Revealing the Hybrid Zone and Genetic Polymorphisms within Pseudo-nitzschia pungens the Cosmopolitan Diatom Species

Abstract

Genetic sub-populations (clades) of cosmopolitan marine diatom Pseudo-nitzschia pungens might have distinct habitats, and their hybrid zone is suspected in the West Pacific area, however, it is still unrevealed because of technical difficulties and lack of evidences in nature. We employed the 137 number of genetic information of P. pungens and its sampling data originated from the West Pacific area, and used field application of qPCR assay for intra-specific level of P. pungens. Only two genotypes, clade I and III, were considered in the West Pacific area. Clade I was distributed from 39 to 32.3 °N, and clade III were from 1.4 to 34.4 °N. The estimated habitat temperature for the clade I and clade III rangeswere 8.1 - 26.9 °C and 24.2 - 31.2 °C, respectively. The latitudal distributions and habitat temperature ranges of each clade were significantly different, however, the results of qPCR assay revealed that their hybrid has being created in the southern Korean coasts. In laboratory condition, the sexual-reproduction was successfully occurred, and offspring cells were produced between clade I and III strains. The offspring strains showed recombinant sequences types, and the high ratios (38.6 and 65.1%) of single nucleotide polymorphism were observed in ITS2 region. The hybrid zone and genetic polymorphism phenomenon should contribute to maintain the genetic diversity and to produce the new genotypes within this