Pseudogamy, hybridization and evolution in Potentilla

Abstract

Related apomicts often coexist within a biotope. Where they intercross, occasional hybrids may be formed. The designations U- and R-hybrids - from fertilized unreduced and reduced egg cells, respectively - are proposed. The more common U-hybrids may have a lower average fitness than R-hybrids. In Potentilla argentea, biotypes of different ploidy show contrasting modes of reproduction. Biotype and species hybrids sometimes appear as well as heteroploid aberrants of uncertain origin. A diploidtetraploid-diploid cycle with sexual tetraploids is known. Selection of well-adapted mutant genotypes continues where recombination is suppressed. - Some other factors important for evolution in apomictic complexes are also briefly discussed.