School of Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, UK.
Proc Biol Sci. 2011 Apr 22;278(1709):1195-202. doi: 10.1098/rspb.2010.1550. Epub 2010 Oct 6.
Inbreeding and a consequent loss of genetic diversity threaten small, isolated populations. One mechanism by which genetically impoverished populations may become extinct is through decreased immunocompetence and higher susceptibility to parasites. Here, we investigate the relationship between immunity and inbreeding in bumblebees, using Hebridean island populations of Bombus muscorum. We sampled nine populations and recorded parasite prevalence and measured two aspects of immunity: the encapsulation response and levels of phenoloxidase (PO). We found that prevalence of the gut parasite Crithidia bombi was higher in populations with lower genetic diversity. Neither measure of immune activity was correlated with genetic diversity. However, levels of PO declined with age and were also negatively correlated with parasite abundance. Our results suggest that as insect populations lose heterozygosity, the impact of parasitism will increase, pushing threatened populations closer to extinction.
近亲繁殖和随之而来的遗传多样性丧失威胁着小型、孤立的种群。遗传贫瘠的种群可能灭绝的一个机制是免疫能力下降和对寄生虫的易感性增加。在这里，我们使用赫布里底群岛的 Bombus muscorum 岛种群研究了蜜蜂的免疫与近亲繁殖之间的关系。我们对 9 个种群进行了采样，记录了寄生虫的流行率，并测量了免疫的两个方面：包囊反应和酚氧化酶（PO）水平。我们发现，肠道寄生虫 Crithidia bombi 的流行率在遗传多样性较低的种群中更高。免疫活性的这两个指标都与遗传多样性无关。然而，PO 水平随年龄下降，与寄生虫丰度呈负相关。我们的结果表明，随着昆虫种群失去杂合性，寄生虫的影响将会增加，从而使受威胁的种群更接近灭绝。
