ORCID Profile
0000-0002-2397-0240
Current Organisation
James Cook University
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Publisher: Magnolia Press
Date: 04-2019
DOI: 10.11646/ZOOTAXA.4576.1.6
Abstract: Recent surveys of rocky rainforest in the Townsville region have found additional populations of Phyllurus geckos. One of these populations was discovered at The Pinnacles, an isolated area of habitat in between the distributions of P. gulbaru and P. amnicola. Genetic and morphological data shows that this population is most similar to P. gulbaru Hoskin, Couper & Schneider, 2003 but ergent in a number of traits. Here we describe this population as a new species, P. pinnaclensis sp. nov., based on genetic ergence and differences in a number of morphometric and scalation traits from other populations of Phyllurus. Phyllurus pinnaclensis sp. nov. appears to be restricted to a few small areas of deeply layered rock with associated dry rainforest. This habitat is fire-sensitive and increased frequency and intensity of fires (due to late season burns and high fuel loads of invasive grasses) threatens to reduce and fragment these dry rainforest patches. Other threats include potential future invasion of the habitat by introduced Asian House Geckos (Hemidactylus frenatus Duméril & Bibron, 1836) and illegal collecting. Given the very small and fragmented distribution and potential reduction in habitat area due to fire, P. pinnaclensis sp. nov. warrants a Critically Endangered listing. Resolving the distributional change of dry rainforest in the Townsville region in recent decades, particularly in regards to fire, is key to resolving the status of this and other locally threatened taxa that depend on this habitat.
Publisher: Wiley
Date: 26-11-2020
DOI: 10.1111/ECOG.05390
Abstract: The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila – parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5°C in mean temperature. Our cost‐effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5–9 host and 5–11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely‐interacting species that are erse enough to be representative, yet still amenable to field and laboratory experiments.
Publisher: CSIRO Publishing
Date: 28-09-2020
DOI: 10.1071/ZO21017
Abstract: Australian lizards are a erse group distributed across the continent and inhabiting a wide range of environments. Together, they exhibit a remarkable ersity of reproductive morphologies, physiologies, and behaviours that is broadly representative of vertebrates in general. Many reproductive traits exhibited by Australian lizards have evolved independently in multiple lizard lineages, including sociality, complex signalling and mating systems, viviparity, and temperature-dependent sex determination. Australian lizards are thus outstanding model organisms for testing hypotheses about how reproductive traits function and evolve, and they provide an important basis of comparison with other animals that exhibit similar traits. We review how research on Australian lizard reproduction has contributed to answering broader evolutionary and ecological questions that apply to animals in general. We focus on reproductive traits, processes, and strategies that are important areas of current research, including behaviours and signalling involved in courtship mechanisms involved in mating, egg production, and sperm competition nesting and gestation sex determination and finally, birth in viviparous species. We use our review to identify important questions that emerge from an understanding of this body of research when considered holistically. Finally, we identify additional research questions within each topic that Australian lizards are well suited for reproductive biologists to address.
Publisher: Wiley
Date: 10-01-2017
DOI: 10.1111/GCB.13553
Publisher: Wiley
Date: 03-07-2019
Publisher: Wiley
Date: 15-03-2010
DOI: 10.1111/J.1461-0248.2010.01448.X
Abstract: A species may overlap with a mosaic of species across its geographic range. Many types of species interaction cause selection on mating traits, but their role in generating within-species ergence has been neglected. The pattern of reproductive character displacement (RCD) has been classically attributed to reinforcement, a process driven by selection against hybridisation. Recent reinforcement research shows that sexual isolation can result between displaced and non-displaced populations. We argue that RCD (and hence potentially speciation) among populations can be generated by a variety of fundamental species interactions beyond reinforcement. We unify these interactions under one process of mating trait ergence and speciation ('RCD speciation'). This process can occur in many geographic settings. Because selection is acting directly on mating traits, rapid speciation can result involving little differentiation in other traits. This pattern of ersification is seen in many groups and regions, and has previously been attributed to sexual selection alone.
Publisher: University of Chicago Press
Date: 11-2011
DOI: 10.1086/662164
Abstract: It is well established from the fossil record and phylogeographic analyses that late Quaternary climate fluctuations led to substantial changes in species' distribution, but whether and how these fluctuations resulted in phenotypic ergence and speciation is less clear. This question can be addressed through detailed analysis of traits relevant to ecology and mating within and among intraspecific lineages that persisted in separate refugia. In a biogeographic system (the Australian Wet Tropics [AWT]) with a well-established history of refugial isolation during Pleistocene glacial periods, we tested whether climate-mediated changes in distribution drove genetic and phenotypic ergence in the rainforest frog Cophixalus ornatus. We combined paleomodeling and multilocus genetics to demonstrate long-term persistence within, and isolation among, one central and two peripheral refugia. In contrast to other AWT vertebrates, the three major lineages differ in ecologically relevant morphology and in mating call, reflecting ergent selection and/or genetic drift in the peripheral isolates. Divergence in mating call and contact zone analyses suggest that the lineages now represent distinct species. The results show that climate shifts can promote genetic and phenotypic ergence and, potentially, speciation and direct attention toward incorporating adaptive traits into phylogeographic studies to better resolve the mechanisms of speciation.
