Niche-based approach to explore the impacts of environmental disturbances on biodiversity.

Globally, species are increasingly at risk from compounding threatening processes, an increasingly prominent driver of which is environmental disturbances. To facilitate effective conservation efforts following such events, methods that evaluate potential impacts across multiple species and provide landscape-scale information are needed to guide targeted responses. Often, the geographic overlap between a disturbance and species' distribution is calculated and then used as a proxy for potential impact. However, such methods do not account for the important influence of environmental heterogeneity throughout species' ranges. To address this shortcoming, we quantified the effects of environmental disturbances on species' environmental niche space. Using the Australian 2019 and 2020 Black Summer fires as a case study, we applied a niche-centric approach to examine the potential impacts of these fires on 387 vertebrate species. We examined the utility of established and novel niche metrics to assess the potential impacts of large-scale disturbance events on species by comparing the potential effects of the fires as determined by our various niche measures to those derived from geographic-based measures of impact. We examined the quality of environmental space affected by the disturbance by quantifying the position in niche space where the disturbance occurred (center or margin), the uniqueness of the environmental space that was burned, and the degree to which the remaining, unburned portion of the niche differed from a species' original prefire niche. There was limited congruence between the proportion of geographic and niche space affected, which showed that geographic-based approaches in isolation may have underestimated the impact of the fires for 56% of modeled species. For each species, when combined, these metrics provided a greater indication of postdisturbance recovery potential than geographic-based measures alone. Accordingly, the integration of niche-based analyses into conservation assessments following large-scale disturbance events will lead to a more nuanced understanding of potential impacts and guide more informed and effective conservation actions.

Estrategia basada en los nichos para explorar el impacto de la perturbación ambiental sobre la biodiversidad Resumen En todo el mundo, las especies corren un riesgo cada vez mayor de verse amenazadas por procesos combinados, entre los que destacan las perturbaciones ambientales. Para facilitar una labor de conservación eficaz después de estos fenómenos, se necesitan métodos que evalúen el impacto potencial en varias especies y proporcionen información a escala de paisaje para orientar las respuestas específicas. A menudo, se calcula el traslape geográfico entre una perturbación y la distribución de las especies y se utiliza como indicador del impacto potencial. Sin embargo, estos métodos no tienen en cuenta la influencia importante de la heterogeneidad ambiental en toda el área de distribución de las especies. Para abordar esta deficiencia, cuantificamos los efectos de las perturbaciones ambientales en el espacio del nicho ambiental de las especies. Usamos los incendios australianos de Black Summer de 2019 y 2020 como caso de estudio y aplicamos un enfoque centrado en el nicho para examinar los impactos potenciales de estos incendios en 387 especies de vertebrados. Analizamos la utilidad de las métricas nuevas y establecidas de nicho para evaluar los impactos potenciales de los eventos de perturbación a gran escala para las especies con la comparación de los efectos potenciales de los incendios determinados por nuestras diversas medidas de nicho con los derivados de las medidas de impacto basadas en la geografía. Examinamos la calidad del espacio ambiental afectado por la perturbación al cuantificar la posición en el espacio del nicho donde se produjo la perturbación (centro o margen), la singularidad del espacio ambiental que se quemó y el grado en que la parte restante no quemada del nicho difería del nicho original de una especie antes del incendio. Hubo una congruencia limitada entre la proporción del espacio geográfico y del nicho afectado, lo que demostró que los enfoques geográficos aislados pueden subestimar el impacto de los incendios para el 56% de las especies modeladas. Para cada especie, estas métricas combinadas proporcionaron una mayor indicación del potencial de recuperación tras las perturbaciones que las medidas geográficas por sí solas. Por lo tanto, la integración de los análisis basados en nichos en las evaluaciones de conservación tras perturbaciones a gran escala permitirá comprender mejor los impactos potenciales y orientar las acciones de conservación de manera más informada y eficaz.

Estimates of heterozygosity from single nucleotide polymorphism markers are context-dependent and often wrong.

