Abstract:
The nine-banded armadillo is unique for producing multiple embryos derived from a single fertilized egg (polyembryony), resulting in the production of four genetically identical offspring. Juvenile littermates are known to maintain close proximity to one another during their first summer above ground, but it is uncertain if they remain together as adults. Typically in armadillo populations adults disperse, which may be due to inbreeding avoidance and/or resource competition. There have been multiple studies that have examined sex-biased dispersal in armadillos, but with conflicting results as to which sex disperses. The goal of the present study was to determine whether spatial genetic structure diminishes at a certain life stage (juvenile, adult) within a population and if there are any detectable differences in the degree of genetic structure between the sexes. Genomic DNA from a total of 402 individual armadillos was isolated from ear clip tissue from a wild population of armadillos inhabiting the Yazoo National Wildlife Refuge, Mississippi. Individuals were grouped based on age (juvenile, adult) and further subdivided between the sexes (male, female) for each age group. Genetic measures of spatial autocorrelation based on eight microsatellite loci were used in correlograms to resolve patterns of spatial genetic structure within this population. My results show significant spatial genetic structure in juveniles (both males, females) and adult males, but not adult females. These results support either female-biased dispersal or high variance in male reproductive success (via polygyny). However, further work is required to discriminate between these two possibilities.