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Chapter 12 : The Evolutionary Implications of an Asexual Lifestyle Manifested by Penicillium marneffei
Category: Fungi and Fungal Pathogenesis
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This chapter highlights that a truly comprehensive understanding of the evolution of sexuality in fungi needs to also account for the occurrence of their antithesis, the mitosporic asexual species. Recent work on the spatial population genetics of one such mitosporic species, the biverticilliate mycosis agent Penicillium marneffei, is shedding much-needed light on the processes and consequences of asexuality in fungi. The accumulation of annotated fungal genome projects has shown that almost all species so far examined contain the genes that are necessary for mating processes, pathway signaling, and meiosis. The accumulation of annotated fungal genome projects has shown that almost all species so far examined contain the genes that are necessary for mating processes, pathway signaling, and meiosis. Evolution is a stochastic process and is most often conceptualized by the classic Wright-Fisher model. This model idealizes species as a group of individuals, of population size N, that draw equally, and synchronously, from an infinite pool of gametes, in this manner creating the next generation, N + 1. P. marneffei is a fungus of the family Trichocomaceae that has emerged since 1990 as a significant agent of human mycosis. The fungus causes a disease, P. marneffei, that occurs in immunosuppressed patients. In summary, the author has put forward an argument suggesting that in fungi where sexual reproduction is facultative loss-of-function mutations in mating-type loci will, generally speaking, be selectively neutral.
Principal-components analysis of the P. marneffei MTs.
Neighbor-joining tree of the P. marneffei MLMT data set.
The relationship between effective population size and population structure inferred from the P. marneffei MLST data set.
eBURST groupings of two simulated populations evolving under a Wright/Fisher model, with n = 1,000 and identical mutation rates. For population A, recombination = 0, and for population B, the recombination rate is twice the background mutation rate. Simulations and diagrams were produced by Katy Turner.
Estimates of noncoding variation in fungi and derived effective population sizes a
Multilocus linkage disequilibria for three populations of P. marneffei in the Eastern and Western clades