Understanding variation in fitness conferring traits

如何在增强适合度的特征中保持遗传变异仍然是进化生物学中的一个根本难题。人们提出了几种主要的理论来解释遗传变异的持久性。这些理论包括基因捕获、波动选择、基因与环境的相互作用、基因与基因的相互作用、杂种优势和拮抗多效性。我和我的学生正在使用一种动物行为方法来测试其中一些理论，这种方法结合了统计遗传学和生态生理学的工具。我们基于实验室和现场的经验研究量化了条件、生活史和性选择特征的表型和基于遗传的变异，并确定了这种变异是如何受到饮食和社会环境的影响的。具体地说，我们的研究考察了(1)必需和有限元素(氮和磷)的饮食变化如何影响条件的遗传学(包括生长速度、发育时间、成体大小、体脂含量和体内营养保持)，以及(2)饮食和条件如何相互作用影响性选择和生活史特征(男性远距离交配广告信号的吸引力、女性交配偏好、终身生殖成功、反掠夺行为、以及父母及其后代的生存)。我们的短期研究目标是确定这些性状之间的相互作用是否会维持较高的遗传变异。我们还将进行一项人工选择实验，短期目标是确定时间波动的选择是否能够保持性别限制和性选择性状的遗传差异。总体而言，我们的研究将明确测试上述维持高遗传变异的两个理论--基因捕获和时间波动的性别限制选择。从长远来看，我的研究计划的首要目标是帮助更全面地理解增强健康的特征中保持高度遗传变异的原因。

How genetic variation is maintained in traits that enhance fitness remains a fundamental dilemma in evolutionary biology. Several major theories have been put forth to explain the persistence of genetic variance. These theories include genic capture, fluctuating selection, genotype-by-environment interactions, genotype-by-genotype interactions, heterosis, and antagonistic pleiotropy. My students and I are testing some of these theories using an animal behaviour approach that incorporates tools from statistical genetics and ecological physiology. Our laboratory and field based empirical research quantifies the phenotypic and genetically based variation in condition, life-history, and sexually selected traits and determines how this variation is influenced by diet and the social environment.  Specifically, our research examines (1) how dietary variation in essential and limited elements (nitrogen and phosphorus) influences the genetics of condition (including growth rate, development time, adult size, body fat content, and nutrient retention in the body), and (2) how diet and condition interact to influence sexually selected and life-history traits (attractiveness of male long-distance mate advertisement signals, female mating preferences, lifetime reproductive success, anti-predatory behaviours, and survival of both parents and their offspring). Our short-term research goals are to determine whether the interactions between these traits act to maintain high genetic variance. We will also conduct an artificial selection experiment with the short-term goal of ascertaining whether temporally fluctuating selection can maintained the genetic variance in sex-limited and sexually selected traits. Overall, our research will explicitly test two of the above theories for the maintenance of high genetic variance - genic capture and temporally fluctuating sex-limited selection. Long-term, the overarching goal of my research program is to contribute to a more complete understanding of how high genetic variance is maintained in traits that enhance fitness.