Meiotic variation in an intergenomic autopolyploid series. II. Pairing behaviour

Pairing behaviour has been studied in PMCs of C0 autotetraploids of seven Lathyrus species exhibiting a range of genome size (10.8-19.9 pg DNA/2C). Each tetrasome within a C0 autotetraploid is equally likely to form a quadrivalent and the great majority of metaphase multivalents (96%) gave evidence of only a single synaptic exchange. Four components of variance in bivalent frequency were detected in the tetraploids. Both chiasma-dependent (0.5%) and chiasma-independent (4.2%) interspecific components were observed, whereas the only intraspecific component between plants (2.8%) was independent of variation in chiasma frequency. The only nonresidual component of variance in minimal incidence of synaptic exchange was interspecific (3.9%) and independent of variation in multivalent frequency.