López-Uribe Margarita M, Morreale Stephen J, Santiago Christine K, Danforth Bryan N
Department of Entomology, Cornell University, Ithaca, New York, 14853, United States of America.
Department of Natural Resources, Cornell University, Ithaca, New York, 14853, United States of America.
PLoS One. 2015 May 7;10(5):e0125719. doi: 10.1371/journal.pone.0125719. eCollection 2015.
Bees are the primary pollinators of flowering plants in almost all ecosystems. Worldwide declines in bee populations have raised awareness about the importance of their ecological role in maintaining ecosystem functioning. The naturally strong philopatric behavior that some bee species show can be detrimental to population viability through increased probability of inbreeding. Furthermore, bee populations found in human-altered landscapes, such as urban areas, can experience lower levels of gene flow and effective population sizes, increasing potential for inbreeding depression in wild bee populations. In this study, we investigated the fine-scale population structure of the solitary bee Colletes inaequalis in an urbanized landscape. First, we developed a predictive spatial model to detect suitable nesting habitat for this ground nesting bee and to inform our field search for nests. We genotyped 18 microsatellites in 548 female individuals collected from nest aggregations throughout the study area. Genetic relatedness estimates revealed that genetic similarity among individuals was slightly greater within nest aggregations than among randomly chosen individuals. However, genetic structure among nest aggregations was low (Nei's GST = 0.011). Reconstruction of parental genotypes revealed greater genetic relatedness among females than among males within nest aggregations, suggesting male-mediated dispersal as a potentially important mechanism of population connectivity and inbreeding avoidance. Size of nesting patch was positively correlated with effective population size, but not with other estimators of genetic diversity. We detected a positive trend between geographic distance and genetic differentiation between nest aggregations. Our landscape genetic models suggest that increased urbanization is likely associated with higher levels of inbreeding. Overall, these findings emphasize the importance of density and distribution of suitable nesting patches for enhancing bee population abundance and connectivity in human dominated habitats and highlights the critical contribution of landscape genetic studies for enhanced conservation and management of native pollinators.
蜜蜂是几乎所有生态系统中开花植物的主要传粉者。全球蜜蜂数量的减少提高了人们对其在维持生态系统功能方面生态作用重要性的认识。一些蜜蜂物种表现出的天生强烈的恋巢行为可能会因近亲繁殖概率增加而对种群生存力产生不利影响。此外，在人类改变的景观（如城市地区）中发现的蜜蜂种群可能会经历较低水平的基因流动和有效种群大小，增加野生蜜蜂种群近亲繁殖衰退的可能性。在本研究中，我们调查了城市化景观中独居蜜蜂不等集蜂的精细种群结构。首先，我们开发了一个预测空间模型，以检测这种地栖蜜蜂的合适筑巢栖息地，并为我们在野外寻找巢穴提供信息。我们对从整个研究区域的巢穴聚集中收集的548只雌性个体的18个微卫星进行了基因分型。遗传相关性估计表明，巢穴聚集中个体之间的遗传相似性略高于随机选择的个体之间。然而，巢穴聚集之间的遗传结构较低（内氏GST = 0.011）。亲本基因型的重建显示，巢穴聚集中雌性之间的遗传相关性高于雄性之间，这表明雄性介导的扩散是种群连通性和避免近亲繁殖的潜在重要机制。筑巢斑块的大小与有效种群大小呈正相关，但与其他遗传多样性估计值无关。我们检测到巢穴聚集之间的地理距离和遗传分化之间存在正趋势。我们的景观遗传模型表明，城市化程度的提高可能与更高水平的近亲繁殖有关。总体而言，这些发现强调了合适筑巢斑块的密度和分布对于提高人类主导栖息地中蜜蜂种群丰度和连通性的重要性，并突出了景观遗传研究对加强本地传粉者保护和管理的关键贡献。
