Data from: Hybridization associated with cycles of ecological succession in a passerine bird

Identifying the diversity of contexts that can lead to hybridization is important for understanding its prevalence and dynamics in natural populations. Despite the potential of ecological succession to dramatically alter species co-occurrence and abundances, it is unknown whether it directly promotes hybridization and if so, has long-lasting consequences. Here, we summarize 30 years of survey data across ten populations to show that, in western and mountain bluebirds, heterospecific pairing occurs during repeatable and transient colonization events at the early stages of species turnover. Despite mixed pairing occurring during only early succession, genetic data showed presence of hybrids at both early and late successional stages. Moreover, hybrids showed novel patterns of variation in morphology and behavior emphasizing that even ephemeral contexts for hybridization can have important evolutionary consequences. Our results suggest that, because ecological succession often brings together closely related competitors in disparate numbers, but only lasts for a brief period of time, it may be a widespread but underappreciated context for hybridization.

明确可引发杂交（hybridization）的各类情境多样性，对于理解其在自然种群中的流行程度与动态变化至关重要。尽管生态演替（ecological succession）具备显著改变物种共存格局与种群丰度的潜力，但目前尚不清楚其是否会直接促进杂交，若存在此种促进作用，是否会产生长期演化后果。本研究整合了10个种群历时30年的调查数据，结果显示：在西蓝鸲（western bluebird）与山蓝鸲（mountain bluebird）中，异种配对（heterospecific pairing）行为发生于物种更替早期阶段可重复且短暂的定殖事件中。尽管仅在演替早期阶段出现异种配对现象，但遗传数据表明，在演替早期与晚期阶段均存在杂交个体（hybrid）。此外，杂交个体在形态与行为上呈现出全新的变异模式，这表明即便仅短暂存在的杂交情境，也可能产生重要的演化后果。本研究结果表明：由于生态演替通常会将亲缘关系较近的竞争者以不均衡的数量聚集在一起，且演替过程仅持续较短时间，因此生态演替可能是一种广泛存在却未被充分认知的杂交发生情境。