Synergistic effects of combining morphological and molecular data in resolving the phylogeny of butterflies and skippers

Abstract

Phylogenetic relationships among major clades of butterflies and skippers have long been controversial, with no general consensus even today. Such lack of resolution is a substantial impediment to using the otherwise well studied butterflies as a model group in biology. Here we report the results of a combined analysis of DNA sequences from three genes and a morphological data matrix for 57 taxa (3258 characters, 1290 parsimony informative) representing all major lineages from the three putative butterfly super-families (Hedyloidea, Hesperioidea and Papilionoidea), plus out-groups representing other ditrysian Lepidoptera families. Recently, the utility of morphological data as a source of phylogenetic evidence has been debated. We present the first well supported phylogenetic hypothesis for the butterflies and skippers based on a total-evidence analysis of both traditional morphological characters and new molecular characters from three gene regions (COI, EF-1alpha and wingless). All four data partitions show substantial hidden support for the deeper nodes, which emerges only in a combined analysis in which the addition of morphological data plays a crucial role. With the exception of Nymphalidae, the traditionally recognized families are found to be strongly supported monophyletic clades with the following relationships: (Hesperiidae+(Papilionidae+(Pieridae+(Nymphalidae+(Lycaenidae+Riodinidae))))). Nymphalidae is recovered as a monophyletic clade but this clade does not have strong support. Lycaenidae and Riodinidae are sister groups with strong support and we suggest that the latter be given family rank. The position of Pieridae as the sister taxon to nymphalids, lycaenids and riodinids is supported by morphology and the EF-1alpha data but conflicted by the COI and wingless data. Hedylidae are more likely to be related to butterflies and skippers than geometrid moths and appear to be the sister group to Papilionoidea+Hesperioidea.

Figure 1

Phylogenetic analyses of the three molecular datasets combined. (a) Strict consensus of three equally maximum parsimonious trees (length 11 908, consistency index 0.18, retention index 0.32), numbers above branches are Bremer support, those to the right of the node are Bootstrap values; (b) tree resulting from Bayesian analysis (average likelihood=−49 408.8), numbers above or below branches are posterior probabilities for the node to the right of each number. Colour codes represent families as follows: pink, Hedylidae; red, Hesperiidae; green, Papilionidae; yellow, Pieridae; purple, Riodinidae; blue, Lycaenidae; orange, Nymphalidae.

Figure 2

Phylogenetic analyses of the combined molecular and morphological datasets. (a) Single most parsimonious tree (length 12 459, consistency index 0.21, retention index 0.34). Numbers above branches are Bremer support/Bootstrap values for the node to the right of the numbers and italicized numbers below branches are node numbers referred to in table 1; (b) tree resulting from Bayesian analysis using mixed models (average likelihood=−51 999.2). Numbers below branches are posterior probabilities for the node to the right of each number. Taxa in parentheses are related substitutes from which sequence data were obtained. Colour codes as in figure 1.