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Pröhl H, Rodríguez A. Importance of Genetic-Fitness Correlations for the Conservation of Amphibians. Animals (Basel) 2023; 13:3564. [PMID: 38003181 PMCID: PMC10668650 DOI: 10.3390/ani13223564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/09/2023] [Accepted: 11/14/2023] [Indexed: 11/26/2023] Open
Abstract
Endangered animals suffer from isolation of their habitats. Isolation leads to a reduction in population size as well as a decrease in genetic diversity and a concomitant increase in the risk of extinction. Amphibians are the most endangered vertebrate class. Besides habitat loss, fragmentation and isolation, amphibians are threatened by emerging diseases e.g., chytrid fungus or Ranavirus. By employing experiments, researchers investigate whether changes in genetic diversity within or among isolated populations affect amphibian fitness. While genetic diversity estimates are based on molecular markers, typically microsatellites, fitness is mostly measured as tadpole performance in rearing experiments often under varying environmental conditions. Tadpole performances (e.g., body mass, growth rate and survival) have been found to be negatively affected by low genetic diversity, as several studies have found a positive association between genetic diversity and these fitness traits. Moreover, infection with pathogens also seems to be more likely in individuals or populations with lower genetic diversity. Overall, these genetic-fitness correlations seem to be more pronounced or detectable in smaller, declining populations but not in larger populations. Genomic studies, which sample a larger fraction of the genome, are still scarce in the conservation genetic literature on amphibians. These are likely to increase in upcoming years and may reveal adaptive variants that protect against dangerous pathogens or environmental changes. Altogether, genetic-fitness correlation studies should be a priority in order to develop effective management plans for the genetic rescue of isolated, imperilled amphibian populations.
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Affiliation(s)
- Heike Pröhl
- Institute of Zoology, University of Veterinary Medicine of Hannover, Bünteweg 17, 30559 Hannover, Germany;
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Scheele BC, Heard GW, Cardillo M, Duncan RP, Gillespie GR, Hoskin CJ, Mahony M, Newell D, Rowley JJL, Sopniewski J. An invasive pathogen drives directional niche contractions in amphibians. Nat Ecol Evol 2023; 7:1682-1692. [PMID: 37550511 DOI: 10.1038/s41559-023-02155-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 07/07/2023] [Indexed: 08/09/2023]
Abstract
Global change is causing an unprecedented restructuring of ecosystems, with the spread of invasive species being a key driver. While population declines of native species due to invasives are well documented, much less is known about whether new biotic interactions reshape niches of native species. Here we quantify geographic range and realized-niche contractions in Australian frog species following the introduction of amphibian chytrid fungus Batrachochytrium dendrobatidis, a pathogen responsible for catastrophic amphibian declines worldwide. We show that chytrid-impacted species experienced proportionately greater contractions in niche breadth than geographic distribution following chytrid emergence. Furthermore, niche contractions were directional, with contemporary distributions of chytrid-impacted species characterized by higher temperatures, lower diurnal temperature range, higher precipitation and lower elevations. Areas with these conditions may enable host persistence with chytrid through lower pathogenicity of the fungus and/or greater demographic resilience. Nevertheless, contraction to a narrower subset of environmental conditions could increase host vulnerability to other threatening processes and should be considered in assessments of extinction risk and during conservation planning. More broadly, our results emphasize that biotic interactions can strongly shape species realized niches and that large-scale niche contractions due to new species interactions-particularly emerging pathogens-could be widespread.
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Affiliation(s)
- Ben C Scheele
- Fenner School of Environment and Society, Australian National University, Canberra, Australian Capital Territory, Australia.
