PDF(Pubmed)
Abstract：
Numerous terrestrial mammal species have experienced extensive population declines during past centuries, due largely to anthropogenic pressures. For some species, including the Eurasian otter (Lutra lutra), environmental and legal protection has more recently led to population growth and recolonization of parts of their historic ranges. While heralded as conservation success, only few such recoveries have been examined from a genetic perspective, i.e. whether genetic variability and connectivity have been restored. We here use large-scale and long-term genetic monitoring data from UK otters, whose population underwent a well-documented population decline between the 1950s and 1970s, to explore the dynamics of a population re-expansion over a 21-year period. We genotyped otters from across Wales and England at five time points between 1994 and 2014 using 15 microsatellite loci. We used this combination of long-term temporal and large-scale spatial sampling to evaluate 3 hypotheses relating to genetic recovery that (i) gene flow between subpopulations would increase over time, (ii) genetic diversity of previously isolated populations would increase and that (iii) genetic structuring would weaken over time. Although we found an increase in inter-regional gene flow and admixture levels among subpopulations, there was no significant temporal change in either heterozygosity or allelic richness. Genetic structuring among the main subpopulations hence remained strong and showed a clear historical continuity. These findings highlight an underappreciated aspect of population recovery of endangered species: that genetic recovery may often lag behind the processes of spatial and demographic recovery. In other words, the restoration of the physical connectivity of populations does not necessarily lead to genetic connectivity. Our findings emphasize the need for genetic data as an integral part of conservation monitoring, to enable the potential vulnerability of populations to be evaluated.
摘要：
在过去的几个世纪中，许多陆地哺乳动物物种经历了广泛的种群减少，主要是由于人为的压力。对于一些物种来说,包括欧亚水獭（Lutralutra），环境和法律保护最近导致人口增长和部分历史范围的重新定居。虽然预示着保护的成功，从遗传的角度来看，只有很少的这样的恢复，即遗传变异性和连通性是否已经恢复。我们在这里使用英国水獭的大规模和长期遗传监测数据，其人口在1950年代至1970年代之间经历了有据可查的人口减少，探索21年人口再扩张的动态。我们使用15个微卫星基因座在1994年至2014年之间的五个时间点对来自威尔士和英格兰的水獭进行了基因分型。我们使用这种长期时间和大规模空间采样的组合来评估与遗传恢复有关的3个假设，即（i）亚群之间的基因流会随着时间的推移而增加，（ii）先前孤立种群的遗传多样性会增加，并且（iii）遗传结构会随着时间的推移而减弱。尽管我们发现亚种群之间的区域间基因流动和混合水平增加，杂合性或等位基因丰富度没有显著的时间变化。因此，主要亚群之间的遗传结构仍然很强，并显示出明显的历史连续性。这些发现凸显了濒危物种种群恢复的一个未被重视的方面：遗传恢复通常可能落后于空间和人口恢复的过程。换句话说,种群物理连接的恢复不一定导致遗传连接。我们的发现强调了遗传数据作为保护监测不可或缺的一部分的必要性，以便能够评估人口的潜在脆弱性。
