Genetic Drift

[@calumjack]

It's incredible when someone takes a potentially complex concept and makes it understandable for anyone. Congratulations Mr Andersen, you've done it again.

[@tianna215]

Calum Williamson such a gift

[@cl-fs6pt]

There's nothing complex about the fact that we are being lied to.

[@silverstrikev8868]

@@cl-fs6pt The hell?

[@GuardianSoulkeeper]

​@@silverstrikev8868He's saying he doesn't understand.

[@rogueronin2455]

It's funny how you've taught more alone in this video than my teacher in 4 weeks

[@marito166]

Video stamps: *Intro:* 0:00 *overview:* 3:48 *Isolated population:* 5:29 *Bottleneck Effect:* 6:15 *Founder Effect:* 9:25

[@geek4freaks]

I honestly have learned more by watching your videos in the past two days, than I have in an entire semester of online biology. All online classes should be taught this way! Thank you so much for helping me find my desire to learn and discover.

[@aahillakhani399]

I thought this comment was from this week not 8 years ago 😅

[@emmabila3480]

we've been expecting you Mr.anderson

[@arose19581]

I'm reviewing for a midterm tomorrow and this was the first thing we learned about this year, so naturally my notes look like another language to me. This was helpful. Thanks!

[@malini6910]

okay so my teacher at school always played your videos to help us understand the topics better and now it's been over 2 years that I've left school but these are still helpful for studying for university and I just wanted to say a HUGE thank you!! (and I also thank my teacher lol)

[@jitsharma8988]

If there happens to be a global prize for best explainer then it wil surely goes to you Sir! A big heart felt gratitude 4 ur tireless service Sir!

[@jf_c137]

Best well spent 11minutes of a lunch break ever. thank you for the insight!

[@lissaaaaaaaaaaaaa]

Thank you soo much! I really can't express how thankful I am that you take the time to make such clear and concise videos of such seemingly complicated topics. Mr. Anderson you are seriously the best teacher out there!

[@GoatRobotics]

Really helpful, described in such a simple way! Perfect. Your videos are great to watch when I forget a concept or are trying to grasp something a bit more detail.

[@sohaibmahmoudalshboul9830]

Hi it's mr.anderson in other words : hi you will finish this video with fully understanding Thank you mr.anderson

[@Fogmaster]

Great information! For people commenting on the bottleneck versus founder effect, I would say functionally there is no difference. The founder effect is just a specific kind of bottle neck based on the geographical isolation of a population. Or, all founder effects are bottlenecks, but not all bottlenecks are founder effects.

[@ComandaKronikk]

Mate, you and Tyler Dewitt are just such great teachers. Both have helped me so much

[@Munkeh999]

Thank you so much for this, I'm not sure what my lecturer was driving at, with lots of strange equations, seemingly-unrelated equations, but this has made it so clear. Thanks again!

[@bobbyald]

Very good explanation. Thanks.

[@iplaidinator]

Bottlenecks can cause founder effects. What happened on Pingelap was that a natural disaster reduced the population significantly (bottleneck). The leader was among the survivors and he carried the gene for colour blindness. The survivors, now the 'founding colony," continued to reproduce among themselves in this limited gene pool, eventually as their numbers began to rise, so did the frequency for the allele causing the special form of colour blindness.

[@shannonlindgren1678]

I know this is several months dated, but this is my understanding: it's due to chance because a change is dependent on the method by which genes are passed on (meiosis). Meiosis is all random chance.The allele frequency of the population could stay the same, but because of the smaller populations, the odds of it varying increase. Just like if you flip a coin ten times, you could get heads all ten times, but this is less likely to be true if you flip the coin one-thousand times.

[@MorganHagg]

got my exam on Monday :D Cramming all weekend -.-

[@desertman33]

I definitely see where you're coming from. The concepts are basically identical, with the exception that the founder effect involves a number of organisms from 1 population beginning their own population in a new location. I wish Mr. Andersen gave some better clarification on this in his example.

[@IshtarNike]

It could be a lot of things. If a species doesn't produce big litters and an individual carrying a rare allele only has say one pup before it dies in a flood, and that pup doesn't carry the rare allele, then that allele has been lost due to chance. Its not selection or anything else, just chance.

