ORCID Profile
0000-0002-2608-2150
Current Organisation
UNSW Evolution and Ecology Research Centre
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Marine and Estuarine Ecology (incl. Marine Ichthyology) | Ecology | Behavioural Ecology | Biological Adaptation
Expanding Knowledge in the Biological Sciences | Marine Flora, Fauna and Biodiversity | Flora, Fauna and Biodiversity at Regional or Larger Scales |
Publisher: Elsevier BV
Date: 12-2013
Publisher: Wiley
Date: 24-06-2016
DOI: 10.1111/EVO.12971
Abstract: We know little about on how frequently transitions into new habitats occur, especially the colonization of novel environments that are the most likely to instigate adaptive evolution. One of the most extreme ecological transitions has been the shift in habitat associated with the move from water to land by hibious fish. We provide the first phylogenetic investigation of these transitions for living fish. Thirty-three families have species reported to be hibious and these are likely independent evolutionary origins of fish emerging onto land. Phylogenetic reconstructions of closely related taxa within one of these families, the Blenniidae, inferred as many as seven convergences on a highly hibious lifestyle. Taken together, there appear to be few constraints on fish emerging onto land given hibious behavior has evolved repeatedly many times across ecologically erse families. The colonization of novel habitats by other taxa resulting in less dramatic changes in environment should be equally, if not, more frequent in nature, providing an important prerequisite for subsequent adaptive differentiation.
Publisher: University of Chicago Press
Date: 2011
DOI: 10.1086/657439
Abstract: Animals communicating socially are expected to produce signals that are conspicuous within the habitats in which they live. The particular way in which a species adapts to its environment will depend on its ancestral condition and evolutionary history. At this point, it is unclear how properties of the environment and historical factors interact to shape communication. Tropical Anolis lizards advertise territorial ownership using visual displays in habitats where visual motion or "noise" from windblown vegetation poses an acute problem for the detection of display movements. We studied eight Anolis species that live in similar noise environments but belong to separate island radiations with ergent evolutionary histories. We found that species on Puerto Rico displayed at times when their signals were more likely to be detected by neighboring males and females (during periods of low noise). In contrast, species on Jamaica displayed irrespective of the level of environmental motion, apparently because these species have a display that is effective in a range of viewing conditions. Our findings appear to reflect a case of species originating from different evolutionary starting points evolving different signal strategies for effective communication in noisy environments.
Publisher: Wiley
Date: 03-05-2011
DOI: 10.1111/J.1558-5646.2011.01319.X
Abstract: We tested hypotheses on how animals should respond to heterospecifics encountered in the environment. Hypotheses were formulated from models parameterized to emphasize four factors that are expected to influence species discrimination: mating and territorial interactions sex differences in resource value environments in which heterospecifics were common or rare and the type of identity cues available for species recognition. We also considered the role of phylogeny on contemporary responses to heterospecifics. We tested the extent these factors explained variation among taxa in species discrimination using a meta-analysis of three decades of species recognition research. A surprising outcome was the absence of a general predictor of when species discrimination would most likely occur. Instead, species discrimination is dictated by the benefits and costs of responding to a conspecific or heterospecific that are governed by the specific circumstances of a given species. The phylogeny of species recognition provided another unexpected finding: the evolutionary relationships among species predicted whether courting males within species-but not females-would discriminate against heterospecifcs. This implies that species recognition has evolved quite differently in the sexes. Finally, we identify common pitfalls in experimental design that seem to have affected some studies (e.g., poor statistical power) and provide recommendations for future research.
Publisher: Wiley
Date: 03-08-2012
DOI: 10.1111/J.1420-9101.2012.02582.X
Abstract: The extent that evolution - including adaptation - is historically contingent (dependent on past events) has often been hotly debated, but is still poorly understood. In particular, there are little data on the degree that behaviour, an aspect of the phenotype that is strongly linked to contemporary environments (social or physical), retains the imprint of evolutionary history. In this study, I examined whether differences in the design of the territorial displays among species of Caribbean Anolis lizards reflect island-specific selection regimes, or historically contingent predispositions associated with different clade histories. Adult males advertise territory ownership using a series of headbobs and dewlap extensions, bouts of which vary in duration among species. When display durations were mapped onto the Anolis phylogeny, prominent differences between species belonging to the Western and Eastern Caribbean radiations were apparent. Statistical analyses confirmed that species differences in the duration of headbob displays, and to some extent the duration of dewlap extensions, were historically contingent. The unique evolutionary histories of each clade have seemingly had a profound effect on the subsequent direction of display evolution among descendent taxa. These results combined with those from previous studies on these lizards show that past history can have an important impact on the type of behaviour exhibited by species today, to the point that adaptive evolution can proceed quite differently in lineages originating from different evolutionary starting points.
