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

舒斯特9726504 两个问题是生态学和群体遗传学研究的核心：（1）复杂性状的遗传基础是什么？（2）基因在不同环境中如何表达？该项目将解决Paracerceis sculpta中的这些问题，Paracerceis sculpta是一种海洋等足类动物，其中三种不同的雄性形态共存：α-雄性最大，并使用细长的后部附属物在海绵中保卫后宫; β-雄性通过模仿雌性行为和成年体型入侵后宫; γ-雄性通过小而秘密地入侵后宫。女性是单形的。一个单一的基因（Ams）控制着P. sculpta的雄性差异。 本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，使家庭性别比发生偏差。等足类动物一年可繁殖八代。 本研究的第一个目的是确定是否观察到的种群动态在成年体型和性别比例可以归因于简单的遗传因素的相互作用。田间采集的雄性动物将与来自两个特定实验室谱系的雌性动物杂交。这些杂交的后代将表现出独特的家庭签名，在成年体型和性别比例取决于他们的父亲的基因型在Ams，Tfr和主要性别决定基因。第二个目标是确定自然环境变化如何影响这些遗传因子的表达。已知遗传背景的个体将在食物、温度、日长和密度的高和低处理下饲养。对于寿命更长的物种，这种详细的实验几乎是不可能的。 雕刻拟银汉鱼提供了一个精确的实验系统，用于确定遗传变异在自然界中是如何维持的，以及基因在不同环境中是如何表达的。这些问题对群体遗传学和进化生物学的意义是深远的。此外，这些问题可以在一个种群生物学和遗传机制已知的物种中得到解决。该系统为研究其他动物的繁殖系统动力学和性比进化提供了基础。

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.