecilian, Ichthyophis multicolor sp. nov., is described on the basis of morphological and molecular data from a s le of 14 specimens from Ayeyarwady Region, Myanmar. The new species resembles superficially the Indian I. tricolor Annandale, 1909 in having both a pale lateral stripe and an adjacent dark ventrolateral stripe contrasting with a paler venter. It differs from I. tricolor in having many more annuli, and in many details of cranial osteology, and molecular data indicate that it is more closely related to other Southeast Asian Ichthyophis than to those of South Asia. The caecilian fauna of Myanmar is exceptionally poorly known but is likely to include chikilids as well as multiple species of Ichthyophis.
Publisher: Springer Science and Business Media LLC
Date: 14-08-2017
DOI: 10.1038/S41559-017-0268-6
Abstract: Developmental changes through an animal's life are generally understood to contribute to the resulting adult morphology. Possible exceptions are species with complex life cycles, where in iduals pass through distinct ecological and morphological life stages during their ontogeny, ending with metamorphosis to the adult form. Antagonistic selection is expected to drive low genetic correlations between life stages, theoretically permitting stages to evolve independently. Here we describe, using Australian frog radiation, the evolutionary consequences on morphological evolution when life stages are under different selective pressures. We use morphometrics to characterize body shape of tadpoles and adults across 166 species of frog and investigate similarities in the two resulting morphological spaces (morphospaces) to test for concerted evolution across metamorphosis in trait variation during speciation. A clear pattern emerges: Australian frogs and their tadpoles are evolving independently their markedly different morphospaces and contrasting estimated evolutionary histories of body shape ersification indicate that different processes are driving morphological ersification at each stage. Tadpole morphospace is characterized by r ant homoplasy, convergent evolution and high lineage density. By contrast, the adult morphospace shows greater phylogenetic signal, low lineage density and ergent evolution between the main clades. Our results provide insight into the macroevolutionary consequences of a biphasic life cycle.
Publisher: Wiley
Date: 15-04-2020
DOI: 10.1002/ECE3.6228
Publisher: Springer Science and Business Media LLC
Date: 22-01-2019
Publisher: Springer Science and Business Media LLC
Date: 23-09-2023
Publisher: University of Chicago Press
Date: 12-2020
DOI: 10.1086/711398
Publisher: Wiley
Date: 14-10-2019
DOI: 10.1111/EVO.13851
Abstract: A defining character of adaptive radiations is the evolution of a ersity of morphological forms that are associated with the use of different habitats, following the invasion of vacant niches. Island adaptive radiations have been thoroughly investigated but continental scale radiations are more poorly understood. Here, we use 52 species of Australian agamid lizards and their Asian relatives as a model group, and employ three-dimensional geometric morphometrics to characterize cranial morphology and investigate whether variation in cranial shape reflects patterns expected from the ecological process of adaptive radiation. Phylogenetic affinity, evolutionary allometry, and ecological life habit all play major roles in the evolution of cranial shape in the s led lizards. We find a significant association between cranial shapes and life habit. Our results are in line with the expectations of an adaptive radiation, and this is the first time detailed geometric morphometric analyses have been used to understand the selective forces that drove an adaptive radiation at a continental scale.
Publisher: Springer Science and Business Media LLC
Date: 12-07-2007
Publisher: Springer Science and Business Media LLC
Date: 26-04-2019
Publisher: Wiley
Date: 07-08-2022
DOI: 10.1002/JEZ.B.23171
Abstract: Domestication leads to phenotypic characteristics that have been described to be similar across species. However, this “domestication syndrome” has been subject to debate, related to a lack of evidence for certain characteristics in many species. Here we review erse literature and provide new data on cranial shape changes due to domestication in the European rabbit ( Oryctolagus cuniculus ) as a preliminary case study, thus contributing novel evidence to the debate. We quantified cranial shape of 30 wild and domestic rabbits using micro‐computed tomography scans and three‐dimensional geometric morphometrics. The goal was to test (1) if the domesticates exhibit shorter and broader snouts, smaller teeth, and smaller braincases than their wild counterparts (2) to what extent allometric scaling is responsible for cranial shape variation (3) if there is evidence for more variation in the neural crest‐derived parts of the cranium compared with those derived of the mesoderm, in accordance with the “neural crest hypothesis.” Our own data are consistent with older literature records, suggesting that although there is evidence for some cranial characteristics of the “domestication syndrome” in rabbits, facial length is not reduced. In accordance with the “neural crest hypothesis,” we found more shape variation in neural crest versus mesoderm‐derived parts of the cranium. Within the domestic group, allometric scaling relationships of the snout, the braincase, and the teeth shed new light on ubiquitous patterns among related taxa. This study—albeit preliminary due to the limited s le size—adds to the growing evidence concerning nonuniform patterns associated with domestication.
