Wednesday, May 28, 2008 - 2:45 PM
463

How well does the morphological taxonomy of aquatic insects correlate with genetic divergence? a molecular comparison of closely-related species in the genus Ephemerella (Ephemeroptera: Ephemerellidae)

Laurie C. Alexander, David J. Hawthorne, and William O. Lamp. Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, MD 20742

In a recent systematic revision of the genus Ephemerella (Ephemeroptera: Ephemerellidae), eight of the more than 20 described North American species including E. inconstans, E. rotunda, and E. floripara were synonymized with the widely distributed E. invaria based on morphology.  A molecular analysis of these genetic lineages was conducted using mitochondrial DNA (mtDNA) markers in comparison to species taxa delineated by morphologic characters. Maximum likelihood and maximum parsimony analyses of mtDNA sequences placed one synonym, E. inconstans, with E. invaria in a well-supported clade (92%, 1000 bootstrap replicates).  However, E. invaria samples were grouped in a nested clade (84% bootstrap support) and average Kimura 2-parameter (K2P) genetic distance between lineages (5.2%) was high relative to K2P distance within lineages (1.3%).  The relationships of synonyms E. rotunda and E. floripara are not resolved by this analysis but estimates of mean genetic distance from the E. invaria clade were high for both (8.7% and 11.2% K2P respectively).  Cryptic diversity and deep divergences were revealed in species other than E. invaria.  While these results reveal high genetic diversity in and among morphologically similar taxa, they do not support use of a “DNA barcoding” approach for identifying species in this genus, as evidence of incomplete mtDNA lineage sorting and retention of ancestral polymorphism also was found.


Web Page: Ephemerellidae, mtDNA, Taxonomy