Date of Completion
Honors College Thesis
Dr. Stephen Keller
Hybridization, Chloroplast Isolation, Picea, Population Structure, Effective Population Size
Understanding the demographic history of a species is pivotal for assessing current population structure and predicting future viability. Here, I use the chloroplast genome to gain a better understanding of red spruce demographic dynamics since the last glacial maximum. This information can be applied to assessments of the future viability of the species, especially in the context of ongoing anthropogenic climate change. Data from whole-exome sequence capture of 340 individuals of red spruce sampled from across the current range were utilized in the phylogeographic analyses that form the basis of this work. The chloroplast genome coverage was greatly improved upon via imputation and the sequence data used to predict changes in effective population size, range-wide genetic structure, and hybridization. In addition to optimizing a chloroplast isolation protocol that will enable greater imputation accuracy in future work, I found a surprising trend in increasing chloroplast effective population size over the last 100,000 years. Furthermore, I showed the absence of an isolation by distance effect in the chloroplast genome, a strong deviation from conclusions drawn using the nuclear genome, supporting the idea that long distance pollen dispersal could potentially connect otherwise isolated populations across the highly fragmented range. Tied through it all, there was a clear signature of hybridization between red and black spruce in the northern part of the current range. Through these results, we confirm that the chloroplast genome provides valuable insight into the demographic history of red spruce and can be used to inform assessments of future population viability.
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.
Bardsley, Katherine Anne, "Inferring the demographic history of red spruce (Picea rubens) from chloroplast genome sequences" (2021). UVM Honors College Senior Theses. 383.