Genetic cost of reproductive assurance in a self-fertilizing plant

Abstract

The transition from outcrossing to self-fertilization is one of the most common evolutionary trends in plants. Reproductive assurance, where self-fertilization ensures seed production when pollinators and/or potential mates are scarce, is the most long-standing and most widely accepted explanation for the evolution of selfing, but there have been few experimental tests of this hypothesis. Moreover, many apparently adaptive floral mechanisms that ensure the autonomous production of selfed seed might use ovules that would have otherwise been outcrossed. This seed discounting is costly if selfed offspring are less viable than their outcrossed counterparts, as often happens. The fertility benefit of reproductive assurance has never been examined in the light of seed discounting. Here we combine experimental measures of reproductive assurance with marker-gene estimates of self-fertilization, seed discounting and inbreeding depression to show that, during 2 years in 10 Ontario populations of Aquilegia canadensis (Ranunculaceae), reproductive assurance through self-fertilization increases seed production, but this benefit is greatly outweighed by severe seed discounting and inbreeding depression.

Reproductive system of a mixed-mating plant responds to climate perturbation by increased selfing

“…What remain unclear, however, are the risks of increased selfing [20]. Persistent selfing in mixed-mating plants has been associated with a range of potentially negative consequences, including inbreeding depression, pollen and seed discounting, and the concentration of juveniles near maternal plants given that selfed seeds tend to be dispersal-limited [11,26].…”

“…For example, various forms of compensatory buffering may provide short-term resiliency in growth and reproduction, but have longer-term costs through the draining of carbohydrate reserves or increased inbreeding depression from selfing [11,20].…”

Breeding system and pollination of Pleroma trichopodum DC. (Melastomataceae): a potential species for the restoration of Atlantic Forest in southern Brazil

“…Moreover, the degradation of the environment in early restoration areas may limit the availability of pollinators (Kremen et al 2007). In this sense, plants that reproduce through selfing have the advantage of reproductive assurance (Pannell & Barrett 1998;Moeller & Geber 2005;Santos et al 2012), but may suffer disadvantages related to high inbreeding rates (Lande & Schemske 1985;Herlihy & Eckert 2002;Maia et al 2017). On the other hand, self-incompatible plants avoid inbreeding (Lande & Schemske 1985), but may be unsuccessful in areas with limited availability of pollinators and mates (Pannell & Barrett 1998;Scobie & Wilcock 2009).…”

Population at the edge: increased divergence but not inbreeding towards northern range limit in Acer campestre

“…Limited dispersal accompanied by low density of pollen donors can lead to pollen limitation syndrome, which often drives inbreeding through increased self-fertilisation (in self-compatible species) or mating between relatives (Kalisz et al 1999;Rajora et al 2002;Johnson et al 2009). In consequence, a decreased heterozygosity (due to inbreeding) facilitates expression of deleterious genes, having negative impact on the fitness and, consequently, increasing extinction risk (Newman and Pilson 1997;Herlihy and Eckert 2002;Reed and Frankham 2003;Vilas et al 2006;Gargano et al 2009). Thus, it is expected that the species characterised by low dispersal capabilities are more prone to negative consequences of fragmentation (White et al 2002;Jump and Penuelas 2006;O'Connell et al 2007;Montoya et al 2008) and, they should also exhibit more apparent central-marginal patterns.…”