Genetic diversity is frequently described using heterozygosity, particularly in a conservation context. Often, it is estimated using single nucleotide polymorphisms (SNPs); however, it has been shown that heterozygosity values calculated from SNPs can be biased by both study design and filtering parameters. Though solutions have been proposed to address these issues, our own work has found them to be inadequate in some circumstances. Here, we aimed to improve the reliability and comparability of heterozygosity estimates, specifically by investigating how sample size and missing data thresholds influenced the calculation of autosomal heterozygosity (heterozygosity calculated from across the genome, i.e. fixed and variable sites). We also explored how the standard practice of tri- and tetra-allelic site exclusion could bias heterozygosity estimates and influence eventual conclusions relating to genetic diversity. Across three distinct taxa (a frog, Litoria rubella; a tree, Eucalyptus microcarpa; and a grasshopper, Keyacris scurra), we found heterozygosity estimates to be meaningfully affected by sample size and missing data thresholds, partly due to the exclusion of tri- and tetra-allelic sites. These biases were inconsistent both between species and populations, with more diverse populations tending to have their estimates more severely affected, thus having potential to dramatically alter interpretations of genetic diversity. We propose a modified framework for calculating heterozygosity that reduces bias and improves the utility of heterozygosity as a measure of genetic diversity, whilst also highlighting the need for existing population genetic pipelines to be adjusted such that tri- and tetra-allelic sites be included in calculations.

Population genomics and sexual signals support reproductive character displacement in Uperoleia (Anura: Myobatrachidae) in a contact zone.

When closely related species come into contact via range expansion, both may experience reduced fitness as a result of the interaction. Selection is expected to favour traits that minimize costly interspecies reproductive interactions (such as mismating) via a phenomenon called reproductive character displacement (RCD). Research on RCD frequently assumes secondary contact between species, but the geographical history of species interactions is often unknown. Population genomic data permit tests of geographical hypotheses about species origins and secondary contact through range expansion. We used population genomic data from single nucleotide polymorphisms (SNPs), mitochondrial sequence data, advertisement call data and morphological data to investigate a species complex of toadlets (Uperoleia borealis, U. crassa, U. inundata) from northern Australia. Although the three species of frogs were morphologically indistinguishable in our analysis, we determined that U. crassa and U. inundata form a single species (synonymized here) based on an absence of genomic divergence. SNP data identified the phylogeographical origin of U. crassa as the Top End, with subsequent westward invasion into the range of U. borealis in the Kimberley. We identified six F1 hybrids, all of which had the U. borealis mitochondrial haplotype, suggesting unidirectional hybridization. Consistent with the RCD hypothesis, U. borealis and U. crassa sexual signals differ more in sympatry than in allopatry. Hybrid males have intermediate calls, which probably reduces attractiveness to females. Integrating population genomic data, mitochondrial sequencing, morphology and behavioural approaches provides an unusually detailed collection of evidence for reproductive character displacement following range expansion and secondary contact.

Phylogenomic analyses of the genus Drosophila reveals genomic signals of climate adaptation.

Many Drosophila species differ widely in their distributions and climate niches, making them excellent subjects for evolutionary genomic studies. Here, we have developed a database of high-quality assemblies for 46 Drosophila species and one closely related Zaprionus. Fifteen of the genomes were newly sequenced, and 20 were improved with additional sequencing. New or improved annotations were generated for all 47 species, assisted by new transcriptomes for 19. Phylogenomic analyses of these data resolved several previously ambiguous relationships, especially in the melanogaster species group. However, it also revealed significant phylogenetic incongruence among genes, mainly in the form of incomplete lineage sorting in the subgenus Sophophora but also including asymmetric introgression in the subgenus Drosophila. Using the phylogeny as a framework and taking into account these incongruences, we then screened the data for genome-wide signals of adaptation to different climatic niches. First, phylostratigraphy revealed relatively high rates of recent novel gene gain in three temperate pseudoobscura and five desert-adapted cactophilic mulleri subgroup species. Second, we found differing ratios of nonsynonymous to synonymous substitutions in several hundred orthologues between climate generalists and specialists, with trends for significantly higher ratios for those in tropical and lower ratios for those in temperate-continental specialists respectively than those in the climate generalists. Finally, resequencing natural populations of 13 species revealed tropics-restricted species generally had smaller population sizes, lower genome diversity and more deleterious mutations than the more widespread species. We conclude that adaptation to different climates in the genus Drosophila has been associated with large-scale and multifaceted genomic changes.

Seen only once: an evolutionarily distinct species of Toadlet (Uperoleia: Myobatrachidae) from the Wessel Islands of northern Australia.

