Zimmer Stefanie M, Krehenwinkel Henrik, Schneider Jutta M
Zoological Institute and Museum, Biozentrum Grindel, University of Hamburg, Hamburg, Germany.
Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, Plön, Germany.
PLoS One. 2014 Apr 23;9(4):e95963. doi: 10.1371/journal.pone.0095963. eCollection 2014.
Few studies investigated whether rapid range expansion is associated with an individual's short-term fitness costs due to an increased risk of inbred mating at the front of expansion. In mating systems with low male mating rates both sexes share potential inbreeding costs and general mechanisms to avoid or reduce these costs are expected. The spider Argiope bruennichi expanded its range recently and we asked whether rapid settlement of new sites exposes individuals to a risk of inbreeding. We sampled four geographically separated subpopulations, genotyped individuals, arranged matings and monitored hatching success. Hatching success was lowest in egg-sacs derived from sibling pairs and highest in egg-sacs derived from among-population crosses, while within-population crosses were intermediate. This indicates that inbreeding might affect hatching success in the wild. Unlike expected, differential hatching success of within- and among-population crosses did not correlate with genetic distance of mating pairs. In contrast, we found high genetic diversity based on 16 microsatellite markers and a fragment of the mitochondrial COI gene in all populations. Our results suggest that even a very recent settlement secures the presence of genetically different mating partners. This leads to costs of inbreeding since the population is not inbred.
很少有研究调查快速的范围扩张是否与个体的短期适应性成本相关，因为在扩张前沿近亲交配风险增加。在雄性交配率较低的交配系统中，两性都分担潜在的近亲繁殖成本，并且有望存在避免或降低这些成本的一般机制。布鲁氏园蛛（Argiope bruennichi）最近扩大了其分布范围，我们研究了新地点的快速定居是否会使个体面临近亲繁殖的风险。我们对四个地理上分离的亚种群进行了采样，对个体进行了基因分型，安排了交配并监测了孵化成功率。来自同胞配对的卵囊孵化成功率最低，来自种群间杂交的卵囊孵化成功率最高，而种群内杂交的孵化成功率处于中间水平。这表明近亲繁殖可能会影响野外的孵化成功率。与预期不同的是，种群内和种群间杂交的不同孵化成功率与交配配对的遗传距离无关。相反，我们基于16个微卫星标记和线粒体COI基因的一个片段在所有种群中发现了高遗传多样性。我们的结果表明，即使是非常近期的定居也确保了存在基因不同的交配伙伴。由于种群没有近亲繁殖，这导致了近亲繁殖的成本。
