Kin Recognition in Polyphenic Species

大卫·芬尼格9512110摘要这项研究将以两栖动物为模型系统，来理解某些动物如何以及为什么识别它们的近亲。亚利桑那州虎蜥蜴幼虫的不同寻常之处在于，它们在自然界中以两种不同的类型出现：典型的和食人的。只有当幼虫密度很高时才会产生食人形态，而这种形态主要以其他老虎火蜥蜴为食。当与亲缘关系不同的较小幼虫呆在一起时，食人者在实验室和野外优先摄取亲缘关系较少的个体。这种歧视在来自特别可能产生食人变种的家庭的幼虫中最为明显。这项研究将检验两个非排他性的进化论假说，即为什么食人族能认出他们的亲戚。首先，通过不吃亲戚，食人者由于共同的血统与他们分享了一些基因，食人者可以间接地增加他们自己的基因代表性或在种群中的“包容性”适合度。或者，食人者可能会避免吃亲戚，以减少他们死于疾病的机会。在自然界中，一种致命的细菌可以感染这些动物，吃人是感染这种疾病的一种特别有效的方式。此外，这种感染源可能在近亲之间高度传播，可能是因为亲属有相似的免疫系统。这项研究将使用现场观察以及现场和实验室实验来检验每个假说做出的具体预测。虎火蜥蜴是区分亲属歧视的直接和间接包容性健康后果的理想模式系统。因此，这项研究有望帮助解决为什么某些动物识别亲属，这对目前关于利他主义进化的理论很重要。这项研究还将增加对亲属关系在疾病传播中的作用的理解。

Pfennig, David 9512110 Abstract This research will use amphibians as a model system to understand how and why certain animals identify their relatives. Larval Arizona tiger salamanders are unusual in that they occur in nature as two distinct types: a 'typical' morph and a 'cannibal' morph. The cannibal morph is produced only when larvae are crowded at high densities, and this morph feeds primarily on other tiger salamanders. When housed with smaller larvae that differ in relatedness, cannibals preferentially consume less related individuals, both in the laboratory and in the field. This discrimination is most pronounced among larvae from families that are especially likely to produce cannibal morphs. This research will test two non-exclusive evolutionary hypotheses on why cannibals recognize their relatives. First, by not eating a relative, with whom the cannibal shares some genes due to common descent, cannibals can indirectly increase their own genetic representation or "inclusive" fitness in the population. Alternatively, cannibals may avoid eating kin to lessen their chances of dying from disease. In nature, a deadly bacterium can infect these animals, and cannibalism is an especially efficient way of acquiring the disease. Moreover, this infectious agent may be highly transmissible among close relatives, perhaps because kin have similar immune systems. This research will use field observations and field and laboratory experiments to test specific predictions made by each hypothesis. Tiger salamanders are an ideal model system for separating the direct and indirect inclusive fitness consequences of kin discrimination. This study thus promises to help resolve why certain animals recognize kin, which is important to current theories concerning the evolution of altruism. The research will also increase understanding of the role of kinship in disease transmission.