payin so today we are going to work on natural selection um so if you're an AP Bio and you're trying to you know get ready for the exam that is in what 20 days from now um you're in the right place because we're going to go over unit 7 which is one of the larger units that is on the AP Bio exam um and so like when you think about like the the levels like the different um units we have um unit 3 and unit 7 are the ones that have the most um so we definitely need to make sure that we have unit 7 down um so you may be wondering why did I start with ap biop Penguins um because of the fact that you sitting in this session as an AP student you are now ready you're going to be prepared for the exam um so I like to say that AP Bio payu was a just success because no matter what happens on that exam um you're prepared you're ready and you're going to rock this exam um so in case you don't know um I do have Daily Review that I do on my Instagram um at this point in the game we're I think I just did 8.2 on Friday um so I'll be on 8. three on Monday um but I do have all those Past reviews all saved on my website so you can easily access those um I also have a 374 page review guide again at this point you don't want to deal with the whole 374 Pages um what you probably want to look more for is uh spot checking so any topic that you uh have trouble with you would go to those specific units as well as at the end of each um unit I've got multiple choice and Fae response practice and that's really where you want to focus right now is doing those practice multip choice questions and doing those practi practice for your response questions um I have a recorded frq Friday on every single frq going from 2013 to 2023 on my website so after you do any of those F frqs and you want to kind of get a little bit of feedback see how another student may have written it I've gone through every one of those f frqs with you um I also have 120 review games on my website so if you go to the page um there'll be just a little code you then go to uh quizzes.com and you type that code in and you'll be able to access that game to review as well as I've got review PowerPoints plus of course all these live streams so today's plan we're going to work on natural selection we'll talk about Hardy Weinberg um and we'll go through philogyny and then like evidence of evolution um then we'll do some practice questions and then I'll give you a chance that you can do some Q&A um now you are able to type in the chat so if you have a question as we're working through this you're welcome to um type it in there I do notice that there is a slight lag um between when I say it and when you type it um and like when I see it so um if I don't get a chance answer your question I should try to I'll probably get it before the end of the slide but I have noticed that some of youall like to answer each other which is very helpful so if you see a question that you know the answer to and I'm in the middle of talking you're welcome to answer each other's questions too um so let's get started so first thing what is natural selection so natural selection was created or developed by Charles Darwin he was on you know the SS beagle he went over South America um and he started noticing um all these different similarities between the organisms that were in South America as well in the Globus Islands as well as over in like kind of where he was from over in Europe um and so he came up with this idea of that we have descent with modifications so each of our descendants are going to see slight modifications um due to um different traits that may have been more favorable okay so the organisms with the more fiable trait they're going to be more likely to survive and because of the fact that they're more likely to survive they're going to be more likely to then have more offspring and those Offspring will also be more likely to survive and so we see that our gene pool will see that those Al in that population are going to increase for the favorable alals and they'll decrease for the unfavorable alals okay so we have a couple different examples that we've seen of this like the peppered moths um so if we were to assume that these little beetles are moths which of course I know they're not but let's assume that they were um what we're looking at is that the individuals that are able to kind of like in this environment they can blend in so that was what kind of happened with the peppered moths is that the um poll the sorry the pollution from like when we went through the Industrial Revolution the pollution then caused like the Moss that cover the trees to die um and so the trees were a darker color and so the um beetles in this case or the uh moths in my example um were more likely to kind of blend in with their environment and so if they can blend in their environment they can camouflage they're less likely to be consumed and so they're more likely of course to survive and pass on those traits and so we can kind of see that over time those individuals that were not consumed of course can reproduce and we see a change in the alil frequency so if we were to say that the dark alil is our capital A and the light alil is our lower case a you see the frequency has increased because this is a more favorable trait we also see this antibiotic resistance so um the bacteria that have the resistance to a bacteria I'm sorry antibiotic um you take the antibiotic you kill the ones that are not resistant now we see there is a higher chance of the probability of or a higher chance of the population of uh bacteria now of course having this resistance so we see an increase of that antibiotic resistance um so often times you'll see that they kind of will alternate between different antibiotics as well as they may um kind of hold off and let your own immune system kind of fight the infection on its own um but when we do think about natural selection we do want to be careful of lamaran statements so lamaran tried real hard um but he was wrong so he had this theory of use and disuse so and I gave this example to my students earlier this week because they were having trouble with one of the questions um that they saw in the practice exam and so the student was like I don't understand like if this thing happened in my lifetime then of course I can pass it on to my kids I'm like if I cut off your ear is your kid going to be born without an ear and they're like well no I said well that's the same thought process of what was happening with Lark okay his thought was that if something happened to you during lifespan that it would then get passed on to your Offspring the only way that you can pass something to your Offspring is in your gamet there has to be a genetic component so some type of M ation some type of change in your DNA and then that has to be in the DNA of your gametes that goes onto that Generation Um you having purple hair it's not going to cause your child to have purple hair um so you do have to kind of watch out for those different lamaran statements as answer choices in these Evolution questions as well as you need to make sure that you don't say these laran statements when you are like kind of answering a free