Transcript of THE EXTENDED PHENOTYPE EXPLAINED!!

natural selection has led some pretty funky adaptations from the carnivorous nature of sun-joo leaves to the slippery slime released by eels all of these adaptations exists so some small microscopic molecules of DNA have a better chance of passing from one generation to the next the sun-joo the eel or you and I are just a vehicle to increase their chances of them doing that we are if you like slaves to our own genes this is basically the idea behind the selfish gene and I personally think it's a rather captivating and humbling way of looking at the natural world however sometimes these genes take it even further sometimes using a body to enhance your survival simply won't cut the mustard sometimes genes have got to come up with other ways of ensuring their indestructibility I'm talking about the extended phenotype an extended phenotype is a functional entity that's made by an organism but isn't part of the organism itself beaver dams and bird's nests are both great examples of extended phenotypes but in my humble opinion if I was to do a video on them that'll be a little bit cringy wouldn't it that a little bit of it cliche I would say yeah well not to worry because I've come up with something else so the organism which I believe is the absolute pinnacle of all things extended phenotype can be found here in this dull unassuming looking pond I can see you don't look particularly convinced there oh come on you have little face puts of yours with you to see the creature in its true majesty we're gonna have to come back when it's dark this creature shouldn't be too difficult I'm just gonna be a patient waiting in hopefully things will start to come to life now it may look like I'm just showing you some random pieces of wood debris right but inside one of these random pieces of wood debris there's a living creature I'm gonna try and get one out and show on to you it looks like a sticker if you look closely it's actually an amalgamation of different pieces of vegetation there's a bit of leaf there's a bit of wood there and this is the larval casing of an invertebrate called a caddis fly now if you wait long enough in fact if I can just show Dad the cameraman there if we wait long enough you should be able to see something emerging from the end of that casing right now that is a caddisfly larvae isn't that amazing caddisflies a part of an order of insects called the Shrike Optra and the adults I've got to be honest a rather dull and unassuming but the larvae are far from BAP has around fourteen thousand species of them worldwide and almost all if not all of them build these incredibly elaborate cases for protection if you look closely it's all the other caddisfly larvae that I've caught they all have slightly different casings some a focus more on woods to build their build their casing some more leaves there's one here which has built its casing out of snail shell it really is absolutely incredible now here's the thing you see this is why I think the caddisfly is such a great example to explain the extended phenotype these creatures never learned how to make these cases no one ever taught them how to stick those little pieces of debris together those behaviors were already pre-programmed into the animal itself the instructions were already included if you like you could say that these creatures are robots under the influence of their own G and that's interesting because that shows you that natural selection can act on behaviors now obviously if we think about human behaviour is a little bit different because our brains are so big it means that we can learn things right but if you think of the extended phenotype in the context of an animal with the brain far smaller than a pinhead then the concept of the extended phenotype suddenly gets a little bit more real I think it just shows how strong the threat of predation must be in order for evolution to be steered in such remarkable directions I'm talking about the extended phenotype right enough right so many dogs you just have oh god you actually first met get out of it