Publisher: The Royal Society
Date: 09-06-2021
Abstract: Social animals are expected to face a trade-off between producing a signal that is detectible by mates and rivals, but not obvious to predators. This trade-off is fundamental for understanding the design of many animal signals, and is often the lens through which the evolution of alternative communication strategies is viewed. We have a reasonable working knowledge of how conspecifics detect signals under different conditions, but how predators exploit conspicuous communication of prey is complex and hard to predict. We quantified predation on 1566 robotic lizard prey that performed a conspicuous visual display, possessed a conspicuous ornament or remained cryptic. Attacks by free-ranging predators were consistent across two contrasting ecosystems and showed robotic prey that performed a conspicuous display were equally likely to be attacked as those that remained cryptic. Furthermore, predators avoided attacking robotic prey with a fixed, highly visible ornament that was novel at both locations. These data show that it is prey familiarity—not conspicuousness—that determine predation risk. These findings replicated across different predator–prey communities not only reveal how conspicuous signals might evolve in high predation environments, but could help resolve the paradox of aposematism and why some exotic species avoid predation when invading new areas.
Publisher: Wiley
Date: 30-06-2021
DOI: 10.1111/ELE.13773
Abstract: Convergence in communication appears rare compared with other forms of adaptation. This is puzzling, given communication is acutely dependent on the environment and expected to converge in form when animals communicate in similar habitats. We uncover deep‐time convergence in territorial communication between two groups of tropical lizards separated by over 140 million years of evolution: the Southeast Asian Draco and Caribbean Anolis . These groups have repeatedly converged in multiple aspects of display along common environmental gradients. Robot playbacks to free‐ranging lizards confirmed that the most prominent convergence in display is adaptive, as it improves signal detection. We then provide evidence from a s le of the literature to further show that convergent adaptation among highly ergent animal groups is almost certainly widespread in nature. Signal evolution is therefore curbed towards the same set of adaptive solutions, especially when animals are challenged with the problem of communicating effectively in noisy environments.
Publisher: Elsevier BV
Date: 08-2012
Publisher: Wiley
Date: 16-06-2020
Publisher: Cold Spring Harbor Laboratory
Date: 21-12-2018
DOI: 10.1101/503516
Abstract: Evolutionary adaptations to life on land include changes to the physiology, morphology and behaviour of an animal in response to physical differences between water and air. The visual systems of hibious species show pronounced morphological adaptations yet, whether molecular changes also occur remains largely unknown. Here, we investigated the molecular evolution of visual pigment genes (opsins) in hibious and terrestrial fishes belonging to the Salariini ision of blennies (Blenniidae). We hypothesized that when conquering land, blenny opsins adapt, in terms of sequence variation and/or gene expression, to match both higher light intensities as well as the broader light spectrum. Using retinal transcriptomes in six species ranging from fully aquatic to fully terrestrial, we found very little variation in opsin gene sequences or gene expression between species. All blennies expressed a single rod opsin gene as well as two cone opsin genes sensitive to longer-wavelengths of light: RH2A-1 (green-sensitive) and LWS (red-sensitive). They also expressed one or two short-wavelength-sensitive cone opsin genes (SWS2Aα, SWS2Aβ blue-sensitive) in a phylogenetically inert manner. However, based on amino acid predictions, both SWS2A proteins confer similar peak spectral sensitivities and differential expression is therefore unlikely to be ecologically significant. Red-sensitivity is likely beneficial for feeding on algae and detritus, the main food source of Salariini blennies, and could be co-adapted to perceive visual displays in terrestrial species, which often use red dorsal fins to signal during aggressive disputes and courtship. Our data suggests that on the molecular level, the visual systems that evolved in aquatic blennies have been retained in species that have transitioned onto land.
Publisher: Proceedings of the National Academy of Sciences
Date: 02-12-2008
Abstract: Environmental noise that reduces the probability that animals will detect communicative signals poses a special challenge for long-range communication. The application of signal-detection theory to animal communication lead to the prediction that signals directed at distant receivers in noisy environments will begin with conspicuous “alerting” components to attract the attention of receivers, before delivery of the information-rich portion of the signal. Whether animals actually adopt this strategy is not clear, despite suggestions that alerts might exist in a variety of taxa. By using a combination of behavioral observations and experimental manipulations with robotic lizard “playbacks,” we show that free-living territorial Anolis lizards add an “alert” to visual displays when communicating to distant receivers in situations of poor visibility, and that these introductory alerts in turn enhance signal detection in adverse signaling conditions. Our results show that Anolis lizards are able to evaluate environmental conditions that affect the degradation of long-distance signals and adjust their behavior accordingly. This study demonstrates that free-living animals enhance the efficiency of long-range communication through the modulation of signal design and the facultative addition of an alert. Our findings confirm that alert signals are an important strategy for communicating in “noisy” conditions and suggest a reexamination of the existence of alerts in other animals relying on long-range communication.
