Question about fruit evolution?

My friend and I were recently discussing plant evolution when we came upon the topic of fruit. Evolutionarily speaking, what purpose does fruit serve to a plant? What evidence is there for fruit evolution, and what did animals eat while fruit and veggies were still evolving?

Question about fruit evolution?
Fruits always contain seeds. Animals pick the fruit and travel with it to a place where it's safe to rest and eat it, or take it home to feed its young. Then it eats the fruit, discarding the seeds. This helps the tree to spread it's seeds, colonizing places far away from the mother tree, and avoiding competition for nutrients between mother and daughter.





Alternatively, the fruit is eaten with seeds but the seeds come out with the feces. Again, since it takes some time before the animal (usually a bird) gets it through its digestion system, the animal is likely to have moved to another place.





Veggies are different. It is not in the interest of the plant to be eaten and many plants developed toxins or thorns to avoid being eaten. But herbivores, in turn, developed enzymes that can neutralize the toxins.





Cultivated veggies are not a result of natural selection, but of artificial selection: farmers selected the seeds from the better-tasting, more nutrient veggies. Therefore, the evolutionary history of veggies is shorter than that of fruits, and veggies are therefore less adapted to being eaten than are fruits: most veggies contain far less calories than fruit do and many contain bitter-tasting compounds, which cause children (and pregnant women!) to dislike them. Those bitter-tasting compounds are typically toxins that evolved to protect the plant's wild ancestor against herbivores.
Reply:There is a wonderful book about this, "The Ghosts of Evolution", by Connie Barlow. (pub. in 2000, by Basic Books) She writes about plants that co-evolved with animals long ago. The animals died out, the plants didn't. Osage oranges, for instance, are still waiting for the mastodons to come back.





A fruit is a plant's gift to an animal; "Here", momma tree says to a mastodon, "eat this, walk a ways and give my child a good home."





The seed ends up hundreds of yards or tens of miles from momma tree, so they don't compete for sunlight and water. It starts life in a fat pile of fertilized soil, moderately hidden from squirrels. The mastodon (horse, cow, elephant, raven . . .) gets a snack. Everyone is happy.





If a tree evolves fruit for a big herbivore, and those big herbivores die, the tree is left to scatter its seeds as best it can, because a blue jay isn't going to swallow an osage orange whole. The fruits roll downhill or are sometimes washed into a river and end up downstream. (If there is a flood, they may end up a couple of miles from the normal river channel.)
Reply:it's purpose is to help it disperse it's seeds therefore ensuring the survival of it's kind.





If the fruit is eaten by an animal, the seed is not digested. In fact, it will be passed out and grow onto of a nutritious culture.
Reply:fruit is delicious so that animals will eat it and spread the seeds.before fruit evolvled,animals ate mostly confers and ferns