Date on Master's Thesis/Doctoral Dissertation

8-2023

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Yanoviak, Stephen

Committee Co-Chair (if applicable)

Dugatkin, Lee

Committee Member

Dugatkin, Lee

Committee Member

Eason, Perri

Committee Member

Fuselier, Linda

Committee Member

Moreau, Corrie

Author's Keywords

antennae; formicidae; multisensory navigation; neuroanatomy; Panama; rainforest

Abstract

In this dissertation, I examined the behavior of foraging twig ants, explored the sensory profile of their homing behavior, and investigated the role of habitat use in shaping the sensory neurobiology of species within the genus Pseudomyrmex (Hymenoptera: Formicidae). In chapter one, I reviewed the ecology of Pseudomyrmex, and introduced the focal species, P. boopis, a neotropical understory-dwelling twig ant. In chapter two, I described the natural history of P. boopis on Barro Colorado Island, Panama—specifically, their nesting habits, activity rhythm, and foraging behavior on understory surfaces. Pseudomyrmex boopis colonies were diurnal and nested in dead twigs in various states of decomposition on or near the leaf litter. Colonies were polydomous (i.e., spread among multiple twigs) and twigs were predominantly filled with larvae. Workers used a variety of surfaces during foraging bouts but were primarily found on leaf surfaces or the ground. Foragers on leaf surfaces spent more time on larger leaves and leaves that were covered with epiphylls. In chapter three, I explored the sensory ecology of the homing behavior of P. boopis by manipulating their vision and olfaction. I painted over their compound eyes and ocelli, and removed their antennae in several combinations, and measured their homing success and efficiency after displacement near their nest twigs. Compound eyes were most important for successful homing; their occlusion often resulted in predation. The ocelli and antennae were important for efficiency in entering the twig nest. Most ants with intact compound eyes homed successfully regardless of other sensory manipulations. In chapter four, I placed questions about the sensory biology of P. boopis in a phylogenetic context and compared the neurobiology of P. boopis to that of two congenerics (P. gracilis and P. oculatus) that exhibit higher degrees of arboreality to determine whether underlying neuroanatomy and antennal structures reflects habitat use. Brain size increased with body size, and all three species had large visual investment compared to most ants. Understory-dwelling was associated with larger body size, having relatively larger brains, and more antennal sensory hairs (sensilla) relative to head width. The canopy was associated with smaller body size, fewer sensilla, and higher relative sensilla density. Collectively, this dissertation contributes to our understanding of twig ant behavior and its connection to neuroecology in habitats ranging from the ground to the canopy of a neotropical forest.

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