Estimating the relatedness in a population of grey squirrels Sciurus carolinensis, using DNA fingerprinting

Abstract

. 1999. Estimating the relatedness in a population of grey squirrels Sciurus carolinensis, using DNA fingerprinting. Acta Theriologica 44: 243-251.Studies on the behaviour of grey squirrels Sciurus carolinensis Gmelin, 1788 and other species belonging to the same genus, suggest they exhibit dominance hierarchies among both males and females, and their mating strategy is promiscuous or polygynous. However, there is little information available on how dominance translates into reproductive success or on the levels of genetic variation or genetic substructuring within a population. To address these questions, we used multilocus DNA fingerprinting to quantify genetic diversity and estimate relatedness amongst individuals in a free--ranging population of grey squirrels. Background band-sharing values revealed a high degree of genetic diversity existed. The frequency distribution of band-sharing values between known first order relatives and presumed unrelated animals was significantly different. Estimates of relatedness between individuals were therefore based on threshold levels of genetic similarity and used as a tool to infer close kinship. Possible kinship groups were identified using the spatial distribution of the home ranges of adults and juveniles. Levels of relatedness between neighbouring adults was low with five family units identified comprised of putative parents and their offspring. Several juveniles from the single cohort revealed levels of relatedness intermediate between first order relatives and unrelated animals, suggesting possible second order relationships (eg half siblings) existed. The implications of these relationships are discussed.

Direct vs. Indirect Benefits of Caching by Gray Squirrels (Sciurus carolinensis)

“…Related females showed a non-significant tendency to live nearer one another than unrelated females, and related males were not more likely to live near each other than unrelated males. A recent study of the genetic structure of a population of introduced gray squirrels in England also showed that adult squirrels living near one another tended to be unrelated (David-Gray et al 1999). Sherman 1981;van Staaden et al 1996;Schulte-Hostedde et al 2001) and other studies with gray squirrels (Koprowski 1996;Gurnell et al Fig.…”

“…DNA was extracted from these tissues and used for RAPD analysis as described above. We used methods similar to those used by David-Gray et al (1999) to determine the genetic similarity of non-relatives. Specifically, data for non-relatives were taken from pairs of squirrels at NATL that met the following criteria: (1) at least five captures, (2) non-overlapping ranges, and (3) 250 m or more between their range centers.…”

“…Lack of more pronounced genetic structuring within our study population is not surprising considering that each squirrel's home range was overlapped by an average of 16 other squirrels (Spritzer 1999). A recent study of the genetic structure of a population of introduced gray squirrels in England also showed that adult squirrels living near one another tended to be unrelated (David-Gray et al 1999). Thus, the limited degree of kin clustering within at least some gray squirrel populations may be insufficient to favor the evolution of kin-biased cache sharing.…”

Genetic Relatedness of Deer Mice (Peromyscus maniculatus) Infected with Sin Nombre Virus

“…Mark-recapture techniques and the spatial distribution of individual animals have been used as aids in identifying putative kinship groups in natural populations (David-Gray et al 1999). Furthermore, routine demographic information (i.e., body mass, location) collected during field studies and used in combination with genetic data can provide a finer level of distinction among related groups than can one technique alone (Descalzi et al 1998).…”