response question about it um artificial selection is that um organisms that have a specific trait that we want um they're going to be uh we're going to kind of breathe them and try to have more of them and I could never figure out how to undo my face so I'm sorry I think I am going to cover up this font I'm I do have the whole PowerPoint um posted on my website so I'm sorry that my uh camera covers it up um but so we have different traits that um we of course bred because like they were something that we liked about them okay um so for example dog breeds there were certain dogs that had certain traits and we thought those were great traits to have so we bred those dogs to have that trait we kept having more of the we made sure that bred the dogs so that they would get certain traits like there were some that were for um hunting and then there were other ones that were supposed to kind of draw out other uh individuals I think like the weasel dog or the the Wier dog um job was to kind of burrow and get the different kind of rodents that were underground to come out um we also see this with wild mustard so the wild mustard they took different parts of it so like the appical stem um the leaves of it and that's where we got cauliflower and broccoli and cabbage and kale and calab um and so like humans are actually impacting this and a lot of students think that antibiotic resistance is technically our FAL selection but it's not um because although we are taking in um antibiotics it's part of the environment it's part of this antibiotic I'm sorry the uh bacteria's environment so it is technically natural selection um so here we can kind of see originally we had the wolf and of course through through uh natural not sorry artificial selection we've selected for certain traits so there we go um so we also see that we have three different types of kind of selection that can take place so we have disruptive selection disruptive selection has to do with if this was like where the population was we had mostly the intermediates um what's going to happen is it's going to disturb the middle it's going to make it so that the two on the outside kind of become the the prevalent one they make them more extreme um and so like let's say for example we have a small beak a medium beak and a large beak bird and then a drought happens and so the seeds that the medium beaked bird used to consume is no longer around and so all we have are the berries that the that the small beaked bird can eat and then these really hard shells that the large beak birds can eat and so because of the lack of that food the medium beaked bird is no longer going to be able to find food okay it's not going to be able to compete with the small beak bird to get the fruit and it's not going to be able to compete with the large beak bird because it can't break open those shells and get the food and so we're going to see a decrease in the medium beaked bird and an increase in the small and the large beak birds okay that's the shups of selection so we select for the two extremes um and it's against that intermediate stabilizing selection is where we're going to select for the intermediate we're selecting for whatever is in the middle of this okay so the intermediate phenotype um so example we could use for this is birth weights um I don't know about y'all um but I was about 6 PB and 15 ounces when I was born and then my kids were somewhere in the 7 PB range and you were probably somewhere in that 6 to 8 PB range um the reasoning why is because back in the day now we're thinking Evolution back in the day if the baby was too small it's probably not going to survive if the baby was too large it also was going to have trouble um coming into this Earth and probably wouldn't survive U because again this is before modern medicine and so we saw that kind of stabilized to that kind of six to8 pound range in the middle and then of course directional selection with directional selection it's moving towards a phenotype there is something about this phenotype over here um that is more um favorable right um and so if we were to think about I don't know horses back in the day horses were kind of small um then we started using them for farming um and so we saw that there was an increase in the kind of the size of the horses and the robustness of the horses now again be careful of a marking statement there it's not because we used them a lot that they became larger is because the ones who were able to carry the farming and were able to be robust they didn't die when we used them um and so we were seeing kind of that changing directional selection of those uh horses okay so hardy Weinberg Hardy Weinberg is a theory okay and it's based on these five different characteristics and um if these five conditions are true then the population is not going to evolve okay so Paul Anderson from Bosman bio he did a Ted Ed video It's called The Five Fingers of evolution and it's a really great video it's maybe like five minutes long um so if you are struggling on Hardy Weinberg um look up his video again it's the Five Fingers of evolution it will look like that this is like the kind of the cover looks like um and it helps you to really get down these five because he's using the fingers of your hand to come up with these different things okay so number one we need to have an extremely large population size having an extremely large population size will account for any type of genetic drift any random thing that happens in your environment like a a natural disaster or whatever um isn't going to drastically decrease your population to the point that we lose our low frequencies because um direct drift is just random things that changes the low frequency okay okay we need there to be random mating there cannot be selection for or against a certain trait it needs to be random that way we're able to continue to pull from that same gene pool we want there to be no mutations if we have a mutation that's immediately going to change the alal frequency of mys okay um and so we're going to of course see a change and then we want there to be no gene flow no individuals can come in or out of my population so no immigration and no immigration and no natural selection no traits can be more favorable or less favorable than another trait and so if these five conditions are true that it's thought that evolution is not going to occur but if some one of these happens then evolution is occurring so how do we know that Evolution occurred we're looking for a change in AAL frequencies okay so as I said genetic drift there are two different types we have our founders effect this has to do with and I think it's actually founder effect I like to put a like a posh the S on it I don't know why it just sounds better when it's like founders effect that of founder effect whatever anyways so the founders effect this is where we have a small population that gets isolated from a larger group okay um and so we have this big group of individuals and then this small little subset just happens to go over here okay and they make their own new population well the small population that went over there is not going to be representative of the