Publisher: University of Chicago Press
Date: 10-2008
DOI: 10.1086/590960
Abstract: A key hypothesis explaining the existence of dawn and dusk choruses in acoustically communicating animals centers on the need to advertise continued territorial occupancy after and before a period of nocturnal inactivity. If this hypothesis is correct, it follows that similar dawn and dusk choruses should occur in territorial animals exploiting other signal modalities. Adult male Anolis lizards defend territories by using elaborate head-bobbing displays and extensions of a throat fan or dewlap. Males are inactive at night and return to their territories at dawn, remaining there until dusk. I quantified the production of visual displays as a function of time of day for four species on the island of Jamaica: Anolis lineatopus, Anolis sagrei, Anolis grahami, and Anolis opalinus. All exhibited dawn and/or dusk peaks in display behavior. These patterns have remarkable parallels with the dawn and dusk choruses reported for many acoustically communicating animals.
Publisher: Wiley
Date: 24-08-2015
DOI: 10.1111/JEB.12709
Abstract: The existence of elaborate ornamental structures in males is often assumed to reflect the outcome of female mate choice for showy males. However, female mate choice appears weak in many iguanian lizards, but males still exhibit an array of ornament-like structures around the throat. We performed a phylogenetic comparative study to assess whether these structures have originated in response to male-male competition or the need for improved signal efficiency in visually difficult environments. We found little evidence for the influence of male-male competition. Instead, forest species were more likely to exhibit colourful throat appendages than species living in open habitats, suggesting selection for signal efficiency. On at least three independent occasions, throat ornamentation has become further elaborated into a large, conspicuously coloured moving dewlap. Although the function of the dewlap is convergent, the underlying hyoid apparatus has evolved very differently, revealing the same adaptive outcome has been achieved through multiple evolutionary trajectories. More generally, our findings highlight that extravagant, ornament-like morphology can evolve in males without the direct influence of female mate choice and that failure to consider alternative hypotheses for the evolution of these structures can obscure the true origins of signal ersity among closely related taxa.
Publisher: Oxford University Press (OUP)
Date: 14-12-2022
Abstract: We identified hypotheses for the cause and consequences of the loss of complexity in animal signals and tested these using a genus of visually communicating lizards, the Southeast Asian Draco lizards. Males of some species have lost the headbob component from their display, which is otherwise central to the communication of this genus. These males instead display a large, colorful dewlap to defend territories and attract mates. This dewlap initially evolved to augment the headbob component of the display, but has become the exclusive system of communication. We tested whether the loss of headbobs was caused by relaxed selection, habitat-dependent constraints, or size-specific energetic constraints on display movement. We then examined whether the consequences of this loss have been mitigated by increased signaling effort or complexity in the color of the dewlap. It appears the increased cost of display movement resulting from the evolution of large body size might have contributed to the loss of headbobs and has been somewhat compensated for by the evolution of greater complexity in dewlap color. However, this evolutionary shift is unlikely to have maintained the complexity previously present in the communication system, resulting in an apparent detrimental loss of information potential.
Publisher: Wiley
Date: 27-06-2016
DOI: 10.1111/JEB.12908
Abstract: Sexual ornamentation needs to be conspicuous to be effective in attracting potential mates and defending territories and indeed, a multitude of ways exists to achieve this. Two principal mechanisms for increasing conspicuousness are to increase the ornament's colour or brightness contrast against the background and to increase the size of the ornament. We assessed the relationship between the colour and size of the dewlap, a large extendible throat-fan, across a range of species of gliding lizards (Agamidae genus Draco) from Malaysia and the Philippines. We found a negative relationship across species between colour contrast against the background and dewlap size in males, but not in females, suggesting that males of different species use increasing colour contrast and dewlap size as alternative strategies for effective communication. Male dewlap size also increases with increasing sexual size dimorphism, and dewlap colour and brightness contrast increase with increasing sexual dichromatism in colour and brightness, respectively, suggesting that sexual selection may act on both dewlap size and colour. We further found evidence that relative predation intensity, as measured from predator attacks on models placed in the field, may play a role in the choice of strategy (high chromatic contrast or large dewlap area) a species employs. More broadly, these results highlight that each component in a signal (such as colour or size) may be influenced by different selection pressures and that by assessing components in idually, we can gain a greater understanding of the evolution of signal ersity.
