Variation in developmental biology and microsatellite DNA in reproductive ecotypes of kokanee, Oncorhynchus nerka: Implications for declining populations in a large British Columbia lake

摘要: Kokanee are the nonanadromous (freshwater resident) form of sockeyesalmon (Oncorhynchus nerka) found in lake ecosystems throughoutthe North Pacific region. commonly exhibit two reproductiveecotypes; `stream-spawners' that reproduce streams tributary tolakes, and `beach-spawners' on submerged lakeshore gravelbeaches. Okanagan Lake, southcentral interior BritishColumbia, Canada, contains beach- stream-spawning kokanee bothecotypes have declined dramatically abundance over last 20 years.We examined developmental biology (developmental rate to hatching andemergence) genetic divergence at eight microsatellite loci toinvestigate phenotypic differentiation between ecotypes tounderstand selective demographic factors might influence therecovery depressed populations. Beach-spawning female weresmaller produced smaller eggs than females from stream-spawningpopulations. There was no striking difference time 50%hatching ecotypes, but beach-spawning developed fasterfrom emergence. Microsatellite were highly polymorphicin (between 5 23 alleles per locus) showed significantdifferentiation among populations (average θ = 0.018). was,however, significant variation attributable spawning ecotype afteraccounting for within ecotypes. Simulated population-mixtureanalyses indicated good potential classification kokaneeas or stream-spawners; estimated mixture proportions within11% actual averaged 50 replications. Our datasuggest Lake constitute least managementunits a single watershed; appear adapted distinctthermal reproductive environments show modest moleculardifferentiation one another. Persistence OkanaganLake may depend, part, management plans recognize thedistinctions sympatric