Purifying selection after episodes of recurrent adaptive diversification in fungal pathogens.

Tests of selective neutrality based on comparative and population genetic data target different time scales of selection. Investigating both time scales on the same genes has rarely been done and yet can provide insights into histories of selection. In pathogens, such a comparison can elucidate whether the same genes experience recurrent positive selection across specialization events onto novel hosts and selection in the short term, e.

Having sex, yes, but with whom? Inferences from fungi on the evolution of anisogamy and mating types.

The advantage of sex has been among the most debated issues in biology. Surprisingly, the question of why sexual reproduction generally requires the combination of distinct gamete classes, such as small and large gametes, or gametes with different mating types, has been much less investigated. Why do systems with alternative gamete classes (i.

Using phylogenies of pheromone receptor genes in the Microbotryum violaceum species complex to investigate possible speciation by hybridization.

Several cases of speciation by hybridization have been reported in fungi, mostly involving recent hybridization between closely related species. In the basidiomycete genus Microbotryum by contrast some species were suspected to have arisen by hybridization between moderately distant species. In particular two species, M.

Finding candidate genes under positive selection in Non-model species: examples of genes involved in host specialization in pathogens.

Numerous genes in diverse organisms have been shown to be under positive selection, especially genes involved in reproduction, adaptation to contrasting environments, hybrid inviability, and host-pathogen interactions. Looking for genes under positive selection in pathogens has been a priority in efforts to investigate coevolution dynamics and to develop vaccines or drugs. To elucidate the functions involved in host specialization, here we aimed at identifying candidate sequences that could have evolved under positive selection among closely related pathogens specialized on different hosts.

MERE1, a low-copy-number copia-type retroelement in Medicago truncatula active during tissue culture.

We have identified an active Medicago truncatula copia-like retroelement called Medicago RetroElement1-1 (MERE1-1) as an insertion in the symbiotic NSP2 gene. MERE1-1 belongs to a low-copy-number family in the sequenced Medicago genome. These copies are highly related, but only three of them have a complete coding region and polymorphism exists between the long terminal repeats of these different copies.