Intraspecific directed deterrence by the mustard oil bomb in a desert plant.
Plant secondary metabolites (SMs) acting as defensive chemicals in reproductive organs such as fruit tissues play roles in both mutualistic and antagonistic interactions between plants and seed dispersers/predators. The directed-deterrence hypothesis states that SMs in ripe fruits deter seed predators but have little or no effect on seed dispersers. Indeed, studies have demonstrated that birds are able to cope with fruit SMs whereas rodents are deterred by them. However, this mechanism was only demonstrated at the class level, i.e., between birds and mammals, based on differences in the vanilloid receptors. Here we present experimental and behavioral data demonstrating the use of the broad-range, class-independent "mustard oil bomb" mechanism in Ochradenus baccatus fruits to force a behavioral change at an ecological timescale, converting rodents from seed predators to seed dispersers. This is achieved by a unique compartmentalization of the mustard oil bomb, causing activation of the system only upon seed and pulp coconsumption, encouraging seed dispersal via seed spitting by rodents. Our findings demonstrate the power of SMs to shift the animal-plant relationship from predation to mutualism and provide support for the directed-deterrence hypothesis at the intraspecific level, in addition to the interspecific level.
Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel. michal.samuni@gmail.com
Michal
M
Samuni-Blank
Ido
I
Izhaki
M Denise
MD
Dearing
Yoram
Y
Gerchman
Beny
B
Trabelcy
Alon
A
Lotan
William H
WH
Karasov
Zeev
Z
Arad
D000818:Animals; D003889:Desert Climate; D005638:Fruit / Q000737:chemistry*; D019684:Magnoliopsida / Q000737:chemistry* / Q000502:physiology*; D009149:Mustard Plant; D010938:Plant Oils; D012377:Rodentia / Q000502:physiology; D058614:Seed Dispersal; D012639:Seeds
D010938:Plant Oils; C027793:mustard oil