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10 Examples of Animal Evolution in Nature

Animals have changed and evolved over millions of years, having descended from earlier ancestors to adapt to changing environmental pressures. The animal kingdom is extremely diverse and animals have had unique and interesting ways to adapt to modern conditions. Here we explore the topic of animal evolution, and look at examples of how animals have adapted to different stimuli in their environments over time.

10 Examples of animal evolution

1.  Some birds develop beak size and shape based on their diet

American goldfinch
American goldfinch

In some of his early work, Charles Darwin studied finches on the Galapagos Islands, documenting his theory of natural selection. Due to a number of factors, such as food availability, competition with other birds and other resource limitations, there are now over 15 species of finch found on the Galapagos.

The species differ most dramatically by the size and shape of their beaks, which have allowed different species to consume different food sources, such as insects, nectar and seeds.

2. Pollution drove the color change in a population of moths

Peppered moth on brown surface
Peppered moth on brown surface | image by gailhampshire via Flickr | CC BY 2.0

The peppered moth, historically, was a light-colored moth which adapted rapidly to the pollution brought on by the Industrial Revolution. The moths mutated to become much darker in color, allowing individuals to camouflage with the sooty environment, and avoid being eaten by predators. Whereas the individuals that were still lighter in color were more easily preyed upon.

3. Birds that once soared across the sky lose their wings

Humboldt penguins
Humboldt penguins | image by Colby Stopa via Flickr | CC BY 2.0

Were flightless birds always flightless? In a nutshell, no. Many modern flightless birds that we know so well today, such as penguins or ostriches and emus, have ancestors which were able to fly. Their flightless adaptation evolved due to different environmental pressures.

Ostriches and emus grew much larger over time, and the structure of their feet allowed them to run quickly across arid landscapes, finding food resources and escaping predators, removing the need to fly altogether. A similar evolutionary pattern can be seen for penguins, which eventually developed flippers and began efficiently swimming to better capture fish prey; eventually removing the need for wings.

4. Cave-dwelling fish lose eyes and color pigments due to dark environment

Mexican cave fish
Mexican cave fish | image by Richard Borowsky (New York University) via Wikimedia Commons | CC BY 3.0

The Mexican cave fish are found in underground caves, void of any light sources. It takes a lot of energy for an animal to use their eyes and convert the visual data in their brains.

The Mexican cave fish adapted to their surroundings by losing their eye structures completely. They have also lost all pigmentation in their scales, since they no longer need to hide from predators.

5. Potato-eating insects become resistant to man-made insecticides

Colorado potato beetle
Colorado potato beetle

The Colorado potato beetle has decimated potato yields on Long Island. An insecticide was made which proved particularly effective at controlling the beetle populations, and saving the potato agriculture. However, a mutation occurred which gave the Colorado potato beetle resistance to the insecticide, which allowed the populations to consume potatoes even in the presence of the insecticide.

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6. Giraffe necks evolved to reach higher leaves, but also to compete for a mate

South african giraffe
South african giraffe

Giraffes developed elongated necks over time to fulfil two important biological needs: feeding and breeding. Over time, giraffes’ necks became longer and longer, which now allows modern day giraffes to reach the highest food sources, unrivaled.

Males now use their long neck as a way to demonstrate their strength and fitness to females. Males will compete with one another via “necking” (a competition of neck strength), demonstrating to females they have long and strong necks that they can pass on to their offspring.

7. Anteaters developed noodle-like tongues to consume ants

Giant Anteaters forage in the grass field
Giant Anteaters forage in the grass field | image by Eric Kilby via Flickr | CC BY-SA 2.0

Anteaters have very bizarre tongues, acting like a long, sticky noodle used to quickly consume ants out of their nests. Their tongue developed over a long time, and is unique when compared to other closely related species, such as armadillos and sloths that have relatively “normal” tongues.

The anteater is now overall well adapted for their ant-specialist diet, using their strong arms and long claws to make short work of ant nests, and using their unique tongues to decimate entire ant colonies.

8. Snakes develop a special spider-shaped tail

Eastern milk snake
Eastern milk snake | image by Peter Paplanus via Flickr | CC BY 2.0

At first, this seems like the strangest of adaptations, since snakes have no legs and spiders have eight. However, one snake species, the spider-tailed horned viper, developed a unique growth at the end of the tail which remarkably resembles a spider.

The snakes move the end of their tails around to mimic the skittery movement of spiders, which fool migratory birds into swooping down for an easy meal. When close enough, the snake quickly grabs the bird to eat.

9. Platypus lose their teeth as adults

Platypus in shallow water
Platypus in shallow water | image by Klaus via Wikimedia Commons | CC BY 2.0

The modern-day platypus is born with a few tiny teeth, that the shed promptly upon leaving the burrow. However, this was not always the case, the ancestors of the platypus retained their teeth as they became adults.

Although the diet of modern platypus consists partly of hard crayfish, which teeth would be extremely useful for, the bill of the platypus has developed electroreceptive organs to help locate crayfish in the murky waters where it hunts. The hard pad within their bill is now used to crush and eat their crayfish prey as they lose their teeth.

10. Squids lose their shells and become more agile to escape predators

Squids on sea bed
Squids on sea bed | Image by sailormn34 from Pixabay

The ancestors of modern squids were once large, slow and heavily armored with thick shells. As predators evolved to become better at capturing and crushing the heavily armored species, the smaller, faster squids were able to escape and reproduce. Eventually, the squids began losing their shells to prioritize speed and agility, creating the soft, torpedo-shaped animals we see today.

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