THE EFFECT OF ENVIRONMETAL FACTORS ON HYBRID FITNESS IN CRYPTOCOCCUS NEOFORMUNS

Abstract

<p>Recent population genetic studies have revealed that there are multiple natural hybridizations among divergent lineages in the human pathogenic fungus <em>Cryptococcus neoformans</em>. However, the biological and phenotypic effects of such hybridization are little understood. In this study, we constructed a laboratory cross between two genetically diverged strains; chosen because they differed in growth at different temperature and medium conditions and in their susceptibilities to the common antifungal drug Fluconazole. Our analyses indicated evidence of environment-specific outbreeding depression and intermediate phenotypes in the hybrid population of <em>C. neoformans</em>. A variable number of progeny displayed evidence of transgressive segregation. With increasing drug concentration, the relative fitness of transgressive hybrids also increased. The analyses showed that the progeny population had a greater phenotypic plasticity than the parental strains. Our study suggested that hybridization can playa significant role in the evolution of this important human pathogenic fungus.</p>