Skull morphometrics of male Subantarctic fur seals (Arctocephalus tropicalis) from Marion and Gough Islands

Abstract

Skull morphometrics of two populations of Subantarctic fur seal (Arctocephalus tropicalis) were compared in order to identify possible geographic variation as an indicator of gene flow between the populations, as well as a potential tool to identify the source of vagrant seals. Nineteen metric variables were recorded from skulls of adult male seals from Marion Island (n=31) and Gough Island (n=41). Comparative univariate and multivariate statistical analyses conducted on the two population samples included standard statistics (mean, standard deviation, coefficient of variation, range), multivariate analysis of variance, stepwise discriminant function analysis, cluster analysis and principal component analysis. No significant separation between the two island groups, based on cranial characteristics of adult males, was found. These findings suggest that gene flow is occurring between these populations.We conclude that skull morphometrics cannot be used to identify the origins of vagrant Subantarctic
fur seals.

Key words: cranial characteristics, population gene flow.