The role of hybridization in the colonization of newly opened habitats

物种之间的杂交是一种创造性的进化力量，它形成了新的基因类型，并允许快速适应新的环境。我们建议使用水蚤杂交复合体作为模型系统，研究杂交特有的特征如何促进新栖息地的殖民。我们将在十个小的采石场湖泊中筛选水蚤群落，这些湖泊在大约20年前才被创造出来，并因此开放给殖民者。此外，与更大的湖泊不同，这些浅而不稳定的栖息地每年春天都会重新开放以供殖民：水蚤只有例外地以克隆血统的形式存活下来。相反，它们需要从有性繁殖的滞育卵子中重新建立。将在15个微卫星座位对群落进行筛选，并将测试杂交维持的三种截然不同的情景：杂交种作为克隆血统存活、反复杂交事件或通过迁徙建立杂交种。此外，利用实验室实验，我们将检验这样的假设：与亲本分类群相比，杂交种具有更多样化的表型(这是由于杂交个体的遗传变异增加)。最后，田间和实验室数据将被用于一个数学模型的参数化，该数学模型将被用来研究不同生态参数对杂交种成功的贡献。提出的经验和理论方法的结合将促进我们对杂交在新栖息地殖民中的作用以及更广泛地说在适应性进化中的基因交换的理解。

Hybridization between species is a creative evolutionary force that forms novel genotypes and allows rapid adaptation to new environments. We propose to study how hybrid-specific traits may facilitate the colonization of novel habitats, using the Daphnia hybrid complex as a model system. We will screen Daphnia communities in ten small quarry lakes which have been created and thus opened for colonization only about 20 years ago. In addition, in contrast to larger lakes, these shallow and unstable habitats are “re-opened” for colonization every spring: Daphnia survive winter only exceptionally as clonal lineages. Instead, they need to be re-established from sexually produced diapausing eggs. Communities will be screened at 15 microsatellite loci and three contrasting scenarios of hybrid maintenance will be tested: survival of hybrids as clonal lineages, recurrent hybridization events or establishment of hybrids through migrants. In addition, using laboratory experiments we will test the hypothesis that hybrids have more diverse phenotypes compared to parental taxa (due to increased genetic variation in hybrid individuals). Finally, the field and laboratory data will be used for parameterization of a mathematical model, which will be developed to study the contribution of different ecological parameters to the success of hybrids. The proposed combination of empirical and theoretical approaches will advance our understanding of the role of hybridization in the colonization of new habitats and, more generally, of genetic exchange in adaptive evolution.