Apomictic biotypes in Potentilla intermedia and P. norvegica

Abstract

Material from localities in N. Scania, Sweden, was used in the present investigation. The chromosome number was 2n=56 in P. intermedia (as previously counted in Polish material) and 2n=70 in P. norvegica (as in many previous counts). Crossing experiments indicated pseudogamy in both species. Apomictic reproduction has been reported previously in P. intermedia, while P. norvegica has been supposed to be sexual. Embryologic studies gave evidence of obligate apospory in P. intermedia, while in P. norvegica some of the primary EMC:s undergo meiosis. In the latter species, partial sexuality is not quite excluded, although it reproduces mainly by apomixis. Meiosis on the male side is fairly irregular in P. intermedia while on the other hand P. norvegica has a quite regular bivalent formation, in spite of its high degree of polyploidy. P. intermedia is supposed to be of hybrid origin, being the result of crosses between P. argentea and P. norvegica. This remains to be proved experimentally, however, since crossing experiments between P. argentea and P. norvegica have so far failed to give any offspring.

Reproductive differentiation into sexual and apomictic polyploid cytotypes in Potentilla puberula (Potentilleae, Rosaceae)

“…15–80 % viable pollen in P. tabernaemontani (Müntzing, 1928; Asker, 1985); approx 40–60 % in P. argentea , approx. 0–40 % in P. collina (Müntzing, 1928, 1958); and 64 % in P. intermedia (Asker, 1970 a )]. Besides apomixis, hybridity was associated with low pollen quality (Müntzing, 1928; Asker, 1970 a ).…”

“…0–40 % in P. collina (Müntzing, 1928, 1958); and 64 % in P. intermedia (Asker, 1970 a )]. Besides apomixis, hybridity was associated with low pollen quality (Müntzing, 1928; Asker, 1970 a ). Thus, the low pollen quality in some tetraploid P. puberula individuals might be the combined effects of a tendency to apomixis and the hybrid origin of the species.…”

“…Müntzing, 1928; Asker, 1970 a ; Czapik, 1975), resulting in aneuploid offspring (Asker, 1971). Such irregularities can be particularly expected in odd-ploids because of the high chance of unpaired chromosomes disrupting meiosis (Dawe, 1998).…”

“…Apomictic elements (i.e. apomeiosis and parthenogenetic origin of embryos) have been documented in at least 16 species (Gentscheff, 1938; Gustafsson, 1947; Löve, 1954; Asker, 1970 a ), while sexual reproduction was claimed for five species based on embryological evidence (Rutishauser, 1945; Håkansson, 1946; Czapik, 1961, 1962 a ). In order to initiate seed formation, in all Potentilla species including apomicts functional pollen is needed to fertilize the endosperm (Asker, 1970 b ), which usually receives a bi-nucleate female contribution (Dobeš et al.…”

A comprehensive chloroplast DNA-based phylogeny of the genus Potentilla (Rosaceae): Implications for its geographic origin, phylogeography and generic circumscription

“…The phylogenetic conflict between the cpDNA and nDNA analysis thereby may be explained by hybridization of the Rivales with the core Potentilla, which was assumed by several authors (cf. Asker, 1970). Phylogeographic interpretation cannot be made for these lineages in a taxonomic context, as taxa may carry haplotypes of a phylogeography history different from the history of species.…”