Patterns of range-wide genetic variation in six North American bumble bee (Apidae: Bombus) species

The increasing evidence for population declines in bumble bee (Bombus) species worldwide has accelerated research efforts to explain losses in these important pollinators. In North America, a number of once widespread Bombus species have suffered serious reductions in range and abundance, although other species remain healthy. To examine whether declining and stable species exhibit different levels of genetic diversity or population fragmentation, we genotyped a set of microsatellite markers from populations sampled across the geographic distributions of two declining (B. occidentalis; B. pensylvanicus) and four stable (B. bifarius; B. vosnesenskii; B. impatiens; B. bimaculatus) Bombus species. Populations of declining species generally have reduced levels of genetic diversity throughout their range compared to co-distributed stable species. Genetic diversity can be affected by overall range size and degree of isolation of local populations, potentially confounding comparisons among spe...全球范围内熊蜂属（Bombus）物种种群衰退的相关证据日益增多，推动学界加大研究力度以阐明这类重要传粉昆虫的种群衰退机制。在北美地区，诸多曾广泛分布的熊蜂物种种群的分布范围与种群丰度均出现严重缩减，而另有部分物种种群仍保持健康状态。为探究衰退型与稳定型熊蜂物种的遗传多样性水平或种群碎片化（population fragmentation）程度是否存在差异，本研究针对覆盖这6种熊蜂各自地理分布范围的种群样本，对一组微卫星标记（microsatellite marker）开展了基因分型分析；其中衰退型熊蜂共2种：西方熊蜂（Bombus occidentalis）、宾夕法尼亚熊蜂（Bombus pensylvanicus），稳定型熊蜂共4种：双带熊蜂（Bombus bifarius）、沃氏熊蜂（Bombus vosnesenskii）、印地安熊蜂（Bombus impatiens）、二斑熊蜂（Bombus bimaculatus）。相较于同域分布的稳定型熊蜂种群，衰退型熊蜂种群在其整个分布范围内的遗传多样性水平普遍偏低。遗传多样性会受种群整体分布范围大小以及局域种群的隔离程度影响，这可能会对不同物种间的比较分析造成混杂偏倚……