Sibling Species Within Paramecium jenningsi Revealed by RAPD

The studies with application of the classical genetic method (strain crosses) and a molecular technique (RAPD-PCR fingerprinting, primer Ro 460-04) revealed the presence of separate sibling species within P. jenningsi. One of these is confined to six genetically related strains originating from Japan, separated from other group (results of strain crosses) and showing only one characteristic band pattern. The other of these includes strains from India, Saudi Arabia and China (Przyboś et al. 2003). We wanted to verify the RAPD markers specific for P. jenningsi and to prove the existence of two sibling species within it (revealed by one primer only), by application of others Ro-type primers. The conducted RAPD-PCR fingerpring analysis revealed that the genomes of the studies strains of P. jenningsi have polymorphic DNA sequences complementary to the four applied primers. The band patterns can be used as species-specific markers for P. jenningsi. DNA amplification by four primers used differentiates P. jenningsi into two groups of strains, one of which includes the Indian, Saudi Arabian and Chinese strains, the other the Japanese strains. Our results are congruent with inter-strain crossing experiments in which reproductive isolation was found when continental and Japanese strains were tested. This is further evidence for the existence of two sibling species, whose reproductive isolation is genetically induced.