The evolutionary ecology of inbreeding depression in wild plant populations and its impact on plant mating systems.

Inbreeding depression, the reduced fitness of inbred relative to outbred individuals was described more than two centuries ago, long before the development of population genetics. Its impact is central to evolutionary ecology and the evolution of mating systems, in particular self-fertilization in hermaphrodites. In the first half of the 20 century, population genetics revealed a mechanism for inbreeding depression through homozygosity.

Fisher's automatic advantage of self-fertilization does not apply in cleistogamous species.

Premise: In hermaphroditic plants, the evolution of self-fertilization is driven by two major forces; the cost of outcrossing or Fisher's automatic advantage of selfing and inbreeding depression. Seminal theoretical works have established that an inbreeding depression threshold of 0.5 governs the evolution.

A hemizygous supergene controls homomorphic and heteromorphic self-incompatibility systems in Oleaceae.

Self-incompatibility (SI) has evolved independently multiple times and prevents self-fertilization in hermaphrodite angiosperms. Several groups of Oleaceae such as jasmines exhibit distylous flowers, with two compatibility groups each associated with a specific floral morph. Other Oleaceae species in the olive tribe have two compatibility groups without associated morphological variation.

Ongoing convergent evolution of a selfing syndrome threatens plant-pollinator interactions.

Plant-pollinator interactions evolved early in the angiosperm radiation. Ongoing environmental changes are however leading to pollinator declines that may cause pollen limitation to plants and change the evolutionary pressures shaping plant mating systems. We used resurrection ecology methodology to contrast ancestors and contemporary descendants in four natural populations of the field pansy (Viola arvensis) in the Paris region (France), a depauperate pollinator environment.