Pollination of the European food-deceptive Traunsteinera globosa (Orchidaceae): the importance of nectar-producing neighbouring plants

Abstract

European food-deceptive orchids generally flower early in spring and rely on naı¨ve pollinators for their reproduction. Some species however, flower later in the summer, when many other rewarding plants species are also in bloom. In dense flowering communities, deceptive orchids may suffer from competition for pollinator resources, or might alternatively benefit from higher community attractiveness. We investigated the pollination strategy of the deceptive species Traunsteinera globosa, and more specifically whether it benefited from the presence of coflowering rewarding species. We carried out a population survey to quantify the density and reproductive success of the orchid as well as the density of all coflowering species. Our results suggest that the deceptive orchid not only benefited from the presence of coflowering species, but that interestingly the density of the species Trifolium pratense was significantly positively correlated with the orchid's reproductive success. This species might simply act as a magnet species attracting pollinators near T. globosa, or could influence the orchid reproductive fitness through a more species-specific interaction. We propose that morphological or colour similarities between the two species should be investigated in more detail to decipher this pollination facilitation effect.

Reproductive success in the Mexican rewardless Oncidium cosymbephorum (Orchidaceae) facilitated by the oil-rewarding Malpighia glabra (Malpighiaceae)

“…Several studies have recorded that animal-pollinated plants, especially those pollinated by insects, may have higher visitation rates when co-occurring in communities with species that attract pollinators (Thomson 1978;Feinsinger 1987;Feldman et al 2004;Moeller 2004). This has been recorded as beneficial to non-rewarding species growing in the same plant community and close to individual species that offer a reward (Laverty 1992;Johnson et al 2003a, Juillet et al 2007). Few studies have demonstrated the intra-inter-or multi-species interactions of facilitation for pollinator attraction and flower pollination (Feldman et al 2004;Moeller 2004;Hegland and Totland 2005).…”

“…Pollination by facilitation is an amazing phenomenon that has been gaining the attention of ecologists who want to understand how the pollination mechanisms between reward and rewardless species work (Johnson et al 2003a;Jersáková et al 2006;Juillet et al 2007). Several studies have recorded that animal-pollinated plants, especially those pollinated by insects, may have higher visitation rates when co-occurring in communities with species that attract pollinators (Thomson 1978;Feinsinger 1987;Feldman et al 2004;Moeller 2004).…”

“…These plant species have developed alternative strategies to ensure constant visits by pollinators and enhance their reproductive success. One of these is to take advantage of neighboring plant species that offer rewards (Laverty 1992;Johnson et al 2003a;Renner 2006;Juillet et al 2007), and another is deceptive pollination (Ackerman 1986;Johnson and Nilsson 1999;Jersáková et al 2006;Renner 2006).…”

“…One third of the orchid species have rewardless flowers (van der Pijl and Dodson 1966;Ackerman 1986), so they obtain pollinator services by mimicking a rewarding model plant (flowers appear similar) (Johnson 1994(Johnson , 2000, or by taking advantage of their proximity to a rewarding plant (flower similarity not necessary) (Johnson et al 2003a;Juillet et al 2007). Rewardless orchid species are a unique study model because pollinium (structure containing pollen grains) is not eaten by the pollinator, and it is deposited in different body places of the pollinators than pollen of the facilitating plant species (Neiland and Wilcock 1998;Johnson and Nilsson 1999).…”

Relationships between the floral neighborhood and individual pollen limitation in two self-incompatible herbs

“…Mostly competitive (Chittka and Schürkens 2001;Brown et al 2002;Bell et al 2005;Totland et al 2006) but also facilitative (Schemske 1981;Moeller 2004) eVects have been found among pollenand/or nectar-rewarding plant species. A special case of facilitation is the "magnet-species eVect," where nonrewarding plant species pollinated by deceit receive more visits when they grow close to attractive plant species than when they grow alone (Laverty 1992;Johnson et al 2003;Juillet et al 2007). A high density of heterospeciWc Xowers can aVect pollination negatively through improper pollen transfer, which occurs when pollinators switch between species (Galen and Gregory 1989;Caruso and Alfaro 2000;Jakobsson et al 2007).…”