Sgarlata Gabriele Maria, Maié Tiago, de Zoeten Tiago, Salmona Jordi, Rasteiro Rita, Chikhi Lounès
Instituto Gulbenkian de Ciência, Oeiras 2780-156, Portugal.
Department of Evolution and Ecology and Center for Population Biology, University of California, Davis, CA 95616.
Proc Natl Acad Sci U S A. 2025 Aug 5;122(31):e2410951122. doi: 10.1073/pnas.2410951122. Epub 2025 Jul 28.
Natural habitats have undergone drastic changes in quality, continuity, and extent during the Pleistocene, influencing the distribution of many species. More recently, human activities have converted continuous habitats into fragmented and isolated patches. Recent meta-analyses suggest that habitat loss and fragmentation (HL&F) have negatively impacted the genetic diversity of species but very few studies have analyzed the consequences of HL&F on the spatial distribution of genetic diversity and on isolation by distance (IBD) patterns (i.e., correlations between genetic and geographical distances) observed in many species. In this work, we use spatial simulations to investigate the speed at which IBD patterns generated in continuous habitats are lost in a context of HL&F. We characterized the behavior of IBD in the case of i) instantaneous HL&F, ii) gradual (two-steps) HL&F, and iii) range expansion followed by instantaneous HL&F. In addition, we show that a spatially explicit theoretical framework based on previous IBD theoretical results can be modified and applied to a toroidal stepping-stone model undergoing HL&F. Our results suggest that IBD patterns can be maintained for long periods of time after HL&F, thus pointing to the long-term persistence of signatures associated to past habitat connectivity in the genetic diversity of many species, even if they went through major and sometimes ancient fragmentation events. This suggests that some present-day fragmented species, who still exhibit significant IBD patterns, may have been partly disconnected for very long periods, on the order of tens of thousands of years for species with long generation time.
在更新世期间,自然栖息地在质量、连续性和范围方面经历了剧烈变化,影响了许多物种的分布。最近,人类活动已将连续的栖息地转变为碎片化和孤立的斑块。最近的荟萃分析表明,栖息地丧失和碎片化(HL&F)对物种的遗传多样性产生了负面影响,但很少有研究分析HL&F对遗传多样性空间分布以及许多物种中观察到的距离隔离(IBD)模式(即遗传距离与地理距离之间的相关性)的影响。在这项工作中,我们使用空间模拟来研究在HL&F背景下,连续栖息地中产生的IBD模式丧失的速度。我们描述了在以下情况下IBD的行为:i)瞬时HL&F,ii)渐进(两步)HL&F,以及iii)范围扩张后接着瞬时HL&F。此外,我们表明,基于先前IBD理论结果的空间明确理论框架可以修改并应用于经历HL&F的环形踏脚石模型。我们的结果表明,IBD模式在HL&F之后可以长时间维持,从而表明与过去栖息地连通性相关的特征在许多物种的遗传多样性中具有长期持续性,即使它们经历了重大且有时是古老的碎片化事件。这表明,一些现今仍表现出显著IBD模式的碎片化物种,可能在很长一段时间内(对于世代时间长的物种而言可达数万年)部分处于隔离状态。