Data from: MHC class II diversity of koala (Phascolarctos cinereus) populations across their range

Major histocompatibility complex class II (MHCII) genes code for proteins
that bind and present antigenic peptides and trigger the adaptive immune
response. We present a broad geographical study of MHCII DA β1 (DAB) and
DB β1 (DBB) variants of the koala (Phascolarctos cinereus; n=191) from 12
populations across eastern Australia, with a total of 13 DAB and 7 DBB
variants found. We identified greater MHCII variation and, possibly,
additional gene copies in koala populations in the north (Queensland and
New South Wales) relative to the south (Victoria), confirmed by STRUCTURE
analyses and genetic differentiation using analysis of molecular variance.
The higher MHCII diversity in the north relative to south could
potentially be attributed to (i) significant founder effect in Victorian
populations linked to historical translocation of bottlenecked koala
populations and (ii) increased pathogen-driven balancing selection and/or
local genetic drift in the north. Low MHCII genetic diversity in koalas
from the south could reduce their potential response to disease, although
the three DAB variants found in the south had substantial sequence
divergence between variants. This study assessing MHCII diversity in the
koala with historical translocations in some populations contributes to
understanding the effects of population translocations on functional
genetic diversity.