Quesnel River Research Articles

Stratigraphy and paleoecology of Pleistocene interstadial sediments, central British Columbia

Two exposures of organic-rich interstadial sediments in central British Columbia provide information on middle Wisconsinan environments and climates near the center of the region subsequently covered by the late Wisconsinan Cordilleran Ice Sheet. Interstadial sediments at Bullion Pit overlie drift of early Wisconsinan or older age and underlie thick drift of late Wisconsinan age. Alluvium (or colluvium) and peat were deposited on the floor of the ancestral Quesnel River valley 46,000–40,000 14C yr ago when the vegetation consisted of spruce forest with dry openings and local fens and the climate was colder and perhaps drier than today. This is broadly consistent with paleoclimatic reconstructions for the same time interval for Babine Lake, 400 km to the northwest, and for Meadow Creek, 400 km to the southeast. Plant-rich pond sediments containing tephra layers and vertebrate remains are exposed between two drifts in a ravine at Mexican Hill, 30 km east of Quesnel. Although they may be contemporaneous with the Bullion Pit beds, the nonglacial sediments at Mexican Hill more likely were deposited sometime after the warmest part of the last interglaciation, but prior to 50,000 yr B.P. At that time, the vegetation at Mexican Hill probably was parkland. The present vegetation at Mexican Hill is boreal forest; thus, a drier and possibly cooler climate is indicated.

Genetic variation in carotenoid pigment deposition in the red-fleshed and white-fleshed chinook salmon (Oncorhynchus tshawytscha) of Quesnel River, British Columbia

Inheritance of the ability to deposit coloured dietary carotenoid pigments in muscle tissue was examined in 16 seapen-reared families of chinook salmon (Oncorhynchus tshawytscha) from the Quesnel River, British Columbia. The progeny red:white ratio varied significantly among families in two sample periods but not between sample periods for individual families. There was no difference between the sexes in proportions of red and white individuals. Total carotenoid extraction of muscle tissue samples from 152 progeny revealed that white individuals contained less carotenoid per gram of tissue (0.24 ± 0.04 μg) than did red ones (3.37 ± 0.14 μg). Estimates of the heritability of flesh colour, when treated as a threshold trait, were 0.93 (sire component) and 0.71 (dam component). A genetic model that invokes two genetic loci, each with two alleles, was proposed to explain the inheritance of flesh colour in Quesnel River chinook salmon. At each locus, one copy of a "red-determining" allele is required for coloured carotenoid pigments to be deposited in muscle tissue. The anomalous red:white ratios among the progeny of one male parent could not be accounted for by tetrasomy or pseudolinkage in conjunction with the proposed model.Key words: Oncorhynchus, salmon, carotenoids, heritability.