Graduation Date
Fall 2022
Document Type
Thesis
Program
Master of Science degree with a major in Biology
Committee Chair Name
Karen Kiemnec-Tyburczy
Committee Chair Affiliation
HSU Faculty or Staff
Second Committee Member Name
Catalina Cuellar-Gempeler
Second Committee Member Affiliation
HSU Faculty or Staff
Third Committee Member Name
Amy Sprowles
Third Committee Member Affiliation
HSU Faculty or Staff
Fourth Committee Member Name
John Reiss
Fourth Committee Member Affiliation
HSU Faculty or Staff
Subject Categories
Biology
Abstract
The American Bullfrog (Rana catesbeiana) is a highly invasive species that has successfully colonized habitats around the world. The genetic variability of immune genes within invasive populations, like that of bullfrogs, may contribute to how resistant a population is to pathogens. The objective of this project was to characterize the genetic diversity of an immune gene in invasive bullfrog populations in California to better understand how persistent these populations might be over time. To characterize immune gene variability, I isolated exon 2 of the Major Histocompatibility Complex (MHC) Class II Beta chain gene and a neutral mitochondrial marker, cytochrome b (cyt b), from five bullfrog populations. I used standard population genetic metrics to compare the genetic diversity between these two loci across populations. I found high diversity in MHC II exon relative to cyt b, however these populations harbored differing levels of diversity at both loci. I also reconstructed a phylogeny of the isolated alleles with those from other ranids and found that the majority of my MHC alleles clustered with other R. catesbeiana alleles instead of with those of other ranids, except two alleles may exhibit transspecies polymorphism. The majority of the selection tests detected significant positive selection acting on MHC alleles, while there was little evidence on cyt b. Overall, these non-native populations have similar genetic diversity to other native amphibian populations. I conclude that they likely have sufficient genetic diversity to persist in the face of novel pathogens they may encounter in non-native habitats.
Citation Style
MLA
Recommended Citation
Segovia, Luisa Nereyda, "Investigating the genetic diversity of immune genes in non-native populations of American bullfrogs (Rana catesbeiana)" (2022). Cal Poly Humboldt theses and projects. 601.
https://digitalcommons.humboldt.edu/etd/601
Included in
Biology Commons, Ecology and Evolutionary Biology Commons, Genetics and Genomics Commons, Laboratory and Basic Science Research Commons, Research Methods in Life Sciences Commons