Coevolution: Examples & Definition

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  • 0:04 Definition of Coevolution
  • 0:27 Two Types of Coevolution
  • 1:24 Mutualistic Coevolution
  • 3:09 Predator and Prey Coevolution
  • 4:05 Parasite and Host Coevolution
  • 4:50 Lesson Summary
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Lesson Transcript
Instructor: Angela Lynn Swafford

Lynn has a BS and MS in biology and has taught many college biology courses.

Can you imagine having a tongue three times the length of your body? There actually exists a moth with such a tongue, and it evolved due to the features of a flower that it feeds on. Learn about this and other examples of organisms that have evolved together.

Definition of Coevolution

Some species interact so intimately that they can cause evolutionary changes in each other over time. This is called coevolution. In coevolution, when one species develops an evolutionary advantage, it triggers a change in a closely associated species. This change may then cause another evolutionary change in the first species.

Two Types of Coevolution

Coevolution is common among organisms participating in a mutual interaction. In mutualism, both the organisms benefit from each other. When coevolution occurs among mutually benefiting species, it is called mutualistic coevolution.

When coevolution is found among species that have negative effects on each other, it is called competitive coevolution. There are two kinds of interactions between species that can lead to competitive coevolution:

  • Predation is when one organism kills and eats another organism. The prey is the species that gets eaten by the predator, which is of course the species that eats the prey.
  • Parasitism is when one organism benefits by damaging, but not killing, another organism. The parasite species benefits from this relationship, while the host species is negatively affected.

Now let's look at some real-life examples of coevolution.

Mutualistic Coevolution: Moths and Orchids

A species of moth called the Morgan's sphinx moth has a proboscis, or tongue, that is almost 12 inches long. This is more than three times its entire body length. Why would a moth need such a long tongue? Because of the flower it feeds on.

The flower is called a Darwin's orchid, and its nectar is stored at the bottom of a really long tube. The only animal that can reach this nectar to feed is the Morgan's sphinx moth. Darwin's orchids, like many flowers, rely on animals to pick up their pollen and transfer it to another flower. This is called pollination and allows the orchid to reproduce.

So where does coevolution come in? If one of these orchids has a slightly shorter nectar tube, the sphinx moth coming to drink nectar would be too far away from the flower to pollinate it. So only those individual orchids with long tubes could reproduce, while those with short nectar tubes died out. Over time, as the nectar tubes got longer, only those sphinx moths with long enough tongues could survive. Sphinx moths with shorter tongues would not be able to reach the nectar and feed. So as sphinx moths got longer tongues to get nectar, the orchids evolved longer tubes so that the moths would touch the flower and pollination would still occur.

Flowers with short nectar tubes die out.
short nectar tube with moth

1: This nectar tube is so short that the moth does not pick up pollen from the flower. These flowers die out.

Moths with tongues that are too short to feed die out.
moth with too short tongue to reach nectar tube

2: The tongue of this moth is too short to feed on nectar at the bottom of the tube. These moths die out.

These moths and orchids coevolve.
moth and nectar tube of appropriate size

3: Only those moths with tongues long enough to reach nectar and those orchids with tubes long enough to ensure pollination survive.

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