Limiting resources and territoriality in microtine rodents.

Abstract

Proposes a set of hypotheses to predict under what conditions females and males should defend territories. 1) Microtines have a low-quality diet and should tend to be food-limited. Females invest a large portion of their energy in reproductive physiology, and their reproductive success should be limited by their ability to acquire food and convert it into weaned offspring. Males invest much less energy in reproductive effort and do not participate in parental care; thus, their reproductive success should be limited by access to females. Territoriality in females should thus be food-based, that in males, female-based. 2) There are 3 main dietary categories for microtines; fruit-seed-fungus, forbs, and grasses. In general, fruits and seeds (in forest habitat) and forbs (in meadows) are patchily distributed, relatively sparse and poorly renewable. Since patchy distribution of a resource increases its defensibility, and since sparseness and poor renewability increase the costs of allowing exploitation by intruders, females relying on these 2 diets should be territorial. Grass in meadows is evenly distributed, abundant and highly renewable. Thus, females of species that rely largely on grasses should be nonterritorial. 3) When females are territorial they tend to be hyperdispersed; when females are nonterritorial they should be clumped in distribution. Since evenly spaced females are difficult to defend, males territoriality should not occur in species showing female territoriality. Conversely, when females are nonterritorial, males should be territorial. -from Author