Molecular systematics of the butterfly genus Ithomia (Lepidoptera: Ithomiinae): a composite phylogenetic hypothesis based on seven genes

Abstract

Butterflies in the nymphalid subfamily Ithomiinae are brightly colored and involved in mimicry. Here we present a phylogenetic hypothesis for 23 of the 24 species in the genus Ithomia, based on seven different gene regions, representing 5 linkage groups and 4469 bp. We sequenced varying length regions of the following genes: (1) elongation factor 1alpha (Ef1alpha; 1028 bp); (2) tektin (tektin; 715 bp); (3) wingless (wg; 405 bp); (4) ribosomal protein L5 (RpL5; 722 bp, exons 1, 2, 3, and introns 1 and 2); and (5) mitochondrial cytochrome oxidase I, II (Co1 and Co2 and intervening leucine tRNA; 1599 bp). The results show incongruence between some genetic loci, although when alternate topologies are compared statistically it was generally true that one topology was supported by a majority of loci sampled. This highlights the need to sample widely across the genome in order to obtain a well-supported phylogenetic hypothesis. A combined evidence topology is presented based on a Bayesian analysis of all the gene regions, except the fast-evolving RpL5. The resulting hypothesis is concordant with the most probable relationships determined from our topological comparisons, although in some parts of the tree relationships remain weakly supported. The tree suggests diversification has largely occurred within biogeographic regions such as Central America, the Amazon, the southern and northern Andes, with only occasional dispersal (or vicariance) between such regions. This phylogenetic hypothesis can now be used to investigate patterns of diversification across the genus, such as the potential role of color pattern changes in speciation.