Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Rebecca Simmons

Abstract

Ctenuchina are a subtribe of tiger moths in the subfamily Arctiinae and are known for their aposematism and mimicry of noxious insects. Their overall appearance signals predators of their unpalatability due to larval sequestration of plant secondary chemicals. The taxonomic history of Ctenuchina is complicated because of convergent phenotypes within the lineage and with other tiger moth groups such as the Euchromiina. Independent evolutionary events that converge on mimetic phenotypes obscure evolutionary relationships and render classifications based on morphology to be suspect. Although morphological phylogenies have since been used less often in favor of quantifiable, molecular-based phylogenies, these studies provide a valuable starting point for arctiine nomenclature. Previous classifications relied on visible adult morphological characteristics, particularly wing venation, to classify genera. These treatments would result in paraphyletic or polyphyletic groupings in modern terms. Previous molecular studies on tiger moths have been performed with the goals of elucidating their phylogenetic relationships and stabilizing taxonomy within the broader group of Arctiinae. However, there is a lack of understanding when it comes to the finer scale of phylogenetic relationships among arctiine subtribes including Ctenuchina. With this study, I constructed a phylogeny for Ctenuchina using molecular data from eight loci for 48 species that span the diversity of the lineage. The loci that I sampled included: cytochrome oxidase I (COI), the DI region of the 28S ribosomal DNA (DI), the DII region of the 28S ribosomal DNA (DII), Elongation Factor 1-alpha (EF1-α), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), isocitrate dehydrogenase (IDH), ribosomal protein S5 (RPS5), and wingless (WGL). I sampled 48 species (53 individuals) including 30 members of the Ctenuchina (15 genera), 14 members of Euchromiina (8 genera), and 9 members of Phaegopterina (7 genera). I performed Sanger sequencing for each locus then concatenated the resulting consensus sequences along with previously published molecular data to form a multi-locus matrix (3700 base pair dataset). I then analyzed the muli-locus matrix using likelihood methods. My results provide support for the monophyly of Ctenuchina with the exception of ctenuchine representatives from Abrochia and Pseudacyltia recovered within Phaeopterina. My results also support monophyly of Euchromiina with respect to Ctenuchina. My multi-locus reconstruction shows strong bootstrap support mainly at apical nodes; my results mainly show strong support relationships between genera at the species level and in small clades. My analysis supports the monophyly of several ctenuchine genera including Theages, Correbia, Correbidia, Heliura, and Euagra. To observe the contribution of each locus to the multi-locus phylogeny, I analyzed each of the eight sampled loci separately using likelihood methods. The resulting DII topology recovered the greatest number of resolved nodes (>70% bs; bootstrap support=bs); the CO1 topology resulted in the fewest. The IDH dataset had the most phylogenetic information and the greatest number of variable sites; the DI topology had the fewest variable sites. My resulting phylogeny provides a robust classification for these moths that will facilitate future studies of their life history and a more detailed revision of demonstrated monophyletic lineages. Future work with increased gene region and taxon sampling will stabilize key nodes, allowing for a better understanding of the evolution of complex characters, such as mimicry and chemical sequestration.

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