Dissertation Research: Testing for Disruptive Competition in Solitary Populations of the Three-spined Stickleback

同域物种形成是指一个种群在进化过程中分裂成两个共存的物种，这一观点50年来一直是争议的根源。许多生物学家认为，只有当种群在地理上划分时，物种才会分裂。对同域物种形成的怀疑是由于理论批评和缺乏明确的例子。最近，由于积累的经验例子和支持性的理论分析，这一观点重新被接受。然而，该理论依赖于从未在自然界得到充分证明的种群动态。该假说认为，群体中个体之间的竞争在普通表现型中最为激烈，在稀有表现型中最弱，因此，一般个体表现不佳，而不寻常的个体逃避竞争，表现相对较好。研究人员将使用观察调查来测试这种破坏性选择是否在淡水棘鱼种群中自然发生。他们还将进行实验性的人口密度操纵，以测试竞争是否是潜在的原因。这项研究将检验物种形成理论最新进展的假设。这也与理解种群中的个体如何细分资源有关，这既影响种群动态，也影响入侵物种如何适应新环境。

Wainwright0105147Sympatric speciation, in which a single population undergoes an evolutionary split into two co-occurring species, has been a source of controversy for 50 years. Many biologists believe species split only when populations are geographically divided. Skepticism about sympatric speciation is due to theoretical criticisms and the paucity of unambiguous examples. The idea has regained acceptance lately, due to accumulating empirical examples and supportive theoretical analyses. However, the theory relies on population dynamics that have never been soundly demonstrated in nature. The hypothesis is that competition among individuals in a population is strongest among common phenotypes, weakest for rare phenotypes, so that the average individual does poorly while unusual individuals escape competition and do relatively well. The investigators will use observational surveys to test whether such disruptive selection occurs naturally in populations of freshwater stickleback fish. They will also conduct experimental population density manipulations to test whether competition is the underlying cause. This research will test the assumptions underlying recent advances in speciation theory. It is also relevant to understanding how individuals in a population subdivide their resources, which affects both population dynamics, and how an invading species adapts to a new environment.