original alal frequency and so we're immediately seeing that major change in alal frequencies in that new population okay um we also have the ball neck effects ball neck effects is when we have this large population right and and then some natural disaster something happens that drastically decreases my population size so when we had this natural thing happen that decreased my population size it wasn't selecting for or against traits it was just random which individuals survived and which ones died and so again our new population isn't going to be representative of the original populations so both of these are going to change my Al frequency um and so any type of change in the AL frequency or genotypic frequency means that Evolutions occurring so on the AP exam they may ask you you know is this population um evolving so you would have to think about is the alal frequency before and after the same if the alal frequency is at all different then that means population did um evolve um okay so in our formula we'll use for this there are five different variables okay there's P there's q p is going to be your dominant Le and Q is your recessive Al now on the actual formula sheet I think it says Al one and Al two um but traditionally when we talk about this we talk about P being our dominant little and Q being our recessive little if the question you have is an incomplete dominant or a to dominant question um then you could just arbitrarily pick p and Q um because they're not going to ask you what is p they're going to ask you what is the frequency of the red Al or whatever okay p^ s is going to be the frequency of homozygous dominant okay so that would be having two Domin LS so if I have P * P that's just p^ s that helps you to remember what p squ is 2pq is going to be the frequency of my hero zgas I remembering that hero zgas have one dominant and one recess so p and Q and of course if you were to look at a punet square of a of a monohybrid cross you know that this square and this Square are both going to be your heterozygous individuals and based on the fact that I don't think it's mirroring you know which diagonal I'm talking about um and then q^ s is be the frequency of my homozygous recessive okay so again Q * Q is Q ^2 so that's going to be um your uh your homozygous recessive so having two of them sorry I got distracted by the fact that I'm like a moment behind because I'm watching the chat just in case I get I got distracted sorry um okay so in the formula we have on the formula sheet we have p + Q = 1 and then p^2 + 2 PQ + q^2 = 1 okay so these are the two formulas we need now whenever you're solving this you always want to start with q^2 so they may tell you the frequency of the dominant phenotype well dominant phenotype is going to be the p^2 and the 2pq so you can't just plug that for that part into this you have to say will one minus that to get it into Q ^2 but once you have q^2 you can go from q^2 to Q by taking the square root and then you can say 1 minus P I'm sorry 1 minus Q which will give you your P once you have P you can find P Squared and then once you have of course p and Q you can find 2pq and so I usually use this little chart um and I tell my students that no matter what they're asking you just go ahead and make this chart and fill out this chart so that you have all of the um information they may be asking okay now there's a second formula now I have 100% just made up this formula um I don't there's probably an official one somewhere I've never found it I call this the counting alals method I don't what anyone else calls it but that's what I call it and in this case you are given the number of individuals that are homozygous dominant you're given the number individuals that are hetero Z you're given the number of individuals that are homozygous recessive you know how many of the three different genotypes and so in this case you have to count the alals to figure out your p and Q so to do this you're going to take two times however many of them are homozygous dominant because if you're homozygous dominant you have two of those dominant leals so two times that will tell you how many dominant leals are in the homozygous dominant individuals and then you're going to add the number that are heterozygous because each heterozygous individual has one dominant Al and so that will allow you to count how many dominant Al you have and you'll divide it by the number of individuals times two why did we multiply by two because each of our individuals is dipl they have two sets of their chromosomes right and so they'll have two of every Al or of whatever LS okay so we'll take that and divide by the total and that gives us it okay same thing with our Q we would do two times the number that are homozygous recessive because the fact that they have two recessive alals and then we're going to add in the heterozygous because they have one recessive alil that tells us the number that are um recessive alals over the total population time 2 which is the totals we have okay um and then p s will just be super simple how many of them are homozygous dominant over the total heterozygous how many of them are um heterozygous over the total Q squar is how many of them are homos recessive over the total so that's super easy um a couple years ago um there was a question that they had where they were doing a Kai Square on this um and so if you were to have to KI Square it you're going to have to compare what you get from the Hardy Weinberg equilibrium and how you would get it from the counting of leals and that's going to determine whether it actually is um in Hardy Weinberg okay so did the population evolve this is going to say okay if the alal frequency or the genotypic frequency changes then the population evolved which I've already mentioned let's do a quick qu practice question on the um the formula just to make sure we understand how to do it so there's a Gard 200 um I'm sorry I said Garden at your school oh say red pink and white snap dragons those are my favorite flower y'all have you ever seen a snap dragon they're amazing if you've never seen a snapd dragon they have this little mouth on them and you just like squeeze them and they're super cute anyways um there's 200 red flowers 300 pink flowers and 500 white flowers determine the AL frequency of the purple I'm sorry of the flower Al color so since I know that there are 200 that are red I'll say 200 divide by a th000 and that tells me that my P squ my um home is I gu dominant or my RR because it's actually incomplete dominance um my red Al uh squared is going to be um 0 2 and then determine the frequency of the pink um this is going to be 2 PQ so 300,000 give me3 my white would be q^2 so 500 over 1,000 being 0.5 because we had 500 that were white okay now that's not usually where you get confused where you get confused is down here so when we're trying to find the um frequency of the red alal we'll do 2 * 200 because there was 200 that were red plus 300 because the pink flowers have one red Al and then we'll divide by the 2,000 give giving us35 and then if we were to do this with uh the white Al so 2 * the white individual being 500 plus the 300 being the pink that