Publisher: PeerJ
Date: 27-06-2018
DOI: 10.7717/PEERJ.5052
Abstract: This paper proposes a new methodology to quantify patterns of egg shape variation using geometric morphometrics of three-dimensional landmarks captured on digitally reconstructed eggshells and demonstrates its performance in capturing shape variation at multiple biological levels. This methodology offers unique benefits to complement established linear measurement or two-dimensional (2D) contour profiling techniques by (i) providing a more precise representation of eggshell curvature by accounting for variation across the entire surface of the egg (ii) avoids the occurrence of correlations from combining multiple egg shape features (iii) avoids error stemming from projecting a highly-curved three-dimensional (3D) object into 2D space and (iv) enables integration into 3D workflows such as finite elements analysis. To demonstrate, we quantify patterns of egg shape variation and estimate morphological disparity at multiple biological levels, within and between clutches and among species of four passerine species of different lineages, using volumetric dataset obtained from micro computed tomography. The results indicate that species broadly have differently shaped eggs, but with extensive within-species variation so that all four-focal species occupy a range of shapes. Within-species variation is attributed to between-clutch differences in egg shape within-clutch variation is surprisingly substantial. Recent comparative analyses that aim to explain shape variation among avian taxa have largely ignored potential biases due to within-species variation, or use methods limited to a narrow range of egg shapes. Through our approach, we suggest that there is appreciable variation in egg shape across clutches and that this variation needs to be accounted for in future research. The approach developed in this study to assess variation in shape is freely accessible and can be applied to any spherical-to-conical shaped object, including eggs of non-avian dinosaurs and reptiles through to other extant taxa such as poultry.
Publisher: Springer Science and Business Media LLC
Date: 16-09-2019
DOI: 10.1007/S11307-019-01429-Z
Abstract: Purpose: To establish multi-modal imaging for the assessment of kidney pH, perfusion, and clearance rate using magnetic resonance imaging (MRI) and multispectral optoacoustic tomography (MSOT) in healthy mice. Kidney pH and perfusion values were measured on a pixel-by-pixel basis using the MRI acidoCEST and FAIR-EPI methods. Kidney filtration rate was measured by analyzing the renal clearance rate of IRdye 800 using MSOT. To test the effect of one imaging method on the other, a set of 3 animals were imaged with MSOT followed by MRI, and a second set of 3 animals were imaged with MRI followed by MSOT. In a subsequent study, the reproducibility of pH, perfusion, and renal clearance measurements were tested by imaging 4 animals twice, separated by 4 days. The contrast agents used for acidoCEST based pH measurements influenced the results of MSOT. Specifically, the exponential decay time from the kidney cortex, as measured by MSOT, was significantly altered when MRI was performed prior to MSOT. However, no significant difference in the cortex to pelvis area under the curve (AUC) was noted. When the order of experiments was reversed, no significant differences were noted in the pH or perfusion values. Reproducibility measurements demonstrated similar pH and cortex to pelvis AUC however, perfusion values were significantly different with the cortex values being higher and the pelvic values being lower in the second imaging time. We demonstrate that using a combination of MRI and MSOT, physiological measurements of pH, blood flow, and clearance rates can be measured in the mouse kidney in the same imaging session.
Publisher: Portland Press Ltd.
Date: 26-07-2010
DOI: 10.1042/BST0381062
Abstract: In the future, stem-cell-based therapies could offer new approaches to treat kidney disease and reduce the incidence of ESRD (end-stage renal disease), but, as yet, research in this area is only being conducted in rodents and it is not clear whether or when it could be applied to human patients. Drug therapies, on the other hand, have been very effective at delaying the progression of kidney disease, but, for various reasons, current drug regimes are not suitable for all patients. A greater understanding of the molecular mechanisms that underlie disease progression in chronic kidney disease could help to identify novel drug targets. However, progress in this area is currently hindered due to the lack of appropriate in vitro culture systems for important renal cell types, such as proximal tubule cells and podocytes. This problem could be overcome if it were possible to direct the differentiation of kidney stem cells to renal cell types in vitro. In the present review, we highlight the potential of surface gradients of small chemical functional groups to direct the differentiation of kidney stem cells.
