Parentage analysis of the canyon mouse (Peromyscus crinitus): evidence for multiple paternity

Mating systems within the genus Peromyscus have traditionally been inferred from field observations of spatial relationships of males and females and from laboratory behavioral studies. The majority of species within Peromyscus are assumed to be promiscuous, but rarely have these conclusions been verified with molecular data. Genotypes constructed from 4 microsatellite loci were used to determine paternity in 10 litters of the canyon mouse (Peromyscus crinitus). We applied 3 criteria for paternity assignment: direct observation of paternal alleles, correlation of sampled male and offspring genotypes (mothers known) including spatial relationship data, and application of a likelihood estimator. Multiple paternity occurred in a minimum of 20% of the litters, yet we found no evidence that would indicate that any putative father sired 2 or more litters. Dispersal of males between the time of copulation and parturition was minimal (7.5-70 m) in most cases, but 1 male was captured in a rock outcropping separate from that of his sired litter (174 m). Our use of 3 different criteria allowed a greater number of male paternity assignments to be inferred than would have been possible when using software program CERVUS alone, and increased confidence in these results. Key words: mating system, microsatellites, multiple paternity, parentage analysis, Peromyscus crinitus