gives me 1300 over 2,000 give me 65 so you're like okay did this match what we would have done with Hardy weberg so if you done it with Hardy Weinberg and said okay well let's start out with q^ squ q^ squ um being my0 65 I did this wrong we're going to go past that because when I quick trying to fix this for the review session I went ahead of myself sorry y'all anyways uh so phogy different evidence that we have for evolution we've got our biochemical as well as our morphological okay um so different uh evidence we can use is that um if you use uh like your DNA or your proteins that's going to be a better way to determine um whether evolu like kind of evolution is occurring you can kind of say that these two are more closely related uh because of the fact that um we're looking at um the number of alal frequency differences or we're looking at number of um Amino I'm sorry amino acid differences or our nucleotide differences um and so between DNA and protein DNA is going to be a better um Source because of the fact that you can have silent mutations mutation could be taking place in an intron um so there's a lot of places where the DNA could change that isn't actually going to change the protein structure um and so between those two DNA is more reliable okay um and then you also have morphological so you could be looking for for similarity in traits um so similarities of traits uh so you could be seeing like that they have similar bone structures um or you could be seeing that they have similar embryonic development um so for example did you know that while you were uh developing you actually had a tail um until of course apoptosis took over and you like lost your tail that's why you still have a tailbone um it's because our ancestors had tails and so there could be ancestral traits things that we got from our ancestors or from different descendants along the way okay um derived traits are the ones that come from our Descendants ancest the ones that come from the ancestor okay you need to be careful of analogous structures analogous structures has to do with um things that look similar but they have no common descent um so sugar glider and a flying squirrel a sugar glider is a um marsupial and a flying squirrel is a mammal um is a penal I'm sorry and so if you know anything about marsupial you know they're in Australia you know like the koala and you know that they go through a premature uh like birth okay so they're born they're itty bitty teeny tiny and then they develop inside of a pouch versus placentals they are full birth okay um full term and so they're not related at all but they look very similar because they both have this little thing underneath them so that kind of shows you oh that's similar so those would be analogous structures so just be careful because they have similar adaptations to a similar environment and that leads them to to having these similar structures but there's no common descent um so someone in the chat says they've never seen that second formula before um in any of their review their stuff I know um so I didn't really like think about this until I was doing an activity with my students a couple years ago um maybe like 10 years ago but um in which we had to count the alals and I discovered that there was slight differences um and so keeping in mind that Hardy Weinberg is a um like it's an equilibrium it's based on a theory um so now the county Al method is a better method to determining the number of each of the things um but if you don't have enough data to be able to count your LS maybe you only know how many of them are um recessive or maybe you only know how many of them are um the dominant phenotype and so because of that you cannot determine exactly what the other ones are um and so that's why this is just more of an approximation it's an estimation based on things we've seen um versus this is a actual number counting okay um so don't be worried you know it's it's a logical kind of equation that's why I I said I made this equation up you could probably write it any way you wanted to but it's not on the formula sheet so I did want to just bring it up to y'all um okay so hardy Weinberg can be either F frqs or multiple choice like it it there's no um determination where it's going to show up on the exam we just know it could show up it's in the standards it's able to be there um so also bi geography so um individuals that are uh in a certain area we could say they may have diverged from one another they could have gone through that speciation event um they could be related because of living in similar environments um so how can we show this so we can make a phenic tree so a couple a lot of students have been asking what's the difference between a tree and a cogram they show very similar things this is a tree you can kind of see it's like rooted here and they kind of like branches out and it looks kind of you look sideways it looks like a tree um and so this was the one from I think the 28 18 exam maybe 17 I can't remember anyways doesn't matter um in which we were looking at different Bears so like black bears European brown bears little polar bears the North American brown bears and Asian brown bears and we're kind of seeing um how long ago they diverged and all that okay and then we also have a cogram so cogram is going to kind of look like this little y-shaped thing um and again it's just showing you different characteristics and on this exam they actually wanted you to tell them kind of where you would have placed these organisms so if we look at this uh chart right here this table okay what you're looking for is where is the smallest number always start with the smallest number and so I see that the brown bear and the black bear when they were kind of connect the square that they connect with is a one which shows me that there's one amino acid difference in the list protein between the brown bear and the black bear so since you see how small this little y shape right here is I'm going to put the black bear and the brown bear there okay and then I see that the black and brown bear are seven and eight away from the polar bear but the black and brown bear are 33 and 34 away from the panda so I know the polar bear is going to be next because they are most closely to the polar bear than to the panda bear and if you know anything about panda bears you know those are actually more closely related to a raccoon than to actual Bears so what they can also say is asking you about what could where where could you have rotated the the axis so l a polar bear and our European brown bear they share this uh Branch point right here and so you could actually rotate along that Branch point and so we could have had polar bear here and the brown bear down there because of that rotation point you could also see it here between the western North American bear and the Asian brown bear okay um and so you were able to just switch those points and so when you're doing the graph down here I picked black and brown but you could have actually done brown and black because they share that Branch point that Branch point is showing you the common ancestor between those two and so if I was looking for the common