Its the shape that matters! The diverse world of genitalia: A taxonomic and evolutionary exploration of the neotropical genus Eois Habner (Lepidoptera: Geometridae: Larentiinae)
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Authors
Doan, Lydia
Issue Date
2023
Type
Dissertation
Language
Keywords
Eois , Genitalia morphology , Geometrid Moth , Lepidoptera , Piper , Tropical diversity
Alternative Title
Abstract
Eois Hübner (Geometridae: Larentiinae) is a hyperdiverse genus of moths containing 267 valid species, but with estimates of 1,000 or more Neotropical species yet to be described. The paucity of contemporary descriptive and distributional data for these moths not only limits monitoring and conservation efforts of potentially vulnerable populations, but also hinders investigations into ecological and evolutionary factors underlying the diversity of Eois. To begin to remedy shortcomings in our knowledge of this moth group, I conducted research on three different aspects of Eois systematics and evolution.1) I conducted morphometric analysis of cryptic species at a site in the Ecuadoran Andes, evaluating relationships between genetic and genitalic variation of morphologically similar (i.e., cryptic) species in the Eois olivacea clade, and investigating the extent that elevation and host plant associations influence evolutionary patterns across Ecuadorian populations. Based on 170 individuals sampled from different elevations and host plants at a single site within the Ecuadorian Andes, population genetic analyses revealed that samples can be assigned to four distinct taxa, with genetic divergence among taxa associated with different host plants. Morphometric analysis indicated that the adult samples belong to three distinct taxa, and molecular dating analysis implied that these taxa form a monophyletic clade that began diverging approximately five million years ago.
2) I circumscribed and described 16 new species of the Eois olivacea clade based on traditional morphological techniques using specimens from various institutional collections (UNR, AMNH, BMNH, USNM and McGuire Center), employing a data matrix of 107 morphological characters. I defined the clade based on wing pattern and other morphological features, and then provided detailed diagnoses and descriptions of each new species, as well as re-examining the four previously described species in the clade.
3) I analyzed male vs. female features of the genitalia to further our understanding of sexual traits and evolution of genitalia in Eois. I considered different mechanisms of diversification of genitalia and differences among the sexes, including genetic drift, pleiotropy, female choice, cryptic female choice, male to male competition, sexual conflict, and the lock-and-key hypothesis. I also explored variation of female versus male traits. Using the morphological data matrix mentioned above, I developed a phylogeny for a sample of 99 species (94 Eois and five outgroup taxa), using maximum parsimony and maximum likelihood methods, and separate dendrograms based on male-only and female-only characters. An examination among trees revealed discordance between dendrograms based on male-only and female-only traits, suggesting at least partially independent evolution of traits between the sexes.
The Neotropical moth genus Eois is a remarkable group, and includes dazzling species with complex ecologies and fascinating evolutionary patterns. Nevertheless, understanding that diversity has been challenging, and if estimates of the species richness are correct, the genus is among the most species-rich in all of Lepidoptera. The results presented here provide a starting point in undertaking the challenging endeavor of describing the hundreds of new species of Eois. The results also represent a foundation for investigating sexual trait evolution in the genus, largely because knowledge of functional morphology of Eois genitalia is limited, as is information on mating interactions, mating costs and benefits, the physical interaction of male and female genital structures, and rates of evolutionary divergence of these animals.