Maintenacne of Parent-Species Reservoirs in a Complex Hybrid Zone

希尔比什 9708074 PI一直在对混合区进行详细分析， 两 物种 海洋贻贝， Mytilus edulis 和 M. 在欧洲同域分布。PI '已经表明，1）强 在杂种中发生定向选择 人口 能消除贻贝和M. edulis类杂种，2）定向选择被M纯群体的移民所抵消。 edulis之间的平衡是目前稳定的，和4）杂交一直是这些物种的进化历史上的一个重要特征。这些研究将未来的研究集中在一个新的方向：理解这个混合区动态的首要问题是确定M。edulis被保留。贻贝纯种群的维持是维持和塑造这一杂交区的扩散和定向选择之间的动态平衡的一个基本要素。 主要研究者将提出检验假设，即M。 edulis有一个上级的生理能力，以科普淤泥在其饮食和纯种群的这一物种是有选择地维持在 泥沙浓度高的河口环境。 这一假说是由观察到的纯种群的M。 edulis与具有高泥沙负荷的河口有关，并且来自单独研究的初步结果表明M。当暴露于含有高浓度淤泥的饮食时，可食蟹猴可能具有更大的吸收效率。 PI还将提出实验室和现场实验的组合来测试这一假设。实验室实验将测试 提出 生理差异M. edulis 和 M. galloprovincialis，而田间实验是必要的，以证明这些差异在自然界中有显着的后果。

Hilbish 9708074 The PIs have been conducting a detailed analysis of a hybrid zone between two species of marine mussels, Mytilus edulis and M. galloprovincialis that are sympatric in Europe. The PIs' have shown that 1) strong directional selection occurs within hybrid populations that eliminates Mytilus edulis and M. edulis-like hybrids, 2) directional selection is offset by immigration from pure populations of M. edulis, 3) the balance between dispersal and selection is presently stable, and 4) hybridization has been an important feature in the evolutionary history of these species. These studies focus future research in a new direction: the primary issue in understanding the dynamics of this hybrid zone is to determine how pure populations of M. edulis are maintained. The maintenance of pure populations of Mytilus edulis is an essential element of the dynamic equilibrium between dispersal and directional selection that maintains and shapes this hybrid zone. The PI will propose to test the hypothesis that M. edulis has a superior physiological capacity to cope with silt in its diet and that pure populations of this species are selectively maintained in estuarine environments where silt concentrations are high. This hypothesis was suggested by the observation that pure populations of M. edulis are associated with estuaries that have high silt loads and preliminary results from separate studies that indicate that M. edulis may have a much greater absorption efficiencies when exposed to diet containing high concentrations of silt. The PI will also propose a combination of laboratory and field experiments to test this hypothesis. Laboratory experiments will test for the proposed physiological differences between M. edulis and M. galloprovincialis while the field experiments are necessary to demonstrate that these differ ences have significant consequences in nature.