Publisher: CSIRO Publishing
Date: 04-03-2022
DOI: 10.1071/AM21047
Abstract: Within-species morphological variation is often observed across spatial and climatic gradients. Understanding this variation is important to conservation planning, as specialised adaptations may influence a population’s persistence following translocation. However, knowing whether local adaptations are prevalent within a species can be challenging when the species has undergone range contractions. Here, we used museum specimens to study size and shape variation of the greater stick-nest rat (Leporillus conditor). We aimed to determine whether intraspecific size and shape variation previously existed within the species across its historical range, and inform on possible implications for translocations of the remaining extant population. We found significantly larger skull size in the Franklin Islands and arid populations, possibly indicating a historically continuous population experiencing similar selection pressures such as high predation pressure, competition with other large arid zone rodents or climatic extremes. Conversely, skull shape variation within the species adheres to an allometric trajectory, indicating no specific local adaptations of skull shape. This absence of local skull shape adaptation suggests that the Franklin Islands population is likely suitable for mainland translocations. However, further research into the historical phylogeography of the species is recommended to identify whether large size resulted from shared ancestry or convergent evolution.
Publisher: Springer Science and Business Media LLC
Date: 10-10-2016
Publisher: Cold Spring Harbor Laboratory
Date: 07-12-2020
DOI: 10.1101/2020.12.06.410928
Abstract: Little is known about how the large brains of mammals are accommodated into the dazzling ersity of their skulls. It has been suggested that brain shape is influenced by relative brain size, that it evolves or develops according to extrinsic or intrinsic mechanical constraints, and that its shape can provide insights into its proportions and function. Here, we characterise the shape variation among 84 marsupial cranial endocasts of 57 species including fossils, using 3D geometric morphometrics and virtual dissections. Statistical shape analysis revealed four main patterns: over half of endocast shape variation ranges between elongate and straight to globular and inclined little allometric variation with respect to centroid size, and none for relative volume no association between locomotion and endocast shape limited association between endocast shape and previously published histological cortex volumes. Fossil species tend to have smaller cerebral hemispheres. We find ergent endocast shapes in closely related species and within species, and erse morphologies superimposed over the main variation. An evolutionarily and in idually malleable brain with a fundamental tendency to arrange into a spectrum of elongate-to-globular shapes – possibly mostly independent of brain function - may explain the accommodation of brains within the enormous ersity of mammalian skull form.
Publisher: Wiley
Date: 03-10-2017
DOI: 10.1111/JEB.13176
Abstract: Parasitic cuckoos lay their eggs in nests of host species. Rejection of cuckoo eggs by hosts has led to the evolution of egg mimicry by cuckoos, whereby their eggs mimic the colour and pattern of their host eggs to avoid egg recognition and rejection. There is also evidence of mimicry in egg size in some cuckoo-host systems, but currently it is unknown whether cuckoos can also mimic the egg shape of their hosts. In this study, we test whether there is evidence of mimicry in egg form (shape and size) in three species of Australian cuckoos: the fan-tailed cuckoo Cacomantis flabelliformis, which exploits dome nesting hosts, the brush cuckoo Cacomantis variolosus, which exploits both dome and cup nesting hosts, and the pallid cuckoo Cuculus pallidus, which exploits cup nesting hosts. We found evidence of size mimicry and, for the first time, evidence of egg shape mimicry in two Australian cuckoo species (pallid cuckoo and brush cuckoo). Moreover, cuckoo-host egg similarity was higher for hosts with open nests than for hosts with closed nests. This finding fits well with theory, as it has been suggested that hosts with closed nests have more difficulty recognizing parasitic eggs than open nests, have lower rejection rates and thus exert lower selection for mimicry in cuckoos. This is the first evidence of mimicry in egg shape in a cuckoo-host system, suggesting that mimicry at different levels (size, shape, colour pattern) is evolving in concert. We also confirm the existence of egg size mimicry in cuckoo-host systems.
