Population divergence associated with spatial asynchrony in precipitation in neotropical frogs

Aim: To test the role of asynchrony in precipitation patterns among populations –a proxy for asynchronous breeding– as a driver of intraspecific genetic divergence across 38 species of Neotropical frogs. In addition, to examine whether regions with more asynchronous precipitation regimes across space have higher frog species richness and have experienced greater speciation rates than regions with more spatially synchronous precipitation regimes. Location: Central and South America Taxon: Anurans Methods: For microevolutionary analyses, we assessed the relationship between spatial asynchrony in precipitation and mtDNA genetic divergence accounting for ecological connectivity using multiple regression and phylogenetic meta-analyses. For macroevolutionary analyses, we assessed the relationship between species richness, speciation rates estimated from a comprehensive molecular phylogeny, and the degree of spatial asynchrony in precipitation using generalized linear models. Results and Main conclusions: Beyond a generalized effect of ecological connectivity on intraspecific genetic divergence, we found that spatial asynchrony in precipitation is positively associated with genetic differentiation in 39% of the species tested, resulting in a weak cross-species effect. However, the effect of asynchrony in precipitation on population divergence seems not to scale to macroevolutionary patterns because spatial asynchrony in precipitation was not associated with geographical patterns of species richness nor present-day speciation rates. Our results indicate that asynchronous breeding may promote genetic divergence even in the absence of geographic barriers in species where breeding is associated with water availability, but such effects may not be stable enough through time to influence macroevolutionary patterns.

研究目的：本研究旨在检验降水格局异步性（作为异步繁殖的替代指标）作为38种新热带蛙类种内遗传分化驱动因子的作用。此外，本研究还将考察：相较于空间降水同步性更强的区域，降水空间异步性更为显著的区域是否拥有更高的蛙类物种丰富度，以及更高的物种形成速率。
研究区域：中美洲及南美洲
研究类群：无尾目（Anurans）动物
研究方法：微观进化分析中，本研究采用多元回归与系统发育元分析方法，在纳入生态连通性变量以控制其影响的前提下，评估降水空间异步性与线粒体DNA（mtDNA）遗传分化之间的关联。宏观进化分析中，本研究借助广义线性模型，基于综合分子系统发育树估算的物种形成速率、物种丰富度与降水空间异步性程度三者间的关联进行分析。
结果与主要结论：除生态连通性对种内遗传分化存在普遍影响外，本研究发现39%的受试物种的降水空间异步性与遗传分化呈正相关，整体呈现微弱的跨物种效应。然而，降水异步性对种群分化的影响似乎并未延伸至宏观进化格局：降水空间异步性既与物种丰富度的地理分布格局无显著关联，也与当前的物种形成速率无关。本研究结果表明，即便在不存在地理屏障的物种中，若繁殖过程与水资源可获得性相关，异步繁殖仍可促进遗传分化，但此类效应随时间推移的稳定性不足，不足以对宏观进化格局产生影响。