Data from: Response to selection on cold tolerance is constrained by inbreeding

The evolutionary potential of any given population is of fundamental importance for its longer-term prospects. Modern land-use practices often result in small and isolated populations, increasing extinction risk through reduced genetic diversity caused by inbreeding or drift. Concomitant genetic erosion may further interfere with a population’s evolutionary potential. In this study we investigate the consequences of inbreeding on evolutionary potential (the ability to increase cold resistance) in the tropical butterfly Bicyclus anynana. We applied artificial selection to chill-coma recovery time, starting from three levels of inbreeding (outbred control, one or two full-sib matings). Ten generations of selection produced highly divergent phenotypes, with the lines selected for increased cold tolerance showing by ca. 28% shorter recovery times after cold exposure relative to unselected controls. Correlated responses to selection in 10 life history and stress resistance traits were essentially absent. Inbred lines showed a weaker response to selection, thus indicating a reduced evolutionary potential. Inbreeding depression was still measurable in some traits after the course of selection. Traits more closely related to fitness showed a clear fitness rebound, suggesting a trait-specific impact of purging. Our findings have important implications for the longer-term survival of small populations in fragmented landscapes.

任何给定种群的进化潜力均对其长期存续前景具有核心重要性。当前的土地利用活动常导致种群规模缩小且彼此隔离，通过近交或遗传漂变降低遗传多样性，进而加剧种群灭绝风险；伴随发生的遗传侵蚀还可能进一步削弱种群的进化潜力。本研究以热带蝴蝶（Bicyclus anynana）为研究对象，探究近交对其进化潜力——即提升耐寒性的能力——的影响。我们以冷昏迷恢复时间为目标开展人工选择育种，实验初始设置了三个近交水平：远交对照组、一次全同胞交配组与两次全同胞交配组。历经10代选择育种后，各品系的表型出现显著分化，相较于未接受选择的对照组，被选育以增强耐寒性的品系在低温暴露后的恢复时间缩短了约28%。在10项生活史与抗逆性状中，几乎未观测到与选择相关的关联响应。近交品系的选择响应强度更低，这表明其进化潜力有所下降。在整个选择育种进程结束后，部分性状仍可检测到近交衰退现象。与适合度关联更为紧密的性状呈现出明显的适合度回升，这提示遗传清除存在性状特异性的影响。本研究结果对于破碎化景观中小种群的长期存续具有重要的启示意义。