Data from: Cryptic lineages of a common alpine mayfly show strong life history divergence

Understanding ecological divergence of morphologically similar but genetically distinct species ̶ previously considered as a single morphospecies ̶ is of key importance in evolutionary ecology and conservation biology. Despite their morphological similarity, cryptic species may have evolved distinct adaptations. If such ecological divergence is unaccounted for, any predictions about their responses to environmental change and biodiversity loss may be biased. We used spatio-temporally replicated field surveys of larval cohort structure and population genetic analyses (using nuclear microsatellite markers) to test for life history divergence between two cryptic lineages of the alpine mayfly Baetis alpinus in the Swiss Alps. We found that the more widespread and abundant cryptic lineage represents a ‘generalist’ with at least two cohorts per year, whereas the less abundant lineage is restricted to higher elevations and represents a ‘specialist’ with a single cohort per year. Importantly, our results indicate partial temporal segregation in reproductive periods between these lineages, potentially facilitating local coexistence and reproductive isolation. Taken together, our findings emphasize the need for a taxonomic revision: widespread and apparently generalist morphospecies can hide cryptic lineages with much narrower ecological niches and distribution ranges.

理解形态相似但遗传分化显著、曾被归为单一形态种的物种间的生态分化，是进化生态学与保护生物学的核心议题。尽管隐存种形态相似，却可能演化出截然不同的适应性特征。若忽略这类生态分化，针对它们对环境变化与生物多样性丧失的响应所做的任何预测都可能存在偏差。本研究通过时空重复的野外幼虫龄群结构调查，以及基于核微卫星标记（nuclear microsatellite markers）的群体遗传分析，对瑞士阿尔卑斯山区高山蜉蝣（Baetis alpinus）的两个隐存支系间的生活史分化展开检验。结果显示，分布更广、种群更丰富的隐存支系为“泛化种”，每年至少可形成两个龄群；而种群较少的支系仅局限于高海拔区域，属于“特化种”，每年仅产生一个龄群。尤为关键的是，本研究结果表明这两个支系的繁殖周期存在部分时间隔离，这或可促进二者在当地共存并实现生殖隔离。综合来看，本研究发现凸显了分类学修订的必要性：分布广泛、看似泛化的形态种，实则可能暗藏生态位与分布范围均更为狭窄的隐存支系。