Publisher: Springer Science and Business Media LLC
Date: 04-2006
DOI: 10.1007/S10886-006-9029-8
Abstract: Although many animals deposit scent marks, previous studies have focused almost entirely on rodents or on the chemical structure of the signal. Here, we study the quantity and temporal pattern of chemical deposition by the territorial sagebrush lizard Sceloporus graciosus, measuring both femoral pore and fecal deposits. Specifically, we tested whether variation in deposition is a good cue of in idual and sexual identity and/or whether it is more closely associated with body size and reproductive state, indicators of physiological condition. The results support the latter hypothesis. We found that although the amount of fluid deposited on a single perch (rarely quantified in mammals) carries little information on in idual or sexual identity, it reflects the physiological condition and reproductive state of in idual lizards and is replenished on a roughly weekly cycle, potentially providing additional information on the producer's activity level. The amount of deposition may thus provide important information to chemical receivers making mate choice and territorial defense decisions. The results further suggest that seasonal increases in gland production allow lizards to mark more sites rather than to influence the quality of the signal on a single perch.
Publisher: Wiley
Date: 24-11-2021
Abstract: Positive allometry has been considered a hallmark of sexual selection whereby larger males of superior condition develop disproportionately larger ornaments for their body size compared to smaller males of poorer condition. Yet many structures known to be sexually selected often exhibit other allometric patterns. This has led to controversy over the utility of allometry in adequately capturing the signature of sexual selection, particularly if static (within population) and evolutionary (across species) allometries are functionally constrained by stabilising natural selection. To investigate this, we evaluated the allometries of ornamental head crests and dorsal fins across multiple species of blenny fish. In particular, we compared species that occupied an aquatic environment—where swimming performance was expected to have constrained ornament size—with species that have transitioned onto land where such biomechanical constraints on ornament size have been removed. Static allometries of both head crest and dorsal fin ornaments were found to be positive in males, but less so in females, across all species examined. This was consistent with the allometric theory of sexual selection that predicts positive allometry specifically in male ornamentation. Nevertheless, male allometric exponents were constrained in aquatic species whereas males of terrestrial species were free to exaggerate the size of their ornaments. Natural selection therefore appears to limit the evolution of ornament size in aquatics, and probably because of the biomechanical constraints associated with swimming. These differences in within‐population static allometry between aquatic and terrestrial species in turn manifested in a greater across‐species evolutionary allometric elevation, but not exponent, for terrestrial species relative to aquatic species. These findings indicate that the study of ornament allometries can provide useful insights into the role of sexual selection on ornament elaboration and also help reveal the presence of opposing natural selection that might result in alternative allometric patterns. The relationship between static and evolutionary allometries remains complex, and our results caution against the interpretation of evolutionary allometry in the absence of a clear understanding of the underlying static allometries associated with it. A free Plain Language Summary can be found within the Supporting Information of this article.
Publisher: Oxford University Press (OUP)
Date: 28-08-2002
Publisher: Wiley
Date: 22-10-2013
DOI: 10.1111/JEB.12261
Abstract: The acquisition of key innovations and the invasion of new areas constitute two major processes that facilitate ecological opportunity and subsequent evolutionary ersification. Using a major lizard radiation as a model, the Australasian diplodactyloid geckos, we explored the effects of two key innovations (adhesive toepads and a snake-like phenotype) and the invasion of new environments (island colonization) in promoting the evolution of phenotypic and species ersity. We found no evidence that toepads had significantly increased evolutionary ersification, which challenges the common assumption that the evolution of toepads has been responsible for the extensive radiation of geckos. In contrast, a snakelike phenotype was associated with increased rates of body size evolution and, to a lesser extent, species ersification. However, the clearest impact on evolutionary ersification has been the colonization of New Zealand and New Caledonia, which were associated with increased rates of both body size evolution and species ersification. This highlights that colonizing new environments can drive adaptive ersification in conjunction or independently of the evolution of a key innovation. Studies wishing to confirm the putative link between a key innovation and subsequent evolutionary ersification must therefore show that it has been the acquisition of an innovation specifically, not the colonization of new areas more generally, that has prompted ersification.
Publisher: Wiley
Date: 22-10-2010
DOI: 10.1111/J.1558-5646.2010.01056.X
Abstract: Adaptations that facilitate the reception of long-range signals under challenging conditions are expected to generate signal ersity when species communicate in different habitats. Although we have a general understanding of how in idual communicating animals cope with conditions influencing signal detection, the extent to which plasticity and evolutionary changes in signal characteristics contribute to interspecific differences in signaling behavior is unclear. We quantified the visual displays of free-living lizards and environmental variables known to influence display detection for multiple species from two separate island radiations. We found evidence of both adaptive evolution and adaptive plasticity in display characteristics as a function of environmental conditions, but plasticity accounted for most of the observed differences in display behavior across species. At the same time, prominent differences between the two island radiations existed in aspects of signaling behavior, unrelated to the environment. Past evolutionary events have therefore played an important role in shaping the way lizards adjust their signals to challenges in present-day environments. In addition to showing how plasticity contributes to interspecific differences in communication signals, our findings suggest the vagaries of evolution can in itself lead to signal variation between species.
