Consequences of cytonuclear epistasis and assortative mating for the genetic structure of hybrid populations

Article Abstract:

Combined action of epistasis and assortative mating appear to be adequate to maintain observed high levels of cytonuclear disequilibria. Changes in disequilibria between life stages in a hybrid Iris population have been studied for information on levels of assortative mating and selection strength. Effects of epistasis and assortative mating between cytoplasmic genomes and interspecific nuclear genomes, that is, cytonuclear incompatibility, on levels of homozygote cytonuclear disequilibria have been analyzed. With random mating, cytonuclear genetic associations are scattered in any one generation. Levels of disequilibria coming from selection are less high than those seen with assortative mating.

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Allozyme segregation and inter-cytotype reproductive barrier in the polyploid complex Centaurea jacea

Article Abstract:

Controlled crosses were carried out within and between cytotypes of the Centaurea jacea complex. Progeny genotypes were looked at using allozyme markers to assess success of inter-cytotype crosses vs intra-cytotype ones to find out whether processes such as minority cytotype exclusion or inter-cytotype gene flow are likely to occur. Assessing the mode of inheritance of allozymes in tetraploids and checking for the occurrence of double reduction were goals. Null alleles were seen in the tetraploids at two enzymatic loci, so the expected difference of null allele frequencies between tetraploids and diploids were considered.

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Identification of native and hybrid elms in Spain using isozyme gene markers

Article Abstract:

Native and hybrid elms have been identified in Spain using isozyme gene markers. The Siberian elm, quite resistant to Dutch elm disease, was likely brought in in the 16th century as an ornamental species, but spread spontaneously in the Iberian Peninsula. Natural hybridization with Ulmus minor occurred, and the resultant trees are high in resistance to the disease. Isozyme markers can be used to distinguish native elms evolved over generations.

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