The Role of Heritability, Environment, and Mechanism in Phenotypic Expression of Paracerceis sculpta (Crustacoa: Isopoda)

舒斯特9726504有两个问题是生态和种群遗传学研究的核心：(1)复杂性状的遗传基础是什么？(2)基因在不同环境中是如何表达的？这个项目将在Paracerceis cutota中解决这些问题，这是一种海洋等足目动物，其中三种不同的雄性形态共存：阿尔法雄性体型最大，使用细长的后肢保护海绵中的后宫；贝塔雄性通过模仿雌性行为和成年身体形态入侵后宫；伽马雄性通过矮小和神秘的身体入侵后宫。雌性是单形性的。一个单基因(Ams)控制着雕塑青霉的雄性差异。这个物种的性别决定是由染色体决定的。另一个基因(Tfr)与Ams和性染色体相互作用，从而影响家庭性别比。等足目动物每年最多完成八代。这项研究的第一个目标是确定观察到的成年体型和性别比例的种群动态是否可以归因于简单遗传因素的相互作用。现场采集的雄性将与来自两个特定实验室血统的雌性杂交。这些杂交后代将在成年体型和性别比例上表现出独特的家族特征，这取决于他们父亲在Ams、Tfr和主要性别决定基因上的基因类型。第二个目标是确定自然环境变化如何影响这些遗传因素的表达。已知遗传背景的个体将在食物、温度、日长和密度的高低处理下饲养。在寿命较长的物种上进行这样详细的实验几乎是不可能的。Paracerceis cultta为确定基因变异在自然界中如何保持，以及基因如何在不同环境中表达提供了一个精确的实验系统。这些问题对种群遗传学和进化生物学的意义是深远的。此外，这些问题可以在种群生物学和遗传机制已知的物种中得到解决。这一系统为其他动物繁殖系统动力学和性别比进化的研究提供了基本的见解。

Shuster 9726504 Two questions are central to research in ecological and population genetics: (1) what is the genetic basis for complex traits, and (2) how are genes expressed in different environments? This project will address these questions in Paracerceis sculpta, a marine isopod in which three distinct male morphs coexist: alpha-males are largest and defend harems in sponges using elongated posterior appendages; beta-males invade harems by mimicking female behavior and adult body form; gamma-males invade harems by being small and secretive. Females are monomorphic. A single gene (Ams) controls male differences in P. sculpta. Sex determination in this species is chromosomal. Another gene (Tfr) interacts with Ams and with sex chromosomes to bias family sex ratio. Isopods complete up to eight generations per year. The first objective of this research is to determine whether observed population dynamics in adult body form and sex ratio can be attributed to the interaction of simple genetic factors. Field-collected males will be crossed with females from two specific laboratory lineages. The progeny of these crosses will exhibit distinctive family signatures in adult body form and sex ratio depending on their fathers' genotypes at Ams, Tfr and primary sex determination genes. The second objective is to determine how natural environmental variation may influence the expression of these genetic factors. Individuals of known genetic background will be reared under high and low treatments of food, temperature, day-length and density. Such detailed experiments are seldom possible with longer-lived species. Paracerceis sculpta provides a precise experimental system for determining how genetic variation is maintained in nature, and how genes are expressed in different environments. The significance of these questions to population genetics and evolutionary biology is profound. Moreover, these questions can be addressed in a species whose population biology and inheritance mechanisms are kno wn. This system thus provides fundamental insights for studies of breeding system dynamics and sex ratio evolution in other animal species.