[@wisewxful]

This is really helpful and makes the concept easy to understand!

[@cherry.25]

You make everything sound so simple and logical 👌🏼

[@desertman33]

No. Founder effect only applies to when some organisms move to a new area. Going by your logic, every single example of a bottleneck would be a founder effect example as well.

[@mau307]

The story about the island of Pingelap was on my biology test. The question was of what kind of genetic drift this story was an example. I put Founders effect because I saw this video, my teacher says this was wrong and it was an example of the bottleneck effect. Is she right or are you right?

[@mau307]

Victoria Guan yeah thanks! Though, i still dont understand why a genius like Bozeman would use such a debatable example

[@billy41289]

I see there's some confusion here on your part as well as your instructor. The fact that he/she said "wrong type of drift" is a very telling comment. Drift is drift, there are not different types. There are different causes that lead to reduction of population size, which in turn leads to a random sampling effect, in the absence of selection on these alleles in question, i.e. the combination of alleles that remain in the reduced population, is random by definition whether the cause is Founder (FE) or Population Bottleneck (PBN). The subtle difference in terminology can be thought of as BN is the process that reduces a large population to a small one, the FE is the genetic result of ANY reduction in population size from large to small. The Pingelap Atoll example is perfectly correct. Pingelap went thru a PBN and the result was FE, one clear result is the high frequency of the colorblindness allele that is normally rare.

[@allahrackball98]

You're far more helpful than my actual professor

[@othertestchannelbeta]

Evolution is basically the change in traits over successive generations.

[@mrsdiggory3211]

isn't the pingelap is more to bottleneck effect since it was caused by some disaster?

[@nkennyish]

Technically the Pinglelap population had gone through a bottle neck effect genetic drift. Founder effect would of been if those 20 people had gotten there from another population, but in reality those 20 people were just left from an existing population that died after the hurricane.

[@AbhishekBhal]

very good explanation, thanks Prof Paul Andersen...

[@pam9451]

i hope that you know that your videos ARE helpful

[@micahalaniz5890]

thank you Mr Anderson.. you make it understandable... my teacher doesn't,

[@TheRABIDdude]

You have a funny thing about getting the very large and the very small mixed up, at 6:50 you said they got "squeezed through a huge bottleneck" and in the genetic fingerprinting video you said the odds of of getting two identical fingerprints were "astronomical". These are brilliant and informative videos but it's funny how, of the two I've seen, you've done that in both :P

[@davidmilgrim]

Thanks. I've been needing clarification of genetic drift. It keeps com in up in books as a measure to establish when species diverged, but I was never clear what was meant. I still need to understand more, but this helps!

[@rusle]

Thank you for a good and easy explanation to understand.

[@dirtylostchild]

He was explaining how the alleles of color blindness is now prevalent in the current population. Founding effect is when the original genetic founder spreads his alleles to the following generations.

[@blinddiver]

Masterfully explained. What's the name of the population simulator you used in the video?

[@forrestwoods8599]

Near the end of the northern elephant seal section, 7:34 - 9:23, he circles "r values". I understood the point; but what is "r value" in light of this study?

[@NidhiSingh-so8wi]

sir..what is the difference on bottle neck effect and founder's effect..? In both a single species led to the formation of whole population..

[@Neeboopsh]

always such well done videos. thank you

[@joltiix]

wouldn't the Pingelap example be more related to the bottleneck effect?

[@faizarafique7666]

thanks for the information and make genetic drift easy for us

[@GtGtiR32]

Great video! What's the difference between your two examples though, why is the second example with colour blindness considered a founder effect and not a bottleneck like the first one?

[@lauraallisonrose]

Both bottleneck and founder are examples of genetic drift. Smaller populations tend to diverge in genetic frequencies simply because of size. i.e. the small group does not have the same genetic frequencies as the parent population.

[@Pixels_Neurons_Scalpels]

you really helped me with these topics.

[@100megahappyman]

Can anyone help me understand why the Pingelap example is not a bottleneck effect?

[@VanTran-fk7cg]

Can you please do a video on the extinction vortex?

[@Alowi33]

A population bottleneck may also cause a founder effect even though it is not strictly a new population.

