Ortego Joaquín, Aparicio Jose Miguel, Calabuig Gustau, Cordero Pedro J
Grupo de Investigación de la Biodiversidad Genética y Cultural, Instituto de Investigación en Recursos Cinegéticos - IREC (CSIC, UCLM, JCCM), Ronda de Toledo s/n, E-13005 Ciudad Real, Spain.
Mol Ecol. 2007 Sep;16(17):3712-20. doi: 10.1111/j.1365-294X.2007.03406.x.
Parasites and infectious diseases are major determinants of population dynamics and adaptive processes, imposing fitness costs to their hosts and promoting genetic variation in natural populations. In the present study, we evaluate the role of individual genetic diversity on risk of parasitism by feather lice Degeeriella rufa in a wild lesser kestrel population (Falco naumanni). Genetic diversity at 11 microsatellite loci was associated with risk of parasitism by feather lice, with more heterozygous individuals being less likely to be parasitized, and this effect was statistically independent of other nongenetic parameters (colony size, sex, location, and year) which were also associated with lice prevalence. This relationship was nonlinear, with low and consistent prevalences among individuals showing high levels of genetic diversity that increased markedly at low levels of individual heterozygosity. This result appeared to reflect a genome-wide effect, with no single locus contributing disproportionably to the observed effect. Thus, overall genetic variation, rather than linkage of markers to genes experiencing single-locus heterosis, seems to be the underlying mechanism determining the association between risk of parasitism and individual genetic diversity in the study host-parasite system. However, feather lice burden was not affected by individual heterozygosity; what suggest that differences in susceptibility, rather than variation in defences once the parasite has been established, may shape the observed pattern. Overall, our results highlight the role of individual genetic diversity on risk of parasitism in wild populations, what has both important evolutionary implications and major consequences for conservation research on the light of emerging infectious diseases that may endanger genetically depauperated populations.
寄生虫和传染病是种群动态和适应性过程的主要决定因素，给宿主带来适应性代价，并促进自然种群中的遗传变异。在本研究中，我们评估了个体遗传多样性在野生红脚隼（Falco naumanni）种群中遭受 Rufa 羽虱寄生风险方面的作用。11 个微卫星位点的遗传多样性与羽虱寄生风险相关，杂合度更高的个体被寄生的可能性较小，并且这种效应在统计上独立于其他也与虱子患病率相关的非遗传参数（群体大小、性别、位置和年份）。这种关系是非线性的，在遗传多样性水平高的个体中患病率低且一致，而在个体杂合度低时患病率显著增加。这一结果似乎反映了全基因组效应，没有单个位点对观察到的效应有不成比例的贡献。因此，总体遗传变异，而非标记与经历单基因杂种优势的基因的连锁，似乎是决定研究的宿主 - 寄生虫系统中寄生风险与个体遗传多样性之间关联的潜在机制。然而，羽虱负担不受个体杂合度影响；这表明易感性差异，而非寄生虫建立后防御能力的变化，可能塑造了观察到的模式。总体而言，我们的结果突出了个体遗传多样性在野生种群寄生风险中的作用，这对于新兴传染病可能危及遗传贫乏种群的情况，在进化方面具有重要意义，对保护研究也有重大影响。
