Breeding system ofDaphniopsis ephemeralis: adaptations to a transient environment |
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Authors: | Steven S Schwartz Paul D N Hebert |
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Institution: | (1) Department of Biology, University of Windsor, N9B 3P4 Windsor, Ontario, Canada;(2) Present address: Department of Biology, University of Houston, 77004 Houston, TX, U.S.A. |
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Abstract: | Populations of the vernal cladoceranDaphniopsis ephemeralis are found in woodland ponds throughout southern Ontario. The species reproduces by cyclic parthenogenesis, and genotype frequencies
at allozyme loci are ordinarily in good agreement with Hardy-Weinberg expectations. Occasional heterozygote deficiencies are
apparently the consequence of admixture of ephippial hatchlings produced in temporally separated bouts of sexual reproduction.
Considerable heterogeneity in genotypic frequencies exists among local populations in southwestern Ontario, indicating that
gene flow among populations is restricted. Inbreeding coefficients suggest that populations receive an average of 0.3 migrants
per generation. The completion of a sexual life cycle is made possible despite the brief persistence of populations by the
emergence of males from ephippial eggs and by the production of equal numbers of male and female progeny in the first parthenogenetic
brood. |
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Keywords: | Daphniopsis ephemeralis Cladocera sex-ratios migration rates |
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