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

Abstract

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.

Sea lampreyPetromyzon marinus: an exception to the rule of homing in anadromous fishes

“…We predict that this same relationship holds for them too, as indicated for Pacific lamprey Entosphenus tridentatus where no significant haplotypic differences were seen among collections from 81 rivers across six zoogeographic regions between British Columbia and California, and where within-river differences also accounted for 99 per cent of the variation (Goodman et al 2008). The life-history pattern identified for marine lampreys appears unique for diadromous fishes, but we note that it is the converse of catadromous anguillid eels that too are panmictic, but where for eels disaggregation occurs as individuals enter freshwaters, not as they exit them.…”

Effects of Body Size and River Environment on the Upstream Migration of Adult Pacific Lampreys

“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Anadromous Pacific lampreys Lampetra tridentata are widely distributed around the Pacific Rim, from Mexico and Baja California (Ruiz-Campos and González-Guzmán 1996;Renaud 2008) north to the Bering Sea (Beamish 1980;Goodman et al 2008) and west to Japan (Yamazaki et al 2005). The species has experienced rangewide population declines and regional extirpations in response to loss and degradation of freshwater habitat, dam-related mortality, and a suite of ecosystem changes (Beamish and Northcote 1989;Close et al 2002;Kostow 2002).…”

A geographical genetics framework for inferring homing reproductive behavior in fishes

“…1.1 Under homing behavior, a high genetic variability is expected to exist among waterheads because individuals reproducing within each one will tend to mate successively within a subsample of the total population (e.g., Stepien and Faber 1998;Waters et al 2000;Exadactylos et al 2003;Hoffman et al 2005;Stepien et al 2007;Pereira et al 2009;Abreu et al 2009;Waldman et al 2008 andGoodman et al 2008 for an inverted reasoning using this type of data-i.e., low levels of population differentiation is indicative of the absence of strong homing behavior). Likewise, kinship (i.e., co-ancestry) among individuals within waterheads will be higher than among individuals belonging to different waterheads.…”