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/WR20003
Abstract: Abstract ContextAcoustic communication is common in some animal groups, with an underlying function typically associated with mating or territoriality. Resolving the function of calls is valuable both in terms of understanding the fundamental biology of the species and, potentially, for applied reasons such as detection. Early detection is a key step in exclusion and eradication of invasive species, and calling behaviour can be used in this regard. The Asian house gecko (Hemidactylus frenatus) is one of a minority of lizards that uses acoustic communication. However, despite how conspicuous the call is, its function remains poorly resolved. It is also one of the world’s most invasive species, with exclusion via early detection being the key form of control. AimsThe aim was to resolve calling patterns and underlying function of the loud, multiple-chirp call (‘chik, chik, chik…’) in H. frenatus, in the context of using the results for developing effective methods for detection of new and establishing populations. MethodsThe calls of wild H. frenatus were recorded to assess peaks in calling activity. Also, laboratory experiments were performed to determine which in iduals call, what causes them to call and the degree of call variation among in iduals. Key resultsAssessment of calling behaviour in the wild revealed greater calling activity in warmer months, and five- to 10-fold peaks in calling activity at sunset and 30min before sunrise. Laboratory experiments revealed that calls were uttered exclusively by males and primarily by adults (although juveniles can call). Males called more when they were paired with females as opposed to other males. Calls differed among geckos, including the expected negative correlation between dominant frequency and body size. ConclusionsThe results suggest that the multiple-chirp call functions as a territory or sexual broadcast by males, perhaps containing information such as body size. ImplicationsDetection success can be maximised by performing acoustic surveys (by human or machine) during the calling peaks at 30min before sunrise and at sunset, particularly during warm nights. However, these surveys will only be effective for detecting adult males. The results also suggest that good quality recordings could potentially be used to identify in idual geckos.
Publisher: Cold Spring Harbor Laboratory
Date: 20-08-2018
DOI: 10.1101/395624
Abstract: Competition within and between species can have large effects on fitness and may therefore drive local adaptation. However, these effects are rarely tested systematically, or considered when predicting species’ responses to environmental change. We used a field transplant experiment to test the effects of intra and interspecific competition on fitness across the ecological niches of two rainforest Drosophila species that replace each other along an elevation gradient. For the species with the broader elevational range, we also tested for adaptation to the local abiotic and biotic environment. In both species, intraspecific competition reduced productivity more than interspecific competition at the centre of its elevational range, while interspecific competition had a stronger effect at the range edge, where the competing species is more abundant. Local adaptation was detected in the centre of the range of the more widespread species, but only in the presence of intraspecific competition. This study is the first to demonstrate that fitness effects of inter-specific competition increase at ecological margins, while intra-specific competition has more pervasive effects at range centres. This is a key assumption of “tangled bank” models of community evolution and has important implications for predicting the resilience of ecological networks to global change.
Publisher: University of Chicago Press
Date: 08-2019
DOI: 10.1086/704059
Abstract: Animals use mating traits to compete for, attract, and choose mates. Because mating traits influence mate choice, the ergence of mating traits between populations can result in reproductive isolation. This can occur without associated morphological ergence, producing reproductively isolated cryptic species that are visually indistinguishable. Thus, identifying the mating traits in morphologically conservative groups is key to resolving ersity and speciation processes. Lizards contain many such groups, with phylogeographic studies often revealing highly ergent but morphologically cryptic lineages within species. Considering that cryptic lizard species can be sympatric but morphologically indistinguishable, we hypothesize that candidate species will exhibit ergent pheromones and that pheromones will have typically erged more than morphology. To test this, we used gas chromatography to characterize pheromones (epidermal pore secretions) from 10 genetically ergent lineages of the Bynoe's gecko (
Publisher: Springer Science and Business Media LLC
Date: 24-01-2015
Publisher: University of Chicago Press
Date: 02-2003
DOI: 10.1086/345783
Abstract: Field populations of Drosophila serrata display reproductive character displacement in cuticular hydrocarbons (CHCs) when sympatric with Drosophila birchii. We have previously shown that the naturally occurring pattern of reproductive character displacement can be experimentally replicated by exposing field allopatric populations of D. serrata to experimental sympatry with D. birchii. Here, we tested whether the repeated evolution of reproductive character displacement in natural and experimental populations was a consequence of genetic constraints on the evolution of CHCs. The genetic variance-covariance (G) matrices for CHCs were determined for populations of D. serrata that had evolved in either the presence or absence of D. birchii under field and experimental conditions. Natural selection on mate recognition under both field and experimental sympatric conditions increased the genetic variance in CHCs consistent with a response to selection based on rare alleles. A close association between G eigenstructure and the eigenstructure of the phenotypic ergence (D) matrix in natural and experimental populations suggested that G matrix eigenstructure may have determined the direction in which reproductive character displacement evolved during the reinforcement of mate recognition.
