Data from: Detecting a hierarchical genetic population structure: the case study of the Fire Salamander (Salamandra salamandra) in Northern Italy

The multi-step method here applied in studying the genetic structure of a low dispersal and philopatric species, like the Fire Salamander Salamandra salamandra, was proved to be effective in identifying the hierarchical structure of population living in broadleaved forest ecosystems in Northern Italy. In this study 477 salamander larvae, collected in 28 sampling populations (SPs) in the Prealpine and in the foothill areas of Northern Italy, were genotyped at 16 specie-specific microsatellites. SPs showed a significant overall genetic variation (Global FST=0.032, p<0.001). The genetic population structure was assessed by using STRUCTURE 2.3.4. We found two main genetic groups, one represented by populations inhabiting the Prealpine belt, which maintain connections with those of the Eastern foothill lowland (PEF), and a second group with the populations of the Western foothill lowland (WF). The two groups were significantly distinct with a Global FST of 0.010 (p<0.001). While the first group showed a moderate structure, with only one divergent sampling population (Global FST =0.006, p<0.001), the second group proved more structured being divided in four clusters (Global FST=0.017, p=0.058). This genetic population structure should be due to the large conurbations and main roads that separate the WF group from the Prealpine belt and the Eastern foothill lowland. The adopted methods allowed the analysis of the genetic population structure of Fire Salamander from wide to local scale, identifying different degrees of genetic divergence of their populations derived from forest fragmentation induced by urban and infrastructure sprawl.

本研究采用的多步分析方法，针对低扩散且具定居恋家性（philopatric）的物种（如火蝾螈（Fire Salamander, *Salamandra salamandra*））开展种群遗传结构研究，经证实可有效识别意大利北部阔叶林生态系统中种群的层级遗传结构。本研究共采集意大利北部前阿尔卑斯山区及山麓地带28个采样种群（sampling populations, SPs）的477只蝾螈幼体，利用16个物种特异性微卫星标记（microsatellites）对其进行基因分型。所有SPs均呈现显著的总体遗传分化系数（Fixation Index, FST=0.032, p<0.001）。本研究借助群体结构分析软件STRUCTURE 2.3.4对种群遗传结构进行解析，共识别出两个主要遗传类群：一类为栖息于前阿尔卑斯带的种群，该类群与东部山麓低地种群存在基因交流（PEF）；另一类为西部山麓低地种群（WF）。两类群间的总体遗传分化系数为0.010（p<0.001），差异显著。其中第一类群仅存在1个分化显著的采样种群（总体FST=0.006, p<0.001），群体结构程度中等；第二类群则呈现更强的层级结构，可进一步划分为4个聚类簇（总体FST=0.017, p=0.058）。该种群遗传结构的形成，或源于大型城市群与主要道路对WF类群与前阿尔卑斯带、东部山麓低地种群的地理隔离作用。本研究所采用的分析方法可实现火蝾螈种群遗传结构从大尺度到局域尺度的解析，明确了由城市与基础设施扩张引发的森林片段化所导致的蝾螈种群遗传分化程度差异。