10
$\begingroup$

Why do many plants produce such large fruits(apples and strawberries,for example) if those contain only relatively small seeds?

$\endgroup$
  • 1
    $\begingroup$ Although I'm not an expert, after a bit searching, I've found this article : link , even if it does not mention about the seed-size relationship, it gives some information about the points that affect size of fruit $\endgroup$ – stackunderflow Mar 21 '15 at 15:44
  • 1
    $\begingroup$ Much of the size of commercial fruits is due to selective breeding by humans. Compare the size of a store-bought strawberry to a wild one, or an apple to a wild crabapple. For wild fruit, the standard explanation is that the fruit serves as a lure: some critter eats the fruit, the seeds pass through its digestive system and are deposited (along with a nice bit of fertilizer) some distance away from the parent. $\endgroup$ – jamesqf Mar 21 '15 at 18:11
12
$\begingroup$

The short answer: Fruits are large compared to seeds because humans have made them large.

In the natural environment, there is a different set of evolutionary pressures. A fruit has to be able to successfully propagate itself using its seeds, while commercially farmed fruit is usually cloned via vegetative propagation. Therefore, the commercial farmed fruits do not need large seeds to propagate, since they are cloned by the farmers. In many cases, their seeds are actually nonviable (i.e. they will not grow when planted).

For example, this is a wild banana, before being selectively bred by humans. As you can see here, the seeds are enormous compared to those in commercial Cavendish bananas. enter image description here enter image description here

Similarly, this is a wild strawberry compared to its commercial farmed variant. enter image description here enter image description here

Fruits with large seeds don't appeal to consumers, and therefore farmers who sell fruits with large seeds will get a poorer return on investment.

Therefore, farmers who plant the fruits which appeal the best to consumers by being the easiest to eat (small seeds) will reap the greatest profits.

$\endgroup$
  • 4
    $\begingroup$ Not true about taste. Farmers tend to plant what grows & ships well, and has eye appeal in the store. Taste is way down the list of desirable factors, if it's considered at all. Compare the taste of 'heirloom' varieties vs common commercial ones: for apples, a Cox's Orange Pippin vs Red Delicious or Honeycrisp. Another factor is that commercial fruit is often treated with growth-enhancers such as gibberellins (or was, back when I was a farm worker), which adds watery size at the expense of flavor. $\endgroup$ – jamesqf Mar 21 '15 at 22:20
  • $\begingroup$ @jamesqf Fair point, updated. $\endgroup$ – March Ho Mar 21 '15 at 22:29
  • $\begingroup$ @jamesqf Can confirm this, working with watermelons. Usually wilder varieties are smaller and more concentrated in flavor, but harder to eat due to seeds, etc. $\endgroup$ – akaltar Mar 21 '15 at 22:49
  • $\begingroup$ Just to note, the Cavendish banana, like all other edible bananas doesn't just have small seeds, it is seedless. In fact, all banana plants (of the same variety of banana) are genetic clones of one another produced by vegetative reproduction rather than sexual reproduction. $\endgroup$ – Jack Aidley Mar 22 '15 at 11:25
  • $\begingroup$ @JackAidley "Seedless" in most cases just means their seeds are non-viable and reduced, not that they do not exist. New Scientist article $\endgroup$ – March Ho Mar 22 '15 at 11:29
1
$\begingroup$

Because seeds are not appealing to animals and they can only be carried by animals if they are made appealing - there are exceptions of course such as this one -. Seeds are covered with juicy layers that can be nutrient to animals in order to be made appealing and to be dispersed. Animals eat those juicy layers along with seeds, seeds resist digestion and fall on the ground where animals defecate. If the layer was thin and provided only protection to seeds, animals would not eat them and the seeds would have to be dispersed by other means. Therefore we would not call them fruits. The reason why seeds are not as large as their fruits is:

  • They have to be dry to resist climate changes while staying dormant below ground. And dry is generally small.

  • Seeds' task is to be dispersed, not to be nutritious to animals. And they usually do not taste very well compared to fruits - some do taste well as we know but I do not know why -. So why make them large and irritate the animal? Make them small so they will be overlooked by the animal and be dispersed happily

$\endgroup$
0
$\begingroup$

Most fruit/seed evolution is probably a reflection of the plants propagation strategy and any existing symbiotic forager relationship.

The strawberry expands its range by creeping with feeder shoots. It is also heavily foraged by small birds , thus the exterior small seeds.

Nut trees i.e. walnuts , are on the other end of the spectrum. The seed is nearly the size of the "fruit". All they want is some little squirrel to shake them loose and fall to the ground, then try to outgrow everything else.

cherries....

Just making all this up.

$\endgroup$
  • 1
    $\begingroup$ If you are "just making all this up", do you mean it is nonsense? If yes, please remove the answer. It sounds OK though. If you support your answer, could you edit it to be a bit more professional? i.e. the "cherries..." doesn't make sense. $\endgroup$ – AliceD Mar 22 '15 at 10:27
  • $\begingroup$ @AliceD: To a certain extent any answer that involves the 'why' of evolution has to be made up, because we're taking a situation that exists as a result of a multitude of factors acting over millions of years, and using reason to try to figure out the 'why'. Since we weren't there watching every step, there has to be a lot of guesswork involved. $\endgroup$ – jamesqf Mar 22 '15 at 17:25
  • $\begingroup$ @jamesqf, obviously, but while educated guesses are appreciable, nonsense, unfounded and fabricated answers should be discouraged $\endgroup$ – AliceD Mar 22 '15 at 21:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.