Mixing in Moderation: Slow Transmission of Non-Local Macroparasites Following a Population Augmentation of an Endangered Australian Skink.

Abstract

Translocating threatened wildlife to more suitable habitat is increasingly necessary for conserving biodiversity. However, parasite dynamics in such translocations are poorly characterised, despite their potential importance for influencing translocation success and contributing to biodiversity and ecosystem function. We used single nucleotide polymorphism (SNP) genotyping to evaluate the transmission of parasites with different population origins following a population augmentation of the endangered pygmy bluetongue lizard (Tiliqua adelaidensis) involving three isolated, wild populations in South Australia. We examined inter-population genetic variation for source and recipient host populations in the ecotoparasitic mite Ophiomegistus michaeli and the nematode pinworm Pharyngodon wandillahensis. Ordination and STRUCTURE analyses of SNP markers revealed population-based genetic structure, particularly for P. wandillahensis. For 2 years following the population augmentation, hosts mostly retained parasite genotypes congruent with their origin, though cluster exceptions suggested some inter-population transmission over time. Modelling of parasite pairwise relatedness over time supported different P. wandillahensis lineages gradually infecting hosts from different sources, as relatedness increased between nematodes collected from different hosts, particularly those from different source populations, and conversely decreased between nematodes collected from the same host. In contrast, O. michaeli pairwise relatedness changed little over time, suggesting minimal inter-host movement. The apparently minimal and slow nature of transmission of non-local mites and nematodes between translocated and resident host lizards is likely driven by the non-social nature of T. adelaidensis and as yet uncharacterised aspects of the parasites' life histories, highlighting the importance of considering these during conservation management.