Dissertations and Theses @ UNI

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Open Access Thesis

Keywords

Bumblebees--Iowa--Genetics; Bumblebees--Iowa--Habitat;

Abstract

Wild bumblebees (Hymenoptera: Apidae) are key pollinators in natural ecosystems and major contributors to pollination in agriculture. Despite this, numerous bee species are in decline from introduced pathogens, pesticides, and habitat fragmentation. In the Midwestern United States, the land is dominated by agricultural landscape, and farming practices result in limited floral resources and frequently disturbed nesting grounds for bee species. In this thesis, I examine the genetic diversity between and within populations of brown-belted bumblebee (Bombus griseocollis) across northeast Iowa and test for population genetic structure between reconstructed prairies within 3 years of establishment and prairies >10 years in establishment using microsatellite genotyping and single nucleotide polymorphisms (SNPs) data from restriction site-associated DNA sequencing (RAD-seq). The RAD-seq included old bee specimens, of which the majority yielded genomic DNA viable for RAD-seq. Overall, there was no evidence of genetic differentiation between reconstructed prairie sites, and it is likely that Bombus griseocollis (B. griseocollis) colonies at the reconstructed prairie sites come from a homogenized gene pool that disperses from nearby roadside ditches and pastureland. There is weak differentiation of B. griseocollis between newly reconstructed prairies and long-established prairies, although there are no populations with distinct genetic structure, indicating that long-established prairie provides enough floral resources and nesting habitat for unique bee populations to emerge. There is also a positive correlation between the percentage of natural landscape surrounding a site and allelic richness that supports this conclusion. Heterozygosity and inbreeding coefficient values show different results between the two genetic studies; Microsatellite genotyping of 7 loci revealed no signs of inbreeding depression, but RAD-seq shows moderate signs of inbreeding depression among single-nucleotide polymorphisms (SNPs). It is important to take caution in the RAD-seq values, however, as they may have resulted in part from using a nonmodel organism and the inclusion of samples with initially degraded genomic DNA.

Year of Submission

2022

Degree Name

Master of Science

Department

Department of Biology

First Advisor

Ai Wen, First Reader

Date Original

7-2022

Object Description

1 PDF file (vii, 65 pages)

Language

en

File Format

application/pdf

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