Microsatellite Gene Diversity Analysis in Landlocked Arctic Char from Maine

Abstract

Using six microsatellite loci, we characterized the 12 remaining populations of Arctic char Salvelinus alpinus naturally occurring in Maine. More specifically, we challenged the hypotheses based on previous analyses with other markers that (1) Arctic char from Floods Pond (known locally as silver char) represent a distinct evolutionary lineage and (2) all other Arctic char populations from Maine belong to the same evolutionary lineage and therefore do not require individual consideration for conservation. The high level of polymorphism observed at microsatellite loci in this study contrasted sharply with the extremely low levels of variation previously reported at other markers. Analyses confirmed that all lakes possess genetically distinct populations among which gene flow is restricted and on which other evolutionary forces may act independently, enhancing their genetic divergence. However, hierarchical gene diversity, population clustering, and population assignment analyses all indicated that the populations from different drainages did not originate from genetically distinct ancestral population assemblages. Our results thus contradict previous conclusions, as we found that the Arctic char from Floods Pond likely did not originate from a distinct evolutionary lineage. Secondly, although all Maine Arctic char appear to belong to a single evolutionary lineage, sufficient divergence was found to reject the hypothesis that all other populations should be considered as genetically equivalent for conservation. We discuss the implications of these findings for the management and protection of these unique Arctic char populations.