Evidence for high levels of gene flow among populations of a widely distributed anadromous lamprey Entosphenus tridentatus (Petromyzontidae)

Damon Goodman

Graduation Date

2006

Document Type

Thesis

Program

Other

Program

Thesis (M.S.)--Humboldt State University, Natural Resources: Fish Biology, 2006

Committee Chair Name

Stewart Reid

Committee Chair Affiliation

HSU Faculty or Staff

Keywords

Pacific lamprey, Humboldt State University -- Theses -- Fisheries, mtDNA, Lampetra tridentata, Phylogeography, Gene flow, Entosphenus tridentatus

Abstract

The objective of this project was to assess genetic population structure in Entosphenus tridentatus (Pacific lamprey) to evaluate whether this lamprey exhibits fidelity to natal streams or regions. I investigated genetic variability in 1246 individuals of E. tridentatus from 81 populations spanning 2600 km of the North American Pacific coast from the Skeena River, British Columbia to the Ventura River, California. Genetic variability was assessed in a 2690 base pair nucleotide sequence of mitochondrial DNA using five restriction enzymes. All unique restriction fragment patterns were sequenced, with the complete data matrix including nucleotide variation at 19 positions. The data matrix contained 29 haplotypes with three common haplotypes composing 92% of the total sample. To assess if geographic genetic structure existed in E. tridentatus, samples were divided into six biogeographic regions based on sample distribution and geographical landmarks. The three most common haplotypes were present at similar frequencies in all regions. Analysis of molecular variance indicated that 99% of the genetic variation in E. tridentatus was explained by variability within drainages. The lack of geographical population structure is likely related to high dispersal capabilities and lack of fidelity to natal streams promoting gene flow among drainages and regions. Relationships among the haplotypes identified two clusters separated by two nucleotide substitutions. One cluster was composed of one common (62.5% of the sample), two rare, and nine drainage-specific haplotypes, and the other cluster was composed of two common (18.2% and 10.9% of the sample), eight rare, and six drainage-specific haplotypes. These two clusters occur sympatrically throughout the sampled region and perhaps represent two different run times of E. tridentatus.

https://scholarworks.calstate.edu/concern/theses/dn39x385v

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