Are teleomorphs really necessary?: modelling the potential effects of Muller's Ratchet on deuteromycetous entomopathogenic fungi

Teleomorphic, or sexual, phases have not been described for many deuteromyc etous fungi and it is debated whether these phases actually exist, or are e ven necessary for some fungi. Muller's Ratchet is a population genetical me chanism, hypothesized in 1964 by H. J: Muller, which describes how certain asexual populations may undergo an unavoidable and progressive decline in f itness, eventually leading to population extinction. With respect to deuter omycetous fungi, Muller's Ratchet could operate because clonally reproducin g populations are not able to reduce their mutational load with each genera tion. Here we used a model to investigate and quantify some of the potentia l effects of the lack of sexual recombination on the accumulation of delete rious mutations using parameters derived from two species of deuteromycetou s entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana. Ou r results suggest that, under certain realistic conditions, Muller's Ratche t may not play a critical role in the fitness of these deuteromycetous ento mopathogenic fungi and it is at least theoretically possible that these fun gi could reproduce through exclusive clonal lineages.