DISSERTATION RESEARCH: Evolution and Development of Polyphenism in the Beetle Onthophagus taurus

在大多数动物物种中，所有个体的身体部位的相对大小有一个相当恒定的关系。然而，在某些物种中，与同一物种的其他个体相比，部分个体的形状不成比例是正常的。这些身体部位的大小和形状的差异存在于各种各样的生物体中，并可能受到遗传、发育或生态因素的控制。本研究将探讨这些因素在甲虫体型快速进化中的重要性。超过临界体型的雄性金牛会在头上长出一对壮观的角，而小于这个临界值的金牛则没有角。最近建立的几个金牛种群在这个临界阈值体型上发生了巨大的分歧。该项目将生态学和形态学方法与控制身体部位生长和比例的发育机制的研究相结合。控制发育机制的进化变化可能在物种形成和生物多样性起源中起着关键作用。该项目将为了解环境条件如何促进自然种群发育控制机制的改变提供重要见解。这些知识对于评估发育过程在形态多样性起源中的作用至关重要。

In most species of animals there is a fairly constant relationship in the relative sizes of body parts for all individuals. In some species, however, it is the normal condition that some fraction of individuals is disproportionately shaped when compared to others in the same species. These differences in the size, and also shape, of body parts occurs in a wide variety of organisms and could be controlled by genetic, developmental or ecological factors. This research will examine the importance of such factors in the rapid evolution of body shape in the beetle Onthophagus taurus. Male O. taurus that exceed a critical body size develop a pair of spectacular horns on their heads, while those smaller than this threshold remain hornless. Several recently established O. taurus populations have diverged dramatically in this critical threshold body size. This project combines ecological and morpholgical approaches with studies on the developmental mechanisms that control growth and proportionality of body parts. Evolutionary changes of mechanisms controlling development may play a pivotal role in speciation and the origin of biodiversity. This project will provide important insights into how environmental conditions can foster modifications of developmental control mechanisms in natural populations. Such knowledge is crucial for evaluating the role of developmental processes in the origin of morphological diversity.