Pikus Ewa, Włodarczyk Radosław, Jedlikowski Jan, Minias Piotr
Department of Biodiversity Studies and Bioeducation, University of Łódź, Łódź, Poland.
Biological and Chemical Research Centre, University of Warsaw, Warsaw, Poland.
PeerJ. 2021 Oct 5;9:e12264. doi: 10.7717/peerj.12264. eCollection 2021.
Urban sprawl is one of the most common landscape alterations occurring worldwide, and there is a growing list of species that are recognised to have adapted to urban life. To be successful, processes of urban colonization by wildlife require a broad spectrum of phenotypic (., behavioural or physiological) adjustments, but evidence for genetic adaptations is much scarcer. One hypothesis proposes that different pathogen-driven selective pressures between urban and non-urban landscapes leads to adaptations in host immune genes. Here, we examined urbanization-related differentiation at the key pathogen-recognition genes of vertebrate adaptive immunity-the major histocompatibility complex (MHC)-in a common waterbird, the Eurasian coot (). Samples were collected from an old urban population (established before the 1950s), a new urban population (established in the 2000s), and two rural populations from central Poland. We found strong significant divergence (as measured with Jost's D) at the MHC class II between the old urban population and the remaining (new urban and rural) populations. Also, there was a moderate, but significant divergence at the MHC between the new urban population and two rural populations, while no divergence was found between the two rural populations. The total number of MHC alleles and the number of private (population-specific) MHC alleles was lower in old urban populations, as compared to the rural ones. These patterns of differentiation at the MHC were not consistent with patterns found for neutral genetic markers (microsatellites), which showed few differences between the populations. Our results indicate that MHC allele composition depended on the level of anthropogenic disturbance and the time which passed since urban colonization, possibly due to the processes of genotype sorting and local adaptation. As such, our study contributes to the understanding of genetic mechanisms associated with urbanization processes in wildlife.
城市扩张是全球范围内最常见的景观变化之一，并且越来越多的物种被认为已经适应了城市生活。野生动物要成功在城市中定殖，需要进行广泛的表型（如行为或生理）调整，但遗传适应的证据却少得多。一种假说认为，城市和非城市景观之间不同的病原体驱动的选择压力导致宿主免疫基因发生适应。在这里，我们研究了一种常见水鸟——白骨顶（Fulica atra）的脊椎动物适应性免疫关键病原体识别基因——主要组织相容性复合体（MHC）与城市化相关的分化。样本采集自一个老城区种群（20世纪50年代之前就已形成）、一个新城区种群（21世纪形成）以及波兰中部的两个农村种群。我们发现，老城区种群与其余（新城区和农村）种群之间在MHC II类基因上存在强烈的显著差异（用Jost's D衡量）。此外，新城区种群与两个农村种群之间在MHC上存在中等程度但显著的差异，而两个农村种群之间未发现差异。与农村种群相比，老城区种群中MHC等位基因的总数和私有（种群特异性）MHC等位基因的数量较低。MHC的这些分化模式与中性遗传标记（微卫星）的模式不一致，后者在种群之间几乎没有差异。我们的结果表明，MHC等位基因组成取决于人为干扰水平和城市定殖后经过的时间，这可能是由于基因型分选和局部适应过程所致。因此，我们的研究有助于理解与野生动物城市化过程相关的遗传机制。
