The Cladocera of Ontario with remarks on some species and distribution

Brandlova, J.; Brandl, Z.; Fernando, C. H.

doi:10.1139/z72-188

Cited by 137 publications

(72 citation statements)

References 12 publications

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“…This result was not unexpected, as prior taxonomic studies established the presence of D. pulicaria in western ponds (Brooks, 1957;Brandlova et al, 1972). 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.…”

Section: Discussionsupporting

confidence: 80%

“…A posteriori morphological studies on each population confirmed that individuals assigned to D. pulex and D. pulicaria showed the divergence in head shape characteristic of these species (Brooks, 1957;Brandlova et at., 1972). To assess the genotypic structure of each population, 44 individuals were scored for allozyme variation at six additional loci (Ao, Fum, Got, Mpi, Pgi, Pgm), which (4) Jasper (5), Blue Ridge (6), Red Deer (7), Medicine Hat (8), Provost (9) Prince Albert (10), Moose Jaw (11), Jan Lake (12) Russell (13) (27) Moncton (28) Yarmouth (29), Sherbrooke (30), Igonish Beach (31) Cavendish (32) are commonly polymorphic.…”

Section: Introductionmentioning

confidence: 82%

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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: Discussionsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 82%

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

et al. 1993

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“…Numerous studies have outlined physiological and life history differences between North American D. pulex and D. pulicaria (e.g., Brandlova et al 1972;Tessier and Consolatti 1991;Dudycha 2004;Weider et al 2004). In some parts of their distribution, D. pulex and D. pulicaria switch to sexual reproduction in response to different photoperiodic cues, resulting in a prereproductive isolating barrier (Deng 1997), and they usually occupy different but geographically overlapping habitats.…”

Section: Resultsmentioning

confidence: 99%

Patterns of Intraspecific DNA Variation in the Daphnia Nuclear Genome

Omilian

Lynch

2009

Genetics

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Understanding nucleotide variation in natural populations has been a subject of great interest for decades. However, many taxonomic groups, especially those with atypical life history attributes remain unstudied, and Drosophila is the only arthropod genus for which DNA polymorphism data are presently abundant. As a result of the recent release of the complete genome sequence and a wide variety of new genomic resources, the Daphnia system is quickly becoming a promising new avenue for expanding our knowledge of nucleotide variation in natural populations. Here, we examine nucleotide variation in six protein-coding loci for Daphnia pulex and its congeners with particular emphasis on D. pulicaria, the closest extant relative of D. pulex. Levels of synonymous intraspecific variation, p s , averaged 0.0136 for species in the Daphnia genus, and are slightly lower than most prior estimates in invertebrates. Tests of neutrality indicated that segregating variation conforms to neutral model expectations for the loci that we examined in most species, while K a /K s ratios revealed strong purifying selection. Using a full maximum-likelihood coalescent-based method, the ratio of the recombination rate to the mutation rate (c/u), averaged 0.5255 for species of the Daphnia genus. Lastly, a divergence population-genetics approach was used to investigate gene flow and divergence between D. pulex and D. pulicaria.

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“…Because multilake studies (e.g. Brandlova et al 1972) have shown that phenotypic variation is much greater among lakes than within lakes, prior allozyme studies have examined only a small fraction of the total morphological variation in the species. Furthermore, the probability of detecting an association between genotype and phenotype increases with the number of allozyme marker loci used.…”

mentioning

confidence: 99%

“…Morph 2's possession of a cephalic crest and its occupancy of lakes in the eastern half of North America provided Brooks (19573) with the justification for its fusion with D. galeata mendotae. However, it is now well known that D. rosea occurs throughout most of North America (Brandlova et al 1972). Moreover, Brooks (1957b) acknowledged that "robust" forms of D. Germany (Wolf and Mort 1986) and 1.3% of the complex in Czechoslovakia (Hebert et al 19893).…”

mentioning

confidence: 99%

Daphnia galeata mendotae as a cryptic species complex with interspecific hybrids

Taylor

Hebert

1992

Limnology & Oceanography

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Daphnia galeata mendotae has been recognized as possessing the greatest morphological variation among North American Daphnia species. Prior work has suggested that this variation is a consequence of phenotypic plasticity. Using allozyme markers, we tested this hypothesis by examining the association between genotype and morphology in 22 populations of D. galeata from lakes in Indiana. Analyses indicated a genetic basis for the phenotypic variability, as two different species and their F1 hybrids were detected. The parent species were D. galeata mendotae sensu stricto and a helmeted form of Daphnia rosea. F, hybrids were detected in 17 of 22 lakes and were dominant in 10. Backcross and F2 individuals were rare, however, suggesting that introgression is limited by the existence of reproductive isolating mechanisms.

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The Cladocera of Ontario with remarks on some species and distribution

Cited by 137 publications

References 12 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

Patterns of Intraspecific DNA Variation in the Daphnia Nuclear Genome

Daphnia galeata mendotae as a cryptic species complex with interspecific hybrids

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