No description available.

Territoriality has been disputed for the red squirrel in different habitats. A small, isolated population of red squirrels in a central Indiana deciduous woods was studied by behavioral observation to determine if territoriality existed. Territorial behavior was operationally defined as consistent display of calling and chasing by one squirrel toward all other squirrels within a particular area.A behavioral map of recorded observations revealed that each adult squirrel possessed an exclusive and clearly bounded area of land which it defended against all intruders. The Wilcoxin Matched-Pairs Signed-Ranks Test revealed that the number of in-own-territory observations differed significantly from out-of-own-territory observations.The establishment of a feeding station in one territory led to confrontations among the red squirrels which eventually resulted in the exclusive possession of the feeding station by a squirrel from another territory. A dominance hierarchy was formed among the red squirrel, chipmunks, and birds at the feeding station.

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Sexual selection is considered a powerful evolutionary force responsible for the enormous diversity found in reproductive morphology, physiology, and behavior. I addressed questions related to selection in the Cape ground squirrel (Xerus inauris), a species characterized as highly social and promiscuous. These attributes often are responsible for variance in male reproductive success and as such, sexual selection theory predicts increased opportunity for sexual selection. I confirm that the predominant mechanism underlying genital evolution and competition for paternity in X. inauris is sperm competition. I find evidence that investment in sperm competition is costly and may reflect immunocompetence. I quantify reproductive success as it relates to alternative male tactics and female resource distribution. I find that male X. inauris alternative reproductive tactics differ within and across populations most likely due to differences in female resource distribution. In areas where females are evenly distributed, dispersed males encounter more estrous females, and therefore have increased breeding opportunities. However, the decision to remain natal does not preclude reproduction. I determine that these tactics are most likely conditional with equal fitness payoffs. Males, regardless of tactic, invest more in post-copulatory competition (e.g. sperm competition, copulatory plugs) than males within a population with a clustered distribution of breeding females. In the latter area, males form dominance hierarchies that affect copulatory success and lead to greater skews in reproduction among males. Both sites have evidence of a highly skewed variance in reproduction and intense sexual selective pressure. My results suggest these populations have increased opportunities for selection but that different mechanisms of intrasexual competition may result in rapid evolutionary change within this species.