Clonal erosion in overwintering populations of Daphnia pulex

水蚤有双重繁殖模式，包括在有利的环境条件下进行孤雌生殖，以及在环境条件恶化时，例如在秋季进行有性繁殖。水蚤有两种不同的越冬策略：水蚤可以投资于生存和越冬，作为孤雌生殖的成虫和/或它们可以投资于繁殖和越冬，作为有性产生的滞育卵(Ephippia)。这两种策略在来自为冬季生存提供合适条件的湖泊的大型水蚤种群中共存(=不要一直冻结到底部)。在这个项目中，我想要研究在24个月的时间里，在这样的田野水蚤种群中克隆成分的季节变化。我感兴趣的是，在冬季的几个月里，是否存在由于选择或随机漂移而造成的克隆侵蚀，以及是否在春季从休眠的卵库恢复了基因变异。我想调查不同的水蚤克隆在生存和繁殖方面的投资是否不同，并可能被选为这两种策略中的一种。这个项目的重点是分析基因类型的多样性，但通过将种群遗传学结果与生态生理学数据相结合，我预计会产生协同效应，并对替代生存和生殖策略的演变有更深入的了解。

Daphnia have a dual reproduction mode including parthenogenetic reproduction during favourable environmental conditions as well as sexual reproduction when environmental conditions deteriorate e.g. in the fall. Two different overwintering strategies exist in Daphnia: Daphnia can invest in survival and overwinter as parthenogenetic adults and/or they can invest in reproduction and overwinter as sexually produced, diapause eggs (ephippia). Both strategies co-exist in Daphnia pulex populations from lakes that provide suitable conditions for survival during winter (= do not freeze all the way to the bottom). In this project I want to investigate the seasonal fluctuations of the clonal composition over 24 months in such a Daphnia pulex field population. I am interested in whether there is clonal erosion due to selection or random drift during the winter months and if the genotypic variability is restored during spring from the resting egg bank. I want to investigate whether different clones of Daphnia invest differently in survival and reproduction and may be selected for either strategy. This project focuses on the analyses of genotypic diversity, but from combining the population genetic results with ecophysiological data I expect synergisms and a deeper insight into the evolution of alternative survival- and reproductive strategies.