Individual Differences And Family Resemblances In Animal Behavior

Author : Nicholas DiRienzo
Publisher :
ISBN 13 : 9781339064406
Total Pages : pages
Book Rating : 4.0/5 (644 download)

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Download or read book The Role of Species Interactions in Generating and Maintaining Consistent Individual Differences in Behavior written by Nicholas DiRienzo and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of consistent individual differences in animal behavior, also known as animal personalities, has become a major focus of animal behavior over the past decade. Historically, behavior has been described in terms of population means, with variation around those means considered as noise. What personality research has demonstrated is that this noise is not random, and that instead individuals often consistently vary in their behavioral tendencies. The result is that some individuals are consistently more bold, active, or aggressive than others in the population. The progress made over the past decade has shown that personalities are present in a broad range of taxa, and that they can influence a range of larger ecological processes such as dispersal, social interactions, predator-prey, etc. My dissertation research has focused on the role of development in generating behavioral differences, as well as mechanisms that may maintain these differences. These questions are critically important as several factors should result in the reduction of behavioral variation over time. For one, personality research suggests that behavioral consistency may carry over into other contexts, and potentially be maladaptive. For example, boldness may be beneficial in the absence of predators, but maladaptive in an individual that lacks the plasticity to reduce boldness when predators are present. Second, many studies typically show greater fitness for one behavioral phenotype relative to the other, such that, for example, active individuals have higher fitness relative to inactive individuals. Together, these two ideas suggest that consistent between-individual differences in behavior should be eroded over evolutionary time, in favor of increased plasticity. However, personalities are typically associated with additive genetic variation and are pervasive in that they have been discovered in essentially every taxa. Several theoretical papers have suggested mechanisms that may maintain and generate differences in personality, but relatively few empirical studies have investigated these mechanisms. I have focused on two factors that may be responsible for both generating and maintaining behavioral differences in the face of factors selecting against behavioral variation. In Chapter 1, I investigated the role of experience during development in shaping subsequent adult personality. Early experience may result in individuals expressing developmental plasticity in order to match their later adult personality type to the "predicted' environment. For example, juveniles exposed to predator cues may express less bold personality types as adults relative to individuals not exposed to predator cues as juveniles. In other words, individuals may use the development period to express plasticity before "fixing" their personality type as adults. My research shows that such responses are indeed possible. First, in the field cricket, Gryllus integer, juveniles reared in the presence of conspecific acoustic cues, which simulates high population densities, are less aggressive than those reared in the absence of acoustic cues, which simulates low population densities. Thus, the average personality type in a population can be affected by developmental experience. In Chapter 2, I investigated the role of early exposure to pathogens, and how it may both influence the development of personality as well as the personality-immune function relationship. My results indicated that juveniles who experienced a single immune challenge lacked between-individual differences in boldness behavior as adults, while control individuals maintained the expected between-individual differences in behavior. Neither the average population-level behavior nor immune function were affected by treatment. Thus, these experiments demonstrated that experiences during development can influence both the average level of behavior in a population, as well as the presence/absence of personality. In Chapter 3 I investigated the role of behavioral interactions in maintaining personality differences between individuals within populations. The fitness of a personality type may be context-dependent and depend on the personality type of the individual is interacting with. Thus, I investigated the role of personality type interactions in a predator-prey system using the western black widow, Latrodectus hesperus, as a predator, and the field cricket, Gryllus integer, as prey. My results indicated that neither predator foraging boldness nor prey boldness alone predicted the outcome (live/die) of a predator encounter, but instead their interaction predicted the outcome. Thus, the fitness associated with a personality type varied depending on the personality type of the interacting individual, which could in turn equalize fitness between personality types. Collectively, my results suggest that experiences during development, as well as behavioral phenotype interactions may both generate and maintain, respectively, between-individual differences in behavior.