Interspecific movement of the paternal sex ratio chromosome

Article Abstract:

Potential for interspecific movement of a supernumerary or B chromosome and stability that follows has been studied. B chromosomes are different from autosomes: they are nonvital nonpairing chromosomes and vary in number between conspecific individuals. The paternal sex ratio chromosome (PSR) of Nasonia vitipennis was introduced into N. longicornis and N. giraulti. It can be seen that the transfers occur at high rates. The meiotic drive system of PSR continues to work in both specimens, resulting in maintenance of PSR at high frequencies. B chromosomes can start in one species and go into another one via interspecific hybridization.

Chromosome abnormalities, Species, Species (Biology), Hybridization

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Paternal inheritance in parthenogenetic forms of the planarian Schmidtea polychroa

Article Abstract:

A number of parthenogenetic organisms appear to have survived for extended periods in spite of the clonal inheritance factor that usually increases the risk of the extinction of the clonal population. One reason for this could be that parthenogens sometimes reproduce through sex-like processes and to better understand the mechanism involved a study of the sex-like processes in the planarian flatworm 'Schmidtea (Dugesia) polychroa was undertaken.

Pathogenic microorganisms, Parthenogenesis

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Genetic structure, reproductive biology and ecology of isolated populations of Asplenium csikii (Aspleniaceae, Pteridophyta)

Article Abstract:

The genetic structure of rock fern Asplenium csikii is compared with a related rock fern to understand population structure in the former. Results reveal that genetic diversity in A. csikii populations is not caused through multiple colonization. Instead, ecological specialization seem to contribute to their genetic variability.

United Kingdom, Statistical Data Included, Colonization, Plant isozymes, Plant isoenzymes, Ferns

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