Evolution Awesomeness Series #3: Convergent Evolution
What’s that you say? Those are the same snake?
Are you calling me a liar?!
Welcome to convergent evolution! When two species develop similar traits and are not related or only distantly related, it’s called convergent evolution, and it is freaking awesome.
The Emerald Tree Boa lives in the Amazonian rainforest of South America, while the Green Tree Python can be found in parts of Australia, New Guinea, and Indonesia. Boas and pythons are totally different groups of snakes but share characteristics in the way they look and live.
What’s that you say? You want another example? Okay, you don’t have to twist my arm.
The top plant is Euphorbia obesa, while the bottom plant is Astrophytum asterias. Both are succulent plants, meaning that their thick skins retain water and they can survive drought conditions. Euphorbias are prolific and found all over the world, while Astrophytums are found only in Mexico and Texas. Each belongs to a separate genus but has evolved to be short, squat, and divided into eight “segments.” Cool, huh?
So why does this happen? Essentially because there are certain adaptations that work in certain environments. Obviously, the conditions of New Guinea and the Amazon Rainforest were similar enough while the two afore-mentioned snakes were evolving that they developed into two separate species that look like twins. Same for the succulents.
According to PBS, “there are a finite number of effective solutions to some challenges, and some of them emerge independently again and again.” My Ph.D-in-Evolutionary-Biology-holding boss agrees; he says there are some traits that would be really effective, but that can’t evolve due to physical constraints. His example: that humans haven’t evolved wheels. Even though having wheels would make getting around a hell of a lot easier and potentially provide for better survival, we can’t make them. (Let’s all take just a moment to ponder what life would be like if we had wheels. Thanks.)
So basically there are some things that are pretty hard to code for genetically, and other things that are easier to code for and therefore show up more. Either way, the environment works together with evolution to shape the animal.
Another example of this awesomeness is the relationship between marsupials (animals that have pouches where the babies hang out after birth) and placentals (that’s you and me): although they occupy different parts of the planet and have different styles of reproduction, a lot of marsupials look like placentals and vice versa. Have a look:
Here’s a marsupial predator, the now-extinct Thylacine. Does it look like any placental predators you’re familiar with? Maybe canine in nature? (It’s a shame the Thylacine is extinct because they look pretty badass and I wouldn’t mind watching video footage of them on Discovery. Taking down kangaroos and shit.)
Look at this PBS page on convergent evolution for a great image comparing four anteating-animals found across the planet. (Click on the image for the full-size.)
I hope you’ve enjoyed today’s EVOLUTION AWESOMENESS SERIES on convergent evolution. I challenge you to find another example of convergent evolution and post it in the comments section! Thanks for reading!
Posted on August 7, 2010, in Biology/Ecology and tagged anteater, astrophytum, biology, convergent, convergent evolution, euphorbia, evolution, genes, genetics, gray wolf, habitat, marsupials, nature, neato, placentals, science, thylacine, traits, zoology. Bookmark the permalink. 18 Comments.