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Name: Rick M.
Status: other
Age: 50s
Location: N/A
Country: N/A
Date: 9/28/2004


Question:
I may not be a student K-12, but I am the parent of two who are. Now that we have had our first frost here in Alaska, the kids and I have been watching our home-grown tomatoes ripen on the kitchen window sill. As we observe, the following questions came to mind (a literature search got us nowhere):

What is the adaptive advantage for fruit to turn color as they ripen? Specifically, why do tomatoes turn from a nice native green to a bright red (or yellow)? Presumably this change must create some reproductive advantage. How does the color (or change in color) contribute to the successful germination of the seeds inside the fruit? Is it a necessary change in chemistry of the surrounding meat required to nourish the seeds? Or does the bright contrasting color attract a symbiotic host (eg. bear) to transport the seeds away from the parent plant? Generally, is there always a functional/reproductive/adaptive reason why fruit changes color as they ripen?


Replies:
Dear Mark,

The changes in color as a fruit ripens is considered to be a signal to potential eaters of the fruit that it is ripe. This is important for plants that rely on their fruit being eaten and the seeds transported by the predator to a different place. Often a developing fruit will be toxic to stop predators from eating fruit with undeveloped seeds.

Dr. Jim Tokuhisa


Think about how fruits usually are hard and bitter or sour when the AREN'T ripe. Any animal who eats a fruit that is unripe learns not to eat them again. When a fruit's seeds are ready for germination, they need to be dispersed away from the parent plant. A color change could signal animals that the fruit is ready to be eaten, which will help in dispersion.

Van Hoeck


The bright colors of mature fruits attract animals that eat the fruits, and disperse the seeds

Anthony Brach Ph.D.



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