Reproductive ecology of three rareNorthAmericanPinguiculaspecies

Abstract

Pinguicula (Lentibulariaceae) is a genus of more than 100 carnivorous plant species. A handful of comprehensive studies have examined the reproductive ecology of these species, mostly in Europe and none in the USA. During 2013–2016 different aspects of the reproductive ecology of P. ionantha, P. lutea and P. planifolia were studied at multiple locations in the Florida Panhandle, USA. All three species are of conservation concern within the study region and some aspects of their reproductive ecology may be contributing to their rarity. For all species, we conducted breeding system studies investigating xenogamy vs. autogamy, self‐incompatibility vs. self‐compatibility, pollen:ovule ratios, flower phenology and longevity, and pollinator visitation, as well as fruit and seed set differences among populations. All three Pinguicula species were determined to be xenogamous and self‐compatible, although the pollen:ovule ratios were extremely low. In addition, these species have floral nastic movements and flower longevity that ranges from 2 to 3 weeks depending on the species. Hymenoptera was identified as the primary group of pollinators visiting all species, although observed visitation events were low. All three Pinguicula species had extremely high levels of fruit set and seed set. Worldwide, Pinguicula species share similar breeding system and reproductive patterns. The rare status of P. ionantha, P. lutea and P. planifolia is more likely due to their ecological requirements, demographics and/or patterns of genetic diversity, than reproduction. This work is among the first and most comprehensive associated with the reproductive ecology of North American Pinguicula.

Effects of crossing distance on fitness components in the carnivorous plant Pinguicula moranensis (Lentibulariaceae)

“…In July 2017, 50 plants bearing floral buds were marked in the Cuernavaca population and randomly assigned to five hand-pollination treatments (n = 10 per treatment). This sample size was previously used in earlier studies to characterize the pollination system of P. moranensis (Villegas & Alcalá, 2017) and other Pinguicula species (Molano-Flores et al, 2018). The treatments performed within the recipient population were: self-fertilization (0 m) and crosses performed at four distances (1, 4, 460 and 9,900 m).…”

“…Thus, the fitness of carnivorous species could depend on interactions with both prey and pollinators (Jürgens, Sciligo, Witt, El-Sayed, & Suckling, 2012). Carnivorous plants display wide diversity of reproductive systems, and studies addressing reproductive ecology have documented variation in flower structure and histochemistry, flower phenology and longevity, mating system, pollination syndrome, and visitation rate, among others (Adam, 1998;Chua, 2000;Clivati, Cordeiro, Płachno, & Miranda, 2014;Hobbhahn, Küchmeister, & Porembski, 2006;Kato, 1993;Lowrie, 2001;Meindl & Mesler, 2011;Molano-Flores et al, 2018;Molau, 1993;Murza & Davis, 2003;Ne´eman et al, 2006;Olivencia, Claver, & Alcaraz, 1995;Płachno et al, 2018;Renner, 1989;Schnell, 1983;Villegas & Alcalá, 2017). These studies have identified selfing and outbreeding species, but the information on the effects of varying distance to pollen donors is scarce in carnivorous plant species.…”

“…This information is needed to improve our understanding of the fitness consequences of outbreeding species when exposed to inbreeding. This scenario is likely to occur as a result of the spatial distribution of individual plants and the foraging pattern of pollinators, despite traits promoting outcrossing (Clivati et al, 2014;Hobbhahn et al, 2006;Molano-Flores et al, 2018;Villegas & Alcalá, 2017).…”

“…Pinguicula L. is a genus comprised of nearly 100 species (Ellison et al, 2003) recognized as a member of the extant carnivorous lineages (Casper, 1966;Legendre, 2000). This genus has spurred zygomorphic flowers that majorly depend on long-tongued insects for fruit production (García, Antor, & Villar, 1994;Lustofin, Świątek, Miranda, & Płachno, 2019;Molano-Flores et al, 2018;Molau, 1993;Zamora, 2002). Xenogamous and selfcompatible species have been commonly reported, but see Molau (1993) for autogamy in P. villosa.…”

“…Xenogamous species share large, long lasting and often colored (i.e, yellow, pink, purple and blue) corollas with nectar guides (García et al, 1994;Molano-Flores et al, 2018;Molau, 1993). The relative position of the stigma surface, extending beyond the two anthers (i.e., herkogamy), is predicted as a mechanism promoting cross-pollination (Schnell, 1979), which has been observed in xenogamous species of Pinguicula (García et al, 1994;Molano-Flores et al, 2018;Molau, 1993) and Utricularia (Clivati et al, 2014). This is because a pollinator probing its tongue toward the spur will deposit outcrossed pollen grains on the receptive lip of the stigma.…”