Rebecca B. Simmons

What kind of signals do mimetic tiger moths send? A phylogenetic test of wasp mimicry systems (Lepidoptera: Arctiidae: Euchromiini)

Mimicry has been examined in field and laboratory studies of butterflies and its evolutionary dynamics have been explored in computer simulations. Phylogenetic studies examining the evolution of mimicry, however, are rare. Here, the phylogeny of wasp–mimicking tiger moths, the Sphecosoma group, was used to test evolutionary predictions of computer simulations of conventional Müllerian mimicry and quasi–Batesian mimicry dynamics. We examined whether mimetic traits evolved individually, or as suites of characters, using concentrated change tests. The phylogeny of these moth mimics revealed that individual mimetic characters were conserved, as are the three mimetic wasp forms: yellow Polybia, black Polybia and Parachartergus mimetic types. This finding was consistent with a ‘supergene’ control of linked loci and the Nicholson two–step model of mimicry evolution. We also used a modified permutation–tail probability approach to examine the rate of mimetic–type evolution. The observed topology, hypothetical Müllerian and Batesian scenarios, and 1000 random trees were compared using Kishino–Hasegawa tests. The observed phylogeny was more consistent with the predicted Müllerian distribution of mimetic traits than with that of a quasi–Batesian scenario. We suggest that the range of discriminatory abilities of the predator community plays a key role in shaping mimicry dynamics.

Transcriptome analysis of the painted lady butterfly, Vanessa cardui during wing color pattern development

BackgroundButterfly wing color patterns are an important model system for understanding the evolution and development of morphological diversity and animal pigmentation. Wing color patterns develop from a complex network composed of highly conserved patterning genes and pigmentation pathways. Patterning genes are involved in regulating pigment synthesis however the temporal expression dynamics of these interacting networks is poorly understood. Here, we employ next generation sequencing to examine expression patterns of the gene network underlying wing development in the nymphalid butterfly, Vanessa cardui.ResultsWe identified 9, 376 differentially expressed transcripts during wing color pattern development, including genes involved in patterning, pigmentation and gene regulation. Differential expression of these genes was highest at the pre-ommochrome stage compared to early pupal and late melanin stages. Overall, an increasing number of genes were down-regulated during the progression of wing development. We observed dynamic expression patterns of a large number of pigment genes from the ommochrome, melanin and also pteridine pathways, including contrasting patterns of expression for paralogs of the yellow gene family. Surprisingly, many patterning genes previously associated with butterfly pattern elements were not significantly up-regulated at any time during pupation, although many other transcription factors were differentially expressed. Several genes involved in Notch signaling were significantly up-regulated during the pre-ommochrome stage including slow border cells, bunched and pebbles; the function of these genes in the development of butterfly wings is currently unknown. Many genes involved in ecdysone signaling were also significantly up-regulated during early pupal and late melanin stages and exhibited opposing patterns of expression relative to the ecdysone receptor. Finally, a comparison across four butterfly transcriptomes revealed 28 transcripts common to all four species that have no known homologs in other metazoans.ConclusionsThis study provides a comprehensive list of differentially expressed transcripts during wing development, revealing potential candidate genes that may be involved in regulating butterfly wing patterns. Some differentially expressed genes have no known homologs possibly representing genes unique to butterflies. Results from this study also indicate that development of nymphalid wing patterns may arise not only from melanin and ommochrome pigments but also the pteridine pigment pathway.

A New Pest Species of Copitarsia (Lepidoptera: Noctuidae) from the Neotropical Region Feeding on Asparagus and Cut Flowers

Abstract The egg, first and last instars, and adult of Copitarsia corruda, n. sp. from Mexico, Colombia, Ecuador, and Peru are described and illustrated. Larval host plant genera include Asparagus (Liliaceae) (Mexico, Colombia, and Ecuador), Iris (Iridaceae) (Ecuador), Ammi (Apiaceae) (Ecuador), Lysimachia (Primulaceae) (Colombia), Callistephus (Asteraceae) (Colombia), and Aster (Asteraceae) (Colombia). The larva of Copitarsia decolora (Guenée) is described and illustrated. In addition to genitalic and larval characters, mitochondrial gene cytochrome oxidase I (COI) was analyzed to differentiate C. corruda from Copitarsia decolora (Guenée), and to examine geographic and host plant differences between the two species.

The Evolution of Androconia in Mimetic Tiger Moths (Noctuoidea: Erebidae: Arctiinae: Ctenuchina and Euchromiina)

ABSTRACT Tiger moth courtship involves an intricate interplay of female calling and male responses, involving pheromones, ultrasound, or both. A comparative phylogenetic approach is needed to separate proximal (ecological) from ultimate (evolutionary) explanations for observed behaviors. This study focused on mimetic tiger moths (Ctenuchina and Euchromiina) to provide a phylogeny to understand the evolution of male courtship structures (androconia). Genetic data from one mitochondrial gene (1,173 basepairs [bp] of COI) and two nuclear genes (238 bp of 28S rRNA D1 loop; 650 bp of EF1-&agr;) were sampled for 29 species and analyzed using maximum parsimony, maximum likelihood, and Bayesian methods to estimate phylogenetic relationships. The ancestral reconstruction of androconia was optimized using parsimony and Bayesian approaches. Excluding three species, Euchromiina and Ctenuchina were recovered as reciprocally monophyletic, contradicting earlier molecular phylogenies. The genus Cosmosoma was found to be polyphyletic, as was Eucereon. Reconstruction of androconial structures revealed that these structures were acquired once, with subsequent losses in particular species.