School of Natural Resources & Environment, University of Florida, Gainesville, FL, United States of America.
Department of Environmental Science, Universidad de Puerto Rico, Rio Pidras, Puerto Rico, United States of America.
PeerJ. 2022 Feb 23;10:e12761. doi: 10.7717/peerj.12761. eCollection 2022.
High levels of within-individual variation (WIV) in reiterative components in plants such as leaves, flowers, and fruits have been shown to increase individual fitness by multiple mechanisms including mediating interactions with natural enemies. This relationship between WIV and fitness has been studied almost exclusively in plant systems. While animals do not exhibit conspicuous reiterative components, they have traits that can vary at the individual level such as erythrocyte size. It is currently unknown if WIV in animals can influence individual fitness by mediating the outcome of interactions with natural enemies as it has been shown in plants. To address this issue, we tested for a relationship between WIV in erythrocyte size, hemoparasite infection status, and body condition (a proxy for fitness) in a Caribbean anole lizard. We quantified the coefficient of variation of adult erythrocytes size in $ = 95$ infected and $ = 107$ non-infected lizards. We found higher degrees of erythrocyte size variation in infected lizards than in non-infected individuals. However, we found no significant relationship between infection status or erythrocyte size variation, and lizard body condition. These results suggest that higher WIV in erythrocyte size in infected lizards is not necessarily adaptive but likely a consequence of the host response to infection. Many hemoparasites destroy their host cells as part of their life cycle. To compensate, the host lizard may respond by increasing production of erythrocytes resulting in higher WIV. Our results emphasize the need to better understand the role of within-animal variation as a neglected driver or consequence of ecological and evolutionary interactions.
个体内变异（within-individual variation，WIV）在植物的重复结构中很常见，例如叶子、花朵和果实，这种变异通过多种机制增加了个体的适合度，包括调节与自然天敌的相互作用。这种 WIV 与适合度之间的关系已经在植物系统中得到了广泛的研究。虽然动物没有明显的重复结构，但它们具有可以在个体水平上变化的特征，例如红细胞大小。目前还不清楚动物的 WIV 是否可以通过调节与自然天敌相互作用的结果来影响个体的适合度，就像在植物中已经证明的那样。为了解决这个问题，我们在加勒比海鬣蜥中检验了红细胞大小的 WIV、血寄生虫感染状态和身体状况（适合度的代表）之间的关系。我们量化了$=95$只感染个体和$=107$只未感染个体成年红细胞大小的变异系数。我们发现感染个体的红细胞大小变异程度高于未感染个体。然而，我们没有发现感染状态或红细胞大小变异与蜥蜴身体状况之间存在显著关系。这些结果表明，感染蜥蜴的红细胞大小的 WIV 较高不一定是适应性的，而是可能是宿主对感染的反应的结果。许多血液寄生虫在其生命周期中破坏宿主细胞。为了补偿，宿主蜥蜴可能会通过增加红细胞的产生来响应，从而导致更高的 WIV。我们的研究结果强调了需要更好地理解个体内变异作为生态和进化相互作用的被忽视的驱动因素或后果的作用。
