Clonal diversity in populations of Daphnia pulex reproducing by obligate parthenogenesis

Hebert, Paul D. N.; Crease, Teresa J.

doi:10.1038/hdy.1983.40

Cited by 123 publications

(129 citation statements)

References 26 publications

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“…The present study has made it clear that F1 hybrids between D. pulex and D. pulicaria are common at sites across Canada and reproduce asexually. Their prevalance in western Canada was not unexpected in light of their predominance in grassland pools in the Great Lakes region (Hebert & Crease, 1983). Whereas the initial conclusion concerning the hybrid origin of these clones was based on the results of allozyme surveys ( Hebert et al,198 9a), this conclusion has recently been supported by rDNA analysis (Crease & Lynch, 1991).…”

Section: Discussionmentioning

confidence: 64%

“…Recent work established the presence of F1 hybrids between these species and has shown that such hybrids always reproduce by obligate parthenogenesis (Hebert et a!., 1989a;Crease & Lynch, 1991). Earlier studies incorrectly classified these hybrids as asexual clones of D. pulex (Hebert & Crease, 1983;Lynch 1983;Innes et al, 1986). It remains clear, however, that D. pulex s.s. shows variable reproductive behaviour, with some populations reproducing by cyclic and others by obligate parthenogenesis.…”

Section: Introductionmentioning

confidence: 87%

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Macrogeographic patterns of breeding system diversity in the Daphnia pulex group. I. Breeding systems of Canadian populations

et al. 1993

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Efforts to deduce the evolutionary significance of sexual reproduction from the taxonomic and ecological distributions of asexuals rely on the presumption that reversions of asexual taxa to sexual reproduction are rare. There is growing evidence, however, that reversions may be likely as long as asexuals are diploid, and some sexual populations persist. However, few systems have been studied in sufficient detail to provide insight into the nature of interactions between the sexual and asexual components of a single taxon. The cladoceran crustaceans Daphnia pulex and D. puilcaria both show variation in breeding system with some populations reproducing by cyclic and others by obligate parthenogenesis. The present study used allozymic analysis to characterize the breeding systems of both species across Canada. Although F1 hybrids were prevalent between the species and invariably reproduced by obligate parthenogenesis, each parent species showed regional variation in its breeding system. D. pulex reproduces by obligate parthenogenesis in eastern Canada but switches to cyclic parthenogenesis in the west with an abrupt transition coincident with the forest/prairie ecotone. D. pulicaria shows a divergent pattern, with populations on the priaries reproducing by obligate parthenogenesis, while those in eastern Canada and the far west are cyclic parthenogens. The results make clear that breeding systems in both taxa tend to be uniform over large areas. The discordance in breeding system employed by each species at specific sites suggests that the patterns of breeding system variation are not linked to environmental factors, but are instead a consequence of the interplay between historical factors, such as dispersion patterns from glacial ref ugia and the sites of origin of mutations promoting the transition to asexuality.

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Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 87%

Macrogeographic patterns of breeding system diversity in the Daphnia pulex group. I. Breeding systems of Canadian populations

et al. 1993

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“…Recent studies (Hobaek et al, 1993;Ward et al, 1994) have shown that populations of D. pulex from Eurasia have a similarly low level of clonal diversity (1.5 and 1.7 clones per pond). Higher clonal diversity estimates have however been reported for D. middendorffiana from a high-arctic site (4.5 clones per pond) and for D. pulex from a temperate zone region (2-4 clones per pond) (Hebert & Crease, 1983; (Weider & Hebert, 1987a;Zhao & King, 1989;Browne, 1992;Wilson & Hebert, 1992). Reasons for the differential distribution of the D. tenebrosa clones are not clear.…”

Section: Mtdna Analysismentioning

confidence: 97%

“…Allozyme analyses have shown that clonal diversity is very high in these obligate parthenogens with thousands of clones occurring over the species distribution. However, single habitats typically contain fewer than three clones in both temperate and lowarctic sites (Hebert & Crease, 1983;Weider & Hebert, 1987a;Wilson & Hebert, 1992). Higher levels of clonal diversity (an average of 4.5 clones per pond) have been found at a high-arctic site occupied almost exclusively by polyploid clones (Weider et a!., 1987).…”

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confidence: 99%

Polyploidy and clonal diversity in an arctic cladoceran

Hebert

1995

Heredity

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Genome size determinations were coupled with allozyme and mtDNA studies to gain insights into the origin of polyploidy and clonal diversity in populations of Daphnia tenebrosa from Churchill, Manitoba. Allozymic variation at five enzyme loci allowed the detection of 32 clones. Analyses of 73 populations in 1981, 27 in 1987 and 45 in 1991 revealed that clonal frequencies were relatively stable and that D. tenebrosa was more clonally diverse (average of three clones per pond) than other species of the D. pulex complex at the same site. Genome size determinations revealed the presence of two clonal assemblages with averages of 0.53 (± 0.01) pg and 0.89 (± 0.03) pg, corresponding to diploid and tetraploid clones. Clustering of allozyme distances revealed three groups, with no association between ploidy level or pigmentation. Similarly, diploid and polyploid clones did not form distinct clusters on the mtDNA dendrogram. The high sequence divergence between the two mtDNA clusters as well as the lack of correspondence between allozyme distance and mtDNA divergence among clonal pairs both suggest that polyploidy arose following reciprocal hybridizations between genetically divergent populations of this species.

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“…Among obligate parthenogens, multiple clones are often present within local populations. For example, Hebert and Crease (1983) observed 22 clones of obligately parthenogenetic Daphnia pulex from ponds near Windsor, Ontario. Clonal diversity estimates for a single habitat (pond) ranged from [1][2][3][4][5][6][7] clones/pond (mean = 40 clones/pond based on 4 enzyme loci).…”

Section: Introductionmentioning

confidence: 99%

Microgeographic genetic heterogeneity of melanic Daphnia pulex at a low-Arctic site

Weider

Hebert

1987

Heredity

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Clonal diversity of obligately parthenogenetic Daphnia pulex was examined in 147 ponds at 13 sites near Churchill, Manitoba. Cellulose acetate electrophoresis of four polymorphic loci allowed the detection of 16, multi-locus genotypes (clones). The three most common clones accounted for 86 per cent of the 3291 animals surveyed. An average of 1•5 clones coexisted in single ponds, while an average of 38 clones was present at each site. Fifteen of the sixteen clones show unbalanced electromorph phenotypes at one or more loci suggesting that they are polyploids. There was significant spatial autocorrelation of the distribution of certain clones within a given site on a scale of tens of metres. Clinal patterns in clone distributions were often found. No significant between-site spatial autocorrelation was found on a scale of 0-20 kilometres, although between-site heterogeneity of clonal frequencies was frequently seen. Microgeographic heterogeneity of D. pulex clones at Churchill is influenced by salinity gradients on a scale of tens of meters. Mechanisms that might influence the clonal structure of this apomictic complex are discussed.

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Clonal diversity in populations of Daphnia pulex reproducing by obligate parthenogenesis

Cited by 123 publications

References 26 publications

Macrogeographic patterns of breeding system diversity in the Daphnia pulex group. I. Breeding systems of Canadian populations

Macrogeographic patterns of breeding system diversity in the Daphnia pulex group. I. Breeding systems of Canadian populations

Polyploidy and clonal diversity in an arctic cladoceran

Microgeographic genetic heterogeneity of melanic Daphnia pulex at a low-Arctic site

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