Discipline: Ecology Environmental and Earth Sciences
Keith A. Parker - Humboldt State University
Co-Author(s): Dr. Andrew Kinziger, Humboldt State University, Arcata, CA
The Klamath River Basin supports the highest number of lamprey species in the world. Anadromous Pacific lamprey (E. tridentatus) have cultural and food importance to the three largest California tribes. Ecologically, lamprey contribute essential biomass of marine-derived nutrients and organic matter to the food web of headwater streams. Populations are at extinction risk due to habitat loss, passage barriers, and pollution. Pacific lamprey in other regions display high gene flow which has homogenized population level neutral genetic variation. However, geography, run-timing, and adult body size have been linked to adaptive genetic variation. We hypothesized at neutral loci, Klamath lamprey exhibit no genetic structure but at adaptive loci, genotype-phenotype associations could be identified. We collected 220 returning adult Pacific lamprey over 12-months at ocean entry to the Klamath River, recorded morphometrics, and genotyped tissue samples. Gonadosomatic index (GSI) measures the sexual maturity of fish in correlation to ovary mass. We found female GSI mean values for Feb-Apr were as much as twice the mean values for May-Jul, suggesting a spring and early summer spawning period. Differing states of sexual maturity (GSI variability) was also substantially higher in the winter as compared to the spring, peaking in April with a one-day GSI spread of 0.25%-5.62%. We found a novel genetic basis for the differing states of sexual maturity, distinct outlier single nucleotide polymorphisms (SNP’s) on the lamprey gene. Using next-generation GT-Seq genotyping, 8 adaptive SNP loci from a panel of 308 well-defined markers showed a significant association with body length. Seventeen additional adaptive SNP loci showed a significant association with egg mass. The 17-SNP locations formed two distinct linkage groups which appear to code for egg mass. A stronger signal for small egg mass over large egg mass was present. A significant change in the proportion of ‘small’ egg mass alleles versus ‘large’ egg mass alleles corresponded to approximately 12.5 gm of egg mass, coupled with a distinct transition from predominantly heterozygote to homozygote genotypes at the linked loci. Significant run-timing and phenotype/genotype egg mass variability relative to spawn timing suggests concurring life histories: (i) a stream-maturing life history where lamprey spend one or more years in freshwater prior to spawning (we term raayoh) and (ii) an ocean-maturing life history where spawning occurs within weeks or months of freshwater entry (we term tewol). The two Klamath River Pacific lamprey ecotypes are different than the ecotypes observed in Pacific salmon and thus warrant unique names (Yurok language) so that they can be accurately recognized. A similar life history is observed in anadromous steelhead (O. mykiss) with distinct winter and summer run timing, yet dissimilar in that lamprey tewol and raayoh types concur in any given month or day with overlapping run-timing.ERN 2018 Conference Abstract.docx
Funder Acknowledgement(s): The National Science Foundation and The Robert and Patricia Switzer Foundation environmental fellowship.
Faculty Advisor: Dr. Andrew Kinziger, Andrew.Kinziger@humboldt.edu
Role: I developed/drafted the thesis research proposal accepted by my committee and funded by the NSF. I was boat certified for the field work. For 12-months, I collected Klamath River Pacific lamprey with a traditional Native American eel hook. I operated my boat in often very poor weather/water conditions, becoming stranded at times. I measured, weighed, dissected, removed eggs, and preserved tissue samples while in the field. In summer 2017, I drove 700 miles to one of the top genetics labs in the World. The Columbia River Inter-tribal Fisheries Commission genetics lab in Idaho sponsored me as a Native American scientist. I was mentored on the relatively new cutting edge GT-Seq genotyping technique. We genotyped 354 of my tissue samples. I am now analyzing genotype-phenotype associations.