Evolutionary consequences of interspecific hybridization: Daphnia resting egg banks as biological archives

尽管植物和动物之间的自然种间杂交研究很多，但很少有研究涵盖足够长的时间段来描述杂交谱系的起源和命运，或者将种间基因流动的水平与环境条件联系起来。在这里，我们建议使用从康斯坦茨湖和格雷芬西湖的沉积物中分离出来的休眠卵来扩大我们对水蚤物种复合体的种群遗传学研究。起初，在这两个湖中只发现了一个物种(D.hyalina)(1950年前)，后来D.galeata入侵了这两个湖，导致了随后的种间杂交。基于我们的初步数据，我们提供了在这两个种群中进行大规模杂交扫描的证据，我们的目标是使用核和线粒体DNA数据来描述20世纪(~100年)杂交的后果(例如，渐渗)。此外，我们将从几个时期(1960年S、1970年S、1990年S和2000年S)孵化个体，并在40年的时间段内测试差异孵化和表型变异。这种种群遗传学和表型分析相结合的方法，使用来自湖泊沉积物的休眠卵，将使我们能够测量上个世纪物种复合体中生殖隔离、基因流动和选择的水平。

Despite many studies on natural interspecific hybridization among plants and animals, few cover long enough time periods to describe the origin and fate of hybrid lineages or to associate levels of interspecific gene flow with environmental conditions. Here we propose to extend our population genetic studies of a Daphnia species complex using resting eggs isolated from sediments of Lake Constance and Lake Greifensee. Initially, only one species (D. hyalina) was found in both lakes (before 1950), later on D. galeata invaded both lakes which resulted subsequently in interspecific hybridization. Based on our preliminary data which provide evidence for a massive hybrid sweep in both populations, we aim to describe the consequences of hybridization (e.g. introgression) during the course of the 20th century (~100 years) using nuclear and mitochondrial DNA data. In addition, we will hatch individuals from several time periods (1960¿s, 1970¿s, 1990¿s and 2000¿s) and test for differential hatching and phenotypic variation over a time period of 40 years. This combined approach of population genetics and phenotypic analyses using resting eggs from lake sediments will allow us to measure the level of reproductive isolation, gene flow, and selection in a species complex during the past century.