Evidence of male-biased dispersal in eastern grey kangaroos (Macropus giganteus)

Abstract

Dispersal reduces the likelihood of inbreeding and maintains gene flow among populations. Many polygynous mammals exhibit male-biased dispersal with female philopatry. Previous observational studies of eastern grey kangaroos (Macropus giganteus) suggested female philopatry while genetic studies showed weak structuring. We tested for sex-biased dispersal using two Queensland populations of kangaroos: one in Sundown National Park and the second at Elanda Point, Australia. Samples from 25 females and 23 males were collected from Sundown National Park, and analysed for partial mtDNA control region sequences (n = 47) and genotypes based on 12 microsatellite loci (n = 41). Samples from 18 males and 22 females from Elanda Point were genotyped at 8 loci and a subset sequenced for mtDNA (n = 19). Analyses showed higher mtDNA haplotype and nucleotide diversity in males than females within both populations, genetic relatedness based on microsatellite data was significantly higher among females, and microsatellite allelic richness was higher in males, suggesting that females are more likely to be philopatric and males more likely to disperse. These findings reinforce the value of including multiple types of genetic markers in dispersal analyses as mtDNA results showed higher male diversity (suggesting male dispersal) but males also contributed microsatellite alleles to the local population, masking differentiation between the sexes and confounding analyses.