ancestor between all of these brown bears I can see that it happened about I don't 33 3.4 hundreds of thousands of years ago um keep in mind that this axis is going this way um so don't say that that's 4.6 because this is a three right here so it's actually going 1 2 3 4 so watch your axis when you're reading data from your graphs on the exam um sometimes things are not in the orientation that they think they you think they are um so speciation speciation is going to be kind of the creation of new species where do we get new species at okay um so this kind of brings us back to biological species concept which we have to know for the exam like make sure you do know this one okay um so two organisms are going to be of the same species if they can interbreed so that means that they're able to try to reproduce together okay and when they reproduce they have fertile viable Offspring so their offspring are also able to reproduce and they are healthy enough to survive okay um and so again they have to be able to reproduce and then those Offspring Have To Be fertile and viable okay and so that brings us into these different reproductive barriers or isolation mechanisms okay so prezygotic use the words we know pre is before and zygotic makes you think of a zygote so these are things that are going to happen before the zygote is created so before the sperm and egg Fus together to make the zygote this is how we're going to of course inhibit or stop this okay so first thing is behavioral isolation this has to do with two organisms are going to have different mating rituals so maybe it's two birds and they have a different mating s maybe it's our bluefoot AB booby and he's got to go out with his little blue feet please tell me you've seen a little blue feet oh my gosh I love them they're so cute anyway so blue foota booby is going to go out and it's going to show its feet off and that's like a mating dance to kind of attract the future mate okay um think about penguins and the Rocks like so there's these rituals that they do so if they have two different rituals you're not going to mate with a different species because it's not doing your ritual okay temporal isolation two organisms they're going to made at different times because the fact that well whatever reason why um and so they could made it different times of the day maybe one's in in like kind of during the day and one of them is at night um maybe different times of the month so like earlier in the month later time in the month maybe it's different months of the year so ones in the spring and ones in the winter like maybe there's different times um and so because they made at different times they don't mate with each other Geographic there's actually a barrier and because of this barrier they cannot M with each other so there's something that kind of actually inhibits them from coming in contact with each other um so habitat are ecological so maybe there's no actual barrier but they live in different habitats so like think about like a um snake that lives in the water of a lake or something and a snake that lives in a tree so because of the fact that one of them's in a tree and one of them's down in the lake they don't ever interact with each other like there's no bear the one in the tree could fall out and into the water and the one in the water could actually come out of the water and come up the tree there's nothing that stops them from going from each other but because they live in those different habitats they usually don't come in contact to make together okay mechanical isolation um best way to say this is they're incompatible anatomically like they just they just can't M with each other okay um and then gimic so usually we see this with like our external fertilization so like a a sea urchin um and so it's going to lay its eggs all on the bottom of the water um and then the sperm is going to get released and it's going to go to try to fertilize those eggs um and so there's different glycoproteins on the membrane of these eggs and so since they have different proteins um we're going to find that the sperm can't fuse and thus it won't be able to fertilize that egg um we also have postzygotic post meaning after so postzygotic means that this is going to take place after reproduction so after the zygote is formed so remember the two parts is interbreed so our prezygotic inhibits this interbreeding it stops them from mating with each other while our postzygotic is going to inhibit this fertile viable part of it okay so first thing is reduce hybrid viability the hybrid is just not viable it's not healthy and so because it's not viable because it's not healthy it's not going to survive it's going to be very weak and feeble and it's probably not going to be able to reproduce so we won't see a continuation of that okay reduce hybrid fertility the hybrid's not fertile think about a horse and a donkey when they mate they make a mule the mule is fertile like I'm sorry it's sterile like it can't mate it's a I also call them a but that's okay anyways so the mule is sterile like it's got actually a different number of chromosomes so um I can't remember off top of my head but it's like it has an odd number and because it has an odd number of chromosomes um you're not going to see that it won't be able to have the homologous pairs for the uh for meosis to take place so they actually can't make their uh gametes and then we have hybrid breakdown so the first generation of hybrid is fine they're good they're they're viable they're they're fertile they're good um but as we see multiple Generations we do see that that hybrid breaks down and so the whole point of this is to keep the species different okay um so the two species are not going to make with each other okay um yes I do know that we sometimes get spe we somehow get new ones but that's okay um so sympatric speciation is how we can create new species in the same area Okay so new species of the Sur surviving inal species um they both have the same geographic area so this is usually du to some type of absence of gene flow okay um so the big example we always use is about these um these flies Okay um so the Hawthorne flies um they were on the Apple Tree versus the berry flies were on another and so because when the new one was introduced half the Flies went to a new habitat they stopped meting with each other so usually this is our habitat isolation is also could do behavioral isolation maybe there's some reason why some of them started doing different Behavior so they stopped meting with each other um sexual selection so now there's some trait that's more favorable and so some of them will pick that trait um and then polyol in case you don't know what polyol is this has to do with that there's um more than two sets of chromosomes um so maybe there was some eror that took place during meosis and that error led to this Offspring being I don't know a tetrol so the tetr plid um individual is not going to be able to mate with the diploid individual and so they become their own new species because these two can't mate with each other anymore um alip Patric has to do with that there is a geographical barrier there's some barrier and