Population ecology of subterranean rodents

BUSCH, CRISTINA; ANTENUCCI, CARLOS DANIEL; DEL VALLE, JUANA CRISTINA; KITTLEIN, MARCELO J.; MALIZIA, ANA INÉS; VASSALLO, ALDO I.; ZENUTO, ROXANA

Life Underground: The Biology of Subterranean Rodents

Chicago University Press

Año: 2000; p. 183 - 226

Interactions between animals and their environments are a critical part of the biology of any species. At thelevel of the individual, interactions with the environment may influence numerous traits, including aspectsof morphology (Chap. 1), physiology (Chap. 2) and reproduction (Chap. 4), as well as patterns ofcommunication among conspecifics (Chap. 3). At the level of the population, interactions with theenvironment determine where animals can live, as well as whether conspecifics occur alone or in groups(Chap. 7). Environmental conditions may also influence population size, including patterns of natality,mortality, and dispersal. In short, ecological interactions between animals and their environment are acritical part of a species? biology.For many mammals, including many rodents, subterranean burrows play an important role ininteractions with the environment. Burrows may be used as places of refuge and storage, as well as nestsites for young (Carter and Encarnacao 1983; ?gren et al. 1989; Carter and Rosas 1997; Hodara et al. 1997).Fossorial rodents often have extensive and very elaborate burrows that contain multiple chambers andopenings (Llanos and Crespo 1952; YaÒez and Jaksic 1978; Scheck and Fleharty 1980; Pearson 1984; Ojedaet al. 1996); the construction, use, and maintenance of these burrows represents a central element of theanimals? lives. Given their importance to the everyday life of subterranean species, underground burrowsare expected to substantially shape the ecology of the rodents that inhabit them.Despite the assumption that a subterranean lifestyle imposes similar selective pressures on all of itsmammalian inhabitants, regional variation in climate, soil and vegetation may be of considerableimportance in generating adaptive differences among populations and species. As a result, seeminglyconvergent taxa may, in fact, display different local adaptive peaks that reflect variation in localenvironments. Further, because adaptations to distinct environments may involve variable commitment tosubterranean life (e.g., strictly subterranean mole-rats versus primarily surface-foraging tuco-tucos),differences in population ecology may reflect the combined effects of underground and surface-relatedselective pressures.There is a clear need to evaluate the validity of long-accepted generalizations regarding thepopulation ecology of subterranean rodents. In particular, assumptions regarding demographic parameterssuch as dispersal, reproductive rate, and predation need to be reconsidered in light of evidence thatsubterranean species are not subject to uniform selective pressures. In this chapter, we explore howdifferences in local environments influence the population ecology of subterranean rodents. Given thecentral role of the burrow system in the lives of these animals, we begin by considering how burrowstructure and location are influenced by environmental conditions. We then explore the foraging ecology ofsubterranean rodents and consider the effects of the subterranean habitus on the life history strategies ofthese animals. We conclude with a discussion of predation that underscores the prevalence of interspecificdifferences in response to local environments among subterranean species.