Female-biased dispersal and non-random gene flow of MC1R variants do not result in a migration load in barn owls

Non-random gene flow is a widely neglected force in evolution and ecology. This genotype-dependent dispersal is difficult to assess, yet can impact the genetic variation of natural populations and their fitness. In this work, we demonstrate a high immigration rate of barn owls (Tyto alba) inside a Swiss population surveyed during 15 years. Using 10 microsatellite loci as an indirect method to characterize dispersal, two third of the genetic tests failed to detect a female-biased dispersal, and Monte-Carlo simulations confirmed a low statistical power to detect sex-biased dispersal in case of high dispersal rate of both sexes. The capture-recapture data revealed a female-biased dispersal associated with an excess of heterozygote for the melanocortin-1 receptor gene (MC1R), which is responsible for their ventral rufous coloration. Thus, female homozygotes for the MC1R_white allele might be negatively selected during dispersal. Despite the higher immigration of females that are heterozygot...

非随机基因流是进化与生态学领域长期被忽视的关键驱动力。此类依赖于基因型的扩散行为虽难以评估，却可对自然种群的遗传变异及其适合度造成显著影响。本研究针对瑞士一个为期15年的监测仓鸮（Tyto alba）种群展开分析，证实该种群存在较高的个体迁入率。研究以10个微卫星位点（microsatellite loci）作为表征扩散行为的间接标记，结果显示三分之二的遗传检测未能检出雌性偏向性扩散；蒙特卡洛（Monte-Carlo）模拟证实，当两性扩散速率均较高时，检测性别偏向性扩散的统计效力偏低。标记重捕数据则显示，雌性偏向性扩散与黑皮质素-1受体基因（MC1R）的杂合子过剩现象存在关联——该基因负责调控仓鸮腹部的红棕色羽色。据此推测，携带MC1R_white等位基因的雌性纯合子可能在扩散过程中受到负选择。尽管杂合子雌性的迁入率更高……