Dissertations, Theses, and Capstone Projects
Date of Degree
9-2025
Document Type
Doctoral Dissertation
Degree Name
Doctor of Philosophy
Program
Biology
Advisor
David Lohman
Committee Members
Christopher Blair
Jessica Ware
Mike Hickerson
Shen-Horn Yen
Subject Categories
Entomology | Evolution
Keywords
Biogeography, Danainae, Phylogenetics
Abstract
The Indo-Australian Archipelago is a megadiverse region characterized by high species richness and endemism. The large concentration of biodiversity in this region is likely driven by the opportunities for isolation on islands which can lead to decreased gene flow, population divergence, and eventual speciation. Despite comprising most of Earth’s biodiversity, insects are rarely used as study systems to explore how islands and historic-geographic processes shape biodiversity patterns in the Paleotropics. This bias is largely driven by the lack of information regarding evolutionary relationships and distributions in many insects apart from some groups like butterflies. In this dissertation, I investigated how islands impact diversification in the butterfly tribe Danaini (Nymphalidae: Danainae). This group has a pantropical distribution with more than half of the ~180 described species being found in the Indo-Australian Archipelago which suggests that there are mechanisms preserving or generating diversity in this region. The goal of this dissertation was to infer a dated phylogenetic backbone for Danaini to enable future comparative work and to investigate how islands can impact the diversification of butterflies. Genetic data for this dissertation was generated using Anchored Hybrid Enrichment (AHE) from many historical specimens. Using metadata from a large anchored-phylogenomic project I investigated what factors were important in determining sequence capture success. The aim was to determine how factors, such as specimen age and storage protocol, impact capture to better inform specimen selection in phylogenomic studies. From this sequence dataset I then inferred a dated phylogeny of ~85% of all Danaini species. I used this phylogeny to reconstruct the biogeographic history of Danaini based on their contemporary distributions to develop a comprehensive dated phylogenetic and biogeographic framework. These analyses showed that the systematics of Danaini is complex as many currently recognized species belong to complexes which likely comprise more than one independently evolving lineage. Additionally, the biogeographic reconstruction showed that a rapid increase in species occurred in the Indo-Australian Archipelago in the last ~3 million years which is consistent with Pleistocene glaciation cycles and differentiation driven by the isolation of populations due to eustasy. I then tested hypotheses of island-driven diversification among species with state-dependent models of diversification using this phylogenetic framework. The diversification analyses suggest that rates are higher in widely distributed species than species that occur only on islands or the mainland. Finally, I investigated how islands and biogeographic barriers shape the genetic population structure at the species-level in the widely distributed Danaini species E. mulciber. Genetic structure and admixture analyses support three distinct groupings within E. mulciber which are associated with Wallace’s and Huxley’s line. Ultimately, this dissertation highlights the importance of using insect systems to understand insular biodiversity patterns as current insect diversity is underestimated.
Recommended Citation
Nunes, Renato A., "Systematics and Biogeography of the Milkweed Butterflies" (2025). CUNY Academic Works.
https://academicworks.cuny.edu/gc_etds/6423
Supplementary Tables S2.1-S4.3
