Only yesterday I suggested that smelling or tasting of faeces might give an advantage to some species by repelling a potential predator which had evolved faecal aversion for obvious reasons. Now today we have a paper published in Nature Plants which shows how smelling of faeces might have another advantage.
Again, this is an example of an evolved feature in one species creating an environment conducive to evolution in a particular direction in another. It's also an example of the sort of deceptive mimicry I wrote about yesterday.
The species gaining the advantage is a plant, Ceratocaryum argenteum, which gets its seeds planted in an unusual way.
The large brown, round, strongly scented seeds of Ceratocaryum argenteum (Restionaceae) emit many volatiles found to be present in herbivore dung. These seeds attract dung beetles that roll and bury them. As the seeds are hard and offer no reward to the dung beetles, this is a remarkable example of deception in plant seed dispersal.
Jeremy J. Midgley, Joseph D. M. White, Steven D. Johnson & Gary N. Bronner
Faecal mimicry by seeds ensures dispersal by dung beetles
Nature Plants 1, Article number: 15141 (2015) doi:10.1038/nplants.2015.141
(That must be one of the most succinct abstracts ever published.)
It seems that this grass-like South African plant produces seed that not only look like but smell and taste like the dung of herbivores - exactly what dung beetles are looking for. Dung beetles collect up balls of herbivore dung and bury them with an egg, as food for their grubs. So the seeds of Ceratocaryum argenteum get planted by dung beetles.
This was demonstrated by the simple device of scattering 195 seeds around the De Hoop Nature Reserve in South Africa and monitoring them with cameras. Within 24 hours, half the seeds had been transported and dispersed by dung beetles. No other possible dispersal agents such as small mammals were seen to be dispersing or eating the seeds.
So, by mimicking faeces, Ceratocaryum argenteum not only avoids having its seeds eaten, but gets them dispersed and planted.
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