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Item Open Access Body size variation and fitness components in lesser snow geese Chen caerulescens caerulescens.(University of California Press, 1988) Davies, J.C.; Rockwell, R.F.; Cooke, F.We examined the potential action of selection on body size in a population of Lesser Snow Geese (Chen caerulescens caerulescens) breeding in the Canadian subarctic. We evaluated the genetic basis of phenotypic variation in body size and examined the association of body size and components of fitness related to fecundity and viability. There was a heritable component to body size in this population derived in part from the action of additive genes. There was no relation between adult body size and the number of eggs laid, the number of eggs surviving predation, the number of goslings that left the nest, or the number of goslings fledged. Small birds entered the breeding population at a younger age. They did so with no reduction in viability and may actually live longer than large birds. The heritable variation in body size combined with the directional selection gradient should lead to a gradual reduction in adult body size in this population. We found no evidence for such a change over 5 generations. We discuss this in terms of additional fitness components, the retarding effects of age structure on the response to selection, and the interaction of selection and gene flow. Received 6 October 1987, accepted 8 May 1988.Item Open Access Genetic analysis of offspring of a female-female pair in the lesser snow goose (Chen caerulescens caerulescens).(University of California Press, 1989) Quinn, T.W.; Davies, J.C.; Cooke, F.; White, B.N.We used restriction-fragment-length polymorphism (RFLP) analysis to establish the parentage of a clutch of eight eggs being incubated by two female Lesser Snow Geese to determine if both females had contributed to the clutch, and whether a single male had fertilized both females. Genotypes at 30 polymorphic restriction enzyme sites were surveyed with 14 cloned DNA probes. Sexing of all individuals was done both by dissection and by use of a DNA probe that detected the presence of the W chromosome in females. Paternal genotypes were reconstructed from haplotypes of the offspring. We determined that both females had contributed to the clutch, and that each was fertilized by a different male. Received 9 May 1988, accepted 30 September 1988