Data from: Non-equilibrium conditions explain spatial variability in genetic structuring of little penguin (Eudyptula minor)

Factors responsible for spatial structuring of population genetic
variation are varied, and in many instances there may be no obvious
explanations for genetic structuring observed, or those invoked may
reflect spurious correlations. A study of little penguins (Eudyptula
minor) in southeast Australia documented low spatial structuring of
genetic variation with the exception of colonies at the western limit of
sampling, and this distinction was attributed to an intervening
oceanographic feature (Bonney Upwelling), differences in breeding
phenology, or sea level change. Here, we conducted sampling across the
entire Australian range, employing additional markers (12 microsatellites
and mitochondrial DNA, 697 individuals, 17 colonies). The zone of elevated
genetic structuring previously observed actually represents the eastern
half of a genetic cline, within which structuring exists over much shorter
spatial scales than elsewhere. Colonies separated by as little as 27 km in
the zone are genetically distinguishable, while outside the zone,
homogeneity cannot be rejected at scales of up to 1400 km. Given a lack of
additional physical or environmental barriers to gene flow, the zone of
elevated genetic structuring may reflect secondary contact of lineages
(with or without selection against interbreeding), or recent colonization
and expansion from this region. This study highlights the importance of
sampling scale to reveal the cause of genetic structuring.