Mitochondrial DNA evidence for high levels of gene flow among populations of a widely distributed anadromous lamprey Entosphenus tridentatus (Petromyzontidae)
Summary
Mitochondrial DNA variation among 1246 individuals of Pacific lamprey (Entosphenus tridentatus) from 81 populations spanning 2600 km from the Skeena River, British Columbia, to the Ventura River, California, was surveyed using five restriction enzymes. A total of 29 composite haplotypes was detected in two gene fragments (ND2 and ND5). The three most common haplotypes, occurring in 91% of all samples, were present at similar frequencies in all regions. Samples were divided into six biogeographic regions based on sample distribution and geographical landmarks to assess geographic genetic structure. Analysis of molecular variance indicated that 99% of the genetic variation was explained by variability within drainages. The lack of geographical [...]
Summary
Mitochondrial DNA variation among 1246 individuals of Pacific lamprey (Entosphenus
tridentatus) from 81 populations spanning 2600 km from the Skeena River, British Columbia,
to the Ventura River, California, was surveyed using five restriction enzymes. A total of 29
composite haplotypes was detected in two gene fragments (ND2 and ND5). The three most
common haplotypes, occurring in 91% of all samples, were present at similar frequencies in all
regions. Samples were divided into six biogeographic regions based on sample distribution and
geographical landmarks to assess geographic genetic structure. Analysis of molecular variance
indicated that 99% of the genetic variation was explained by variability within drainages. The
lack of geographical population structure is likely related to a life-history pattern that includes
a prolonged larval freshwater stage, migration to oceanic feeding and return to fresh water to
spawn. The lack of strong natal homing apparently promotes gene flow among drainages and
regions.
