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之间存在着相当恒定的关系。然而，在一些物种中，与同一物种中的其他个体相比，某些部分的个体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。这项研究将考察这些因素在金牛甲虫体型快速进化中的重要性。超过临界体型的雄性金牛在头上长出一对壮观的角，而低于这个门槛的金牛座则保持无角。最近建立的几个金牛座种群在这个关键的门槛体型上有很大的分歧。该项目将生态学和形态学方法与控制身体各部分生长和比例的发育机制研究结合起来。控制发展的机制的进化变化可能在物种形成和生物多样性的起源中发挥关键作用。该项目将为环境条件如何促进自然人口的发育控制机制的改变提供重要的见解。这些知识对于评价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.