Conservation Implications of Widespread Misclassification and Hybridization of the Endangered Aplochiton zebra and A. taeniatus in South America

Aplochiton zebra and Aplochiton taeniatus are two galaxiid fishes endemic to Patagonia and, in the case of Aplochiton zebra, also present in the Falklands Islands where they are threatened by salmonid invasions. Identification of Aplochiton is complicated because the two species are ecologically and morphologically very similar and include resident as well as migratory ecotypes that may confound classification. We used DNA barcoding (COI, cytochrome b) and a new developed set of microsatellite markers to identify Aplochiton zebra from Aplochiton taeniatus and to assess the validity of in-situ field identification in Chilean Patagonia. We also assessed the extent of cross-species amplification of recently developed microsatellite DNA primers for A. zebra.  Cross-species amplification was demonstrated in 11 of 13 loci tested. On a sample of 456 Aplochiton, phenotypic misclassification ranged from 0 % for A. zebra and 70 % for A. taeniatus, the latter species being more widespread than previously thought. We also report on the potential of hybridization between both species with findings of first generation hybrids in rivers where both species co-exist. Aplochiton zebra populations showed strong population structuring in relation to both life-history differences (anadromous bversus landlocked populations) and post-galcial origin. We will discuss the implications of our results for the conservation and management of Aplochiton populations.