Genetic diversity and population structure of Corollospora maritima sensu lato: new insights from population genetics

The study of genetic variation in fungi has been poor since the development of the theoretical underpinnings of population genetics, specifically in marine taxa. Corollospora maritima sensu lato is an abundant cosmopolitan marine fungus, playing a crucial ecological role in the intertidal environment. We evaluated the extent and distribution of the genetic diversity in the nuclear ribosomal internal transcribed spacer region of 110 isolates of this ascomycete from 19 locations in the Gulf of Mexico, Caribbean Sea and Pacific Ocean. The diversity estimates demonstrated that C. maritima sensu lato possesses a high genetic diversity compared to other cosmopolitan fungi, with the highest levels of variability in the Caribbean Sea. Globally, we registered 28 haplotypes, out of which 11 were specific to the Caribbean Sea, implying these populations are genetically unique. We detected populations inhabiting human-impacted sites with null genetic variation. As long-term exposure to contaminants has been proven to decrease genetic diversity, a conservation genetics approach to assess this matter is urgent. Our results revealed the occurrence of five genetic lineages with distinctive environmental preferences and an overlapping geographical distribution, agreeing with previous studies reporting physiological races within this species.