Publisher: Figshare
Date: 2018
Publisher: Figshare
Date: 2018
Publisher: Springer Science and Business Media LLC
Date: 08-01-2019
Publisher: Wiley
Date: 24-11-2017
DOI: 10.1111/EVO.13382
Abstract: Ontogenetic allometry, how species change with size through their lives, and heterochony, a decoupling between shape, size, and age, are major contributors to biological ersity. However, macroevolutionary allometric and heterochronic trends remain poorly understood because previous studies have focused on small groups of closely related species. Here, we focus on testing hypotheses about the evolution of allometry and how allometry and heterochrony drive morphological ersification at the level of an entire species-rich and erse clade. Pythons are a useful system due to their remarkably erse and well-adapted phenotypes and extreme size disparity. We collected detailed phenotype data on 40 of the 44 species of python from 1191 specimens. We used a suite of analyses to test for shifts in allometric trajectories that modify morphological ersity. Heterochrony is the main driver of initial ergence within python clades, and shifts in the slopes of allometric trajectories make exploration of novel phenotypes possible later in ergence history. We found that allometric coefficients are highly evolvable and there is an association between ontogenetic allometry and ecology, suggesting that allometry is both labile and adaptive rather than a constraint on possible phenotypes.
Publisher: Springer Science and Business Media LLC
Date: 14-03-2022
DOI: 10.1007/S10682-022-10164-X
Abstract: As snakes are limbless, gape-limited predators, their skull is the main feeding structure involved in prey handling, manipulation and feeding. Ontogenetic changes in prey type and size are likely to be associated with distinct morphological changes in the skull during growth. We investigated ontogenetic variation in diet from stomach contents of 161 Dugite specimens ( Pseudonaja affinis , Elapidae) representing the full range of body size for the species, and skull morphology of 46 specimens (range 0.25–1.64 m snout-vent-length SVL). We hypothesised that changes in prey type throughout postnatal ontogeny would coincide with distinct changes in skull shape. Dugites demonstrate a distinct size-related shift in diet: the smallest in iduals ate autotomised reptile tails and reptiles, medium-sized in iduals predominantly ate mammals, and the largest in iduals had the most erse diet, including large reptiles. Morphometric analysis revealed that ~40% of the variation in skull shape was associated with body size (SVL). Through ontogeny, skulls changed from a smooth, bulbous cranium with relatively small trophic bones (upper and lower jaws and their attachments), to more rugose bones (as a likely reflection of muscle attachment) and relatively longer trophic bones that would extend gape. In idual shape variation in trophic bone dimensions was greater in larger adults and this likely reflects natural plasticity of in iduals feeding on different prey sizes/types. Rather than a distinct morphological shift with diet, the ontogenetic changes were gradual, but positive allometry of in idual trophic bones resulted in disproportionate growth of the skull, reflected in increased gape size and mobility of jaw bones in adults to aid the ingestion of larger prey and improve manipulation and processing ability. These results indicate that allometric scaling is an important mechanism by which snakes can change their dietary niche.
Publisher: Springer Science and Business Media LLC
Date: 05-03-2022
DOI: 10.1007/S10682-022-10162-Z
Abstract: Despite only comprising seven species, extant sea turtles (Cheloniidae and Dermochelyidae) display great ecological ersity, with most species inhabiting a unique dietary niche as adults. This adult ersity is remarkable given that all species share the same dietary niche as juveniles. These ontogenetic shifts in diet, as well as a dramatic increase in body size, make sea turtles an excellent group to examine how morphological ersity arises by allometric processes and life habit specialisation. Using three-dimensional geometric morphometrics, we characterise ontogenetic allometry in the skulls of all seven species and evaluate variation in the context of phylogenetic history and diet. Among the s le, the olive ridley ( Lepidochelys olivacea ) has a seemingly average sea turtle skull shape and generalised diet, whereas the green ( Chelonia mydas ) and hawksbill ( Eretmochelys imbricata ) show different extremes of snout shape associated with their modes of food gathering (grazing vs. grasping, respectively). Our ontogenetic findings corroborate previous suggestions that the skull of the leatherback ( Dermochelys coriacea ) is paedomorphic, having similar skull proportions to hatchlings of other sea turtle species and retaining a hatchling-like diet of relatively soft bodied organisms. The flatback sea turtle ( Natator depressus ) shows a similar but less extreme pattern. By contrast, the loggerhead sea turtle ( Caretta caretta ) shows a peramorphic signal associated with increased jaw muscle volumes that allow predation on hard shelled prey. The Kemp’s ridley ( Lepidochelys kempii ) has a peramorphic skull shape compared to its sister species the olive ridley, and a diet that includes harder prey items such as crabs. We suggest that diet may be a significant factor in driving skull shape differences among species. Although the small number of species limits statistical power, differences among skull shape, size, and diet are consistent with the hypothesis that shifts in allometric trajectory facilitated ersification in skull shape as observed in an increasing number of vertebrate groups.
