Vertucci Samantha, Pepper Mitzy, Edwards Danielle L, Roberts J Dale, Mitchell Nicola, Keogh J Scott
Division of Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australia.
School of Natural Sciences, University of California, Merced, CA, United States of America.
PLoS One. 2017 Mar 15;12(3):e0173348. doi: 10.1371/journal.pone.0173348. eCollection 2017.
Southwest Australia (SWA) is a global biodiversity hotspot and a centre of diversity and endemism for the Australo-Papuan myobatrachid frogs. Myobatrachus gouldii (the turtle frog) has a highly derived morphology associated with its forward burrowing behaviour, largely subterranean habit, and unusual mode of reproduction. Its sister genera Metacrinia and Arenophryne have restricted distributions in Western Australia with significant phylogeographic structure, leading to the recent description of a new species in the latter. In contrast, Myobatrachus is distributed widely throughout SWA over multiple climatic zones, but little is known of its population structure, geographic variation in morphology, or reproduction. We generated molecular and morphological data to test for genetic and morphological variation, and to assess whether substrate specialisation in this species may have led to phylogeographic structuring similar to that of other plant and animal taxa in SWA. We assembled sequence data for one mitochondrial and four nuclear DNA loci (3628 base pairs) for 42 turtle frogs sampled throughout their range. Likelihood phylogenetic analyses revealed shallow phylogeographic structure in the mtDNA locus (up to 3.3% genetic distance) and little variation in three of the four nDNA loci. The mtDNA haplotype network suggests five geographically allopatric groups, with no shared haplotypes between regions. These geographic patterns are congruent with several other SWA species, with genetic groups restricted to major hydrological divisions, the Swan Coastal Plain, and the Darling Scarp. The geographically structured genetic groups showed no evidence of significant morphological differentiation (242 individuals), and there was little sexual size dimorphism, but subtle differences in reproductive traits suggest more opportunistic breeding in lower rainfall zones. Call data were compared to sister genera Metacrinia and Arenophryne and found to be highly conservative across the three genera. Like many taxa in SWA, topographic variation and Plio-Pleistocene arid fluctuations likely were historic drivers of diversification in M. gouldii.
澳大利亚西南部（SWA）是一个全球生物多样性热点地区，也是澳大拉西亚 - 巴布亚的肌蟾科蛙类的多样性和特有性中心。古氏肌蟾（龟蛙）具有与其向前挖掘行为、主要地下栖息习性和不寻常繁殖方式相关的高度特化形态。它的姐妹属Metacrinia和沙蟾属在西澳大利亚分布受限，具有显著的系统地理学结构，导致后者最近描述了一个新物种。相比之下，肌蟾属广泛分布于整个澳大利亚西南部的多个气候区，但对其种群结构、形态的地理变异或繁殖情况知之甚少。我们生成了分子和形态学数据，以测试遗传和形态变异，并评估该物种的底物特化是否可能导致了类似于澳大利亚西南部其他动植物类群的系统地理学结构。我们收集了在其整个分布范围内采样的42只龟蛙的一个线粒体和四个核DNA位点（3628个碱基对）的序列数据。似然系统发育分析揭示了线粒体DNA位点的浅层次系统地理学结构（遗传距离高达3.3%），并且四个核DNA位点中的三个几乎没有变异。线粒体DNA单倍型网络表明有五个地理上异域分布的群体，各区域之间没有共享单倍型。这些地理模式与其他几个澳大利亚西南部物种一致，遗传群体局限于主要的水文分区、天鹅海岸平原和达令陡崖。地理结构的遗传群体没有显著形态分化的证据（242个个体），并且几乎没有两性异形，但繁殖性状的细微差异表明在降雨较少的地区繁殖更具机会性。将叫声数据与姐妹属Metacrinia和沙蟾属进行比较，发现这三个属的叫声数据高度保守。与澳大利亚西南部的许多类群一样，地形变化和上新世 - 更新世干旱波动可能是古氏肌蟾多样化的历史驱动因素。
