Subterranean ant nest architecture and its variation between species and environment

Drager, Kim Ivy

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https://hdl.handle.net/2142/116223 Copy

Description

Title

Subterranean ant nest architecture and its variation between species and environment

Author(s)

Drager, Kim Ivy

Issue Date

2022-07-13

Director of Research (if dissertation) or Advisor (if thesis)

Suarez, Andrew V

Doctoral Committee Chair(s)

Suarez, Andrew V

Committee Member(s)

• Bell, Alison M
• Anderson, Philip SL
• Wander, Michelle M

Department of Study

Evolution Ecology Behavior

Discipline

Biology

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

ant nest architecture, Formicidae, myrmecology, soil biology, soil casting, functional groups, ecology

Abstract

Ants are widespread and abundant organisms that can excavate subterranean nests that may range in size by orders of magnitude. These nests are large biopores that may influence soil properties such as chemical transport, erosion rates, and the amount of plant-available water. Nest architecture has been proposed to be species-specific and stable through time, suggesting that the behaviors responsible for architecture have a genetic component. Unfortunately, subterranean nest architecture is often only incidentally reported, reported as a simple tracing of a soil pit face, described textually or drawn from memory to represent a “typical” nest. The objective of this dissertation work is to: 1) establish methods for preserving ant nests in 3 dimensions for further analysis, 2) cast and analyze ant nests of two different species and compare architectural variations and correlate them with species or environmental differences, and 3) develop a functional ecology framework using morphometric analysis of ants in order to establish a link between ant morphology, trophic position, and nest architectural properties. Preserving biopore geometry is an important first step in evaluating ant nests’ effects on the movement of water, air, and chemical substances through the soil. Soil casting presents a number of unique challenges caused by the size and/or complexity of the biopore combined with the trouble of casting into the soil material itself. Techniques may fail due to a lack of infiltration caused by the volume or tortuosity of the biopore, or due to penetration of the casting material into the soil matrix. I compiled and reviewed methods for preserving biopores in the field and evaluated them based on preservation quality, time, cost, and practicality. Overall, I recommend zinc casting due to its cost, preservation quality, and durability, although dental plaster casting is suitable for most purposes and has the advantage of preserving specimens trapped inside the cast for later analyses. Additionally, I present instructions for a lightweight and cost-effective propane powered field kiln for casting biopores using zinc or aluminum scrap. The propane powered field kiln developed in the first chapter was used to document the nest architecture of two common ants, Dorymyrmex bureni (n=10) and Dorymyrmex elegans (n=32) via zinc casting in the field at Archbold Biological Reserve near Venus, Florida. Casts were 3-D scanned and digitally measured to determine differences between species as well as variation associated with environmental variables (i.e., slope and aspect). The two species differed, with nests of D. bureni tending to contain one major gallery, whereas D. elegans often had 1–2 shorter galleries with smaller, less-developed chambers that branched from one large main gallery close to the soil surface. D. elegans also had deeper nests with a higher number of chambers than D. bureni. D. bureni nests were found primarily along crest of the hill, while D. elegans also nested along the slopes. Comparing nest properties of D. elegans relative to nest location, chamber volume tended to be smaller in nests cast from the summit compared to nests from slopes. In addition, the aspect of the nest predicted total volume and chamber volume, suggesting that nest architecture may vary with respect to position along a slope. This geographical consistency means that ant nest architecture may likely be stable through time, reflecting intrinsic (e.g., genetic) more than environmental factors, and provides further evidence that contemporary studies can be a useful for identifying ant nest ichnofossils Finally, we used morphometric and isotopic data to correlate ant trait measurements with trophic position, establishing a framework for future use with ant nest data to eventually link morphological traits with nest traits. Using data on the relative trophic position of 592 ant (Formicidae) samples comprising 393 species from 11 subfamilies and 19 globally distributed communities, we tested the extent to which commonly used functional proxies (i.e., morphometric traits) predict diet / trophic position as estimated from stable isotopes (15N). We measured 12 traits that have previously been identified as functionally significant, and corrected trait values for size and evolutionary history by using phylogenetically corrected trait residuals. 15N values of ant species ranged from -1 to 14‰ or roughly 4 relative trophic positions (ranging from primary producers to specialized predators of other ants). Morphological data spanned nearly the entire size range seen in ants from the smallest (e.g. Strumigenys mitis total length 1.12 mm) to the largest species (e.g. Dinoponera australis total length 28.25 mm). We found overall body size, relative eye position, and scape length to be informative for predicting diet / trophic position in these communities. Specifically, trophic position was negatively correlated with body size and positively correlated with sensory traits (higher eye position and scape length).

Graduation Semester

2022-08

Type of Resource

Thesis

Copyright and License Information

Copyright 2022 Kim Drager

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