Location: Systematic Entomology LaboratoryTitle: A large-scale, higher-level, molecular phylogenetic study of the insect order Lepidoptera (moths and butterflies)) Author
Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2013
Publication Date: 3/14/2013
Publication URL: http://doi:10.1371/journal.pone.0058568
Citation: Reigier, J.C., Mitter, C.E., Zwick, A., Bazinet, A., Cummings, M.P., Kawahara, A., Sohn, J.C., Zwickl, D.J., Cho, S., Davis, D., Baixeras, J., Brown, J.W., Parr, C., Weller, S.J., Lees, D., Mitter, K. 2013. A large-scale, higher-level, molecular phylogenetic study of the insect order Lepidoptera (moths and butterflies). PLoS One. 8(3):e58568. Interpretive Summary: Butterflies and moths comprise one the largest insect orders, with more than 157,000 described species. In natural terrestrial ecosystems they play a major role as herbivores, pollinators, and prey; but in agricultural systems many are economically important pests of crops (fruit, vegetable, grains, wood). The complexity and abundance of their interactions with plants and other animals is not easily captured across space and time, so a tree-of-life (phylogeny) that includes this insect order would provide a valuable framework for examining large-scale environmental and evolutionary processes and patterns. This paper presents the most thorough molecular analysis of the order to date. The methods used in this paper will be of interest to scientists studying phylogenetic (geneological) relationships within any group of organisms, and the findings will be interesting to scientist trying to understand relationships among the families of butterflies and moths. The latter has important implications for understanding invasiveness and host-plant feeding, both of which have strong agricultural implications.
Technical Abstract: Higher-level relationships within the Lepidoptera, and particularly within the species-rich subclade Ditrysia, are generally not well understood, although recent studies have yielded progress. 483 taxa spanning 115 of 124 families were sampled for 19 protein-coding nuclear genes. Their aligned nucleotide sequences were analyzed using GARLI to generate maximum likelihood estimates and bootstrap percentages. The thoroughness of tree-space exploration was assessed by examining clade recovery after 1000 (for 505 bootstrap data sets) or thousands (for the unaltered data set) of search replicates, but in both cases it was shown that topologies of higher likelihood probably remain to be discovered. More thorough searches were currently deemed impractical, even with grid computing. The effect of this under-searching on the bootstrap percentage of the best supported relationships was always to underestimate their true value. Other analyses explored the effects of sampling nonsynonymous change only, partitioned and unpartitioned total nucleotide change, deletion of rogue taxa, and compositional heterogeneity. Relationships among the non-ditrysian lineages previously inferred from morphology were largely confirmed with strong support. Robust support was also found for divergences among non-apoditrysian lineages of Ditrysia, but only rarely so within Apoditrysia. Paraphyly for Tineoidea is strongly supported by analysis of nonsynonymous-only signal; conflicting, strong support for tineoid monophyly when synonymous signal was added back is shown to result from compositional heterogeneity. Support for relationships outside the Apoditrysia is now generally strong, but such support within remains largely elusive. This study highlights the challenge of finding optimal topologies through heuristic searches when analyzing hundreds of taxa. It also shows that some nodes get strong support only when analysis is restricted to nonsynonymous change, while total change is necessary for strong support of others, indicating that multiple types of analyses will be necessary to resolve the entire Lepidoptera.