There is a high rate of recent species discovery in remote regions of northern Australia, especially for amphibians and reptiles. The Wessel Islands, located in the northeastern corner of the Northern Territory, has recently been identified as a region of high species and phylogenetic endemism based on samples collected during the sole reptile and amphibian survey there in 1993. Using a phylogenetic approach, we describe a new, evolutionarily distinct species of Uperoleia endemic to the Wessel Islands. This description is based on three specimens, one female and two juveniles, which represent the only confirmed vouchers of the species. Due to the low number of specimens, this new species cannot be diagnosed morphologically from other closely related Uperoleia, and nothing is currently known about the mating call or basic biology. The discovery of this species provides further evidence for the islands importance as an area of endemism and identifies an urgent need for further surveys to document the unique biological diversity of the Wessel Islands.

A bird-like genome from a frog: Mechanisms of genome size reduction in the ornate burrowing frog, Platyplectrum ornatum.

The diversity of genome sizes across the tree of life is of key interest in evolutionary biology. Various correlates of variation in genome size, such as accumulation of transposable elements (TEs) or rate of DNA gain and loss, are well known, but the underlying molecular mechanisms driving or constraining genome size are poorly understood. Here, we study one of the smallest genomes among frogs characterized thus far, that of the ornate burrowing frog (Platyplectrum ornatum) from Australia, and compare it to other published frog and vertebrate genomes to examine the forces driving reduction in genome size. At ∼1.06 gigabases (Gb), the P. ornatum genome is like that of birds, revealing four major mechanisms underlying TE dynamics: reduced abundance of all major classes of TEs; increased net deletion bias in TEs; drastic reduction in intron lengths; and expansion via gene duplication of the repertoire of TE-suppressing Piwi genes, accompanied by increased expression of Piwi-interacting RNA (piRNA)-based TE-silencing pathway genes in germline cells. Transcriptomes from multiple tissues in both sexes corroborate these results and provide insight into sex-differentiation pathways in Platyplectrum Genome skimming of two closely related frog species (Lechriodus fletcheri and Limnodynastes fletcheri) confirms a reduction in TEs as a major driver of genome reduction in Platyplectrum and supports a macroevolutionary scenario of small genome size in frogs driven by convergence in life history, especially rapid tadpole development and tadpole diet. The P. ornatum genome offers a model for future comparative studies on mechanisms of genome size reduction in amphibians and vertebrates generally.

Genome-wide patterns of differentiation over space and time in the Queensland fruit fly.

The Queensland fruit fly, Bactrocera tryoni, is a major pest of Australian horticulture which has expanded its range in association with the spread of horticulture over the last ~ 150 years. Its distribution in northern Australia overlaps that of another fruit fly pest to which some authors accord full species status, Bactrocera aquilonis. We have used reduced representation genome-wide sequencing to genotype 359 individuals taken from 35 populations from across the current range of the two taxa, plus a further 73 individuals from six of those populations collected 15-22 years earlier. We find significant population differentiation along an east-west transect across northern Australia which likely reflects limited but bidirectional gene flow between the two taxa. The southward expansion of B. tryoni has led to relatively little genetic differentiation, and most of it is associated with a move into previously marginal inland habitats. Two disjunct populations elsewhere in Australia and three on Melanesian islands are each clearly differentiated from all others, with data strongly supporting establishment from relatively few founders and significant isolation subsequently. Resequencing of historical samples from one of the disjunct Australian populations shows that its genetic profile has changed little over a 15-year period, while the Melanesian data suggest a succession of 'island hopping' events with progressive reductions in genetic diversity. We discuss our results in relation to the control of B. tryoni and as a model for understanding the genetics of invasion and hybridisation processes.

Ecological Drivers and Sex-Based Variation in Body Size and Shape in the Queensland Fruit Fly, Bactrocera tryoni (Diptera: Tephritidae).

The Queensland fruit fly (Bactrocera tryoni; Q-fly) is an Australian endemic horticultural pest species, which has caused enormous economic losses. It has the potential to expand its range to currently Q-fly-free areas and poses a serious threat to the Australian horticultural industry. A large number of studies have investigated the correlation between environmental factors and Q-fly development, reproduction, and expansion. However, it is still not clear how Q-fly morphological traits vary with the environment. Our study focused on three morphological traits (body size, wing shape, and fluctuating asymmetry) in Q-fly samples collected from 1955 to 1965. We assessed how these traits vary by sex, and in response to latitude, environmental variables, and geographic distance. First, we found sexual dimorphism in body size and wing shape, but not in fluctuating asymmetry. Females had a larger body size but shorter and wider wings than males, which may be due to reproductive and/or locomotion differences between females and males. Secondly, the body size of Q-flies varied with latitude, which conforms to Bergmann's rule. Finally, we found Q-fly wing shape was more closely related to temperature rather than aridity, and low temperature and high aridity may lead to high asymmetry in Q-fly populations.

