Mammal pollinators lured by the scent of a parasitic plant

Abstract

To communicate with animals, plants use signals that are distinct from their surroundings. Animals generally learn to use these signals through associative conditioning; however, signals are most effective when they elicit innate behavioural responses. Many plant species have flowers specialized for pollination by ground-dwelling mammals, but the signals used to attract these pollinators have not been elucidated. Here, we demonstrate the chemical basis for attraction of mammal pollinators to flowers of the dioecious parasitic plant Cytinus visseri (Cytinaceae). Two aliphatic ketones dominate the scent of this species; 3-hexanone, which elicits strong innate attraction in rodents, and 1-hexen-3-one, which repels them in isolation, but not in combination with 3-hexanone. The aliphatic ketone-dominated scent of C. visseri contrasts with those of insect-pollinated plants, which are typically dominated by terpenoids, aromatic or non-ketone aliphatic compounds. 3-hexanone is also known from some bat-pollinated species, suggesting independent evolution of plant signals in derived, highly specialized mammal-pollination systems.

Nectar feeding by the Cape rock elephant-shrew Elephantulus edwardii (Macroscelidea) — A primarily insectivorous mammal pollinates the parasite Hyobanche atropurpurea (Orobanchaceae)

“…The only other known flower-visiting elephant-shrew, the Short-snouted elephant-shrew, E. brachyrhynchus A. Smith, is also omnivorous (Leirs et al, 1995). The species was most recently found to be a pollinator of another parasitic plant, Cytinus visseri Burgoyne (Johnson et al, 2011), a member of the Cytinaceae (Rosids), not closely related to Hyobanche (Orobanchaceae, Asterids; APG III, 2009). It is not unlikely that additional species of elephant-shrews act as pollinators.…”

“…Besides mice also Cape rock elephant-shrews (Elephantulus edwardii A. Smith), endemic small mammals of South Africa, were caught near the inflorescences. Elephant-shrews have only recently been detected to drink nectar and pollinate flowers (Johnson et al, 2011;Wester, 2010). They are neither closely related to shrews nor to rodents (mice), but belong to the order Macroscelidea (family Macroscelididae) with currently 17 species in four genera distributed in Africa (Rathbun, 2009;Skinner and Chimimba, 2005 of the clade Afrotheria (including also aardvarks, tenrecs, golden moles, hyracoids, sirenians and elephants) (Skinner and Chimimba, 2005).…”

“…As almost nothing is known about the behaviour of elephantshrews at flowers (Fleming and Nicolson, 2002;Johnson et al, 2011;Wester, 2010;Wiens and Rourke, 1978;Wiens et al, 1983), observations were carried out in order to investigate whether these animals are possible pollinators of H. atropurpurea. …”

The physiology of the honey possum, Tarsipes rostratus, a small marsupial with a suite of highly specialised characters: a review

“…Its visual discrimination is poor and suggestions that it locates its food solely by colour, conXict with the fact that it feeds primarily at night. Nectar is highly aromatic, often containing aliphatic ketones that attract small mammals (Johnson et al 2011), and would appear to be an obvious signal that could reli- ably be used by honey possums in locating sources of food in the dark.…”

Diversity and biomass of terrestrial small mammals at a Malaysian primary rainforest reserve (Segari Melintang Forest Reserve, Peninsular Malaysia)

“…They consist of various taxonomic groups and represent a vital component of this ecosystem. For example, they act as pollinators [2][3][4], fruit predators and seed dispersers [5][6][7][8][9] or valuable energy source when becoming a prey for larger carnivores [10].…”