Ecology and genetics of hybrid animals

杂交越来越被认为是动物进化中的一种多样化力量。高杂交适应度在新的、边缘的或动态的生境中更为常见。然而，高杂交适应性的原因只知道一部分。我的研究项目采用了一种综合的方法，包括实地研究和实验研究，结合遗传表征，研究新的基因组合如何在动态生态环境中提供更高的适应性。我利用了Fundulus杂交复合体，在那里，两种通常在不同盐度发现的鱼类（Fundulus heteroclitus和F. diaphanus）杂交产生有性生殖和雌性生殖的杂种。后者由全雌性克隆体组成，需要来自眼底雄性的精子来触发卵子发育。在河口、潮滩、沿海湖泊和泻湖等中等和/或可变盐度生境中，进行了生态调查，以确定亲本和杂交形式的相对分布。同时，利用AFLP标记进行全基因组遗传表征，对杂交频率、渗入水平和克隆多样性进行初步估计。生态和遗传知识通过检查与健康相关的特征，如离子调节能力，在田间（移植实验）和实验室（普通花园实验）中的生存和生长相结合。在这里，固定克隆基因型的可用性特别适合于解开影响适合度成分的表型变异的遗传、母体和环境来源。考虑到它们恒定的遗传背景，克隆也可以用于检测杂交体中等位基因的表达。这种对自然雌性激素的综合分析将为检验关于克隆生态广度的竞争性假设提供机会。这项研究也将涉及到以异交梭菌为模式生物的功能、环境生理学和基因组学等领域。这项研究将涉及一名博士、三名硕士和五名学士。这些学生将接受培训，从整体的角度记录和解释生态、表型和遗传变异。

Hybridization is increasingly recognized as a diversifying force in animal evolution. High hybrid fitness is more frequent in novel, marginal, or dynamic habitats. Causes of higher hybrid fitness, however, are only partly known. My research program employs an integrative approach involving field and experimental studies coupled with genetic characterization to investigate how new genetic combinations can provide higher fitness in dynamic ecological settings. I take advantage of the Fundulus hybrid complex where two fish species (Fundulus heteroclitus and F. diaphanus) typically found at different salinities have hybridized to produce sexually reproducing and gynogenetic hybrids. The latter comprises all-female clones that need sperm from Fundulus males to trigger egg development. Ecological surveys are conducted to establish the relative distribution of parental and hybrid forms in habitats of intermediate and/or variable salinity such as estuaries, tidal rapids, coastal lakes and lagoons. In parallel, preliminary estimates of hybrid frequency, introgression levels and clonal diversity are refined by genome-wide genetic characterization with AFLP markers. Ecological and genetic knowledge are coupled by examining fitness-related traits such as ionoregulation ability, survival and growth in the field (transplant experiments) and in the lab (common garden experiments). Here, the availability of fixed clonal genotypes is particularly appropriate to disentangle the genetic, maternal, environmental sources of phenotypic variation impacting on fitness components. Given their constant genetic background, clones are also useful to examine allelic gene expression in hybrids. This integrated analysis of natural gynogens will offer opportunities to test competing hypothesis on the ecological breadth of clones. This research will also be relevant to the fields of functional and environmental physiology and genomics, which use F. heteroclitus as a model organism. The proposed research will involve one Ph. D., three M. Sc., and five B. Sc students. These students will be trained in documenting and interpreting ecological, phenotypic and genetic variation from a holistic point of view.