Publisher: Elsevier BV
Date: 08-2002
DOI: 10.1016/S0376-6357(02)00045-1
Abstract: Video playback has been used to explore many issues in animal communication, but the scope of this work has been constrained by the lack of stimulus-subject interaction. In many natural contexts, each participant's signalling behaviour is dependent from moment-to-moment on that of the other. Analyses of acoustic communication demonstrate the value of reproducing such social contingencies. We assessed the utility of interactive playback for studies of visual signalling by comparing the responses of male Jacky dragons, Amphibolurus muricatus, to interactive and non-interactive digital video playbacks of a life-sized conspecific. Displays produced by lizards in the interactive condition had the effect of suppressing the aggressive display of their simulated opponent. Each stimulus sequence generated during an interactive playback was subsequently played to a size-matched control animal. Males that could interact with the video stimulus responded principally with aggressive displays, while those that could not produced a mixture of aggressive and appeasement signals. Adding a degree of receiver responsiveness is hence sufficient to alter the type of signal evoked, even when video stimuli are physically identical. Interactive playback permits the experimental study of a broader range of theoretical topics and can enhance the realism of video stimuli.
Publisher: Wiley
Date: 08-12-2006
DOI: 10.1111/J.1420-9101.2005.01050.X
Abstract: The expression in females of ornaments thought to be the target of sexual selection in males is a long-standing puzzle. Two main hypotheses are proposed to account for the existence of conspicuous ornaments in both sexes (mutual ornamentation): genetic correlation between the sexes and sexual selection on females as well as males. We examined the pattern of ornament gains and losses in 240 species of dragon lizards (Agamidae) in order to elucidate the relative contribution of these two factors in the evolution of mutual ornamentation. In addition, we tested whether the type of shelter used by lizards to avoid predators predicts the evolutionary loss or constraint of ornament expression. We found evidence that the origin of female ornaments is broadly consistent with the predictions of the genetic correlation hypothesis. Ornaments appear congruently in both sexes with some lineages subsequently evolving male biased sexual dimorphism, apparently through the process of natural selection for reduced ornamentation in females. Nevertheless, ornaments have also frequently evolved in both sexes independently. This suggests that genetic correlations are potentially weak for several lineages and sexual selection on females is responsible for at least some evolutionary change in this group. Unexpectedly, we found that the evolutionary loss of some ornaments is concentrated more in males than females and this trend cannot be fully explained by our measures of natural selection.
Publisher: University of Chicago Press
Date: 05-2017
DOI: 10.1086/691155
Abstract: An ecological release from competition or predation is a frequent adaptive explanation for the colonization of novel environments, but empirical data are limited. On the island of Rarotonga, several blenny fish species appear to be in the process of colonizing land. Anecdotal observations have implied that aquatic predation is an important factor in prompting such hibious fish behavior. We provide evidence supporting this hypothesis by demonstrating that hibious blennies shift their abundance up and down the shoreline to remain above predatory fishes that periodically move into intertidal areas during high tide. A predation experiment using blenny mimics confirmed a high risk of aquatic predation for blennies, significantly higher than predation experienced on land. These data suggest that predation has played an active role in promoting terrestrial activity in hibious blennies and provide a rare ex le of how ecological release from predation could drive the colonization of a novel environment.
Publisher: Elsevier BV
Date: 06-2013
Publisher: The Royal Society
Date: 07-11-2004
Publisher: Elsevier BV
Date: 2012
Publisher: Wiley
Date: 28-07-2016
DOI: 10.1111/JEB.12936
Abstract: Predator-prey relationships play a key role in the evolution and ecology of carnivores. An understanding of predator-prey relationships and how this differs across species and environments provides information on how carnivorous strategies have evolved and how they may change in response to environmental change. We aim to determine how mammals overcame the challenges of living within the marine environment specifically, how this altered predator-prey body mass relationships relative to terrestrial mammals. Using predator and prey mass data collected from the literature, we applied phylogenetic piecewise regressions to investigate the relationship between predator and prey size across carnivorous mammals (51 terrestrial and 56 marine mammals). We demonstrate that carnivorous mammals have four broad dietary groups: small marine carnivores (< 11 000 kg) and small terrestrial carnivores ( 11 000 kg) feed on prey equal to 0.01% of the carnivore's body size, compared to 45% or greater in large terrestrial carnivores (> 11 kg). We propose that differences in prey availability, and the relative ease of processing large prey in the terrestrial environment and small prey in marine environment, have led to the evolution of these novel foraging behaviours. Our results provide important insights into the selection pressures that may have been faced by early marine mammals and ultimately led to the evolution of a range of feeding strategies and predatory behaviours.