because of that barrier we have speciation taking place so this happened back in the day uh Colorado River separated I think they were squirrels they read the check mon or squirrels anyways um but so the Colorado R separated the two and so because of that they couldn't make with each other cuz the squirrel or chipmunk or whatever it was couldn't get across the water and so there was an absence of gene flow and so now that the Colorado River dried up and we of course Grand Canyon is there um and they can come in contact with each other they're not able to mate because now they're actually two different species okay and so here is that I think it's a squirrel I don't really know it's okay so that was all the content from unit 7 like that was of course quick review of it only 30 minutes but you got there okay so let's do some multi Choice practice and some free response practice so by discharging electric Sparks into a uh laboratory chamber atmosphere that consists of Wilder Vapor hydrogen gas methane and ammonia um Stanley Miller obtained data that showed that the number of organic molecules including many amino acids could be synthesized Miller was attempting to model early um Earth conditions as served by 1950s the results of Miller's experiments best support which of the foll hypothesis okay so we're trying to say okay he set up this experiment he had electric charges that came in that was originally water vapor hydrogen gas methane and ammonia in there and he was able to somehow without life make organic materials okay so we want to read through this to see which one of these sounds like something that could have happened in there so molecules of Cal life today did not exist at the time Earth was first formed okay that is a true statement but it's not something that we got from the results of his experiment okay the molecules of essential life today could not have been carried to primordial Earth by a common or meteorite well he's proving that we're able to make these things in the old Earth so I wouldn't go with B either C molecules essential life today could have formed under early Earth conditions he proved this right we had our our uh amino acids and the things that are part of life today have been synthesized he used early Earth's environment where we had the water Vapors and electric charges and all this okay so I think C's good but let's keep rolling the molecules essential life were initially self-replicating proteins that were synthesized approximately 4 billion years ago so again although that is a true statement it's not based on the data we have here they're wanting you to look at the results from his experiment okay so making sure that you were using the information given so of course ah that is off it should be C I promise it's c um so apple maggot fly um is native to the North American initially fed on fruit of the wild Hawthorne since the mid 1800s a population of flies emerged that instead of feeding on domesticated apples Apple magga fly typically mate on or near the fruit of their host plants many varieties of apples ripen um 3 to four weeks before the hawthor plants okay so the food that they're eating are going to kind of ripen at different times so they're going to be eating and on those trees at different times the different fruit preferences of the two fly populations will most likely have which of the following effects the flies that eat hawor fruit will increase in number while the flies that eat apples will decrease in number because of insecticides did we talk about insecticides no the single fly species will evolve into two distinct species because of the lack of gene flow between the two populations so if this group is going to that plant to eat and this group is going to that plant to eat are they going to be in the same place together well no and so I do see a lack in gene flow let's say I like B so far C the ability to survive on a diet of two different fruits will help the Flies to learn to eat many more types of fruits that does not have anything to do with what I'm talking about the flies that eat hawthor fruit will lay some of their eggs on the early ripening apples to minimize competition among larae although that sounds like a true statement that really doesn't give us the effects that seeing so of course our answer is B hey and I my thing had right the reason why there's errors is because I pull them from one PowerPoint to the other and I um change the font to make it cuter and that's sorry y'all so here we have the data uh that we have for the presence of uh different traits so if it has a presence it's a positive it has an absence it's a negative of these different uh traits in the different species are shown in this table we need to figure out which of these is a representation of the data and this is how you might see these file trees or cladograms on the exam is they may have you have a character table and you've got to pick out the right one or they may give you a blank cogram that you need to fill in yourself okay so looking at this data I can see that one of them kind of stands out why stands out I see all of these negatives so why is missing all the traits and so I would call this my outg group it doesn't share any of the characteristics with the other individuals okay so that's going to show that y has to kind of come off on itself so Y is right here by itself Y is right here by itself and then Y is kind of right here by itself so that's going to help me to eliminate B because of the fact that um in this one I see that y should be closely related to X and that's not what I see based on my data okay so that one's gone and then of course I see this one gone because it's not closely related to the V and the X okay so now if I look here at x and z I can see that x and z are closely related um they both share a character one but they don't share character 5 so I would find them kind of branched together if I look here at C I don't see that um the X and the Z are sharing a branch together but over here I do see them okay um and so that shows me that a is my answer because of of course we have these two that are closely related using that X and that y um and then you also see that the V and the W are closely because they share one two and then three is where they differ and then of course they share the same thing for four and five and so I know that that is my um favorable one or the one that's the right one so amino acid sequence of cyto C was dered for five different uh species of vertebrates table below shows the number of species um differences in our sequences so using the data in the table we want to create a phenetic treat on the template provided to reflect the evolutionary relationships of the organisms and then provide reasoning for the placement on the tree okay um so if they give you a uh cogram on your FR FR Cube it's going to look like this they're going to give you a blank one that you have to fill in the information and of course they'll give you data okay um there was a phalogenic tree on last year's exam where they were um modifying it okay um so I do not predict that you will be doing one this year but they're could do the same thing two years in a row