Publisher Correction: Open Science principles for accelerating trait-based science across the Tree of Life.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Open Science principles for accelerating trait-based science across the Tree of Life.

Synthesizing trait observations and knowledge across the Tree of Life remains a grand challenge for biodiversity science. Species traits are widely used in ecological and evolutionary science, and new data and methods have proliferated rapidly. Yet accessing and integrating disparate data sources remains a considerable challenge, slowing progress toward a global synthesis to integrate trait data across organisms. Trait science needs a vision for achieving global integration across all organisms. Here, we outline how the adoption of key Open Science principles-open data, open source and open methods-is transforming trait science, increasing transparency, democratizing access and accelerating global synthesis. To enhance widespread adoption of these principles, we introduce the Open Traits Network (OTN), a global, decentralized community welcoming all researchers and institutions pursuing the collaborative goal of standardizing and integrating trait data across organisms. We demonstrate how adherence to Open Science principles is key to the OTN community and outline five activities that can accelerate the synthesis of trait data across the Tree of Life, thereby facilitating rapid advances to address scientific inquiries and environmental issues. Lessons learned along the path to a global synthesis of trait data will provide a framework for addressing similarly complex data science and informatics challenges.

A new phylogenetic protocol: dealing with model misspecification and confirmation bias in molecular phylogenetics.

Molecular phylogenetics plays a key role in comparative genomics and has increasingly significant impacts on science, industry, government, public health and society. In this paper, we posit that the current phylogenetic protocol is missing two critical steps, and that their absence allows model misspecification and confirmation bias to unduly influence phylogenetic estimates. Based on the potential offered by well-established but under-used procedures, such as assessment of phylogenetic assumptions and tests of goodness of fit, we introduce a new phylogenetic protocol that will reduce confirmation bias and increase the accuracy of phylogenetic estimates.

The Potential for Rapid Evolution under Anthropogenic Climate Change.

Understanding how natural populations will respond to rapid anthropogenic climate change is one of the greatest challenges for ecologists and evolutionary biologists. Much research has focussed on whether physiological traits can evolve quickly enough under rapidly increasing temperatures. While the simple Breeder's equation helps to understand how extreme temperatures and genetic variation might drive within-population evolution under climate change, it does not consider two key areas: how different forms of phenotypic plasticity interact and variation among populations. Plasticity can modify the exposure to climatic extremes and the strength of selection from those extremes, while differences among populations provide adaptive diversity not apparent within them. Here, we focus on terrestrial vertebrates and, with a case study on a tropical lizard, demonstrate the complex interplay between spatial, genetic and plastic contributions to variation in climate-relevant physiological traits. We identify several problems that need to be better understood: which traits are under selection in a changing climate; the different forms of plasticity relevant to population persistence and rapid evolution; plastic versus genetic contributions to geographic variation in climate-associated traits and whether plasticity can be harnessed to promote persistence of species. Given ongoing uncertainties around whether natural populations can evolve rapidly enough to persist, we advocate the use of field trials aimed at increasing rates of adaptation, especially in systems known to be strongly impacted by human-driven changes in climate.

How mountains shape biodiversity: The role of the Andes in biogeography, diversification, and reproductive biology in South America's most species-rich lizard radiation (Squamata: Liolaemidae).

Testing hypotheses on drivers of clade evolution and trait diversification provides insight into many aspects of evolutionary biology. Often, studies investigate only intrinsic biological properties of organisms as the causes of diversity, however, extrinsic properties of a clade's environment, particularly geological history, may also offer compelling explanations. The Andes are a young mountain chain known to have shaped many aspects of climate and diversity of South America. The Liolaemidae are a radiation of South American reptiles with over 300 species found across most biomes and with similar numbers of egg-laying and live-bearing species. Using the most complete dated phylogeny of the family, we tested the role of Andean uplift in biogeography, diversification patterns, and parity mode of the Liolaemidae. We find that the Andes promoted lineage diversification and acted as a species pump into surrounding biomes. We also find strong support for the role of Andean uplift in boosting the species diversity of these lizards via allopatric fragmentation. Finally, we find repeated shifts in parity mode associated with changing thermal niches, with live-bearing favored in cold climates and egg-laying favored in warm climates. Importantly, we find evidence for possible reversals to oviparity, an evolutionary transition believed to be extremely rare.