Publisher: Elsevier BV
Date: 11-2015
Publisher: Springer Science and Business Media LLC
Date: 03-2016
DOI: 10.1007/S00442-016-3593-6
Abstract: The colonisation of new environments is a central evolutionary process, yet why species make such transitions often remains unknown because of the difficulty in empirically investigating potential mechanisms. The most likely explanation for transitions to new environments is that doing so conveys survival benefits, either in the form of an ecological release or new ecological opportunity. Life history theory makes explicit predictions about how traits linked to survival and reproduction should change with shifts in age-specific mortality. We used these predictions to examine whether a current colonisation of land by fishes might convey survival benefits. We found that blenny species with more terrestrial lifestyles exhibited faster reproductive development and slower growth rates than species with more marine lifestyles a life history trade off that is consistent with the hypothesis that mortality has become reduced in younger life stages on land. A plausible explanation for such a shift is that an ecological release or opportunity on land has conveyed survival benefits relative to the ancestral marine environment. More generally, our study illustrates how life history theory can be leveraged in novel ways to formulate testable predictions on why organisms might make transitions into novel environments.
Publisher: Wiley
Date: 26-08-2011
Publisher: University of Chicago Press
Date: 10-2009
DOI: 10.1086/605372
Abstract: Researchers have suggested that animals should respond more strongly to conspecific than to heterospecific communication signals used in territorial or courtship contexts. We tested this prediction by reviewing studies that appeared in six prominent journals over the past 10 years. A meta-analysis based on these empirical studies revealed that overall support for this hypothesis was weaker than anticipated. To help clarify the extent to which experimental design might contribute to equivocal findings, we performed playback experiments in the field, using robotic lizards. We examined whether male tropical lizards, Anolis gundlachi, responded more strongly to robots producing conspecific territorial advertisement displays than to robots producing equivalent displays of a novel heterospecific. Although this experiment was conducted under natural conditions in the field, at signaler-receiver distances typical for animals at this locality, and with high statistical power, we found that lizards responded just as aggressively to a simulated rival performing a display they had never seen before as to the same rival performing a conspecific display. Our findings suggest that predicting how animals will respond to conspecific versus heterospecific signals is more complicated than has generally been anticipated.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2005
Publisher: The Royal Society
Date: 12-2014
Abstract: Populations of the Bornean gliding lizard, Draco cornutus , differ markedly in the colour of their gliding membranes. They also differ in local vegetation type (mangrove forest versus lowland rainforest) and consequently, the colour of falling leaves (red and brown/black in mangrove versus green, brown and black in rainforest). We show that the gliding membranes of these lizards closely match the colours of freshly fallen leaves in the local habitat as they appear to the visual system of birds (their probable predators). Furthermore, gliding membranes more closely resembled colours of local fallen leaves than standing foliage or fallen leaves in the other population's habitat. This suggests that the two populations have erged in gliding membrane coloration to match the colours of their local falling leaves, and that mimicking falling leaves is an adaptation that functions to reduce predation by birds.
Publisher: Springer Science and Business Media LLC
Date: 22-03-2014
DOI: 10.1007/S00442-014-2921-Y
Abstract: Sympatric species that initially overlap in resource use are expected to partition the environment in ways that will minimize interspecific competition. This shift in resource use can in turn prompt evolutionary changes in morphology. A classic ex le of habitat partitioning and morphological differentiation are the Caribbean Anolis lizards. Less well studied, but nevertheless striking analogues to the Anolis are the Southeast Asian Draco lizards. Draco and Anolis have evolved independently of each other for at least 80 million years. Their comparison subsequently offers a special opportunity to examine mechanisms of phenotypic differentiation between two ecologically erse, but phylogenetically distinct groups. We tested whether Draco shared ecological axes of differentiation with Anolis (e.g., habitat use), whether this differentiation reflected interspecific competition, and to what extent adaptive change in morphology has occurred along these ecological axes. Using existing data on Anolis, we compared the habitat use and morphology of Draco in a field study of allopatric and sympatric species on the Malay Peninsula, Borneo and in the Philippines. Sympatric Draco lizards partitioned the environment along common resource axes to the Anolis lizards, especially in perch use. Furthermore, the morphology of Draco was correlated with perch use in the same way as it was in Anolis: species that used wider perches exhibited longer limb lengths. These results provide an important illustration of how interspecific competition can occur along common ecological axes in different animal groups, and how natural selection along these axes can generate the same type of adaptive change in morphology.
