Data from: Estimating synchronous demographic changes across populations using hABC, and its application for a herpetological community from Northeastern Brazil

Many studies propose that Quaternary climatic cycles contracted and /or expanded the ranges of species and biomes. Strong expansion-contraction dynamics of biomes presume concerted demographic changes of associated fauna. The analysis of temporal concordance of demographic changes can be used to test the influence of Quaternary climate on diversification processes. Hierarchical approximate Bayesian computation (hABC) is a powerful and flexible approach that models genetic data from multiple species, and can be used to estimate the temporal concordance of demographic processes. Using available single-locus data we can now perform large-scale analyses, both in terms of number of species and geographic scope. Here we first compared the power of four alternative hABC models for a collection of single-locus data. We found that the model incorporating an a priori hypothesis about the timing of simultaneous demographic change had the best performance. Secondly, we applied the hABC models to a dataset of 7 squamate and 4 amphibian species occurring in the Seasonally Dry Tropical Forests (Caatinga) in Northeastern Brazil, which, according to paleoclimatic evidence, experienced an increase in aridity during the Pleistocene. If this increase was important for the diversification of associated xeric-adapted species, simultaneous population expansions should be evident at the community level. We found a strong signal of synchronous population expansion in the Late Pleistocene, supporting the expansion of the Caatinga during this time. This expansion likely enhanced the formation of communities adapted to high aridity and seasonality and caused regional extirpation of taxa adapted to wet forest.

已有诸多研究指出，第四纪（Quaternary）气候周期会收缩甚至扩张物种与生物群系（biomes）的分布范围。生物群系的剧烈扩张-收缩动态，往往伴随相关动物类群同步的种群数量变化。对种群变化时间同步性的分析，可用于检验第四纪气候对物种分化过程的影响。分层近似贝叶斯计算（hierarchical approximate Bayesian computation, hABC）是一种高效且灵活的分析方法，可对多物种的遗传数据建模，用以估算种群动态过程的时间同步性。借助现有单基因座（single-locus）数据，当前我们可开展兼具物种数量与地理覆盖范围双重维度的大规模分析。本研究首先针对一组单基因座数据集，比较了四种备选hABC模型的性能。研究发现，纳入"种群变化同步发生时间"先验假设的模型表现最优。其次，我们将hABC模型应用于巴西东北部季节性热带旱林（Seasonally Dry Tropical Forests, Caatinga）分布的7个有鳞目（squamate）物种与4个两栖类（amphibian）物种的数据集；根据古气候证据，更新世（Pleistocene）期间该区域的干旱程度曾有所加剧。若该干旱加剧过程对适应干旱环境的关联耐旱物种（xeric-adapted species）的分化具有关键作用，那么群落层面应能观测到同步的种群扩张信号。本研究在更新世晚期观测到显著的种群同步扩张信号，佐证了该时期卡廷加生物群系的扩张。此次扩张或推动了适应高干旱与季节波动的群落的形成，并导致适应湿润森林的类群在该区域局部灭绝。