- Macroevolution and Macroecology Group, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
| | - Geoffrey W Heard
- Terrestrial Ecosystem Research Network and Centre for Biodiversity and Conservation Science, University of Queensland, Brisbane, Queensland, Australia
| | - Marcel Cardillo
- Macroevolution and Macroecology Group, Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Richard P Duncan
- Centre for Conservation Ecology and Genomics, University of Canberra, Canberra, Australian Capital Territory, Australia
| | - Graeme R Gillespie
- Science, Economics and Insights Division, Department of Planning and Environment, Parramatta, New South Wales, Australia
- School of Biosciences, University of Melbourne, Melbourne, Victoria, Australia
| | - Conrad J Hoskin
- College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
| | - Michael Mahony
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales, Australia
| | - David Newell
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Jodi J L Rowley
- Australian Museum Research Institute, Australian Museum, Sydney, New South Wales, Australia
- Centre for Ecosystem Science; School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, New South Wales, Australia
| | - Jarrod Sopniewski
- Fenner School of Environment and Society, Australian National University, Canberra, Australian Capital Territory, Australia
- School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia
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Zhang L, Chen J, Zhao R, Zhong J, Lin L, Li H, Ji X, Qu Y. Genomic insights into local adaptation in the Asiatic toad Bufo gargarizans, and its genomic offset to climate warming. Evol Appl 2023; 16:1071-1083. [PMID: 37216027 PMCID: PMC10197391 DOI: 10.1111/eva.13555] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 03/31/2023] [Accepted: 04/20/2023] [Indexed: 05/24/2023] Open
Abstract
Genomic signatures of local adaptation have been identified in many species but remain sparsely studied in amphibians. Here, we explored genome-wide divergence within the Asiatic toad, Bufo gargarizans, to study local adaptation and genomic offset (i.e., the mismatch between current and future genotype-environment relationships) under climate warming scenarios. We obtained high-quality SNP data for 94 Asiatic toads from 21 populations in China to study spatial patterns of genomic variation, local adaptation, and genomic offset to warming in this wide-ranging species. Population structure and genetic diversity analysis based on high-quality SNPs revealed three clusters of B. gargarizans in the western, central-eastern, and northeastern portions of the species' range in China. Populations generally dispersed along two migration routes, one from the west to the central-east and one from the central-east to the northeast. Both genetic diversity and pairwise F ST were climatically correlated, and pairwise F ST was also correlated with geographic distance. Spatial genomic patterns in B. gargarizans were determined by the local environment and geographic distance. Global warming will increase the extirpation risk of B. gargarizans.
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Affiliation(s)
- Lu‐Wen Zhang
- College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Jun‐Qiong Chen
- College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Ru‐Meng Zhao
- College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Jun Zhong
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental SciencesWenzhou UniversityWenzhouChina
| | - Long‐Hui Lin
- College of Life and Environmental SciencesHangzhou Normal UniversityHangzhouChina
| | - Hong Li
- College of Life SciencesNanjing Normal UniversityNanjingChina
| | - Xiang Ji
- Zhejiang Provincial Key Laboratory for Water Environment and Marine Biological Resources Protection, College of Life and Environmental SciencesWenzhou UniversityWenzhouChina
| | - Yan‐Fu Qu
- College of Life SciencesNanjing Normal UniversityNanjingChina
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4
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Conservation genomics reveals fine-scale population structuring and recent declines in the Critically Endangered Australian Kuranda Treefrog. CONSERV GENET 2023. [DOI: 10.1007/s10592-022-01499-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
AbstractThe 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, samples 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 individuals 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.
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Rudin-Bitterli TS, Evans JP, Mitchell NJ. Fitness consequences of targeted gene flow to counter impacts of drying climates on terrestrial-breeding frogs. Commun Biol 2021; 4:1195. [PMID: 34663885 PMCID: PMC8523558 DOI: 10.1038/s42003-021-02695-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 09/16/2021] [Indexed: 11/22/2022] Open
Abstract
Targeted gene flow (TGF) could bolster the adaptive potential of isolated populations threatened by climate change, but could also lead to outbreeding depression. Here, we explore these possibilities by creating mixed- and within-population crosses in a terrestrial-breeding frog species threatened by a drying climate. We reared embryos of the crawling frog (Pseudophryne guentheri) on wet and dry soils and quantified fitness-related traits upon hatching. TGF produced mixed outcomes in hybrids, which depended on crossing direction (origin of gametes from each sex). North-south crosses led to low embryonic survival if eggs were of a southern origin, and high malformation rates when eggs were from a northern population. Conversely, east-west crosses led to one instance of hybrid vigour, evident by increased fitness and desiccation tolerance of hybrid offspring relative to offspring produced from within-population crosses. These contrasting results highlight the need to experimentally evaluate the outcomes of TGF for focal species across generations prior to implementing management actions.
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Affiliation(s)
- Tabitha S Rudin-Bitterli
- School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
- Centre for Evolutionary Biology, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Jonathan P Evans
- School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
- Centre for Evolutionary Biology, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Nicola J Mitchell
- School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.
