Life Sciences Commons^™

Incorporating The “Invisibles” In Ant Seed Dispersal: Microbial Mortality Agents In Myrmecochory, Chloe L. Lash

Doctoral Dissertations

Ant-mediated seed dispersal, myrmecochory, is a diffuse mutualism in which ants are rewarded for seed dispersal services with food via a seed-coat derived appendage, the elaiosome. Seeds gain dispersal benefits including escape from distance- and density- dependent mortality agents, protection from seed predators, and a nutrient-rich germination site in or near ant nests. However, microbes, have been essentially overlooked in this mutualism, despite their pathogenicity to the ants and plants involved. The work presented here investigates the effects of microbial mortality agents on the risks and benefits offered to ant and plant partners in myrmecochory. First, I investigate the effects …

Identifying Extinction Risk Patterns In Pollination Networks And Conservation Planning To Reduce The Cost Of Management-Necessitated Travel, Christine Elise Dumoulin

Doctoral Dissertations

Extinction rates are currently far above background levels, as a result of human activity. Although conservation spending is substantial, there is a shortfall between the cost of meeting biodiversity targets and the resources available to do so. Consequently, decision-makers are faced with the task of identifying which taxonomic groups and geographical regions are of greatest concern, and prioritizing approaches with the greatest conservation benefit. In this dissertation, I develop novel approaches in both of these areas.

First, I take a stochastic, community dynamic approach to modeling extinction risk patterns in pollination networks. Despite the ecological and agricultural importance of pollination …

The Meat-Farming Ants: Predatory Mutualism Between Melissotarsus Ants (Hymenoptera: Formicidae) And Armored Scale Insects (Hemiptera: Diaspididae), Scott A. Schneider

Doctoral Dissertations

Ant agricultural mutualisms are common, well studied, and receive attention from scientific and public spheres due to shared similarities with human agriculture (i.e. ant/fungus ‘crop farming’ and ant/insect ‘dairy farming’). They also serve as important model systems for studying many facets of mutualism. This study reveals that the repertoire of ant agriculture may also include ‘meat farming’. Predatory mutualisms occur between Melissotarsus ants and various species of armored scale insects. This dissertation employs a multi-disciplinary approach to investigate the evolutionary history and nature of ant/diaspidid mutualisms. Chapter 1 reviews the current state of knowledge regarding species composition of these associations …

On Global Change, Direct And Indirect Interactions, And The Structure Of Ecological Communities: Theoretical And Empirical Tests, Mariano Alberto Rodriguez Cabal

Doctoral Dissertations

Human induced global change (climate change, CO₂ enrichment, nitrogen deposition, habitat degradation and biological invasions) is the most serious threat to biodiversity. Understanding how ecosystems will respond to different components of global change, and how these responses will affect key ecological processes, has become essential in contemporary ecology. For example, several studies have shown that exotic invasive species have negative impacts on the composition of communities, habitat structure and ecosystem processes. Particularly, exotic species may have negative effects on species interactions due to local extinctions, competition and/or replacement of interactions. Despite the large body of research demonstrating the negative …