The evolution of caste-specific morphology and colony structure in ants
type: CreativeWork
description: An organism can adapt to its environment physiologically, behaviorally, and morphologically, but biological functions may conflict with each other and therefore constrain their evolution. Eusocial organisms live in colonies that possess morphologically distinct castes that divide biological roles among individuals. Males and reproductive females fill the reproductive role of the colony which includes mating, dispersal and egg laying. The typically sterile worker caste performs other tasks for the colony such as food collection, defense, and brood care. Workers are therefore released from the morphological constraints of reproduction and can physically adapt to other roles. In addition to exhibiting large degrees of morphological variation, eusocial insect colonies can also vary in colony structure. For example, some species have a single reproductive queen while others can vary in queen number that in turn influences the genetic relatedness of colony members. Furthermore, colonies can be centralized in one nest, or dispersed over several spatially separated nests. Variation in morphology and colony structure within and among species reflects a combination of adaptation to ecological pressures and historical constraints. My research goals were to investigate intra and interspecific variation in caste specific morphology and colony structure in a comparative framework to understand how traits evolve relative to species’ ecology. In chapter 2, I studied the species rich ant genus Pheidole to understand how worker morphology can adapt to environmental factors. Workers of Pheidole are almost always dimorphic, comprising a small minor subcaste and a major or soldier subcaste with a distinctively large head. Pheidole species vary in their diet, but many specialize on seeds that are milled by majors using large jaws powered by mandible closer muscles that fill the head cavity. I hypothesized that seed harvesting species will have majors with larger heads compared to non-see…
abstract: An organism can adapt to its environment physiologically, behaviorally, and morphologically, but biological functions may conflict with each other and therefore constrain their evolution. Eusocial organisms live in colonies that possess morphologically distinct castes that divide biological roles among individuals. Males and reproductive females fill the reproductive role of the colony which includes mating, dispersal and egg laying. The typically sterile worker caste performs other tasks for the colony such as food collection, defense, and brood care. Workers are therefore released from the morphological constraints of reproduction and can physically adapt to other roles. In addition to exhibiting large degrees of morphological variation, eusocial insect colonies can also vary in colony structure. For example, some species have a single reproductive queen while others can vary in queen number that in turn influences the genetic relatedness of colony members. Furthermore, colonies can be centralized in one nest, or dispersed over several spatially separated nests. Variation in morphology and colony structure within and among species reflects a combination of adaptation to ecological pressures and historical constraints. My research goals were to investigate intra and interspecific variation in caste specific morphology and colony structure in a comparative framework to understand how traits evolve relative to species’ ecology. In chapter 2, I studied the species rich ant genus Pheidole to understand how worker morphology can adapt to environmental factors. Workers of Pheidole are almost always dimorphic, comprising a small minor subcaste and a major or soldier subcaste with a distinctively large head. Pheidole species vary in their diet, but many specialize on seeds that are milled by majors using large jaws powered by mandible closer muscles that fill the head cavity. I hypothesized that seed harvesting species will have majors with larger heads compared to non-see…
author: Holley, Jo-anne
keywords: biological invasion, Linepithema, Pheidole, caste-specific morphology, colony structure
date published: 2015-07-22T22:15:27Z
date modified: 2026-07-22T22:26:11Z
provider: University of Illinois - Urbana-Champaign
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Illinois at Urbana-Champaign

PropertyValue
property ID: Handle
value: http://hdl.handle.net/2142/78285