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.

厘清形态相似但遗传分化显著的物种——此前曾被归为同一形态种（morphospecies）——的生态分化机制，是进化生态学与保护生物学领域的核心议题。尽管形态上高度相似，隐存种（cryptic species）往往已演化出截然不同的适应性特征。若未考虑此类生态分化，针对这些物种应对环境变化与生物多样性丧失的预测结果可能存在偏差。本研究通过对瑞士阿尔卑斯山区高山蜉蝣（Baetis alpinus）的两个隐存谱系开展时空重复的野外调查（分析幼虫同龄群结构）与群体遗传分析（采用核微卫星标记[nuclear microsatellite markers]），以检验二者的生活史分化情况。研究结果显示，分布更广、种群更为丰富的隐存谱系为‘泛化种’，每年至少可产生两个同龄群；而种群数量较少的谱系则仅分布于高海拔区域，属于每年仅产生一个同龄群的‘特化种’。尤为重要的是，本研究结果表明这两个谱系的繁殖期存在部分时间隔离，这可能有助于它们在局域尺度上实现共存与生殖隔离。综合来看，本研究结果凸显了分类学修订的必要性：看似分布广泛、泛化的形态种，实则可能隐藏着生态位与分布区狭窄得多的隐存谱系。