Fitness, Adaptation, and Artificial Selection

by Jason Amores Sumpter
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So where did Darwin's ideas come from? I mean, he didn't just think them up. One day he actually came up with these ideas based on his experiences and one of the most influential experiences that Darwin had was his travel on the boat. The Beagle? Yes, like the dog like Snoopy. And he traveled on this boat or I should say voyaged because it really was a much grander expedition. He voyaged on the beagle to the Galapagos Islands amongst other places, and there he noticed some variation between the finches on the different islands. And this got him thinking he said, Huh, difference between these finches. Oh, get the gears turning Boom evolution. No, it wasn't that simple, actually, Darwin came up with some various ideas that helped him piece together the puzzle we talked about in the previous page. One of these ideas was something he called fitness, which is the ability of an organism to survive and reproduce. So different features are going to affect an organism's fitness. Now, another idea came up with is an adaptation. This is a trait that is maintained and evolved by natural selection that enhances the fitness of an organism So in looking at all these different finches, he noticed that the morphology of these finches, the way they appeared, was pretty different. And he assumed that due to different pressures on the different islands, different adaptations were favored in some places and not in others. And it caused these finches to become so different from each other, even though they were all kind of in this small area of these chain of islands. Now, a nice example of evolution at work is with the peppered moth, and it relates to this idea called industrial melon is, um so basically, industrial melon is amiss simply when organisms evolved darker pigmentation due to industrial pollution. So, you know, rewind time a little bit. Thio industrial England And before the Industrial Revolution, all the peppered moths or most the peppered moths anyways looked like this like they had pepper on them. Hence the name. But after the industrial revolution, pretty much all the moths looked like this one basically solid black. What caused the change? Well, the idea here is that because the environment changed right because of the industrial revolution because of the pollution that was getting into the environment, it made everything darker. So as the environment got darker, these light peppered moths became easier to see. Or as the the few peppered moths who were all dark colored. They had they were more fit. Their fitness was better because they were harder to spot on the now darkening environment. So over generations, what happened was these light colored pepper moths they got picked off. They were the ones who got eaten because they were easier to see. So they contributed less and less to the gene pool. The dark moths. They had more fitness, so they contributed more and more to the gene pool. So over successive generations there were fewer and fewer light colored peppered moths and more and more dark colored peppered moths. Now, you don't need to worry about knowing about the peppered moths in particular or industrial melon is, Um, I just think this is a really nice example off evolution at playing that was recorded by humans during human history. So another process in evolution that we can observe quite readily is artificial selection, and this is the process by which humans breed organisms for certain traits. And this was something that Darwin was quite familiar with and influenced his thinking about evolution. So a great example. Our dogs, various breeds of dogs have been selected by humans. The various traits of those breeds were selected for when humans. We're breeding these animals. And today we have a huge range of traits that different breeds of dogs can have. And just to illustrate that wide range of traits we have here a great Dane, a very, very large dog. And you might notice his coat is a lighter color. And then right here, we've got this anybody little black Chihuahua. So ah, lot of variation in color, size, shape, artifice. Official selection can produce ah, lot of different forms, just like evolution can produce all the forms that we see today. Now, one other example before we turn the page is corn. Yeah, corn actually used to look like this garbage, but you don't want to eat that. And you spend all this hard working time trying to grow this plant. You just get this little dinky stock of edible material that's not gonna fly. So humans selectively bred corn until boom. It looks like this like we know it today. So artificial selection has been a big part of human history because, well, humans have selected for various traits and farm animals, farm crops, all sorts of agricultural things. All right, now let's turn the page, Talk about some more detail.