Conservation of a fossorial grassland species (Geomys bursarius) through understanding niche reduction, landscape genetics, and phylogenetics

Considering species conservation through temporal and spatial lenses better identifies threats and can inform management. This is particularly true for grassland species such as the plains pocket gopher (Geomys bursarius) that persist in anthropogenically altered landscapes. Here, I first identified ongoing habitat degradation due to agricultural intensification since the 1950s for G. bursarius in Illinois. I created species distribution models for G. bursarius in Illinois during two eras, the 1950s and the 2010s, and estimated niche shift and niche breadth. Geomys bursarius in Illinois exhibited niche shifts and a decrease in niche breadth, with increased occurrence at lower elevations and in sandier soils. The core of the G. bursarius distribution in Illinois decreased in suitability, a common phenomenon for species under anthropogenic pressures. Second, I identified genetic structure and gene flow patterns for G. bursarius at different spatial scales, and then partitioned gene flow to multiple isolating factors: barriers, distance, and environment. Rangewide, major rivers functioned as barriers, but in Illinois, distance predominantly explained genetic variance. At both spatial scales, soil sand percentage and soil color explained a small proportion of genetic variance. Finally, I inferred a phylogenetic tree for subspecies of G. bursarius with a focus on whether G. b. illinoensis was monophyletic using mitochondrial genomes (mitogenomes). I found that G. b. illinoensis was monophyletic and genetically unique from the other G. bursarius subspecies, and that additional subspecies (e.g., G. b. wisconsinensis) were genetically unique as well. Geomys bursarius illinoensis demonstrated admixture from G. jugossicularis and G. b. missouriensis, likely due to retaining ancestral mitogenomes. Overall, G. b. illinoensis should be considered an Evolutionary Significant Unit currently facing niche reduction and niche shifts, and management should focus on increasing connectivity and occupancy in regions where G. bursarius occurred in the 1950s.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Natural Res & Env Sciences

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2023

Author dc:creator

• Alexander, Nathan

Contributors dc:contributor

• Schooley, Robert L
• Fraterrigo, Jennifer
• Larson, Eric
• Cosentino, Bradley J

• Geomys Bursarius
• Niche Reduction Hypothesis
• Landscape Genetics
• Isolation By Environment
• Mitogenomics
• Phylogenetics

Statement dc:rights

• Copyright 2023 Nathan Alexander

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/122022

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F122022