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Genomic Approaches for Conservation Management in Australia under Climate Change. Life (Basel) 2021; 11:life11070653. [PMID: 34357024 PMCID: PMC8304512 DOI: 10.3390/life11070653] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/02/2021] [Accepted: 07/03/2021] [Indexed: 12/28/2022] Open
Abstract
Conservation genetics has informed threatened species management for several decades. With the advent of advanced DNA sequencing technologies in recent years, it is now possible to monitor and manage threatened populations with even greater precision. Climate change presents a number of threats and challenges, but new genomics data and analytical approaches provide opportunities to identify critical evolutionary processes of relevance to genetic management under climate change. Here, we discuss the applications of such approaches for threatened species management in Australia in the context of climate change, identifying methods of facilitating viability and resilience in the face of extreme environmental stress. Using genomic approaches, conservation management practices such as translocation, targeted gene flow, and gene-editing can now be performed with the express intention of facilitating adaptation to current and projected climate change scenarios in vulnerable species, thus reducing extinction risk and ensuring the protection of our unique biodiversity for future generations. We discuss the current barriers to implementing conservation genomic projects and the efforts being made to overcome them, including communication between researchers and managers to improve the relevance and applicability of genomic studies. We present novel approaches for facilitating adaptive capacity and accelerating natural selection in species to encourage resilience in the face of climate change.
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Draining the Swamping Hypothesis: Little Evidence that Gene Flow Reduces Fitness at Range Edges. Trends Ecol Evol 2021; 36:533-544. [DOI: 10.1016/j.tree.2021.02.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 01/27/2021] [Accepted: 02/05/2021] [Indexed: 11/23/2022]
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Hoffmann EP, Cavanough KL, Mitchell NJ. Low desiccation and thermal tolerance constrains a terrestrial amphibian to a rare and disappearing microclimate niche. CONSERVATION PHYSIOLOGY 2021; 9:coab027. [PMID: 33959292 PMCID: PMC8084025 DOI: 10.1093/conphys/coab027] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/25/2021] [Accepted: 03/29/2021] [Indexed: 05/30/2023]
Abstract
Drier and hotter conditions caused by climate change threaten species that exist close to their physiological limits, as well as those with limited ability to move. Habitat specialists may also be particularly vulnerable if they have specific abiotic requirements. Here we assess whether thermal and hydric constraints can explain the highly restricted and declining distributions of the critically endangered terrestrial-breeding frog, Geocrinia alba. We also evaluate the species' vulnerability to climate change based on the similarity of current microclimatic conditions to their physiological limits. We found that G. alba had low thresholds of thermal and desiccation tolerance relative to other anuran species. The estimated thermal optimum (Topt ) and critical thermal maxima (CTmax ) were 23.3°C and 29.6°C, respectively, and adult frogs had an absorption threshold (AT, the lowest water potential at which water can be absorbed from a substrate) of -50 kPa, the lowest recorded for an amphibian. Comparing environmental conditions and water loss in the field using agar models showed that riparian habitats where frogs occur provide a unique microclimate in the landscape, offering significantly lower desiccation risk during extreme summer conditions compared to immediately adjacent riparian and terrestrial habitats. Monitoring of microclimate conditions within occupied frog habitats over 2 years showed that in extreme dry and hot years the AT was exceeded at six of eight sites, and Topt was exceeded at two of eight sites. Given their specific physiological limits, the apparent rarity of suitable microclimates and a regional drying-warming trend, we suggest that G. alba occupies a potentially disappearing niche and may be indicative of other habitat specialists that rely on ephemeral drainages. More broadly, this study highlights that desiccation thresholds may tightly constrain amphibian distributions and need to be considered along with thermal tolerance thresholds when predicting the impacts of climate change.
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Affiliation(s)
- Emily P Hoffmann
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
| | - Karen L Cavanough
- Perth Zoo, Department of Biodiversity, Conservation and Attractions, PO Box 489, South Perth, Western Australia 6951, Australia
| | - Nicola J Mitchell
- School of Biological Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
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Sex assignment in a non-model organism in the absence of field records using Diversity Arrays Technology (DArT) data. CONSERV GENET RESOUR 2021. [DOI: 10.1007/s12686-021-01203-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Xia J, Wang J, Niu S. Research challenges and opportunities for using big data in global change biology. GLOBAL CHANGE BIOLOGY 2020; 26:6040-6061. [PMID: 32799353 DOI: 10.1111/gcb.15317] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 07/13/2020] [Indexed: 06/11/2023]
Abstract
Global change biology has been entering a big data era due to the vast increase in availability of both environmental and biological data. Big data refers to large data volume, complex data sets, and multiple data sources. The recent use of such big data is improving our understanding of interactions between biological systems and global environmental changes. In this review, we first explore how big data has been analyzed to identify the general patterns of biological responses to global changes at scales from gene to ecosystem. After that, we investigate how observational networks and space-based big data have facilitated the discovery of emergent mechanisms and phenomena on the regional and global scales. Then, we evaluate the predictions of terrestrial biosphere under global changes by big modeling data. Finally, we introduce some methods to extract knowledge from big data, such as meta-analysis, machine learning, traceability analysis, and data assimilation. The big data has opened new research opportunities, especially for developing new data-driven theories for improving biological predictions in Earth system models, tracing global change impacts across different organismic levels, and constructing cyberinfrastructure tools to accelerate the pace of model-data integrations. These efforts will uncork the bottleneck of using big data to understand biological responses and adaptations to future global changes.
