WSL Swiss Federal Research Institute, Zürcherstrasse 111, CH-8903, Birmensdorf, Switzerland.
Mol Ecol. 2012 Dec;21(23):5640-2. doi: 10.1111/mec.12032.
Identifying landscape elements that influence gene flow and migration in wild species is the current main topic of landscape genetics. Most landscape genetic studies infer gene flow and migration from genetic distances among populations or individuals and statistically relate these measurements to landscape composition and configuration. This approach assumes symmetrical gene flow between pairs of populations. Such an assumption, however, will often be violated, especially in source–sink systems. Source populations provide more emigrants than they receive immigrants, and sink populations get many immigrants, but release few emigrants. Source–sink dynamics cannot be explored using common landscape genetic approaches relying on genetic distances. In this issue of Molecular Ecology, Andreasen et al. (2012) apply an alternative approach allowing them to infer asymmetrical migration. They use a Bayesian assignment test among objectively defined populations of mountain lions (Puma concolor) in western USA to estimate recent and directional migration rates. The study shows that an area with a high amount of wildlife refuges and low hunting pressure harbours a source population for mountain lion dispersal, while areas with high hunting pressures form sink populations; a result helpful in making informed decisions in conservation management.
确定影响野生生物基因流动和迁移的景观要素是当前景观遗传学的主要课题。大多数景观遗传学研究从种群或个体之间的遗传距离推断基因流动和迁移，并从统计学上把这些测量数据与景观组成和结构联系起来。这种方法假设种群对之间的基因流动是对称的。然而，这种假设往往会被违反，特别是在源-汇系统中。源种群提供的迁出者多于迁入者，而汇种群接收很多迁入者，但释放的迁出者很少。依赖于遗传距离的常用景观遗传学方法无法用来研究源-汇动态。在本期的《分子生态学》杂志上，Andreasen 等人（2012）应用了一种替代性方法，可以推断出不对称的迁移。他们使用贝叶斯分配测试来估计美国西部山狮（Puma concolor）客观定义的种群中的近期和定向迁移率。该研究表明，野生动物保护区数量多且狩猎压力低的地区是山狮扩散的源种群栖息地，而狩猎压力大的地区则形成汇种群；这一结果有助于在保护管理中做出明智的决策。
