Phylogenetic Relationships of Phyciodes Butterfly Species (Lepidoptera: Nymphalidae): Complex Mtdna Variation and Species Delimitations
Systematic Entomology (2003) 28, 257±273 Phylogenetic relationships of Phyciodes butterfly species (Lepidoptera: Nymphalidae): complex mtDNA variation and species delimitations NIKLAS WAHLBERG*, RITA OLIVEIRA* andJAMES A. SCOTTy *Metapopulation Research Group, Department of Ecology and Systematics, University of Helsinki, Finland, and yLakewood, Colorado, U.S.A. Abstract. Mitochondrial DNA variation wasstudied in the butterfly genus Phyciodes (Lepidoptera: Nymphalidae) by sequencing 1450 bp of the COI gene from 140 individuals of all eleven currently recognized species. The study focused on four species in particular that have been taxonomically difficult for the past century, P. tharos, P. cocyta, P. batesii and P. pulchella. A cladistic analysis of ninety-eight unique haplotypesshowedthat Phyciodes formsa monophyletic group with P. graphica as the most basal species. Of the three informal species groupsdescribed for Phyciodes, only one (the mylitta-group) isunambiguously monophyletic. Within the tharos-group, seven well supported clades were found that correspond to three taxa, P. tharos, P. pulchella and a grade consisting of P. cocyta and P. batesii haplotypesinterdigitated with each other. None of the clades is formed exclusively by one species. The patterns of haplotype variation are the result of both retained ancient polymorphism and introgression. Introgression appearsto be mostcommon between P. cocyta and P. batesii; however, these two species occur sympatrically and are morphologically and ecologically distinct, suggesting that the level of current introgression does not seem to be enough to threaten their genetic integrity. The results indicate that mitochondrial DNA sequences must be used with great caution in delimiting species, especially when infraspecific samples are few, or introgression seems to be rampant.
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