Publisher: Wiley
Date: 26-11-2018
DOI: 10.1002/ECE3.4733
Publisher: PeerJ
Date: 22-09-2016
DOI: 10.7717/PEERJ.2453
Abstract: The skull of leporids (rabbits and hares) is highly transformed, typified by pronounced arching of the dorsal skull and ventral flexion of the facial region (i.e., facial tilt). Previous studies show that locomotor behavior influences aspects of cranial shape in leporids, and here we use an extensive 3D geometric morphometrics dataset to further explore what influences leporid cranial ersity. Facial tilt angle, a trait that strongly correlates with locomotor mode, significantly predicts the cranial shape variation captured by the primary axis of cranial shape space, and describes a small proportion (13.2%) of overall cranial shape variation in the clade. However, locomotor mode does not correlate with overall cranial shape variation in the clade, because there are two district morphologies of generalist species, and saltators and cursorial species have similar morphologies. Cranial shape changes due to phyletic size change (evolutionary allometry) also describes a small proportion (12.5%) of cranial shape variation in the clade, but this is largely driven by the smallest living leporid, the pygmy rabbit ( Brachylagus idahoensis ). By integrating phylogenetic history with our geometric morphometric data, we show that the leporid cranium exhibits weak phylogenetic signal and substantial homoplasy. Though these results make it difficult to reconstruct what the ‘ancestral’ leporid skull looked like, the fossil records suggest that dorsal arching and facial tilt could have occurred before the origin of the crown group. Lastly, our study highlights the ersity of cranial variation in crown leporids, and highlights a need for additional phylogenetic work that includes stem (fossil) leporids and includes morphological data that captures the transformed morphology of rabbits and hares.
Publisher: Wiley
Date: 26-07-2017
DOI: 10.1111/JEB.13137
Abstract: An important question in evolutionary biology is how often, and to what extent, do similar ecologies elicit distantly related taxa to evolve towards the same phenotype? In some scenarios, the repeated evolution of particular phenotypes may be expected, for instance when species are exposed to common selective forces that result from strong functional demands. In bivalved scallops (Pectinidae), some species exhibit a distinct swimming behaviour (gliding), which requires specific biomechanical attributes to generate lift and reduce drag during locomotive events. Further, a phylogenetic analysis revealed that gliding behaviour has independently evolved at least four times, which raises the question as to whether these independent lineages have also converged on a similar phenotype. Here, we test the hypothesis that gliding scallops display shell shape convergence using a combination of geometric morphometrics and phylogenetic comparative methods that evaluate patterns of multivariate trait evolution. Our findings reveal that the gliding species display less morphological disparity and significant evolutionary convergence in morphospace, relative to expectations under a neutral model of Brownian motion for evolutionary phenotypic change. Intriguingly, the phylomorphospace patterns indicate that gliding lineages follow similar evolutionary trajectories to not one, but two regions of morphological space, and subsequent analyses identified significant differences in their biomechanical parameters, suggesting that these two groups of scallops accomplish gliding in different ways. Thus, whereas there is a clear gliding morphotype that has evolved convergently across the phylogeny, functionally distinct morphological subforms are apparent, suggesting that there may be two optima for the gliding phenotype in the Pectinidae.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United States of America
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2024
End Date: 2027
Funder: Marsden Fund
View Funded ActivityStart Date: 2023
End Date: 2025
Funder: Australia and Pacific Science Foundation
View Funded ActivityStart Date: 2020
End Date: 2023
Funder: Australian Research Council
View Funded ActivityStart Date: 2020
End Date: 2024
Funder: Australian Research Council
View Funded ActivityStart Date: 2020
End Date: 2020
Funder: University of Adelaide
View Funded ActivityStart Date: 04-2020
End Date: 06-2024
Amount: $425,930.00
Funder: Australian Research Council
View Funded ActivityStart Date: 2020
End Date: 05-2024
Amount: $681,697.00
Funder: Australian Research Council
View Funded Activity