Sib-mating enhances fitness in a haplodiploid beetle

Inbreeding is generally avoided in animals due to the risk of inbreeding depression following an increase in homozygous deleterious alleles and loss of heterozygosity. Species that regularly inbreed challenge our understanding of the fitness effects of these risks. We investigated fitness consequences of extended inbreeding in the haplodiploid date-stone beetle, Coccotrypes dactyliperda. We hypothesized that continuous inbreeding could result in reduced fitness, while outbreeding would either increase fitness due to heterosis or lower fitness if co-adapted gene complexes are disrupted. We established three breeding treatments with beetles from two geographically separated populations: Sib-mating (inbreeding), and outbreeding within- and between-populations. Between-population outbreeding groups of both populations had lower fecundity and collapsed before the experiment ended, while sib-mated and within-population breeding groups persisted for ten generations. Sib-mated females had highe...动物繁育中通常会避免近交，原因是近交后纯合有害等位基因频率上升、杂合性丧失，会引发近交衰退风险。而那些经常性发生近交的物种，则挑战了我们对这类风险对适合度影响的认知。本研究以单倍二倍体的枣核小蠹（Coccotrypes dactyliperda）为对象，探究了长期近交对其适合度的影响。我们提出如下假说：持续近交可导致适合度下降；而异交则可能因杂种优势提升适合度，但若协同适应基因复合体遭到破坏，则会降低适合度。我们利用来自两个地理隔离种群的枣核小蠹，设置了三种繁育处理方式：同胞交配（近交）、种群内异交以及种群间异交。两个种群的种群间异交组均表现出较低的繁殖力，且在实验结束前就出现种群崩溃；而同胞交配组与种群内异交组则持续繁衍了十代。同胞交配的雌虫具有更高……