Biogeography places the geographical distribution of biodiversity in an evolutionary context. Ants (Hymenoptera: Formicidae), being a group of ubiquitous, ecologically dominant, and diverse insects, are useful model systems to understand the evolutionary origins and mechanisms of biogeographical patterns across spatial scales. On a global scale, ants have been used to test hypotheses on the origin and maintenance of the remarkably consistent latitudinal diversity gradient where biodiversity peaks in the equatorial tropics and decreases towards the poles. Additionally, ants have been used to posit and test theories of island biogeography such as the mechanisms of the species-area relationship, being the increase of biodiversity with cumulative land area. However, there are still unanswered questions about ant biogeography such as how specialized life histories contribute to their global biogeographical patterns. Furthermore, there remain island systems in the world’s biodiversity hotspots that harbor much less ant species than predicted by the species-area relationship, which potentially suggests a place ripe for discovery. In this dissertation, I use natural history, taxonomic, geographic, and phylogenetic data to study ant biodiversity and biogeography across spatial scales. First, I study the global biodiversity and biogeography of a specialized set of symbiotic interactions between ant species, here referred to as myrmecosymbioses, with an emphasis on social parasitism where one species exploits the parental care behavior and social colony environment of another species. In addition to characterizing a new myrmecosymbiosis, I use a global biogeographic and phylogenetic dataset to show that ant social parasitism is distributed along an inverse latitudinal diversity gradient where species richness and independent evolutionary origins of social parasitism peak within the northern hemisphere where the least free-living ant diversity exists. Second, I study the unexplored ant fauna of the Vanuatuan archipelago in the South Pacific. Using approximately 10,000 Vanuatuan ant specimens coupled with phylogenomics, I fill in a historical knowledge gap of South Pacific ant biogeography and demonstrate that the Vanuatuan ant fauna is a novel biodiversity hotspot. With these studies, I provide insights into how specialized life histories and unique island biotas shape the global distribution of biodiversity in different ways, especially in the ants.

In many social groups, reproduction is shared between group members, whocompete for position in the social hierarchy for reproductive dominance. This reproductive conflict can lead to different means of enforcing reproductive differences, such as dominance displays or limited control of social hierarchy through antagonistic encounters. In eusocial insects, archetypal colonies contain a single, singly-mated fertile queen, such that no reproductive conflict exists within a colony. However, many eusocial insects deviate from this archetype and have multiply-mated queens (polyandry), multiple queens in a single colony (polygyny), or both. In these cases, reproductive conflict exists between the matrilines and patrilines represented in a colony, specifically over the production of sexual offspring. A possible outcome of reproductive conflict may be the emergence of cheating lineages, which favor the production of sexual offspring, taking advantage of the worker force produced by nestmate queens and/or patrilines. In extreme examples, inquiline social parasites may be an evolutionary consequence of reproductive conflict between nestmate queens. Inquiline social parasitism is a type of social parasitism that is usually defined by a partial or total loss of the worker caste, and the “infiltration” of host colonies to take advantage of the host worker force for reproduction. It has been hypothesized that these inquiline social parasites evolve through the speciation of cheating queen lineages from within their incipient host species. This “intra- specific” origin model involves a foundational hypothesis that the common ancestor of host and parasite (and thus, putatively, the host at the time of speciation) should be functionally polygynous, and that parasitism evolves as a “resolution” of reproductive conflict in colonies. In this dissertation, I investigate the hypothesized role of polygyny in the evolution of inquiline social parasites. I use molecular ecology and statistical approaches to validate the role of polygyny in the evolution of some inquiline social parasites. I further discuss potential mechanisms for the evolution and speciation of social parasites, and discuss future directions to elucidate these mechanisms.

Ants are widespread species of eusocial insects, and myrmecophily describes the species which are associated with ants. Many mites are myrmecophilous species and interact with hosts in many ways such as phoresis or parasitism. The relationship between ants and mites are interesting as parasitic species could be used to control the spread of invasive ant species. For this project, I reviewed the existing literature on myrmecophilous mites around the world and compiled a database of ant-mite associations, which I then used to characterize factors such as host specificity, attachment sites, and biogeographical patterns. This work demonstrates that existing research on myrmecophilous mites has been both geographically and taxonomically biased and highlights the need for much more comprehensive surveys of mites living in association with ants.

Vitellogenin (Vg) is an ancient and highly conserved multifunctional protein. It is primarily known for its role in egg-yolk formation but also serves functions pertaining to immunity, longevity, nutrient storage, and oxidative stress relief. In the honey bee (Apis mellifera), Vg has evolved still further to include important social functions that are critical to the maintenance and proliferation of colonies. Here, Vg is used to synthesize royal jelly, a glandular secretion produced by a subset of the worker caste that is fed to the queen and young larvae and which is essential for caste development and social immunity. Moreover, Vg in the worker caste sets the pace of their behavioral development as they transition between different tasks throughout their life. In this dissertation, I make several new discoveries about Vg functionality. First, I uncover a colony-level immune pathway in bees that uses royal jelly as a vehicle to transfer pathogen fragments between nestmates. Second, I show that Vg is localized and expressed in the honey bee digestive tract and suggest possible immunological functions it may be performing there. Finally, I show that Vg enters to nucleus and binds to deoxyribonucleic acid (DNA), acting as a potential transcription factor to regulate expression of many genes pertaining to behavior, metabolism, and signal transduction pathways. These findings represent a significant advance in the understanding of Vg functionality and honey bee biology, and set the stage for many future avenues of research.

Weevils are one of the most diverse groups of animals with thousands of species suspected to remain undiscovered. The Conoderinae Schoenherr, 1833 are no exception, being especially diverse and unknown in the Neotropics where they are recognizable for their unique behaviors and color patterns among weevils. Despite these peculiarities, the group has received little attention from researchers in the past century, with almost nothing known about their evolution. This dissertation presents a series of three studies that begin to elucidate the evolutionary history of these bizarre and fascinating weevils, commencing with an overview of their biology and classificatory history (Chapter 1).

Chapter 2 presents the first formal cladistic analysis on the group to redefine the New World tribes Lechriopini Lacordaire, 1865 and Zygopini, Lacordaire, 1865. An analysis of 75 taxa (65 ingroup) with 75 morphological characters yielded six equally parsimonious trees and synapomorphies that are used to reconstitute the tribes, resulting in the transfer of sixteen genera from the Zygopini to the Lechriopini and four generic transfers out of the Lechriopini to elsewhere in the Conoderinae.

Chapter 3 constitutes a taxonomic revision of the genus Trichodocerus Chevrolat, 1879, the sole genus in the tribe Trichodocerini Champion, 1906, which has had an uncertain phylogenetic placement in the Curculionidae but has most recently been treated in the Conoderinae. In addition to redescriptions of the three previously described species placed in the genus, twenty-four species are newly described and an identification key is provided for all recognized species groups and species.

Chapter 4 quantitatively tests the similarity in color pattern among species hypothesized to belong to several different mimicry complexes. The patterns of 160 species of conoderine weevils were evaluated for 15 categorical and continuous characters. Non-metric multidimensional scaling (NMDS) is used to visualize similarity by the proximity of individual species and clusters of species assigned to a mimicry complex in ordination space with clusters being statistically tested using permutational multivariate analysis of variance (PERMANOVA).