Discriminating Familiar Conspecifics: Behavior, Fitness, and Interplay with Spatial

Recognition of familiar individuals is known to be important in social interactions in many species of animals. Social structure, population dynamics, and evolutionary processes can depend on differentiating between familiar and unfamiliar animals through a variety of cues because recognition of familiar can affect social behaviors, which influence reproductive success and survival. Decreased aggression and increased antipredator responses are often cited results of interactions with familiar individuals with obvious benefits. In my dissertation, I studied the influence of familiarity-based interactions on the red-backed salamander, Plethodon cinereus, an abundant species in eastern North America, especially at my study sites at Mountain Lake Biological Station in the southern Applachian Mountains of Virginia. Red-backed salamanders are a model species for the study of behavioral ecology, and, more importantly, red-backed salamanders can identify familiar conspecifics in a variety of social situations. I was interested in whether adult-juvenile interactions are influenced by familiarity because of the importance of the juvenile life-stage to growth and dispersal. I investigated the effects of adult-juvenile familiarity on foraging success and growth while also testing for greater than average kinship between familiar salamanders in the forest. I found that familiarity benefits juveniles, increasing foraging activity and increasing growth, regardless of kinship with adults. While these types of effects of familiarity on individuals are not uncommon, it is not known whether individual-level effects of familiarity can lead to population-level effects on the distribution of relatedness within populations. I used genetic tests to determine that a population of red-backed salamanders was structured based on relatedness, with near individuals more related to each other than distant   individuals, concomitant with familiarity-based interactions in the population. Finally, I used spatial models to determine that benefits to reproductive success due to familiarity of neighbors can increase clustering of related individuals in populations. My dissertation draws attention to how behaviors between individuals can affect, not only the growth and movements of individuals, but also clusters related individuals in space. Many ecological and evolutionary processes are influenced by the distribution of related individuals in a population so the effects of social interactions can be significant.

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