Publisher: Public Library of Science (PLoS)
Date: 19-05-2016
Publisher: Elsevier BV
Date: 06-2005
Publisher: Elsevier BV
Date: 05-2002
Publisher: Elsevier BV
Date: 06-2006
Publisher: The Royal Society
Date: 30-01-2007
Abstract: Extensive research over the last few decades has revealed that many acoustically communicating animals compensate for the masking effect of background noise by changing the structure of their signals. Familiar ex les include birds using acoustic properties that enhance the transmission of vocalizations in noisy habitats. Here, we show that the effects of background noise on communication signals are not limited to the acoustic modality, and that visual noise from windblown vegetation has an equally important influence on the production of dynamic visual displays. We found that two species of Puerto Rican lizard, Anolis cristatellus and A. gundlachi , increase the speed of body movements used in territorial signalling to apparently improve communication in visually ‘noisy’ environments of rapidly moving vegetation. This is the first evidence that animals change how they produce dynamic visual signals when communicating in noisy motion habitats. Taken together with previous work on acoustic communication, our results show that animals with very different sensory ecologies can face similar environmental constraints and adopt remarkably similar strategies to overcome these constraints.
Publisher: The Royal Society
Date: 05-07-2012
Abstract: The complex social worlds of many animal species may be linked to complex communicative systems in those species. We now have evidence in erse taxa and in different communicative modalities suggesting that complexity in social groups can drive complexity in signalling systems. The aim of this theme issue is to develop the theory behind this link between social complexity and communicative complexity, and to provide an overview of the lines of research testing this link.
Publisher: Public Library of Science (PLoS)
Date: 23-09-2015
Publisher: The Royal Society
Date: 05-07-2012
Abstract: The ‘social complexity hypothesis’ for communication posits that groups with complex social systems require more complex communicative systems to regulate interactions and relations among group members. Complex social systems, compared with simple social systems, are those in which in iduals frequently interact in many different contexts with many different in iduals, and often repeatedly interact with many of the same in iduals in networks over time. Complex communicative systems, compared with simple communicative systems, are those that contain a large number of structurally and functionally distinct elements or possess a high amount of bits of information. Here, we describe some of the historical arguments that led to the social complexity hypothesis, and review evidence in support of the hypothesis. We discuss social complexity as a driver of communication and possible causal factor in human language origins. Finally, we discuss some of the key current limitations to the social complexity hypothesis—the lack of tests against alternative hypotheses for communicative complexity and evidence corroborating the hypothesis from modalities other than the vocal signalling channel.
Publisher: The Royal Society
Date: 05-07-2012
Abstract: Complex social communication is expected to evolve whenever animals engage in many and varied social interactions that is, sociality should promote communicative complexity. Yet, informal comparisons among phylogenetically independent taxonomic groups seem to cast doubt on the putative role of social factors in the evolution of complex communication. Here, we provide a formal test of the sociality hypothesis alongside alternative explanations for the evolution of communicative complexity. We compiled data documenting variations in signal complexity among closely related species for several case study groups—ants, frogs, lizards and birds—and used new phylogenetic methods to investigate the factors underlying communication evolution. Social factors were only implicated in the evolution of complex visual signals in lizards. Ecology, and to some degree allometry, were most likely explanations for complexity in the vocal signals of frogs (ecology) and birds (ecology and allometry). There was some evidence for adaptive evolution in the pheromone complexity of ants, although no compelling selection pressure was identified. For most taxa, phylogenetic null models were consistently ranked above adaptive models and, for some taxa, signal complexity seems to have accumulated in species via incremental or random changes over long periods of evolutionary time. Becoming social presumably leads to the origin of social communication in animals, but its subsequent influence on the trajectory of signal evolution has been neither clear-cut nor general among taxonomic groups.
Publisher: Springer Science and Business Media LLC
Date: 11-10-2012
Publisher: Elsevier BV
Date: 11-2023
Publisher: SPIE
Date: 04-06-2004
DOI: 10.1117/12.539228
Publisher: University of Chicago Press
Date: 02-09-2016
DOI: 10.1086/687560
Abstract: Understanding the interacting outcomes of selection and historical contingency in shaping adaptive evolution remains a challenge in evolutionary biology. While selection can produce convergent outcomes when species occupy similar environments, the unique history of each species can also influence evolutionary trajectories and result in different phenotypic end points. The question is to what extent historical contingency places species on different adaptive pathways and, in turn, the extent to which we can predict evolutionary outcomes. Among lizards there are several distantly related genera that have independently evolved an elaborate extendible dewlap for territorial communication. We conducted a detailed morphological study and employed new phylogenetic comparative methods to investigate the evolution of the underlying hyoid that powers the extension of the dewlap. This analysis showed that there appear to have been multiple phenotypic pathways for evolving a functionally convergent dewlap. The biomechanical complexity that underlies this morphological structure implies that adaptation should have been constrained to a narrow phenotypic pathway. However, multiple adaptive solutions have been possible in apparent response to a common selection pressure. Thus, the phenotypic outcome that subsequently evolved in different genera seems to have been contingent on the history of the group in question. This blurs the distinction between convergent and historically contingent adaptation and suggests that adaptive phenotypic ersity can evolve without the need for ergent natural selection.
