Genetics of endangered species Chasmistes liorus, (June sucker)

Chasmistes is an extant genus of American Cenozoic freshwater suckers (Catostomidae). They occurred in Miocene to Pleistocene deposits of six western states. The subterminal mouth and branched gill rakers make them distinct from other members of the sucker family. Chasmistes liorus (June sucker), endemic to Utah Lake, is one of the three extant and endangered Chasmistes. Once abundant, it has been declining in numbers since a severe drought in the mid-1930's and has changed somewhat morphologically. Miller and Smith (1981) asserted that the original C. liorus went extinct during the drought, and they hypothesized that the present day C. liorus is a hybrid of June and Utah suckers (Catostomus ardens). However, their analysis did not include a molecular genetic analysis nor did it take the longer term history of Utah Lake into consideration. I compared June and Utah suckers using RAPD to assess nuclear DNA, and RFLP and PAUP to assess ND2 region of mtDNA. Chasmistes cujus (Cuiui sucker) and Catostomus tahoensis (Tahoe sucker), which inhabit Pyramid Lake in Nevada were also analyzed. While the Cuiui and Tahoe suckers are district from each other on all the analyses, no significant differences between June and Utah Lake Utah suckers and no diagnostic molecular markers were found to distinguish the two. The Utah Lake Utah sucker showed haplotype district from the Utah sucker from all other drainage in Utah. During three documented extremely severe and long lasting droughts in history, June and Utah suckers were forced into devastating circumstances that their cross mating and reticulation (hybridization) became possible for many times. This situation may make the June sucker unlikely a proper taxon under the protection of present conservational policy of ESA.