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IMAGE: The cells adhere to each other, and the direct contact, a cytoplasmic bridge, occurs between the partners. view more
Credit: SPbU
The mating process is one of the most important mechanisms for maintaining genetic variation in natural populations. The emergence of sexual reproduction turned out to be the most important evolutionary innovation that facilitated the evolution of eukaryotes. Paramecium is a well-known genus of ciliated protists with a complex system of sexes , or mating types. Paramecium reproduces asexually, by binary fission, which is not related to the mating process. During conjugation, Paramecium of compatible mating types exchange haploid nuclei, equivalent to gametes. The nuclei of each organism then fuse to form a diploid genome. This genome is stored in germline micronuclei of the exconjugants. It then undergoes large-scale rearrangements in the somatic macronucleus, including the elimination of virtually all non-coding DNA. Thus, t