N sorry um but so what's going to happen is that in if this happens um then question five is where you'll see you having to modify that's where they always have you modifying a diagram and so make sure that you fill in the one that is in your book okay um so you're going to have a question book and you'll have a response book so make sure you're doing your graph for number two and your whatever modification you're doing on question five in the book don't do it in the questions because your readers will not see the questions um somebody just said when am I doing my unit a review um it's I think next weekend I think I'm doing like literally every weekend until the AP exam because that was the only way I could fit the schedule all right so how can we fill this in so I said before we wanted to look at the ones that were most closely related so if I look here I can see that there's a number one okay that would be between my e feris and my e africanist so I'm going to put those on the branch right here they're closest together that Branch kind of is nice and tight so we know those are there okay now is there another number that is small in this chart well I see right here there's a three G gas and a forestry which PS that's a penguin y'all isn't that so cool they put a penguin on the exam I know it's just for me it's okay anyway so we know the G gas and the a forestry or whatever however say that are closely related so we're going to put those together and then the one that is most similar from them all would be dpus if if you look at Deep it's 18 17 20 and there's another one and 21 away so you can see that one has the most differences So I placed it here because it's the outgroup because it has the most differences in its amino acid structure okay so Part B says Identify whether morphological data or amino acid sequence data are more likely to accurately represent the true evolutionary relationships among the species and provide reasoning for your answer so as we said earlier the one that is most favorable and the one that's going to give us the most accurate is of course going to be a med acids or our molecular data okay um because of the fact that morphological data could show convergent evolution could show things that are similar due to a similar selective Advantage um not because they have common descent um also we're going to see direct changes that are taking place a mutation they had the same DNA a mutation took place and now there's one or two differences from them so they share that genetic code okay but College wear was really nice on this one and so they said to identify whether one or the other so you have a 50/50 shot here right so on the exam if you don't know something and they're giving you two options just guess if they say predict what's going to happen to something increase decrease stay the same like make a prediction even if you don't know try you could accidentally get a point but College Bo I said was really nice on this one and they actually accepted either one of them you could have also said morphological data so on this one no matter if you wrote morphological data or amino acid sequence you still got one point here so that's awesome okay um and so the reason they say sometimes our molecular sequences could result in different morphologies um so even though they may have a similar DNA structure they could still look different um and then an example of the fact that you have similar protein but different morphology so thinking about like a chimp versus a human um kind of looking at that morphological data okay so here we've got these Guppies so we have these man uh these adult male guppies they exhibit genetically determined spot so the spots are due to genetics um in a study of selection of males and female guppies from a genetically diverse population they were collected um from different streams and placed together with no Predators so they're all together okay study maintained for several Generations isolated area before separating them into two groups you can see here we've separated them into the groups one group is going to be where there's a predator another group is going to be where there is no predator and I think I just liel the wrong ones that's okay um at different times we then determine the number of means the vertical bars represent the errors of the mean okay so so thinking to yourself and thinking about your teacher and how much they have honed into you they've always talked to you about these air bars and they said if the air bars overlap that means that the data is not significant right and so what we're looking for of course is air bars overlapping okay but what does the air bar actually tell us the air bar is showing us the difference in the data like so the stretch or the like the the range the data is okay so right here when we're at zero they were genetically diverse population there's a lot of differences in the the DNA so we're going to see a lot of differences in those um the mean number of spots there's a large Variety in them okay verus if I have a smaller sem bar that means the data is very kind of precisely together okay so there's less differences in my data so that means that most of the fish are going to be kind of in that 12ish area Okay so on this question we are not looking for the air bars to overlap because what they're going to ask us is describe the change in genetic variation in the population between 0 and 6 months so between 0 to 6 months I see that zero we had 10 spots at 6 months I have 12 spots so I'm seeing that my variation in my data is that oh we got more spots but that's not what they're asking you they're asking you about the actual DNA they're asking you about the stretch of that bar and so I see that my arrow bar goes from being very large to being very small and so because of that my uh genetic variation is actually decreasing okay so my genetic variation decreases because my sem bars got smaller so be very careful not to fall into traps okay um they're asking about the range of the sem bar they were not asking about the number of spots okay so be very very careful there um Part B propos one type of M behavior that could have result in observed change in the number of spots and the Guppies between 6 and 12 months in the absence of a predator why is that on the wrong spot I can't do that I'm okay there's fix um so in the absence of the predor um we see that it is increasing right and so when the Predator is not there okay um why do I see an increase well it has to do with the fact that um without a predator and we seeing sexual selection okay the ones with more spots are going to be selected for we're going to see more of those females selecting for those um and so we're going to see the of course increase of those um number of spots okay versus random May fa we'll see um just maybe randomly they made it and that caused there to be the increase okay part C evolutionary mechanism that changes over time oh good I have the right one um 6 to 20 months in the presence of a predator I said that back any was no presence okay so here we see it's decreasing um and so why would I have the spots decreasing it has to do with the fact that since