CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France.
Department of Biology, Utah State University, Logan, UT, USA.
Nat Commun. 2024 Mar 13;15(1):2273. doi: 10.1038/s41467-024-46294-9.
Speciation is often viewed as a continuum along which populations diverge until they become reproductively-isolated species. However, such divergence may be heterogeneous, proceeding in fits and bursts, rather than being uniform and gradual. We show in Timema stick insects that one component of reproductive isolation evolves non-uniformly across this continuum, whereas another does not. Specifically, we use thousands of host-preference and mating trials to study habitat and sexual isolation among 42 pairs of taxa spanning a range of genomic differentiation and divergence time. We find that habitat isolation is uncoupled from genomic differentiation within species, but accumulates linearly with it between species. In contrast, sexual isolation accumulates linearly across the speciation continuum, and thus exhibits similar dynamics to morphological traits not implicated in reproductive isolation. The results show different evolutionary dynamics for different components of reproductive isolation and highlight a special relevance for species status in the process of speciation.
物种形成通常被视为一个连续体，在这个连续体上，种群逐渐分化，直到它们成为生殖隔离的物种。然而，这种分化可能是不均匀的，是间歇性的，而不是均匀和渐进的。我们在 Timema 竹节虫中表明，生殖隔离的一个组成部分在这个连续体上的进化是不均匀的，而另一个组成部分则不是。具体来说，我们使用数千次的宿主偏好和交配试验，研究了跨越基因组分化和分化时间范围的 42 对分类群之间的栖息地和性隔离。我们发现，物种内的栖息地隔离与基因组分化无关，但在物种间则呈线性积累。相比之下，性隔离在物种形成的连续体上呈线性积累，因此表现出与生殖隔离无关的形态特征相似的动态。研究结果表明，生殖隔离的不同组成部分具有不同的进化动态，并突出了物种地位在物种形成过程中的特殊重要性。