Correction: Lineage Range Estimation Method Reveals Fine-Scale Endemism Linked to Pleistocene Stability in Australian Rainforest Herpetofauna.

[This corrects the article DOI: 10.1371/journal.pone.0126274.].

Phylogeographic structure across one of the largest intact tropical savannahs: Molecular and morphological analysis of Australia's iconic frilled lizard Chlamydosaurus kingii.

The spectacular threat display of the savannah specialist Australo-Papuan frilled lizards has made them one of the world's most iconic reptiles. They are increasingly used as a model system for research in evolutionary biology and ecology but little is known of their population structure. Their distribution across northern Australia and southern New Guinea also provides an opportunity to examine biogeographic patterns as they relate to the large-scale movement of savannah habitat during the Plio/Pleistocene and the associated increase in aridity. We generated sequence data for one mitochondrial and four nuclear DNA loci (5052 base pairs) for 83 frilled lizards sampled throughout their range. We also quantified body proportion variation for 279 individuals. Phylogenetic analyses based on maximum likelihood and Bayesian species-tree methods revealed three shallow clades that replace each other across the monsoon tropics. We found the expected pattern of male biased sexual size dimorphism in both maximum body size and head size but there was no sexual dimorphism in overall body shape or in frill size, relative to head size, supporting the hypothesis that the frill is used primarily as a threat display rather than a sexual display. The genetic clades are broadly consistent with known clinal variation in frill color that gradually shifts from west to east (red, orange, yellow/white) but otherwise show little morphological differentiation in body proportion measures. The biogeographic breaks between clades occur at the Carpentaria Gap and the lowlands surrounding the Ord River, and our ecological niche modeling predicts lower habitat suitability for C. kingii in these regions. While this biogeographic pattern is consistent with numerous other taxonomic groups in northern Australia, the overall low genetic diversity in frilled lizards across the entire monsoon tropics and southern New Guinea contrasts starkly to patterns seen in other terrestrial vertebrates. Extremely low intra-clade genetic diversity over vast geographic areas is indicative of recent gene flow that would likely have been facilitated by widespread savannah during interglacials, or alternatively may reflect population bottlenecks induced by extreme aridity during Pleistocene glacials. The shallow divergence between Australian and New Guinean samples is consistent with recent connectivity between Australia and New Guinea that would have been possible via a savannah corridor across the Torres Strait. Based on our molecular and morphological data, we do not support taxonomic recognition of any of the frilled lizard clades and instead consider C. kingii a single species with shallow phylogeographic structure and clinal variation in frill color.

Resources for phylogenomic analyses of Australian terrestrial vertebrates.

High-throughput sequencing methods promise to improve our ability to infer the evolutionary histories of lineages and to delimit species. These are exciting prospects for the study of Australian vertebrates, a group comprised of many globally unique lineages with a long history of isolation. The evolutionary relationships within many of these lineages have been difficult to resolve with small numbers of loci, and we now know that many lineages also exhibit substantial cryptic diversity. Here, we present a set of phylogenetically diverse transcriptome resources to enable exon-based sequence capture studies of Australian vertebrates, including transcriptome sequences for four species of birds, four frogs, seven lizards and seven mammals. We also use exon data from the marsupial transcriptomes we generated to examine an approach for choosing a moderate number (dozens or hundreds) of phylogenetically informative exons based on a single transcriptome sequence, and a relatively distant reference genome.

Incorporating evolutionary adaptation in species distribution modelling reduces projected vulnerability to climate change.

Based on the sensitivity of species to ongoing climate change, and numerous challenges they face tracking suitable conditions, there is growing interest in species' capacity to adapt to climatic stress. Here, we develop and apply a new generic modelling approach (AdaptR) that incorporates adaptive capacity through physiological limits, phenotypic plasticity, evolutionary adaptation and dispersal into a species distribution modelling framework. Using AdaptR to predict change in the distribution of 17 species of Australian fruit flies (Drosophilidae), we show that accounting for adaptive capacity reduces projected range losses by up to 33% by 2105. We identify where local adaptation is likely to occur and apply sensitivity analyses to identify the critical factors of interest when parameters are uncertain. Our study suggests some species could be less vulnerable than previously thought, and indicates that spatiotemporal adaptive models could help improve management interventions that support increased species' resilience to climate change.

