Dissertation Research: Evolutionary Effects of Interspecific Competition on Townsend's Solitaires

目前研究该领域种间竞争的两种方法提供了不确定的结果。这些是个体在存在和不存在其假定竞争对手的情况下的行为观察，以及种群移除实验。行为学研究很少衡量竞争对个体适应性的影响，种群研究很少阐明竞争的潜在因果机制。需要一种综合的方法，同时测量资源的可用性，竞争者对其共享的有限资源的影响，对彼此的影响，以及竞争对个体适应度的影响。这项研究将把这种合成方法应用于汤森孤树和其他在非繁殖季节以杜松子为食的物种之间的觅食竞争。它将量化竞争对手对个体独龟捍卫冬季觅食领地的干扰和剥削效应。它还将在两年内通过监测越冬生存和羽翼未丰的情况来衡量50-60只独翅鸟的健康状况。量化个体竞争强度与其适合度之间的关系，将为该物种种间竞争的进化意义提供实证检验。

Two current approaches to studying interspecific competition in the field provide inconclusive results. These are behavioral observations of individuals in the presence and absence of their putative competitors, and population removal experiments. Behavioral studies rarely measure the effects of competition on individual fitness, and population studies seldom elucidate the underlying causal mechanisms of competition. A synthetic approach is needed which simultaneously measures resource availability, effects of competitors upon their shared limiting resources and on one another, and effects of competition on individual fitness. This study will apply this synthetic approach to foraging competition between Townsend's solitaires and other species which feed upon juniper berries during the nonbreeeding season. It will quantify both interference and exploitive effects of competitors on individual solitaires defending winter feeding territories. It will also measure the fitness of 50-60 solitaires over two years by monitoring overwinter survival and fledgling success. Quantifying the relationship between the intensity of competition experienced by individual solitaires and their fitness will provide an empirical test of the evolutionary significance of interspecific competition to this species.