[@hannahr1150]

If anyone wants more in depth research on the founder’s effect, be sure to check out Island Of The Colorblind by Oliver Sacks! It’s a fantastic book that delves into just how this effect modifies life in modern day on Pingelap

[@MrSrb95]

Great video! Can you just explain to me how does geographical isolation lead to a formation of a new species

[@fizzy2o11]

Uhm I think the loss in alleles which are not of an advantage should be more put down to selection pressures which are imposed

[@mahederkore7647]

Wouldn't the example about pingelap island be a bottleneck effect because it was a natural disaster that wiped out most of the population?

[@candyazz28]

Bottleneck @4:32, Northern Elephant Seal Bottleneck effect @7:07, (consequences of tribalism) Human version @9:24

[@moaj6088]

Is gene pool all the alleles of 'all existent traits' present in a population or is it all alleles of 'one particular trait' present in a population? Hope I make sense. Thanks

[@ThatisnotHair]

Isn't that dominant alleles that reproduce more.

[@TFScientist]

Outstanding! Thank you so much for sharing!

[@zhuolunzhang2918]

Thank you very much for your video! I have a question about the example of founder effect. In this island, did the leadership of the color-blind guy cause the increase of the color-blindness? I think if the color-blind person was not the leader, or there was no leader, the disease would have a big chance to disappear in some day because of genetic drift, so the color-blindness was not an expected result of both founder effect and genetic drift if he was not a leader. Am I correct?

[@gulnaroguz2510]

I don't know much about this island, but I think that the reason why there is lots of complete colorblindness is because there are only 20 people on the Island. There was also inbreeding. So even if someone else who was not the leader had complete colorblindness, there would be many people with the disorder because of the island's low population and inbreeding. Or maybe the leadership of the island did play a role. Maybe he had many children with different people so the next generation also had the disorder but I am not sure if it had anything to do with the guy's leadership. If the island had a large population, then there wouldn't be much complete colorblindess as it is a rare disorder. Hope that helps.

[@MariaNRibeiro62]

Very good way to learn about this issue!

[@grandparentslara8196]

What a great presentation!!

[@liganjinxeseverything3174]

Okay, so some of the genetic information was lost as a result of the bottleneck. Is there a way for these species to regain the lost genetic information just through mutation and natural selection or is that kind of far fetched?

[@2MC]

Possible? Yes. Probable? No. It would be highly unlikely that the same set of circumstances would arise for the genetic information to return.

[@HowJesusLOVESUs]

I'm a little confused on the difference between the bottleneck and founder effects....can you explain please?

[@EducatorSharmin]

he is the best teacher ever!

[@doctornot.strange]

Thanks a lot Mr Anderson

[@FcoMp]

When genetic drift was first used or created? How this process was developed?

[@mbanana23456]

...? genetic rift wasn't created it was discovered

[@reactionhits4]

Your videos are really amazing sir

[@Nikvaylo]

@bozemanbiology Can you share the web adress that you used @ 02:55?

[@shahad8472]

people like you need to exist more

[@emp1cyrus]

So genetic drift results in loss of the unadvantagous alleles within a population? Also in the bottleneck effect, the seals had different skull sizes so they more genetic diversity how is that bad is it not advantagous?

[@0904Carlin]

Hi Mr Andersen, I still don't understand the way you say genetic drift are due to chance, what do you mean by chance?

[@jasonla3481]

Its actually both, but in biological stand point its more so Founder E. because, the NES/SES were intentionally hunted and killed ''BOTTLED'' effect , but the islanders decrease of population was caused by a natural disaster. hes explaining how the ''FOUNDER'' of an area * that last remaining population in that island* changed the dramatic pool of genes for future occupants. its similar to a bottle neck yet its not. The SES/NES didn't change much but the shape and measurements.

[@desertman33]

Did anyone else notice how the island of Pingelap example was actually of the bottleneck effect. He described how the people were cut down to 20. They were not moved to a new area, though, so this would not actually be the founder effect... Did anyone else notice this? Gimme some thumb ups if you did, too, lol

[@michaelesper9648]

wow this was insanely helpful!! thank you!

[@damiccathedesigner]

I didn't see much difference between the bottleneck effect and the founder effect.

[@dolmalhamu6000]

saved me so many hours n boosted my confidence. Thanku..

