Zappes Ighor Antunes, Fabiani Anna, Sbordoni Valerio, Rakaj Arnold, Palozzi Roberto, Allegrucci Giuliana
Department of Biology, University of Rome Tor Vergata, Rome, Lazio, Italy.
PLoS One. 2017 Aug 10;12(8):e0182922. doi: 10.1371/journal.pone.0182922. eCollection 2017.
In this paper, we studied the genetic variability in Weddell seal from colonies in Terra Nova Bay and Wood Bay, both sites located in the Ross Sea area, Antarctica. Two mitochondrial genes and one nuclear gene, with different mutation rates, were sequenced to investigate the haplotype diversity of the colonies and to test for a possible recent expansion. Fifteen microsatellites were used to analyze their genetic structure. Sequenced genes and microsatellites were also used to estimate the effective population size of the studied colonies and the Ross Sea seal population. The Ross Sea has a high density population of Weddel seals, with an estimated effective number of 50,000 females, and 1,341 individuals for the sampling area, possibly due to its high primary production. The colonies showed high diversity (Hd > 0.90) and many exclusive haplotypes (> 75%), likely a consequence of the surprisingly high site fidelity of Weddell seals, despite the proximity of the colonies. Nevertheless, there was low microsatellite differentiation between colonies, suggesting that they are part of a single larger population. Their expansion seemed to have started during the last glacial cycle (around 58,000 years ago), indicating that the Ross Sea seal populations have been present in the area for long time, probably due to the lack of hunting by humans and terrestrial predation. As a top predator, the role of Weddell seals in the Ross Sea ecology is crucial, and its demographic dynamics should be monitored to follow the future changes of such an important ecosystem.
在本文中，我们研究了南极罗斯海地区的特拉诺瓦湾和伍德湾殖民地威德尔海豹的遗传变异性。对两个线粒体基因和一个具有不同突变率的核基因进行了测序，以调查殖民地的单倍型多样性，并测试是否可能存在近期扩张。使用15个微卫星来分析它们的遗传结构。测序的基因和微卫星也用于估计所研究殖民地和罗斯海海豹种群的有效种群大小。罗斯海威德尔海豹种群密度很高，估计有效雌性数量为50,000只，采样区域有1,341只个体，这可能是由于其初级生产力高。这些殖民地表现出高度的多样性（Hd>0.90）和许多独特的单倍型（>75%），尽管殖民地距离很近，但这可能是威德尔海豹惊人的高地点忠诚度的结果。然而，殖民地之间的微卫星分化程度较低，这表明它们是一个更大单一种群的一部分。它们的扩张似乎始于上一个冰川周期（约58,000年前），这表明罗斯海海豹种群在该地区已经存在很长时间，可能是由于缺乏人类捕猎和陆地捕食。作为顶级捕食者，威德尔海豹在罗斯海生态系统中的作用至关重要，应该监测其种群动态以跟踪这一重要生态系统未来的变化。