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Affiliation(s)
- Jianyang Xia
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Research Center for Global Change and Ecological Forecasting, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
| | - Jing Wang
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, Research Center for Global Change and Ecological Forecasting, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, China
- Shanghai Institute of Pollution Control and Ecological Security, Shanghai, China
| | - Shuli Niu
- Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, China
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Rudin-Bitterli TS, Mitchell NJ, Evans JP. Extensive geographical variation in testes size and ejaculate traits in a terrestrial-breeding frog. Biol Lett 2020; 16:20200411. [PMID: 32991823 PMCID: PMC7532705 DOI: 10.1098/rsbl.2020.0411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 09/08/2020] [Indexed: 11/12/2022] Open
Abstract
Ejaculate traits vary extensively among individuals and species, but little is known about their variation among populations of the same species. Here, we investigated patterns of intraspecific variation in male reproductive investment in the terrestrial-breeding frog Pseudophryne guentheri. Like most anurans, breeding activity in P. guentheri is cued by precipitation, and therefore the timing and duration of breeding seasons differ among geographically separated populations, potentially leading to differences in the level of sperm competition. We, therefore, anticipated local adaptation in sperm traits that reflect these phenological differences among populations. Our analysis of six natural populations across a rainfall gradient revealed significant divergence in testes and ejaculate traits that correspond with annual rainfall and rainfall seasonality; males from the northern and drier edge of the species range had significantly smaller testes containing fewer, smaller and less motile sperm compared with those from mesic central populations. These findings may reflect spatial variation in the strength of postcopulatory sexual selection, likely driven by local patterns of precipitation.
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Affiliation(s)
| | | | - Jonathan P. Evans
- School of Biological Sciences, University of Western Australia, Crawley, WA 6009, Australia
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Rudin-Bitterli TS, Evans JP, Mitchell NJ. Geographic variation in adult and embryonic desiccation tolerance in a terrestrial-breeding frog. Evolution 2020; 74:1186-1199. [PMID: 32255513 DOI: 10.1111/evo.13973] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 02/28/2020] [Accepted: 03/09/2020] [Indexed: 02/03/2023]
Abstract
Intraspecific variation in the ability of individuals to tolerate environmental perturbations is often neglected when considering the impacts of climate change. Yet this information is potentially crucial for mitigating deleterious effects of climate change on threatened species. Here we assessed patterns of intraspecific variation in desiccation tolerance in the frog Pseudophryne guentheri, a terrestrial-breeding species experiencing a drying climate. Adult frogs were collected from six populations across a rainfall gradient and their dehydration and rehydration rates were assessed. We also compared desiccation tolerance of embryos and hatchlings originating from within-population parental crosses from four of the populations. Embryos were reared on soil at three soil-water potentials and their desiccation tolerance was assessed across a range of traits. We found significant and strong patterns of intraspecific variation in almost all traits, both in adults and first-generation offspring. Adult frogs exhibited clinal variation in their water balance responses, with populations from drier sites both dehydrating and rehydrating more slowly compared to frogs from more mesic sites. Similarly, desiccation tolerance of first-generation offspring was significantly greater in populations from xeric sites. Our findings suggest that populations within this species will respond differently to the regional reduction in rainfall predicted by climate change models.
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Affiliation(s)
- Tabitha Silja Rudin-Bitterli
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, 6009, Australia.,Centre for Evolutionary Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Jonathan Paul Evans
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, 6009, Australia.,Centre for Evolutionary Biology, The University of Western Australia, Crawley, Western Australia, 6009, Australia
| | - Nicola Jane Mitchell
- School of Biological Sciences, The University of Western Australia, Crawley, Western Australia, 6009, Australia
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