Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Barcelona, Spain.
Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain.
Mol Ecol. 2024 Nov;33(22):e17547. doi: 10.1111/mec.17547. Epub 2024 Oct 14.
The spider genus Dysdera has undergone a remarkable diversification in the oceanic archipelago of the Canary Islands, with ~60 endemic species having originated during the 20 million years since the origin of the archipelago. This evolutionary radiation has been accompanied by substantial dietary shifts, often characterised by phenotypic modifications encompassing morphological, metabolic and behavioural changes. Hence, these endemic spiders represent an excellent model for understanding the evolutionary drivers and to pinpoint the genomic determinants underlying adaptive radiations. Recently, we achieved the first chromosome-level genome assembly of one of the endemic species, D. silvatica, providing a high-quality reference sequence for evolutionary genomics studies. Here, we conducted a low coverage-based resequencing study of a natural population of D. silvatica from La Gomera island. Taking advantage of the new high-quality genome, we characterised genome-wide levels of nucleotide polymorphism, divergence and linkage disequilibrium, and inferred the demographic history of this population. We also performed comprehensive genome-wide scans for recent positive selection. Our findings uncovered exceptionally high levels of nucleotide diversity and recombination in this geographically restricted endemic species, indicative of large historical effective population sizes. We also identified several candidate genomic regions that are potentially under positive selection, highlighting relevant biological processes, such as vision and nitrogen extraction as potential adaptation targets. These processes may ultimately drive species diversification in this genus. This pioneering study of spiders that are endemic to an oceanic archipelago lays the groundwork for broader population genomics analyses aimed at understanding the genetic mechanisms driving adaptive radiation in island ecosystems.
在加那利群岛的海洋群岛中，狼蛛属经历了显著的多样化，自群岛起源以来的 2000 万年中，约有 60 个特有种起源。这种进化辐射伴随着大量的饮食变化，通常表现为包括形态、代谢和行为变化在内的表型修饰。因此，这些特有种蜘蛛是理解进化驱动因素和确定适应辐射背后的基因组决定因素的绝佳模型。最近，我们完成了其中一个特有种 D. silvatica 的首个染色体水平基因组组装，为进化基因组学研究提供了高质量的参考序列。在这里，我们对来自拉戈梅拉岛的 D. silvatica 自然种群进行了基于低覆盖的重测序研究。利用新的高质量基因组，我们对该种群的全基因组核苷酸多态性、分歧和连锁不平衡进行了特征描述，并推断了该种群的历史人口动态。我们还进行了全面的全基因组近期正选择扫描。我们的发现揭示了这个地理上受限制的特有种中异常高的核苷酸多样性和重组水平，表明其历史上的有效种群规模较大。我们还确定了几个可能处于正选择下的候选基因组区域，突出了一些相关的生物学过程，如视觉和氮提取，作为潜在的适应目标。这些过程可能最终推动了该属中物种的多样化。这项对海洋群岛特有蜘蛛的开创性研究为更广泛的种群基因组学分析奠定了基础，旨在理解驱动岛屿生态系统中适应辐射的遗传机制。
