Liedtke H Christoph, Müller Hendrik, Hafner Julian, Penner Johannes, Gower David J, Mazuch Tomáš, Rödel Mark-Oliver, Loader Simon P
Department of Environmental Science (Biogeography), University of Basel, Klingelbergstrasse 27, 4056 Basel, Switzerland
Ecology, Evolution and Developmental Group, Department of Wetland Ecology, Estación Biológica de Doñana (CSIC), 41092 Sevilla, Spain.
Proc Biol Sci. 2017 Mar 29;284(1851). doi: 10.1098/rspb.2016.2598.
How evolutionary novelties evolve is a major question in evolutionary biology. It is widely accepted that changes in environmental conditions shift the position of selective optima, and advancements in phylogenetic comparative approaches allow the rigorous testing of such correlated transitions. A longstanding question in vertebrate biology has been the evolution of terrestrial life histories in amphibians and here, by investigating African bufonids, we test whether terrestrial modes of reproduction have evolved as adaptations to particular abiotic habitat parameters. We reconstruct and date the most complete species-level molecular phylogeny and estimate ancestral states for reproductive modes. By correlating continuous habitat measurements from remote sensing data and locality records with life-history transitions, we discover that terrestrial modes of reproduction, including viviparity evolved multiple times in this group, most often directly from fully aquatic modes. Terrestrial modes of reproduction are strongly correlated with steep terrain and low availability of accumulated water sources. Evolutionary transitions to terrestrial modes of reproduction occurred synchronously with or after transitions in habitat, and we, therefore, interpret terrestrial breeding as an adaptation to these abiotic conditions, rather than an exaptation that facilitated the colonization of montane habitats.
进化新奇性如何演化是进化生物学中的一个主要问题。人们普遍认为，环境条件的变化会改变选择最优值的位置，而系统发育比较方法的进步使得对这种相关转变进行严格测试成为可能。脊椎动物生物学中一个长期存在的问题是两栖动物陆地生活史的进化，在此，通过对非洲蟾蜍科进行研究，我们测试了陆地繁殖方式是否已进化为对特定非生物栖息地参数的适应。我们重建并确定了最完整的物种水平分子系统发育，并估计了繁殖方式的祖先状态。通过将来自遥感数据和地点记录的连续栖息地测量与生活史转变相关联，我们发现陆地繁殖方式，包括胎生，在该类群中多次进化，最常见的是直接从完全水生方式进化而来。陆地繁殖方式与陡峭地形和累积水源的低可用性密切相关。向陆地繁殖方式的进化转变与栖息地转变同步发生或在栖息地转变之后发生，因此，我们将陆地繁殖解释为对这些非生物条件的适应，而不是一种促进山地栖息地定殖的预适应。
