Plants can't choose where their seeds end up. Some float on the wind, others on the water. Many seeds hitch a ride on—or inside—animals. And the farther a seed gets from its parent, and any predators or disease the parent might have, the better its chance of survival. Or so the theory goes.
Researchers studied that phenomenon in the South American chili pepper Capsicum chacoense, which relies on birds like flycatchers to spread its seed. To get realistic samples, researchers plucked chili seeds from the droppings of captive flycatchers. Then they scattered them near and far from wild chili bushes in Bolivia. Contrary to the prevailing theory, distant seeds fared no better than seeds directly beneath chili plants.
But it turns out the trip through the birds gave seeds a different competitive edge. The passage stripped them of predator-attracting chemicals and pathogenic fungi—which quadrupled the seeds' survival rate, compared to their undigested counterparts. The results appear in the journal Ecology Letters. [Evan C. Fricke et al., When condition trumps location: seed consumption by fruit-eating birds removes pathogens and predator attractants]
So even though these chili seeds don't need to go the distance to survive, you might say that a seed in the bird is worth about four on the bush.
[The above text is a transcript of this podcast.]