Teeming Millions,
Why should fruit be poisonous? As the plant’s fruit only existence is to disseminate the seeds within, usually through ingestion and subsequent defecation, why should the plant prevent this from happening by poisoning the fruit? Are there any advantages at all in having poisonous fruit?
poisonously yours
Biggusignoramus
Not an expert by any means, but I would think like this: Not all fruit is neccessarily meant to be eaten…cactus have thorns to prevent animals from eating them…certain bugs and frogs and snakes are brightly colored to indicate “hey, I’m deadly, don’t eat me”
I think nature has a predisposition to not being devoured and propagating itself…just a thought.
D.
Daylon’s right. Some plants found an evolutionary advantage in making poisonous fruit so that animals wouldn’t eat it, and the seed could get all the nutrients directly from the fruit. Other plants found an advantage in making tasty, nonpoisonous fruit so that animals would eat it and pass the seeds through along with some fertilizer.
Poisonous to humans doesn’t necessarily mean poisonous to all animals. I’ve seen birds eating berries that are poisonous to us, etc.
I was going to bring up the whole bird vs. mammal consumption angle – the journey through a bird’s digestive tract is usually quicker and less, shall we say, corrosive (usually - there are exceptions) to the outer covering of a seed than the journey through, for instance, the intestine of a cow. So, by being poisonous/distasteful to mammals, but not so to birds, seeds are dispersed widely (because birds fly significant distances) without being destroyed by the carrier.
On the other hand, some seeds want to be eaten by cows and the like… they have protective coatings to survive the trip through the mammalian digestive tract and are deposited in a rich source of fertilizer. In fact, some seeds can’t germinate unless they are eaten first. In this case, the plant doesn’t want to go through a bird, so may be unpleasent for birds but now cows, deer, horses, people, etc.
Just different strategies, really.
digesting answers provided. thanks for the ideas. Broomstick’s “just different strategies really,” sums it up tersely. Bastard plants taking us animals for a ride. Makes me feel less guilty for cutting them down.
There’s actually a species of tree on the island of Mauritius that was slowly going extinct because the only way its seeds could germinate was by being eaten and excreted by the dodo. Apparently they’ve recently found out that turkey’s digestive tracts will abrade the seed coating enough to allow them to sprout as well, so the dodo tree is on its way to a comeback.
COMMENTS:
The seeds of many plants depend on the ingestion by various animals as a way of distributins them far and wide by means of the animal’ waste disposal system.
What is poisonus to one species is not to another. This insures some animals will participate in the distribuion effort.
To expand, if a fruiting body (fruit) is dependant on a specific animial or class of animals to disseminate its seeds, being poisonous to other, less useful animials makes more fruit available to the more useful ones.