Tracking the evolution of thermal niches in Palearctic lacertid lizards

我们提出了一个创新的研究整合的方法，在基因组学，生理学，骨骼学和古生物学，了解蜥蜴的热生理适应的演变。蜥蜴科的物种是欧洲的主要蜥蜴，在化石记录中有广泛的代表性。它们既包括微特有物种，也包括分布极广的物种。从它们的生态偏好，可以假设，lacertid分支可能是差异化的温度和湿度制度。因此，蜥蜴类可能构成一个理想的模型组，以了解现在和过去的气候变化的生物影响。我们将使用从转录组，锚定杂交富集测序，和传统的桑格测序获得的DNA序列的超矩阵，以产生一个高度支持的，时间校准的系统发育树，这些蜥蜴与近完整的物种覆盖，特别是侧重于Lacertini分支主要分布在西部古北。基于所有124个现存的蜥蜴类物种的骨骼的微CT扫描，我们将定义骨骼特征状态，通过结合分子形态学系统发育分析优化这些，并使用它们来分配化石的分支。实验评估的最佳，首选，现场，和临界最低和最高温度为所有Lacertini物种将被用来模拟他们现在和过去的潜在分布范围。热生理生态位将被重建为性状沿着的进化史，以定义专门为特定生态位的分支，这些分支的化石分布将验证古模式。使用设想的广泛的数据集，我们将测试的假设，（a）一个组合的基因组学和骨骼学数据允许解决快速新生代辐射，如蜥蜴，包括一个可靠的位置，许多化石类群，（B）相当大一部分蜥蜴化石可以分配到特定的蜥蜴分支的基础上，详细检查骨骼和分支的特征状态的定义，（c）热生理特征往往是各分支特有的，有助于从化石组合推断过去的气候，（d）耐热性的变化与蜥蜴的纬度范围大小相关，（e）基于化石的古分布可以为预测气候变化影响的生理模型提供严格的验证。通过适当选择转录组确定的外群，我们的数据将进一步大大有助于解决深层的有鳞动物的繁殖，和热生理学知情的分布模型将直接进入爬行动物灭绝风险的全球评估。

We propose an innovative study integrating approaches in phylogenomics, physiology, osteology and paleontology to understand the evolution of thermophysiologial adaptations in lacertid lizards. Species in the family Lacertidae are the predominant lizards in Europe and widely represented in the fossil record. They comprise both microendemic and extremely widespread species. From their ecological preferences, it can be hypothesized that lacertid clades might be differentially specialized to temperature and humidity regimes. Lacertids therefore might constitute an ideal model group to understand biotic impacts of present and past climatic change. We will use a supermatrix of DNA sequences obtained from transcriptomes, anchored hybrid enrichment sequencing, and traditional Sanger sequencing to produce a highly supported, time-calibrated phylogenetic tree of these lizards with near-complete species coverage, focusing in particular on the Lacertini clade which is distributed mainly in the Western Palearctic. Based on micro-CT scans of the skeletons of all 124 extant Lacertini species we will define osteological character states, optimize these via combined molecular-morphological phylogenetic analysis, and use them to assign fossils to clades. Experimentally assessed optimum, preferred, field, and critical minimum and maximum temperatures for all Lacertini species will be used to model their present and past potential distribution ranges. Thermophysiological niches will be reconstructed as traits along the phylogeny to define clades specialized to particular niches, and the fossil distribution of these clades will validate paleomodels. Using the envisaged extensive data set we will test the hypotheses that (a) a combination of phylogenomic and ostelogical data allows resolving fast Cenozoic radiations such as the Lacertini, including a reliable placement of many fossil taxa, (b) a substantial portion of lacertid fossils can be assigned to particular lacertid clades based on a detailed examination of skeletons and cladistic definitions of character states, (c) thermophysiological traits are often clade-specific and help inferring past climates from fossil assemblages, (d) variation in thermal tolerances correlates with latitudinal range size of lizards, (e) paleodistributions based on fossils can provide a stringent validation of physiology-based models to predict climate-change effects. By appropriate choice of outgroups for transcriptome determination our data will further considerably contribute to resolving deep phylogeny of squamates, and the thermophysiology-informed distribution models will directly feed into a global assessment of reptile extinction risks.