Phenotypic fitness effects of B chromosomes in the pseudogamous parthenogenetic planarian Polycelis nigra

Article Abstract:

Phenotypic fitness effects of B chromosomes, or extra chromosomes, in planarian Polycelis nigra, a pseudogamous parthenogenetic planarian, are discussed. The number of phenotypic fitness aspects of worms, with and without B chromosomes, have been compared using worms from the field. The dynamics of one B chromosome seem to conform to a parasitic model, with Bs accumulating through occasional paternal inheritance, despite being selected against by hurting juvenile growth and cocoon production.

Germany, Statistical Data Included, Genetic aspects, DNA, Natural selection, Heredity, Chromosome numbers

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Allozyme variability in sexual and parthenogenetic freshwater planarians: evidence for polyphyletic origin of parthenogenetic lineages through hybridization with coexisting sexuals

Article Abstract:

Allozyme variability has been studied in sexual and parthenogenetic freshwater planarians. Evidence of genotypic diversity suggests a polyphyletic origin of parthenogenetic lines in mixed populations via hybridization with coexisting sexuals. New, genetically distinct parthenogenetic lines may arise in natural populations through the hybridization of sympatric sexuals and parthenogens.

Genotype, Genotypes, Hybridization, Isoenzymes, Gametogenesis

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Genetic variability and adaptive evolution in parthenogenetic root-knot nematodes

Article Abstract:

A focus on the root-knot nematodes (RKN)species that reproduce exclusively by mitotic parthogenesis (apomixis), in contrast to those that have meiotic/ amphimitic events in their life cycle is presented. The molecular and chromosomal mechanisms that could contribute to genome plasticity leading to persistent genetic variation and adaptive evolution in apomictic RKN is discussed.

Science & research, Apomixis, Plant asexual reproduction, Genetic variation

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