Schregel Julia, Kopatz Alexander, Eiken Hans Geir, Swenson Jon E, Hagen Snorre B
Norwegian Institute of Bioeconomy Research, NIBIO - Svanhovd, Svanvik, Norway.
Norwegian University of Life Sciences, Faculty of Environmental Sciences and Natural Resource Management, Ǻs, Norway.
PLoS One. 2017 Jul 3;12(7):e0180701. doi: 10.1371/journal.pone.0180701. eCollection 2017.
The degree of gene flow within and among populations, i.e. genetic population connectivity, may closely track demographic population connectivity. Alternatively, the rate of gene flow may change relative to the rate of dispersal. In this study, we explored the relationship between genetic and demographic population connectivity using the Scandinavian brown bear as model species, due to its pronounced male dispersal and female philopatry. Thus, we expected that females would shape genetic structure locally, whereas males would act as genetic mediators among regions. To test this, we used eight validated microsatellite markers on 1531 individuals sampled noninvasively during country-wide genetic population monitoring in Sweden and Norway from 2006 to 2013. First, we determined sex-specific genetic structure and substructure across the study area. Second, we compared genetic differentiation, migration/gene flow patterns, and spatial autocorrelation results between the sexes both within and among genetic clusters and geographic regions. Our results indicated that demographic connectivity was not a reliable indicator of genetic connectivity. Among regions, we found no consistent difference in long-term gene flow and estimated current migration rates between males and females. Within regions/genetic clusters, only females consistently displayed significant positive spatial autocorrelation, indicating male-biased small-scale dispersal. In one cluster, however, males showed a dispersal pattern similar to females. The Scandinavian brown bear population has experienced substantial recovery over the last decades; however, our results did not show any changes in its large-scale population structure compared to previous studies, suggesting that an increase in population size and dispersal of individuals does not necessary lead to increased genetic connectivity. Thus, we conclude that both genetic and demographic connectivity should be estimated, so as not to make false assumptions about the reality of wildlife populations.
种群内部和种群之间的基因流动程度，即遗传种群连通性，可能与种群的人口统计学连通性密切相关。或者，基因流动速率可能相对于扩散速率发生变化。在本研究中，我们以斯堪的纳维亚棕熊为模式物种，探讨遗传和种群人口统计学连通性之间的关系，因为该物种具有明显的雄性扩散和雌性留居特征。因此，我们预计雌性会在局部塑造遗传结构，而雄性则会在不同区域间充当遗传媒介。为了验证这一点，我们在2006年至2013年瑞典和挪威全国性遗传种群监测期间，对1531个通过非侵入性采样获得的个体，使用了8个经过验证的微卫星标记。首先，我们确定了整个研究区域内特定性别的遗传结构和亚结构。其次，我们比较了遗传簇和地理区域内部及之间两性的遗传分化、迁移/基因流动模式以及空间自相关结果。我们的结果表明，人口统计学连通性并非遗传连通性可靠的指标。在不同区域之间，我们发现雄性和雌性在长期基因流动以及估计的当前迁移率方面没有一致的差异。在区域/遗传簇内部，只有雌性始终表现出显著的正空间自相关性，表明存在雄性偏向的小规模扩散。然而，在一个遗传簇中，雄性表现出与雌性相似的扩散模式。在过去几十年里，斯堪的纳维亚棕熊种群数量大幅回升；然而，与之前的研究相比，我们的结果并未显示其大规模种群结构有任何变化，这表明种群数量的增加和个体的扩散并不一定会导致遗传连通性的增强。因此，我们得出结论，应该同时估计遗传连通性和人口统计学连通性，以免对野生动物种群的实际情况做出错误假设。