the Predator was there spots are going to allow them to be seen and because they can be seen we're going to see that they're going to of course consume them and so directional selection against the individuals with large spots directional selection for individuals with fewer spots um natural selection will be used if you as long as you used in context talking about that the Predators could see them and would consume them and so they're less likely to survive and less likely to pass on that trait um and so we see of course the ones that have less spots are more likely to survive and more likely to pass on those trait we see the decrease taking place there so what questions do you have and so while you're coming up with your questions and throwing those into the chat I'm going to go ahead and tell you about a couple resources that I think would be helpful for you um so check out Marco learning um Marco learning has um tons of YouTube videos not just for Bio but for other subjects um and so go check them out they the couple weekends before the AP exam we're going to be doing some live streams on there um to help you review for the AP exam um and so check out Marco learning absolute recap okay Melanie King it from the absolute recap she's doing she has the podcast um that you can use so if you like to go for a walk and listen to your content go check her out she had um I think government physics chemistry biology and music theory so check her out um and then etot science I mean sorry s.com is a new platform that's kind of getting started um and so what's really cool about them is that they're going to kind of email you each day and so like if you were to do these topics right um so if let's say that's our answer and you're not really sure about it it's going to tell you kind of additional information to kind of back it up and then whether you mark it correct or incorrect is then going to determine if it's going to cycle around if you get it correct it's going to cycle it a couple days versus if you get it incorrect it's going to cycle it more frequently um and so this is kind of using the same kind of Technology as dual lingal and it's going to try to kind of help you to better understand so this is kind of a good resource that you can just use each day um to do some quick review um as I said they do have like some information on there um that can kind of help you to better understand like they've given you some pictures and it's based off of the Open Stacks textbook so if you're needing kind of like a textbook um they work really closely with the Open Stacks book okay um and of course don't forget I've got review on my Instagram um I post Tik Tok while Tik tok's still around although I did hear that they just passed the law where they're not going to have it anymore um and of course you're already on my YouTube so we're good okay so what questions do we have um I see when will I do my unit a review that's going to be next weekend I do it I believe it's 3 o'clock same time um can I explain how airor bars represent D variation yeah so with this what we were seeing was the variation in the data and in the DNA okay so this is where the mean population is right so if we were to take every single like piece of Da DNA right and we were thinking about okay this individual has five spots this individual has four slots and how many spots do they have and we average them together the average was 10 but there was a large stretch of the data and so I had a lot of them that were in the two range and a lot of them that were in the 10 range which I probably should use the example but a lot of them were in the eight range versus a lot of them were in the 12 range and so since there was a large spread of my data that gives me a large genetic variation right there's a lot of differences here versus over here they were all in that 12 range and so that shows me that there's less variation in that DNA and less variation in the DNA okay um do I have any tips on how you should be studying um so at this point we have 20 days till the exam um and I'm not sure when you're watching this video if you're live of course it's 20 days um if it's later on then you have however many days there's always a countdown on my on my uh website um so you need to be kind of more spot checking okay so what is it that you struggle with what topics are hard for you um and if you're needing like more of a a holistic like I don't even know just going to look at everything then watch somebody's YouTube vide so either watch one on mine you could watch um bzen bio crash course you could watch Rob Tate you could watch my kids favorite um poser what's his first name um gab poser um so there's a ton of YouTube people out there there's a this Mike Chipman there's a lot of different YouTube teachers okay um you can use any of them that you want okay um watch a unit video and kind of get a quick review um you also probably want to be looking at multiple choice and free response now can you do every single free response between now in the exam I don't have many exams you're taking but if you can I would do at least one or two f frqs a day just to kind of help you get that practice in um and get you ready for the exam um if you needing a spot check on something go find again a video on that um or go look up go watch uh the AP classroom on that see if your teacher will open up the topic questions for you or the ppcs or the performance progress checks um get them to open those up for you if they open those for you then you can of course practice those different um topics to review and those are the same people that are writing the AP exam that are writing the PPC so that's the best multiple choice practice you can use um and then if you can convince your teacher to Proctor a mock exam that's going to be phenomenal for you so so one um overview different YouTube videos two um work on Multi choice and Fe response practice three take a mock and four do some like specific studying on your weakest subjects um so somebody asked where that is I think I actually like completely closed it um it was et.com or ET learn.com um and so that's where that was I think I had logged in before so you could have seen it like full but they also have like an AI that they're working on um and so you can like ask it questions but sadly that costs money um like you could like you know buy it I think it's like $9 for a month or something um so it's not like too crazy um but they do have that if you're needing it um yeah anyways uh so what is the difference between bottleneck and genetic drift um bottleneck effect is going to be where we have a large population or a population um that gets drastically decreased by some type of natural disaster that is a type of genetic drift genetic drift has bottleneck as well as the founder effect okay um and so bottleneck was an example of it and so since I had that drastic decrease my new population is not representative of the original population and I think that that is all the questions that we have no one else has posted questions in there um so sorry for all my issues today with my uh errors on my uh PowerPoint um remember AP Penguins just success and I hope you