A new species of Australian frog (Myobatrachidae: Uperoleia) from the New South Wales mid-north coast sandplains.

The discovery of new vertebrate species in developed countries is still occurring at surprising rates for some taxonomic groups, especially the amphibians and reptiles. While this most often occurs in under-explored areas, it occasionally still happens in well-inhabited regions. We report such a case with the discovery and description of U. mahonyi sp. nov., a new species of frog from a highly populated region of New South Wales, Australia. We provide details of its morphology, calls, embryos and tadpoles, and phylogenetic relationships to other species of eastern Uperoleia. We also provide the results of targeted surveys to establish its distribution and provide observations of its habitat associations. As a consequence of these surveys, we comment on the likely restricted nature of the species' distribution and habitat, and place this in the context of a preliminary assessment of its putative conservation status, which should be assessed for listing under the IUCN's red list. We note this species, which is morphologically distinct, has gone unnoticed for many decades despite numerous ecological surveys for local development applications.

Lineage range estimation method reveals fine-scale endemism linked to Pleistocene stability in Australian rainforest herpetofauna.

Areas of suitable habitat for species and communities have arisen, shifted, and disappeared with Pleistocene climate cycles, and through this shifting landscape, current biodiversity has found paths to the present. Evolutionary refugia, areas of relative habitat stability in this shifting landscape, support persistence of lineages through time, and are thus crucial to the accumulation and maintenance of biodiversity. Areas of endemism are indicative of refugial areas where diversity has persisted, and endemism of intraspecific lineages in particular is strongly associated with late-Pleistocene habitat stability. However, it remains a challenge to consistently estimate the geographic ranges of intraspecific lineages and thus infer phylogeographic endemism, because spatial sampling for genetic analyses is typically sparse relative to species records. We present a novel technique to model the geographic distribution of intraspecific lineages, which is informed by the ecological niche of a species and known locations of its constituent lineages. Our approach allows for the effects of isolation by unsuitable habitat, and captures uncertainty in the extent of lineage ranges. Applying this method to the arc of rainforest areas spanning 3500 km in eastern Australia, we estimated lineage endemism for 53 species of rainforest dependent herpetofauna with available phylogeographic data. We related endemism to the stability of rainforest habitat over the past 120,000 years and identified distinct concentrations of lineage endemism that can be considered putative refugia. These areas of lineage endemism are strongly related to historical stability of rainforest habitat, after controlling for the effects of current environment. In fact, a dynamic stability model that allows movement to track suitable habitat over time was the most important factor in explaining current patterns of endemism. The techniques presented here provide an objective, practical method for estimating geographic ranges below the species level, and including them in spatial analyses of biodiversity.

Aridification drove repeated episodes of diversification between Australian biomes: evidence from a multi-locus phylogeny of Australian toadlets (Uperoleia: Myobatrachidae).

Australia is a large and complex landmass that comprises diverse biomes ranging from tropical rainforests to harsh deserts. While Australian biotic diversity has evolved in response to landscape and climate changes, evidence of Miocene or later biome shifts are few. The Australo-Papuan endemic frog genus Uperoleia is widely distributed across mesic, monsoonal tropic and arid regions of Australia. Thus, it represents an ideal system to evaluate biome shifts as they relate to known landscape and climate history. We comprehensively sampled the distributional range of 25 described Uperoleia species and generated a detailed molecular phylogeny for the genus based on one mitochondrial and five nuclear loci. Our results support a single origin of monsoonal tropic taxa, followed by diversification within the region under the influence of the Australian monsoon. Molecular dating analyses suggest the major divergence between eastern mesic and monsoonal species occurred in the Miocene approximately 17million years ago, with repeated evolution of species from monsoonal biomes to arid or mesic biomes in the later Miocene, early Pliocene and at the beginning of the Pleistocene. Our detailed sampling helps to clarify the true distributions of species and contributes to on-going work to improve the taxonomy of the genus. Topological differences between nuclear and mitochondrial phylogenies within major clades suggest a history of mitochondrial introgression and capture, and reduce the ability to resolve close interspecific relationships.