Publisher: PeerJ
Date: 21-10-2014
DOI: 10.7717/PEERJ.627
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/ZO18036
Abstract: North Queensland harbours many microendemic species. These species are of conservation concern due to their small and fragmented populations, coupled with threats such as fire and climate change. We aimed to resolve the distribution and population genetic structure in two localised Phyllurus leaf-tailed geckos: P. gulbaru and P. amnicola. We conducted field surveys to better resolve distributions, used Species Distribution Models (SDMs) to assess the potential distribution, and then used the SDMs to target further surveys. We also sequenced all populations for a mitochondrial gene to assess population genetic structure. Our surveys found additional small, isolated populations of both species, including significant range extensions. SDMs revealed the climatic and non-climatic variables that best predict the distribution of these species. Targeted surveys based on the SDMs found P. gulbaru at an additional two sites but failed to find either species at other sites, suggesting that we have broadly resolved their distributions. Genetic analysis revealed population genetic structuring in both species, including deeply ergent mitochondrial lineages. Current and potential threats are overlain on these results to determine conservation listings and identify management actions. More broadly, this study highlights how targeted surveys, SDMs, and genetic data can rapidly increase our knowledge of microendemic species, and direct management.
Publisher: Cold Spring Harbor Laboratory
Date: 22-07-2020
DOI: 10.1101/2020.07.21.213678
Abstract: The analysis of interaction networks across spatial environmental gradients is a powerful approach to investigate the responses of communities to global change. Using a combination of DNA metabarcoding and traditional molecular methods we built bipartite Drosophila -parasitoid food webs from six Australian rainforest sites across gradients spanning 850 m in elevation and 5° Celsius in mean temperature. Our cost-effective hierarchical approach to network reconstruction separated the determination of host frequencies from the detection and quantification of interactions. The food webs comprised 5-9 host and 5-11 parasitoid species at each site, and showed a lower incidence of parasitism at high elevation. Despite considerable turnover in the relative abundance of host Drosophila species, and contrary to some previous results, we did not detect significant changes to fundamental metrics of network structure including nestedness and specialisation with elevation. Advances in community ecology depend on data from a combination of methodological approaches. It is therefore especially valuable to develop model study systems for sets of closely-interacting species that are erse enough to be representative, yet still amenable to field and laboratory experiments.
Publisher: Springer Science and Business Media LLC
Date: 17-01-2023
DOI: 10.1007/S10592-022-01499-7
Abstract: The Kuranda Treefrog occurs in tropical north-east Australia and is listed as Critically Endangered due to its small distribution and population size, with observed declines due to drought and human-associated impacts to habitat. Field surveys identified marked population declines in the mid-2000s, culminating in very low abundance at most sites in 2005 and 2006, followed by limited recovery. Here, s les from before (2001–2004) and after (2007–2009) this decline were analysed using 7132 neutral genome-wide SNPs to assess genetic connectivity among breeding sites, genetic erosion, and effective population size. We found a high level of genetic connectivity among breeding sites, but also structuring between the population at the eastern end of the distribution (Jumrum Creek) versus all other sites. Despite finding no detectable sign of genetic erosion between the two times periods, we observed a marked decrease in effective population size (Ne), from 1720 in iduals pre-decline to 818 post-decline. This mirrors the decline detected in the field census data, but the magnitude of the decline suggested by the genetic data is greater. We conclude that the current effective population size for the Kuranda Treefrog remains around 800 adults, split equally between Jumrum Creek and all other sites combined. The Jumrum Creek habitat requires formal protection. Connectivity among all other sites must be maintained and improved through continued replanting of rainforest, and it is imperative that impacts to stream flow and water quality are carefully managed to maintain or increase population sizes and prevent genetic erosion.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 20-10-2000
DOI: 10.1126/SCIENCE.290.5491.519
Abstract: Natural selection on mate recognition may often contribute to speciation, resulting in reproductive character displacement. Field populations of Drosophila serrata display reproductive character displacement in cuticular hydrocarbons when sympatric with Drosophila birchii . We exposed field sympatric and allopatric populations of D. serrata to experimental sympatry with D. birchii for nine generations. Cuticular hydrocarbons of field allopatric D. serrata populations evolved to resemble the field sympatric populations, whereas field sympatric D. serrata populations remained unchanged. Our experiment indicates that natural selection on mate recognition resulted in the field pattern of reproductive character displacement.
Publisher: Springer Science and Business Media LLC
Date: 2002
Publisher: Wiley
Date: 17-01-2013
DOI: 10.1111/JEB.12035
No related grants have been discovered for Megan Higgie.