Phylogenetic relationships of North American damselflies of the genus Ischnura (Odonata : Zygoptera : Coenagrionidae) based on sequences of three mitochondrial genes

Relationships of North American damselflies of the genus Ischnura (Odonata: Zygoptera: Coenagrionidae) were investigated using a total of 1205 bp from portions of three mitochondrial genes: cytochrome b, cytochrome oxidase II , and 12S ribosomal DNA, Parsimony and neighbor joining analyses reveal a m onophyletic group consisting of I. damula, I. demorsa, I. perparva, I. posi ta posita, I. posita atezca, I. verticalis, and probably I, denticollis, li kely reflecting a recent radiation in North America. Ischnura Kellicotti, I . barberi, I. prognata, I. hastata, I. ramburri, and L capreola appear to r epresent much earlier divergences in the group. Many previous hypotheses of relationships among North American species of Ischnura are not supported b y the molecular-based analyses. However, there is agreement in many respect s between the results of the molecular phylogenetic analyses and the morpho logically based conclusions of Kennedy (1919, "The Phylogeny of the Zygopte ra," Ph.D. Dissertation, Cornell University, Ithaca). Although results of s ingle-gene phylogenetic analyses often differ, there are very few cases in which there is strong support for conflicting relationships using different partitions of the data. Combined analysis of all three genes yields trees with stronger support overall than the single-gene analyses, and the combin ed data trees that result from diverse data treatments are congruent with o ne another in most respects. (C) 1999 Academic Press.