Data from: Reproductive isolation between phylogeographic lineages scales with divergence

Phylogeographic studies frequently reveal multiple morphologically cryptic lineages within species. What is not yet clear is whether such lineages represent nascent species or evolutionary ephemera. To address this question, we compare five contact zones, each of which occurs between ecomorphologically cryptic lineages of skinks from the rainforests of the Australian Wet Tropics. Although the contacts probably formed concurrently in response to Holocene expansion from glacial refugia, we estimate that the divergence times (τ) of the lineage pairs range from 3.1 to 11.5 Ma. Multi-locus analyses of the contact zones yielded estimates of reproductive isolation that are tightly correlated with divergence time and, for lineages with older divergence times (τ > 5 Myr), substantial. These results show that phylogeographic splits of increasing depth represent stages along the speciation continuum, even in the absence of overt change in ecologically relevant morphology.

系统发育地理学（phylogeographic）研究常揭示物种内存在多个形态隐秘支系（morphologically cryptic lineages）。目前尚不明确这类支系究竟属于新生物种（nascent species），还是进化昙花一现的类群（evolutionary ephemera）。为解答这一科学问题，我们对5处接触带（contact zones）展开比较分析：每处接触带均形成于澳大利亚湿热带雨林中石龙子（skinks）的一对生态形态隐秘支系（ecomorphologically cryptic lineages）之间。尽管这些接触带可能因全新世（Holocene）时期冰期避难所种群的扩张而同步形成，但我们估算得到各支系对的分化时间（τ）介于3.1至11.5 Ma之间。针对这些接触带的多位点（multi-locus）分析结果显示，生殖隔离（reproductive isolation）程度与分化时间紧密相关；对于分化时间较久（τ > 5 Myr）的支系对，其生殖隔离程度已相当显著。本研究结果表明，分化深度不断增加的系统发育地理学分化事件，代表了物种形成连续体（speciation continuum）上的不同演化阶段，即便在与生态适应相关的形态未发生显著改变的情况下亦是如此。