Levy E, Byrne M, Coates D J, Macdonald B M, McArthur S, van Leeuwen S
Science and Conservation Division, Department of Parks and Wildlife, Perth, Western Australia, Australia.
PLoS One. 2016 Oct 21;11(10):e0163995. doi: 10.1371/journal.pone.0163995. eCollection 2016.
The influence of geographic range on species persistence has long been of interest and there is a need for a better understanding of the genetic consequences for species with restricted distributions, particularly with the increasing rate of global species extinctions. However, the genetic effects of restricted range are often confounded by the impacts of population distribution. We compared chloroplast and nuclear genetic diversity and differentiation in two acacias, the restricted, patchily distributed Acacia atkinsiana and the widespread, semi-continuously distributed A. ancistrocarpa. Lower intra-population diversity and higher differentiation between populations were seen in A. atkinsiana compared to its widespread congener, A. ancistrocarpa. There was little evidence of geographical influences on population genetic structure in A. ancistrocarpa whereas A. atkinsiana exhibited nuclear genetic structure with isolation by distance, differentiation of near-coastal populations from those in the ranges, and differentiation of peripheral populations from those in the centre of the distribution. These results are consistent with expectations of the effect of geographic range and population distribution on genetic diversity, but indicate that distribution of populations rather than geographic range has influenced the observed genetic structure. The contrasting patterns observed here demonstrate that conservation approaches for species management and ecological restoration need to consider the distribution of populations in geographically restricted species.
地理分布范围对物种存续的影响长期以来备受关注，而且有必要更好地理解分布受限物种的遗传后果，尤其是在全球物种灭绝速率不断上升的情况下。然而，分布范围受限的遗传效应常常因种群分布的影响而混淆。我们比较了两种金合欢的叶绿体和核基因多样性及分化情况，即分布受限、呈斑块状分布的阿特金斯金合欢（Acacia atkinsiana）和分布广泛、呈半连续分布的弯果金合欢（A. ancistrocarpa）。与分布广泛的同属物种弯果金合欢相比，阿特金斯金合欢的种群内多样性较低，种群间分化较高。几乎没有证据表明地理因素对弯果金合欢的种群遗传结构有影响，而阿特金斯金合欢则表现出核基因结构的距离隔离，近岸种群与内陆种群的分化，以及边缘种群与分布中心种群的分化。这些结果与地理分布范围和种群分布对遗传多样性影响的预期一致，但表明种群分布而非地理分布范围影响了观察到的遗传结构。此处观察到的对比模式表明，物种管理和生态恢复的保护方法需要考虑地理分布受限物种的种群分布情况。
