Okay, we'll get started here. Welcome to lesson three. Have it in supporting the three of evolution. Today we're going to look at some concepts that Darwin and his main maiden voyage on the Beagle found and some of the general ideas that he founded with regards to evolution. So the video that I posted in your outline is for you to watch. I encourage you all to watch it and fill in the first little bit with regards to Darwin and the Beagle. Specifically, I'm going to talk about his observations revolving around what he saw and I'll leave it up to the rest of YouTube film, the other aspect. So the key three components that he found with regards to his voyages through South America, he found that in a place called Patagonia that there were many modern and extinct animals that resembled each other and had similar habitats in common. So the similar habitats between modern and extinct animals was a good key point for him to kind of see that there were some relations between those two species. And the second point that he saw was then the Andes Mountains. He discovered fossils of aquatic organisms, which he found quite interesting because of the nature of how high up they were despite having aquatic bone and supposed physiological structures. And then lastly, with regards to the Galapagos Islands, he realized that there was unique and unusual plant in animal life that was similar, but not quite the same as in South America. So when you look at where the Galapagos is relative to South America, it's interesting to see that there were some similarities with regards to the life that lived on both those places, or both those places. So with regards to biogeography, he came up with the idea that the, or didn't come up with the idea, but kind of coined the general foundations of the ideas and the theories. And it's this general idea that the study of geographical distribution of organisms is based on both living species and fossils. So it's not just where they exist, the species where they exist. It's also the fossils and the areas surrounding that place where they currently exist. So it's the main idea of the answer in the question, why do things live where they do? And he was one of the early biogeographists, and as well as with Lial and a couple of others, which we're going to go into too much detail. Among his many observations, specifically with regards to the Galapagos, he began to see that there was a link between habitat of an organism and the traits of that organism. So those beneficial traits, they tend to be appearing more often in specific environments. And so if a trait allows for an animal or species to be successful in that area, usually, usually, it's not going to be that they will be successful in other areas that don't have the same or similar geographical components. So the main observations of the Galapagos islands and the theories on remote islands in general are kind of underpinning ideas of evolution as a whole in terms of what Darwin found in terms of what Darwin discovered on his voyages. I'm going to go through each of the four observations and then the hypotheses that are connected to them in terms of remote islands. So the first observation that he made with regards to the Galapagos islands is that many species of plants, birds, insects, and sometimes reptiles exist there. And they're able to get to the islands from the mainland. So despite their isolation, despite how far away they are from the mainland, there are tons of those species that are on the island, and it's because they're able to travel from the island to the mainland and back. The second observation that there are no native amphibians and very, very few land mammals, this kind of ties into the first observation because like those species of plants, birds, insects, and sometimes reptiles, amphibians and land mammals are unable to get from mainland to island by swimming. It's not possible for them to do that. And the ones that are already there, chances are they were there when the islands kind of broke off from that larger land mass. The third observation, many unique species are found nowhere else on earth. This concept is a result of that original population that was there when the island land mass broke off so to speak. They were very similar to what was found on the mainland. But as a result of the change, i.e. breaking off from a larger land mass and then becoming an island, that population started to change based on that the new habitat. As that habitat changed from becoming a part of a land mass to becoming an island, it in turn changed the species as a result of that. And lastly, that unique species most closely resemble species to the nearest mainland continent. Again, this is the idea that the original population likely came from the nearby continent. And when that island kind of broke off, the species changed, but the change was so subtle that they still kind of resembled their mainland counterparts. But obviously some differences have come up due to that new environment. So you're going to look at two things with regards to homologous features and analogueous features. In terms of the development patterns, I won't go into too much detail with this, but with regards to homologous feature, it's same physical structure, different function. When you think about the human arm all the way from the shoulder joint to the philanges or the the fingers, all of the bone structures, they tend to be very similar if not the exact same as a bunch of bipedal or quadrupedal or flying and even some oceanic mammals in that their bone structure, they have the same number of philanges, same radius and almost structure, same humorous, same number of metacarpules, it's just different functions. Cat leg versus whale, fin versus bat arm versus human arm, all four of those are completely different structures or sorry functions, but with the same structure or similar structure. Likewise, with analogueous features, it's going to have similar function but very different structures as a result of different evolutionary traits. In terms of the homologous, it shows that there's common ancestry there, I forgot to mention that. But with analogueous features, when you look at insects, wings, bird wings and bat wings, all of them allow for flight, except their structures are so different, it shows that flight evolved in those species separate from each other, they didn't really have any shared common ancestry. And then last thing I want to talk about is something called vestigial features, these, the concept or idea that there are traits that stuck around as the species changed over time, but it provided less and less function for that species as it continued to go through time. So a modern species will have a trait or a structure that isn't really quite useful or functional, but it would have been useful and functional in that species long before that modern species came to fruition. So when you think about appendicitis and the appendix as a whole, the appendix for the most part is useless to the human species and you can have it removed absolutely consequence free, usually if it's infected or inflamed or what have you. Tailbone specifically coccyx, they are another vestigial feature, but ultimately it's a trait for a structure that's no longer functional in that modern species, but at one point did provide some function for precursor species. And this is just some more evidence to support our concept of evolution. Okay folks, that's it for today's lesson. If you have questions, please come to the chat or the office hours or post them in that document and I'll be more than happy to help out. Take care.