Data from: Effects of founding genetic variation on adaptation to a novel resource

Population genetic theory predicts that adaptation in novel environments is enhanced by genetic variation for fitness. However, theory also predicts that under strong selection, demographic stochasticity can drive populations to extinction before they can adapt. We exposed wheat-adapted populations of the flour beetle (Tribolium castaneum) to a novel suboptimal corn resource, to test the effects of founding genetic variation on population decline and subsequent extinction or adaptation. As previously reported, genetically diverse populations were less likely to go extinct. Here, we show that among surviving populations, genetically diverse groups recovered faster after initial population decline. Within two years, surviving populations significantly increased their fitness on corn via increased fecundity, increased egg survival, faster larval development, and higher rate of egg cannibalism. However, founding genetic variation only enhanced the increase in fecundity, despite existing genetic variation – and apparent lack of tradeoffs – for egg survival and larval development time. Thus, during adaptation to novel habitats the positive impact of genetic variation may be restricted to only a few traits, although change in many life-history traits may be necessary to avoid extinction. Despite severe initial maladaptation and low population size, genetic diversity can thus overcome predicted high extinction risk in new habitats.

种群遗传学理论指出，与适合度（fitness）相关的遗传变异可增强物种在全新环境中的适应能力。然而该理论同时预测，在强选择压力下，种群统计随机性（demographic stochasticity）可能会导致种群在完成适应前便走向灭绝。
我们将适应小麦环境的赤拟谷盗（Tribolium castaneum）种群置于一种新型次优玉米基质中，以探究奠基者遗传变异对种群衰退以及后续灭绝或适应过程的影响。正如此前研究所报道的那样，遗传多样性更高的种群灭绝概率更低。
本研究结果显示，在存活的种群中，遗传多样性更高的群体在经历初始种群衰退后恢复速度更快。在两年内，存活种群在玉米基质中的适合度得到显著提升，具体表现为繁殖力（fecundity）增强、卵存活率提高、幼虫发育速率加快以及卵同类相食率（egg cannibalism）上升。
尽管针对卵存活率和幼虫发育时长存在已有的遗传变异，且未发现明显的适应性权衡（trade-off），但奠基者遗传变异仅能促进繁殖力的提升。因此，在适应全新生境的过程中，遗传变异的积极影响可能仅局限于少数性状，尽管改变诸多生活史性状或许是避免种群灭绝的必要条件。尽管初始阶段存在严重的适应性不足（maladaptation）且种群规模极小，但遗传多样性仍能够帮助种群规避新环境中预测的高灭绝风险。