Effects of disturbance on genetic diversity in the submersed aquatic plant Vallisneria americana

In summer 2011, Tropical storms Lee and Irene caused an estimated 90% decline of the submersed aquatic plant Vallisneria americana Michx. (Hydrocharitaceae) in the Hudson River, of New York (USA). To understand the genetic impact of such large-scale demographic losses, we compared diversity at 10 microsatellite loci in 135 samples collected from 5 sites just before the storms with 239 shoots collected from 9 sites four years after. Although 80% of beds sampled in 2011 lacked V. americana in 2015, we found similar genotypic and genetic diversity and effective population sizes in pre-storm versus post-storm sites. These similarities suggest that despite local extirpations concentrated at the upstream end of the sampling area, V. americana was regionally resistant to genetic losses. Similar geographically based structure among sites in both sampling periods suggested that cryptic local refugia at previously occupied sites facilitated re-expansion after the storms. However, this apparent re...2011年夏季，热带风暴李（Tropical Storm Lee）与艾琳（Irene）致使美国纽约州哈德逊河中的沉水水生植物苦草（Vallisneria americana Michx.，水鳖科Hydrocharitaceae）种群数量估计下降90%。为厘清此类大规模种群衰退带来的遗传影响，本研究对比了风暴前从5个采样点采集的135份样本，与四年后从9个采样点采集的239株植株在10个微卫星位点（microsatellite loci）上的多样性差异。尽管2011年采样的80%水生植物群落在2015年已无苦草分布，但研究发现风暴前与风暴后采样点的基因型多样性、遗传多样性及有效种群规模均无显著差异。上述相似性表明，即便采样区域上游集中发生了局部灭绝，苦草在区域尺度上仍未出现遗传多样性流失。两个采样时期中，各采样点间均呈现出相似的地理空间遗传结构，这暗示先前分布区域内存在隐秘的本地避难所，助力风暴后种群的重新扩张。然而这一表观上的恢复……