Ecological research
I study population ecology and seek to understand how global changes affect population dynamics of diverse taxa. Specifically, I focus on aspects of variation within species, biologically-generated patterns, and the relationship between rarity and vulnerability.
During my PhD I studied the relationships between greater short-horned lizards (Phrynosoma hernandesi) and their primary prey, ants, and asked how the distribution and life history traits of these taxa vary throughout their ranges. My dissertation work involved 1) Identifying factors potentially limiting the distribution and abundance of the greater short-horned lizard (Phrynosoma hernandesi); 2) Quantifying population-level consequences of intraspecific niche breadth variation; and 3) Assessing the ecological consequences of spatial patterning of a known ecosystem engineer, the western harvester ant (Pogonomyrmex occidentalis).
During my PhD I studied the relationships between greater short-horned lizards (Phrynosoma hernandesi) and their primary prey, ants, and asked how the distribution and life history traits of these taxa vary throughout their ranges. My dissertation work involved 1) Identifying factors potentially limiting the distribution and abundance of the greater short-horned lizard (Phrynosoma hernandesi); 2) Quantifying population-level consequences of intraspecific niche breadth variation; and 3) Assessing the ecological consequences of spatial patterning of a known ecosystem engineer, the western harvester ant (Pogonomyrmex occidentalis).
Niche relationships: horned lizards
In Wyoming, the greater short-horned lizard (Phrynosoma hernandesi) is classified as a Species of Greatest Conservation Need based on its vulnerable population status and associated limiting factors. Unfortunately, we have little understanding of what those factors are that most limit the species’ distribution and abundance. Specialist species, like most horned lizards, are generally thought to be at heightened risk in changing landscapes, as they may be increasingly unable to meet their narrow ecological requirements. The most pressing threat at this time is energy development, and we know little about how horned lizards will respond to related land cover changes.
In my dissertation work, I address the following questions: 1) What ecological factors most limit greater short-horned lizards in Wyoming? 2) How do individuals and populations vary in their dietary selection? What do differences in specialization tell us about population dynamics? 3) Are increasing energy developments likely to impact horned lizards? If so, what aspects of energy development are most threatening? |
Consequences of spatial patterns: ants
An important but understudied aspect of community structure involves the spatial patterning of species and processes within the landscape. While classic community ecology is, and continues to be, largely founded on non-spatial analyses, we now understand that spatial heterogeneity and patterning is often a critical driver of ecological dynamics. Organisms that self-organize can have highly variable patterning and densities, with corresponding effects on their community functions. The sagebrush steppe and short-grass prairie regions of the intermountain west are shaped by the activities of ecosystem engineers, such as the western harvester ant (Pogonomyrmex occidentalis), that can affect diversity at several scales.
We used remote imagery to characterize the spatial structure and densities of P. occidentalis mounds at sites spanning their range within the sagebrush areas of Wyoming. Our goals in this work were to: 1) Assess how stable or variable both densities and spatial patterning of harvester ants are across significant environmental clines; 2) Test the ability of abiotic factors to explain differences in either densities or non-randomness in ant mound occurrences; 3) Assess the importance of density vs. patterning in shifting the likely ecosystem effects of harvester ants within their communities. |
Demographic PVA: Desert yellowhead
We study the demography of an extremely rare desert plant, desert yellowhead (Yermo xanthocephalus). This plant has been identified at only two locations--both in central Wyoming. We conducted demographic surveys for four years to assess the Yermo population viability.
Stay tuned for results... |
Niche relationships: Frogs
Landscape management schemes can have unanticipated effects on native species. While we tend to label habitat alterations as distinctly good or bad for specific species, it is not always clear what constitutes good habitat and what is low quality habitat. In Ireland, afforested blanket bogs are managed to create a cycle of mature conifer forest alternating with a clear-felled landscape. These plantation forests have the potential to fragment naturally occurring amphibian habitat and reduce access to suitable breeding sites, though it is not clear how each management stage actually affects amphibian populations.
I studied the European Common Frog (Rana temporaria), to identify if parts of these plantations contained good breeding habitat. I conducted my study in the west of Ireland, comparing breeding habitat availability and use among pools in mature plantation forests, clear-felled areas, unplanted blanket bogs, and roadside drainage ditches. |
Statisitical methods: Jackalopes
Stay tuned for Jackalope ecology...