Data from: Strong selection against hybrids maintains a narrow contact zone between morphologically cryptic lineages in a rainforest lizard

Phenotypically cryptic lineages comprise an important yet understudied part of biodiversity; in particular, we have much to learn about how these lineages are formed and maintained. To better understand the evolutionary significance of such lineages, we studied a hybrid zone between two morphologically-cryptic phylogeographic lineages in the rainforest lizard, Lampropholis coggeri. Analyzing a multilocus genetic dataset through cline inference, individual-based methods and population measures of disequilibrium and using simulations to explore our genetic results in context of theoretical expectations, we inferred the processes maintaining this hybrid zone. We find that these lineages meet in a hybrid zone that is narrow (~400 m) relative to inferred dispersal rate. Further, the hybrid zone exhibits substantial genetic disequilibrium and sharply coincident and largely concordant clines. Based on our knowledge about the region's biogeography, the species' natural history, and our simulation results, we suggest that strong selection against hybrids structures this system. As all clines show a relatively narrow range of introgression, we posit that this hybrid zone might not yet be in equilibrium. Nonetheless, our results clearly show that phylogeographic lineages can evolve substantial reproductive isolation without concomitant morphological diversification, suggesting that such lineages can constitute a significant component of evolutionary diversity.

表型隐秘支系（phenotypically cryptic lineages）是生物多样性中一类重要却未被充分研究的组成部分；具体而言，我们对于这类支系的形成与维持机制仍有诸多有待探索之处。为深入理解这类支系的进化意义，我们以雨林蜥蜴（Lampropholis coggeri）为研究对象，探究了两个形态隐秘系统地理学支系（morphologically-cryptic phylogeographic lineages）之间的杂交带（hybrid zone）。我们通过渐变群推断（cline inference）、基于个体的分析方法（individual-based methods）以及群体不平衡度量（population measures of disequilibrium）对多位点遗传数据集（multilocus genetic dataset）进行分析，并借助模拟实验将遗传结果置于理论预期框架下展开探究，以此推断维持该杂交带的核心过程。研究发现，相较于推断的扩散速率，这两个支系所形成的杂交带范围较为狭窄（约400米）。此外，该杂交带表现出显著的遗传不平衡，且存在显著重合且整体高度一致的渐变群。结合该区域的生物地理学背景、该物种的自然历史特征以及本研究的模拟结果，我们认为针对杂交个体的强烈选择塑造了这一杂交带系统。由于所有渐变群均表现出相对狭窄的基因渐渗（introgression）范围，我们推测该杂交带可能尚未达到平衡状态。尽管如此，我们的研究结果清晰表明，系统地理学支系可以在未发生伴随形态分化的情况下演化出显著的生殖隔离（reproductive isolation），这暗示这类支系可构成进化多样性的重要组成部分。