Dissertation Research: Phylogenetic Origins of Diapause in Marine Harpacticoid Copepods

小行星9701524 在假死状态下生存的能力通常被称为休眠或滞育。 真菌和细菌的孢子，高等植物的种子，某些昆虫的幼虫，以及一些甲壳类动物的包囊，特别是卤虫（卤虫），都是生物滞育阶段的较好例子。 在甲壳类动物（螃蟹、龙虾、虾及其近亲）中，那些生活在内陆水体中的动物，特别是那些偶尔结冰或干燥的动物，比生活在海洋中的物种更有可能拥有滞育阶段。 滞育发生，正如预期的那样，在许多种小型淡水甲壳类动物称为harpacticoid桡足类，但它也发生，出乎意料的是，在至少两个海洋物种。 由于海洋环境不太可能冻结或干燥，滞育的好处尚不清楚。 三种可能的解释了海洋物种滞育的存在：（1）滞育发生在海洋硬足类桡足类，并保留在其淡水后代;（2）滞育发生在淡水硬足类桡足类，并保留在其海洋后代;（3）滞育发生在淡水和海洋的硬足类桡足类谱系独立。 在这项研究中，布鲁斯库尔和博士候选人里贾纳韦策将使用分子和解剖数据，以建立属于已知的家庭包含滞育物种的海洋和淡水桡足类的系统发育关系。 这些“家谱”和比较的方法将允许Coull和Wetzer确定滞育在密切相关的家庭harpacticoid桡足类的进化历史，特别是，找出最好的解释滞育如何出现在海洋qspecies的假说。 这项工作可能有助于提供一个更普遍的解释滞育如何在环境中出现是稳定的，缺乏波动，如Ocold-hotO或Owet-dryO季节。

9701524 COULL The ability to survive in a state of suspended animation is commonly called dormancy or diapause. The spores of fungi and bacteria, the seeds of higher plants, the larvae of certain insects, and the cysts of some crustaceans, notably the brine shrimp (Artemia), are among the better known examples of diapausing stages in organisms. Among crustaceans (crabs, lobsters, shrimp, and their kin) those inhabiting inland bodies of water, especially those that occasionally freeze or dry, are more likely to possess a diapausing stage than are species living in the ocean. Diapause occurs, as expected, in many species of miniature freshwater crustacea called harpacticoid copepods, but it also occurs, unexpectedly, in at least two marine species. Since the marine environment is not likely to freeze or dry, the benefits of diapause are unclear. Three possible explanations account for the presence of diapause in marine species: (1) diapause arose in marine harpacticoid copepods and was retained in their freshwater descendants; (2) diapause arose in freshwater harpacticoid copepods, and was retained in their marine descendants; (3) diapause arose independently in freshwater and marine lineages of harpacticoid copepods. In this research, Bruce Coull and doctoral candidate Regina Wetzer will use molecular and anatomical data to establish the phylogenetic relationships of marine and freshwater copepods belonging to families known to contain diapausing species. These "family trees" and comparative methods will allow Coull and Wetzer to ascertain the evolutionary history of diapause in closely related families of harpacticoid copepods, and, in particular, to find out which hypothesis best explains how diapause arose in marine qpecies. The work may help provide a more general explanation of how diapause can arise in environments that are OstableO, lacking fluctuations such as Ocold-hotO or Owet-dryO seasons.