All in an afternoon: mixed breeding system in one-day lasting flowers of Hypericum elodes L. (Hypericaceae)

Abstract

Knowledge about mixed mating systems can improve our understanding of the evolutionary dynamics of reproductive systems. Here we report a study of the floral and reproductive biology of Hypericum elodes, an Atlantic-European soft-water pools specialist which shows a flower architecture consistent with both self-and crosspollination. Controlled pollination experiments were performed in a natural population during three consecutive years. Marked flowers were monitored until fruit production, and laboratory germination experiments were conducted with the seeds produced. Plants were self-compatible (SCI > 0.75), however, compared with selfing, cross-pollination enhanced fruit-set, seed-set and seedling growth, but not seed germination. Inbreeding depression (δ) was mild in the pre-dispersal stages (δ = 0.22 for fruit set, 0.18 for seed set and 0.13 for seed mass), low for germination percentage (δ = 0.003) and mild for seedling growth (δ = 0.23). The breeding system of H. elodes promotes outcrossing and assures reproductive success by means of competitive autogamy. Our results suggest a mixed mating strategy for the studied population, characterized by mild inbreeding depression (cumulative δ = 0.57), highlighting the benefit of this reproductive mode in unpredictable habitat, as the typical shallowwater meadows where H. elodes grows.

Mating system modulates degree of seed dormancy inHypericum elodesL. (Hypericaceae)

“…In nature H. elodes normally produces seeds by both self-fertilization and outcrossing. Indeed, its breeding system promotes outcrossing by morphological and physiological traits and ensures reproductive success when outcrossing is erratic, by means of competitive autogamy (Carta et al , 2015b).…”

“…Plants grow over an area of 4000 m 2 in a system of shallow pools which is flooded in the winter–spring season and completely dry during the summer. The water level can vary among years, leading to a marked oscillation of seedling recruitment and of the number of flowering individuals (Carta et al , 2015b).…”

“…Thus, the breeding system might facilitate the onset of environment-driven adaptation through the variation in degrees of dormancy, allowing the seeds to spread germination across time and bet-hedge against an unpredictable, variable environment. Hypericum elodes L., a typical species of periodically inundated shores of softwater ponds (Murphy, 2002), is a good model for the study of these issues: recent studies highlighted a mixed mating system (Carta et al , 2015b) and also the existence of dormancy-degree variation (Carta et al , 2015a) for this perennial, insect-pollinated herb displaying an Atlantic–European distribution. As in other plants, the maintenance of a mixed mating system is not yet fully clarified (Goodwillie et al , 2005; Winn et al , 2011).…”

Conservation biology of the last Italian population of Cistus laurifolius (Cistaceae): demographic structure, reproductive success and population genetics

“…Population size strongly affects local adaptation (Leimu et al 2008), whereas population structure can influence breeding systems and, eventually, reproductive outcomes (Carta et al 2016a). Population dynamics are usually age-stage-dependent and related to the survival potential of a species (Harper 1977).…”

Reproductive assurance in three Neotropical species of Podostemaceae: strategies of self-pollination and the first report of apomixis1

“…Although these species have similar floral morphology, they possess different strategies of self-pollination (prior versus competing). The mechanisms to promote self-pollination in Podostemaceae are more complex than those described in Hypericum elodes (Hypericaceae, sister-group of Podostemaceae), because the pollen grains are deposited on the stigma just after the flower opens, by the proximity to the anthers without any movement or filament elongation (Carta et al 2015). In Podostemaceae, the floral structures are well-exposed and in close proximity; these morphological features can facilitate the contact between receptive stigmas and anthers or autonomous deposition of pollen in all flower stages (inside the buds, during anthesis or in the final stages of anthesis).…”