Survival and mating behaviour of progeny and germination of zygotes from intra- and interspecific crosses of Chlamydomonas eugametos and C. moewusii (Chlorophyceae, Volvocales)

Intra- and interspecific matings of Chlamydomonas eugametos and C. moewusii were conducted to compare germination percentages of zygotes and survival and mating behaviour of F1 progeny. Zygotes from both intra- and interspecific crosses germinated at equal frequencies. Progeny survival differed greatly in the various crosses, however, and gone lethality was experienced in all crosses. The C. moewusii intraspecific cross yielded the highest progeny survival rate. Progeny survival in the C. eugametos intraspecific cross was less than that for C. moewusii. Both interspecific crosses showed a high degree of progeny lethality and most zygotes yielded no viable progeny. Equal numbers of each mating type were found among surviving progeny of an interspecific cross. The C. moewusii parental strains showed a higher mating efficiency than the C. eugametos strains. Groups of F1 progeny from intra- and interspecific crosses, backcrossed to C. moewusii parental strains, showed different ranges of mating efficiencies. These ranges were discontinuous for the two intraspecific progeny groups, while the interspecific progeny group showed a range which partially overlapped those of both intraspecific progeny groups. Mean mating efficiencies for intraspecific F1 progeny groups were similar to those of parental strains. The interspecific F1 progeny group showed an intermediate mean mating efficiency. These results suggest that mating may be passed on to offspring.