'Prudent habitat choice': a novel mechanism of size-assortative mating

Assortative mating, an ubiquitous form of nonrandom mating, strongly impacts Darwinian fitness and can drive biological diversification. Despite its ecological and evolutionary importance, the behavioural processes underlying assortative mating are often unknown, and in particular, mechanisms not involving mate choice have been largely ignored so far. Here, we propose that assortative mating can arise from ‘prudent habitat choice’, a general mechanism that acts under natural selection, and that it can occur despite a complete mixing of phenotypes. We show that in the cichlid Eretmodus cyanostictus size-assortative mating ensues, because individuals of weaker competitive ability ignore high-quality but strongly competed habitat patches. Previous studies showed that in E. cyanostictus, size-based mate preferences are absent. By field and laboratory experiments, here we showed that (i) habitat quality and body size are correlated in this species; (ii) territories with more stone cover are ...选型交配（assortative mating）是一类广泛存在的非随机交配形式，对达尔文适合度具有显著影响，并可推动生物多样化进程。尽管其在生态学与进化生物学领域具备重要意义，但选型交配背后的行为机制仍有待阐明，尤其是不涉及配偶选择的相关机制，迄今尚未得到充分关注。本研究提出，选型交配可源于「审慎栖息地选择」——这是一种受自然选择作用的通用机制，即便种群表型完全混合，该机制仍可催生选型交配。研究证实，在慈鲷（cichlid）饰鳍丽体鲷（Eretmodus cyanostictus）中存在体型选型交配现象，其成因在于竞争力较弱的个体，会回避那些优质但竞争激烈的栖息地斑块。此前已有研究表明，饰鳍丽体鲷并不存在基于体型的配偶偏好。本研究通过野外与室内实验证实：其一，该物种的栖息地质量与个体体型存在相关性；其二，石质覆盖度更高的领地为……