The Study of Evolution
What is Evolution?
Have you ever heard of the “gene pool”? It’s not actually a pool filled with denim trousers but something much more interesting!
Gene pools are simply the collection of all the genes that make a species. Genes themselves are simply the codes, or blueprints, that make the building blocks of a living organism. There’s a separate gene pool for every species of organism, from Canada geese to portobello mushrooms to iguanas.
Gene pools don’t always stay the same; they are constantly shifting and changing as brand new genes come into the gene pool and others move out and are lost forever.
In fact, this is the definition of evolution: changes in the gene pool that happen over time. By studying evolution, scientists can get a handle on how organisms changed in the past, what’s happening to them now, and how they might differ in the future.
The Untamed Science evolution portal is a gateway for learning about various topics on evolution. Check out the articles on the right, or see some of them below:
- History of Life: Origins
- How To Become A Fossil
- Molecular Clock
- Sexual Selection
- The Cambrian Explosion
How does evolution work?
Evolution is simply the change in the gene pool of a population over time. Individual organisms don’t evolve; once you have your genes, they can’t really be changed except for a very few rare circumstances. But there are five different ways that genes can change a population over time:
Mutation is very important in evolution because it’s the only way that completely new genes ever happen. In fact, every single gene in the world started as a mutation! The other four mechanisms are just different ways that genes can be reshuffled, but with mutation, it’s something new that’s never been seen before.
Most mutations don’t have any effect on the organism, or they may even have a negative effect. But, every once in a while, a mutation happens that actually improves the organism in some way. Maybe it’s just a bit faster, has sharper teeth, or a better brain. When this happens, the organism is more likely to survive, reproduce, and pass on the new gene to its offspring. When those genes spread in the population, it’s said to have evolved.
When organisms move in and out of an area, they also take their genes with them!
In conservation, one of the main concerns is how the wild landscape is becoming increasingly fragmented. More roads, farms, and shopping malls are built, and shy animals don’t move around like they did historically.
Now, a very real possibility is that some populations will become too isolated and may eventually evolve to become inbred. If this happens, they’re more likely to succumb to disease or be unable to adapt to a changing environment because they won’t have access to new genes that may help them survive better.
It might seem like “natural selection” is a difficult-to-understand concept dating back to Darwin and his Galapagos finches, but it’s actually pretty simple.
Organisms are exposed to different conditions that affect how likely they are to survive and have babies. That’s it! These different conditions, called selective pressures, can be external (in the environment) or internal (within their own bodies).
Examples of selective pressures might be the pH of ocean water (crab shells will dissolve when it’s too acidic), a new disease (Tasmanian devils are evolving to become more resistant to an infectious facial tumor), or how attractive an organism is to others (“beautiful” or “handsome” animals are more likely to find mates and reproduce than their “ugly” counterparts).
Artificial selection is similar to natural selection, except the limitation to which organisms are allowed to reproduce is decided by humans. We do this because we want to develop a certain trait in an organism, like high-productivity wheat or friendlier kitties.
Check out this cool example of artificial selection in some things you may eat all the time:
Dogs are a great example of artificial selection. There are 340 different breeds of dog in the world, all created by people for a certain purpose. In some cases, such as English Bulldogs or Chihuahuas, these dogs’ genes are manipulated to make them physically attractive but can actually cause unhealthy side effects. It’s not very likely that these dogs would have evolved as such in the wild.
Most genes don’t have selective pressures on them forcing them to evolve one way or another. They just casually float along in a population, and each time a new organism is born, its genes from its parents get reshuffled randomly.
This has some interesting effects. If a population is very small, it’s more likely to show a phenomenon called genetic drift—random changes in the gene pool. Larger populations serve as big reservoirs of rare genes so it’s hard to lose them completely. On the flip side, it’s easier for rare genes to be lost from small populations because there aren’t very many to begin with.
For example, let’s think of a small population of just 20 birds. If only one of these birds has a rare gene and that bird dies, that gene is lost from the population. But, if there are 10,000 birds and 50 of those birds have the rare gene, that gene is much more likely to stay in the population by passing it on to offspring. It’s unlikely that all 50 of the special birds would be struck by lightning at the same time!