Daco Laura, Matthies Diethart, Hermant Sylvie, Colling Guy
Musée national d'histoire naturelle Luxembourg Luxembourg.
University of Marburg, Department of Biology Marburg Germany.
Ecol Evol. 2022 Aug 4;12(8):e9167. doi: 10.1002/ece3.9167. eCollection 2022 Aug.
The abundant centre model (ACM) predicts that the suitability of environmental conditions for a species decreases from the centre of its distribution toward its range periphery and, consequently, its populations will become scarcer, smaller and more isolated, resulting in lower genetic diversity and increased differentiation. However, little is known about whether genetic diversity shows similar patterns along elevational and latitudinal gradients with similar changes in important environmental conditions. Using microsatellite markers, we studied the genetic diversity and structure of 20 populations each of along elevational gradients in the Alps from the valleys to the elevational limit (2500 m) and along a latitudinal gradient (2500 km) from Central Europe to the range margin in northern Scandinavia. Both types of gradients corresponded to an 11.5°C difference in mean annual temperature. Genetic diversity strongly declined and differentiation increased with latitude in line with the predictions of the ACM. However, as population size did not decline with latitude and genetic diversity was not related to population size in , this pattern is not likely to be due to less favorable conditions in the North, but due to serial founder effects during the post-glacial recolonization process. Genetic diversity was not related to elevation, but we found significant isolation by distance along both gradients, although the elevational gradient was shorter by orders of magnitude. Subarctic populations differed genetically from alpine populations indicating that the northern populations did not originate from high elevational Alpine ones. Our results support the notion that postglacial latitudinal colonization over large distances resulted in a larger loss of genetic diversity than elevational range shifts. The lack of genetic diversity in subarctic populations may threaten their long-term persistence in the face of climate change, whereas alpine populations could benefit from gene flow from low-elevation populations.
丰富中心模型（ACM）预测，环境条件对某一物种的适宜性从其分布中心向分布边缘递减，因此，其种群数量将变得更加稀少、规模更小且更加孤立，从而导致遗传多样性降低和分化增加。然而，对于遗传多样性是否会在海拔和纬度梯度上呈现出类似模式，且重要环境条件发生类似变化，我们却知之甚少。我们使用微卫星标记，研究了阿尔卑斯山脉从山谷到海拔上限（2500米）的海拔梯度上以及从中欧到斯堪的纳维亚半岛北部分布边缘的2500公里纬度梯度上各20个种群的遗传多样性和结构。这两种梯度对应的年均温度差异均为11.5°C。与ACM的预测一致，遗传多样性随纬度强烈下降，分化增加。然而，由于种群规模并未随纬度下降，且遗传多样性与种群规模无关，这种模式不太可能是由于北方条件较差，而是由于冰期后重新定殖过程中的连续奠基者效应。遗传多样性与海拔无关，但我们发现沿着这两种梯度均存在显著的距离隔离，尽管海拔梯度短了几个数量级。亚北极种群在遗传上与高山种群不同，这表明北方种群并非起源于高海拔的高山种群。我们的结果支持这样一种观点，即冰期后远距离的纬度定殖导致的遗传多样性丧失比海拔范围变化更大。面对气候变化，亚北极种群缺乏遗传多样性可能会威胁到它们的长期存续，而高山种群可能会从低海拔种群的基因流动中受益。
