Jha S
Department of Integrative Biology, The University of Texas at Austin, 401 Biological Laboratories, Austin, TX, 78712, USA.
Mol Ecol. 2015 Mar;24(5):993-1006. doi: 10.1111/mec.13090.
Much of the world's terrestrial landscapes are being altered by humans in the form of agriculture, urbanization and pastoral systems, with major implications for biodiversity. Bumble bees are one of the most effective pollinators in both natural and cultivated landscapes, but are often the first to be extirpated in human-altered habitats. Yet, little is known about the role of natural and human-altered habitats in promoting or limiting bumble bee gene flow. In this study, I closely examine the genetic structure of the yellow-faced bumble bee, Bombus vosnesenskii, across the southwestern US coast and find strong evidence that natural oceanic barriers, as well as contemporary human-altered habitats, limit bee gene flow. Heterozygosity and allelic richness were lower in island populations, while private allelic richness was higher in island populations compared to mainland populations. Genetic differentiation, measured for three indices across the 1000 km study region, was significantly greater than the null expectation (F(ST) = 0.041, F'(ST) = 0.044 and D(est) = 0.155) and correlated with geographic distance. Furthermore, genetic differentiation patterns were most strongly correlated with contemporary (2011) not past (2006, 2001) resistance maps calibrated for high dispersal limitation over oceans, impervious habitat and croplands. Despite the incorporation of dramatic elevation gradients, the analyses reveal that oceans and contemporary human land use, not mountains, are the primary dispersal barriers for B. vosnesenskii gene flow. These findings reinforce the importance of maintaining corridors of suitable habitat across the distribution range of native pollinators to promote their persistence and safeguard their ability to provide essential pollination services.
世界上许多陆地景观正以农业、城市化和畜牧系统的形式被人类改变，这对生物多样性产生了重大影响。熊蜂是自然景观和人工栽培景观中最有效的传粉者之一，但往往是在人类改变的栖息地中最先灭绝的物种。然而，对于自然栖息地和人类改变的栖息地在促进或限制熊蜂基因流动方面所起的作用，人们知之甚少。在这项研究中，我仔细研究了美国西南海岸黄脸熊蜂（Bombus vosnesenskii）的遗传结构，发现有力证据表明，自然海洋屏障以及当代人类改变的栖息地限制了蜜蜂的基因流动。岛屿种群的杂合度和等位基因丰富度较低，而与大陆种群相比，岛屿种群的私有等位基因丰富度较高。在1000公里的研究区域内，通过三个指标测量的遗传分化显著大于零假设预期值（F(ST) = 0.041，F'(ST) = 0.044，D(est) = 0.155），并且与地理距离相关。此外，遗传分化模式与当代（2011年）而非过去（2006年、2001年）针对海洋、不透水栖息地和农田的高扩散限制校准的抗性地图相关性最强。尽管纳入了显著的海拔梯度，但分析表明，海洋和当代人类土地利用而非山脉是黄脸熊蜂基因流动的主要扩散障碍。这些发现强化了在本地传粉者分布范围内维持适宜栖息地走廊的重要性，以促进它们的生存，并保障它们提供重要传粉服务的能力。
