Otalora Katherin, Riera Joan Lluís, Tavecchia Giacomo, Rotger Andreu, Igual José Manuel, Trotta Jean-Remi Paul, Baldo Laura
Department of Evolutionary Biology, Ecology and Environmental Sciences, Biology Faculty University of Barcelona (UB) Barcelona Spain.
Fundación FUNMAJO, EBA, RAIEC, Biodiversity Branch Tunja Boyacá Colombia.
Ecol Evol. 2024 May 23;14(5):e11407. doi: 10.1002/ece3.11407. eCollection 2024 May.
Islands provide a great system to explore the processes that maintain genetic diversity and promote local adaptation. We explored the genomic diversity of the Balearic lizard , an endemic species characterized by numerous small insular populations with large phenotypic diversity. Using the newly available genome for this species, we characterized more than 300,000 SNPs, merging genotyping-by-sequencing (GBS) data with previously published restriction site-associated DNA sequencing (RAD-Seq) data, providing a dataset of 16 island populations (191 individuals) across the range of species distribution (Menorca, Mallorca, and Cabrera). Results indicate that each islet hosts a well-differentiated population ( = 0.247 ± 0.09), with no recent immigration/translocation events. Contrary to expectations, most populations harbor a considerable genetic diversity (mean nucleotide diversity, = 0.144 ± 0.021), characterized by overall low inbreeding values ( < 0.1). While the genetic diversity significantly decreased with decreasing islet surface, maintenance of substantial genetic diversity even in tiny islets suggests variable selection or other mechanisms that buffer genetic drift. Maximum-likelihood tree based on concatenated SNP data confirmed the existence of the two major independent lineages of Menorca and Mallorca/Cabrera. Multiple lines of evidence, including admixture and root testing, robustly placed the origin of the species in the Mallorca Island, rather than in Menorca. Outlier analysis mainly retrieved a strong signature of genome differentiation between the two major archipelagos, especially in the sexual chromosome Z. A set of proteins were target of multiple outliers and primarily associated with binding and catalytic activity, providing interesting candidates for future selection studies. This study provides the framework to explore crucial aspects of the genetic basis of phenotypic divergence and insular adaptation.
岛屿为探索维持遗传多样性和促进局部适应的过程提供了一个绝佳的系统。我们研究了巴利阿里蜥蜴的基因组多样性，这是一种特有物种，其特征是有众多小型岛屿种群，具有很大的表型多样性。利用该物种新获得的基因组，我们对30多万个单核苷酸多态性（SNP）进行了特征分析，将测序基因分型（GBS）数据与先前发表的限制性位点相关DNA测序（RAD-Seq）数据合并，提供了一个涵盖该物种分布范围（梅诺卡岛、马略卡岛和卡夫雷拉岛）的16个岛屿种群（191个个体）的数据集。结果表明，每个小岛都有一个分化良好的种群（FST = 0.247 ± 0.09），近期没有移民/迁移事件。与预期相反，大多数种群拥有相当高的遗传多样性（平均核苷酸多样性，π = 0.144 ± 0.021），其特征是总体近亲繁殖值较低（FIS < 0.1）。虽然遗传多样性随着小岛面积的减小而显著降低，但即使在微小的小岛上也能维持大量的遗传多样性，这表明存在可变选择或其他缓冲遗传漂变的机制。基于串联SNP数据的最大似然树证实了梅诺卡岛和马略卡岛/卡夫雷拉岛两个主要独立谱系的存在。包括混合分析和根检验在内的多条证据有力地表明该物种起源于马略卡岛，而非梅诺卡岛。异常值分析主要发现了两个主要群岛之间基因组分化的强烈信号，尤其是在性染色体Z上。一组蛋白质是多个异常值的靶点，主要与结合和催化活性相关，为未来的选择研究提供了有趣的候选对象。本研究为探索表型分化和岛屿适应的遗传基础的关键方面提供了框架。
