Speciation potential of the Pilosella (Asteraceae) agamic complex. 2. Natural interspecies hybridization

摘要

Cytotaxonomical and distributional characteristics of natural intersectional hybrids forming a fragment of a Pilosella agamic complex from Saratov region. P.x praealta-officinarum, P.x vaillantii-officinarum, P.x officinarum-echioides, P.x echioides-praealta, P.x praealta vaillantii, P.x echioides-vaillantii were determined. The peculiarities of hybrid reproductive biology such as the time of flowering, pollen fertility, modes of reproduction, seed set and seed germinating ability suggest that some of them exist as local microspecies possessing a stable morphotype and a definite area, and some have no stable morphotype. It has been shown that interspecies hybridization between apomictic forms occurs intensively and leads to more significant consequences for synthesogenetic speciation than hybridization between sexual and apomictic forms. Different types of hybridogenic forms, constituting an agamic complex structure have been analysed. A conclusion that all the hybrids being investigated have an intracoenotical origin is made.