Spatial and Temporal Genetic Heterogeneity in a Natural Daphnia Population: Ecological and Physiological Differences Between Genotypes (Cladocera, Freshwater, Parthenogenesis)
Weider, Lawrence J.
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https://hdl.handle.net/2142/77620
Description
Title
Spatial and Temporal Genetic Heterogeneity in a Natural Daphnia Population: Ecological and Physiological Differences Between Genotypes (Cladocera, Freshwater, Parthenogenesis)
Author(s)
Weider, Lawrence J.
Issue Date
1984
Department of Study
Ecology, Evolution, and Conservation Biology
Discipline
Ecology, Evolution, and Conservation Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Ecology
Language
eng
Abstract
A three and one-half year study of spatial and temporal genetic heterogeneity in a population of the cyclically, parthenogenetic cladoceran, Daphnia pulex, inhabiting a permanent farm pond in east-central Illinois, indicated that electrophoretically distinct genotypes (clones) are frequently distributed non-randomly in the pond, both vertically and horizontally. Spatial autocorrelation analysis indicated that the genotypic distributions exhibited significant horizontal spatial pattern on occasion. The horizontal pattern may be influenced greatly by the vertical component (depth factors at a given station) as demonstrated by a series of vertical-horizontal transect surveys.
Diel vertical migration surveys demonstrated significant differences in vertical distribution and vertical migration activity among genotypes, strongly suggesting a genetic component to vertical migration, and implying that genetically determined habitat selection exists in this population.
The effects of food concentration, temperature, and pond water quality on life histories of genotypes were examined in the laboratory. Results indicated significant genotype x environment interactions under certain treatments; no single genotype was most fit when raised under all experimental conditions, indicating that selection may be operating to favor genotypes in different spatial and/or temporal microhabitats.
Dissolved oxygen experiments in the laboratory showed significant clonal differences in low oxygen tolerance and hemoglobin synthesis implying that low dissolved oxygen concentrations in nature may be an important selective pressure affecting the spatial and temporal genetic heterogeneity in planktonic cladoceran populations. The evolutionary and ecological implications of these data are discussed in reference to the maintenance of genetic variation in heterogeneous environments.
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