[@aNewBeginning99]

That was the point of the example....

[@JimboNintendo]

Question, did anyone actually find this playlist of ap bio helpful on the ap exam?

[@karinebarclay7584]

Great video! Thank you!

[@anne-mariehuster9980]

This was very helpful, my notes are not very good on this. Thank you

[@TeAmoNormaJean]

I am confused on gene pool! Is a gene pool all the genetic material in a population?

[@lukehebert6207]

+Kaylia Williams Yep! It's the sum total of genetic information in a population at a given time.

[@TeAmoNormaJean]

+Luke Hebert Thanks.

[@TeAmoNormaJean]

+Countless Productions Thanks

[@neelamrevankar4907]

9

[@laurentndonje7455]

good presentation

[@media1critter]

What is the website of the simulator

[@rindin100]

oh wow this helped a lot a lot :D wonderful! thank you so much! you are a gem!

[@naseerahmedkhan2697]

Really your a great hero of universe.

[@Yomomma-jf9iy]

You also have genetic mutations that alter the behavior imprinting.

[@moltenice5]

dude youre khan academy 2.0

[@tianna215]

Mohammad Hussain ***better than Khan academy

[@TheJoeMinaj]

Seriously, your videos are why I'm passing AP Bio...

[@Mario_DiSanto]

I'm actually studying Mr.Veres!

[@jhetao]

does anyone know the site for that simulator?

[@youngatheist4833]

what is the simulator you used?

[@useurcamera]

thanks, the founder effect kinda bugged me

[@jojo6061]

Thanks for the help!

[@RebornLevi]

He may have not successfully distinguished the genetic drift type in that examples, but I think what he was attempting to explain that the bottleneck effect can be a precursor to the founder effect.

[@mehmetalpozlem]

you are amazing .... thanks a LOT

[@Jack70903]

no founder implys there is migration involved and an exploitation of multiple new niches.

[@SebastianHernandez-gw5ur]

this was helpful. Thanks!

[@eqisoftcom]

I don't think one needs to speak about recessive and dominant alleles. It's a statistical phenomenon.

[@izzy2610]

This is really good thank you!

[@desertman33]

Are you this dense normally, or are you making a special effort here? He described the founder effect, and then moved on to describe an example of the bottleneck effect... I don't have a PhD, but I think it's safe to say that that was a mistake.

[@Bella-sj6dq]

So you better do Erawesome :) this is a good video :)

[@Markus9705]

Still don't understand. If p and q is 50 % each, wouldn't the laws of possibility make the p and q value of the next generation pretty much the same, like if you flipping a coin?

[@adamsimon27]

Yes, they would be "pretty much" the same, but not always 50/50. The allele frequencies changed a bit after the first generation simply due to random chance (An understanding of meiosis helps here), but notice, once there became only a few copies of an allele, the effect of genetic drift is larger, and when there are many copies the effect is smaller. Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation, which Mr Anderson showed in his example

[@Markus9705]

Adam Simon It should still fluctuate around one value (0.5). Is there anything I'm missing here?

[@Chiungalla79]

You miss the whole point: Genes are passed on from generation to generation. So take this example: You have 100 animals, 50 blue and 50 red. You randomly pick 50 animals out of this 100 animals, and each one gets 2 children for the next generation. The other 50 die without offspring. Actually there will be litte chance to get a 50:50 population for the next generation. Most populations will favour one color or the other. Starting off with such a "biased" 2nd generation, the chances to form the 3rd generation are no longer 50:50. Eventually the colors will become equally frequent again, or the bias will increase or something. But the point is: After generation 2 it's no cointoss any more. In huge populations with very common alleles the genetic drift isn't such an big issue. But in small populations with rare alleles genetic drift can seriously affect the genepool.

[@Markus9705]

Chiungalla79 "Most populations will favour one color or the other." The whole point of genetic drift is that it's *not* natural selection. So.

[@Chiungalla79]

TheLeftLibertarianAtheist The favour wasn't about selection. It was meant as just a statement, that most populations will not end up 50:50, because that's an improbable constellation. And many biologists recon that genetic drift is part of natural selection, and it's often considered as a kind of selective pressure.

[@baroonono]

wow this is really nice