Publisher: Springer Science and Business Media LLC
Date: 14-05-2022
DOI: 10.1007/S10682-022-10181-W
Abstract: It has been argued that disproportionately larger ornaments in bigger males—positive allometry—is the outcome of sexual selection operating on the size of condition dependent traits. We reviewed the literature and found a general lack of empirical testing of the assumed link between female preferences for large ornaments and a pattern of positive allometry in male ornamentation. We subsequently conducted a manipulative experiment by leveraging the unusual terrestrial fish, Alticus sp. cf. simplicirrus , on the island of Rarotonga. Males in this species present a prominent head crest to females during courtship, and the size of this head crest in the genus more broadly exhibits the classic pattern of positive allometry. We created realistic male models standardized in body size but differing in head crest size based on the most extreme allometric scaling recorded for the genus. This included a crest size well outside the observed range for the study population (super-sized). The stimuli were presented to free-living females in a manner that mimicked the spatial distribution of courting males. Females directed greater attention to the male stimulus that exhibited the super-sized crest, with little difference in attention direct to other size treatments. These data appear to be the only experimental evidence from the wild of a female preference function that has been implicitly assumed to drive selection that results in the evolution of positive allometry in male ornamentation.
Publisher: Wiley
Date: 02-09-2010
DOI: 10.1111/J.1420-9101.2010.02083.X
Abstract: Recently, two squirrel species ( Spermophilus spp.) were discovered to anoint their bodies with rattlesnake scent as a means of concealing their odour from these chemosensory predators. In this study, we tested multiple species with predator scents (rattlesnake and weasel) to determine the prevalence of scent application across the squirrel phylogeny. We reconstructed the evolutionary history of the behaviour using a phylogenetic analysis and fossil records of historic predator co‐occurrence. Squirrels with historical and current rattlesnake co‐occurrence all applied rattlesnake scent, whereas no relationship existed between weasel scent application and either weasel or rattlesnake co‐occurrence. This was surprising because experimental tests confirmed rattlesnake and weasel scent were both effective at masking prey odour from hunting rattlesnakes (the primary predator of squirrels). Ancestral reconstructions and fossil data suggest predator scent application in squirrels is ancient in origin, arising before co‐occurrences with rattlesnakes or weasels in response to some other, now extinct, chemosensory predator.
Publisher: Wiley
Date: 30-09-2022
DOI: 10.1111/JEB.14102
Abstract: Visual ornaments have long been assumed to evolve hyper‐allometry as an outcome of sexual selection. Yet growing evidence suggests many sexually selected morphologies can exhibit other scaling patterns with body size, including hypo‐allometry. The large conspicuous throat fan, or dewlap, of arboreal Caribbean Anolis lizards was one ornament previously thought to conform to the classical expectation of hyper‐allometry. We re‐evaluated this classic ex le alongside a second arboreal group of lizards that has also independently evolved a functionally equivalent dewlap, the Southeast Asian Draco lizards. Across multiple closely related species in both genera, the Anolis and Draco dewlaps were either isometric or had hypo‐allometric scaling patterns. In the case of the Anolis dewlap, variation in dewlap allometry was predicted by the distance of conspecifics and the light environment in which the dewlap was typically viewed. Signal efficacy, therefore, appears to have driven the evolution of hypo‐allometry in what was originally thought to be a sexually selected ornament with hyper‐allometry. Our findings suggest that other elaborate morphological structures used in social communication might similarly exhibit isometric or hypo‐allometric scaling patterns because of environmental constraints on signal detection.
Publisher: Springer Science and Business Media LLC
Date: 10-07-2015
Publisher: Springer Science and Business Media LLC
Date: 2014
Publisher: The Royal Society
Date: 02-2017
Abstract: Effective communication requires animal signals to be readily detected by receivers in the environments in which they are typically given. Certain light conditions enhance the visibility of colour signals and these conditions can vary depending on the orientation of the sun and the position of the signaller. We tested whether Draco sumatranus gliding lizards modified their position relative to the sun to enhance the conspicuousness of their throat-fan (dewlap) during social display to conspecifics. The dewlap was translucent, and we found that lizards were significantly more likely to orient themselves perpendicular to the sun when displaying. This increases the dewlap's radiance, and likely, its conspicuousness, by increasing the amount of light transmitted through the ornament. This is a rare ex le of a behavioural adaptation for enhancing the visibility of an ornament to distant receivers.
Publisher: Wiley
Date: 20-06-2017
DOI: 10.1002/ECE3.3126
Start Date: 2012
End Date: 12-2017
Amount: $300,000.00
Funder: Australian Research Council
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