UNIT 7, NATURAL SELECTION

Spore or Sports being released into the environment some will survive at some point okay and so what he kind of inferred from this is that individuals who have trades that give them a higher chance of surviving they're just more likely to reproduce and what that means is that over time it's going to lead to the accumulation of favorable traits the traits that are a disadvantage of more likely to disappeared in that I need you to write stuff down today otherwise just for the time being just you know follow along with being listening you can always jump back to some of this stuff like that so I want you to make sure you got this topic about natural selection and the process the reason that natural selection works the way that it does is because there's competition for limited resources so if you're a flower growing in the Prairies this competition for light is competition for water there's competition for nutrients Savannah in Africa is competition for food competition for water competition for mates whatever it might do but there's always going to be a limit on the resources right there's not enough for every single living thing to survive and what we mean by variation is that there's genetic variation right so where does that variation come from Mostly from mutations to your different combinations of genes because of that but also specifically with species that do sexual sexual reproduction and of the things that created variation leaving that context of sexual reproduction think of what we learned about in context of meiosis random assortment what the name is where those chromosomes swap fluid cross section? What that means is that you're going to ultimately end up with different phenotypes so different individuals have different physical characteristics and what you find is that some individuals have a better chance of surviving than others because of their phenotype maybe they're a bit taller maybe they're a bit faster maybe they're better camouflage maybe they have a resistance to a disease so the ones that survive and pass on their jeans tend the Industrial Revolution it's very quickly basically in the Industrial Revolution in England in particular all of that pollution that was going into the atmosphere from burning of the fossil fuel he started to kill all the lights in the grill untreats an organism that grows on the trees and so usually the light eaten by Predators increase then sort of fast forward a couple of hunger about 100 years and we said the pollution decrease because of the new laws and new technology and now the life can start to grow back on the treats and so those light-colored now they have the advantage and the dark colors have a disadvantage and so you sort of actually swing back the other way so again natural selection and evolution that individuals that are better adapted to the environment they're more likely to survive and reproduce that's really the heart of what we're talking ears that would be an adaptation having longer fur darker further that's an adaptation okay so adaptations just mean some sort of characteristic or trade that gives you some sort of Advantage when it comes to your survival and by the way if populations become so different to one another that they can no longer reproduce that's when you end up with new space so we'll talk about that so I think specifically with those but there are other species of awesome too in there they're sort of so he's some adaptations to the beaches that were in the Galapagos Island this is one of the things that Darwin noticed necessarily have looked at before but when we're talking Evolution when we're talking natural selection you often come across this term Fitness and when we say Fitness we don't mean like being physically fit what we actually mean by that is the ability of an organism to survive and then produce fertile offspring I know that's kind of a little specific that you're kind of see why in this department that's not fertile that's been right because they can't reproduce so their Fitness is still zero because they're not actually able to continue that lineage they can't keep us going so Fitness is about that idea of continually passing your genes through the generations so you'll see that word come up a bit so just to kind of like playing the ship here a little bit with this topic environments change and because environments change you see species change you already know that if you kind of went back the clock 10,020,000 years and we stepped out the door if you'd probably see a lot of wooly moments around here ever been fully mamas like dug up underground in Kenosha County so if you go back to the most recent Ice Age which ended about 10,000 years ago there were lots of these large Mamas and other kind of animal s and so it makes sense that you have species that are adapted for that anymore but it's not that cold anymore do they have that same Advantage here anymore no it's a disadvantage to have all that long with the ETC so they've swung back the other way so you see a change in species in sometimes that doesn't necessarily mean that they're going to change as a species it might just mean to go extinct which is what happened with a lot of these species changing because environments last vocab I need you to understand kids I got you before there's this one little two lucky I just want to show you once the light for is this term selective pressures we use this the other day too so a selective pressure is a factor that influences survivability in other words it's the thing that's causing some species to have a better or a worse chance of surviving so when we looked at those mice in the video that I can people remember what we said the selective pressure was in that context the Predators right yeah so the birds the Hawks the owls snakes they're The Selective pressure because they're the ones that are eating the mice and so they're the ones that are visually seeing mice so the selective pressure is whether you get pizza or not selective precious can be all sorts of things climate predation disease