Genetic Drift
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- Опубліковано 6 вер 2024
- 003 - Genetic Drift
Paul Andersen describes genetic drift as a mechanism for evolutionary change. A population genetics simulator is used to show the importance of large population size in neutralizing random change. The near extinction of the northern elephant is used as an example of the bottleneck effect. The high incidence of total colorblindness due to a typhoon that hit the small island of Pingelap is also included.
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All of the images are licensed under creative commons and public domain licensing:
Agency, U. S. Central Intelligence. English: Map of the Federated States of Micronesia., 1999. Federated States of Micronesia (Political) 1999 from Perry-Castañeda Library Map Collection: Federated States of Micronesia Maps. commons.wikimed....
Center, Astronaut photograph ISS008-E.-19646 was taken March 7, 2004, with a Kodak DCS760 digital camera equipped with an 50-mm lens, and is provided by the Earth Observations Laboratory, Johnson Space. English: Before the Year 2004, Only Two Tropical Cyclones Had Ever Been Noted in the South Atlantic Basin, and No Hurricane. However, a Circulation Center Well Off the Coast of Southern Brazil Developed Tropical Cyclone Characteristics and Continued to Intensify as It Moved Westward. The System Developed an Eye and Apparently Reached Hurricane Strength on Friday, March 26, before Eventually Making Landfall Late on Saturday, March 27, 2004., March 26, 2004. NASA. commons.wikimed....
"File:Example-of-adaptive-radation.svg." Simple English Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. simple.wikipedi....
"File:Founder Effect with Drift.jpg." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:Mirounga Angustirostris Distribution.png." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:Northern Elephant Seal, San Simeon2.jpg." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:Random Genetic Drift Chart.png." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:Random Sampling Genetic Drift.svg." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:RGB 24bits Palette Sample Image.jpg." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
"File:Southern Elephant Seal Area.png." Wikipedia, the Free Encyclopedia. Accessed November 1, 2013. en.wikipedia.or....
Smurrayinchester. A Satellite Photo of the Atoll of Pingelap, Federated States of Micronesia, [object HTMLTableCellElement]. Own work. commons.wikimed....
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It's incredible when someone takes a potentially complex concept and makes it understandable for anyone. Congratulations Mr Andersen, you've done it again.
Calum Williamson such a gift
There's nothing complex about the fact that we are being lied to.
@@cl-fs6pt The hell?
@@silverstrikev8868He's saying he doesn't understand.
It's funny how you've taught more alone in this video than my teacher in 4 weeks
Video stamps:
*Intro:* 0:00
*overview:* 3:48
*Isolated population:* 5:29
*Bottleneck Effect:* 6:15
*Founder Effect:* 9:25
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.
I thought this comment was from this week not 8 years ago 😅
we've been expecting you Mr.anderson
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!
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)
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!
got my exam on Monday :D Cramming all weekend -.-
Very good explanation. Thanks.
Best well spent 11minutes of a lunch break ever. thank you for the insight!
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!
isn't the pingelap is more to bottleneck effect since it was caused by some disaster?
Hi it's mr.anderson in other words :
hi you will finish this video with fully understanding
Thank you mr.anderson
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.
thank you Mr Anderson.. you make it understandable... my teacher doesn't,
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?
I think that it's more of a bottleneck effect. It's because the bottleneck effect is caused by natural disasters - wildfire, typhoons (like the example), etc. Founder effect is more geared towards separating from the group and settling on somewhere new. I also didn't know this, so I had to ask a few friends for help. Hope this helped...kinda?? :D
Victoria Guan yeah thanks! Though, i still dont understand why a genius like Bozeman would use such a debatable example
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.
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.
Mate, you and Tyler Dewitt are just such great teachers. Both have helped me so much
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.
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!
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
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.
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?
Possible? Yes. Probable? No. It would be highly unlikely that the same set of circumstances would arise for the genetic information to return.
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.
This is really helpful and makes the concept easy to understand!
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!
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.
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?
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.
Evolution is basically the change in traits over successive generations.
You're far more helpful than my actual professor
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.
wouldn't the Pingelap example be more related to the bottleneck effect?
You make everything sound so simple and logical 👌🏼
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.
Masterfully explained. What's the name of the population simulator you used in the video?
very good explanation, thanks Prof Paul Andersen...
Thank you for a good and easy explanation to understand.
Can you please do a video on the extinction vortex?
Uhm I think the loss in alleles which are not of an advantage should be more put down to selection pressures which are imposed
he is the best teacher ever!
Can anyone help me understand why the Pingelap example is not a bottleneck effect?
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.
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?
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
Isn't that dominant alleles that reproduce more.
thanks for the information and make genetic drift easy for us
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..
i hope that you know that your videos ARE helpful
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.
Great video!
Can you just explain to me how does geographical isolation lead to a formation of a new species
saved me so many hours n boosted my confidence. Thanku..
Thanks a lot Mr Anderson
dude youre khan academy 2.0
Mohammad Hussain ***better than Khan academy
Very good way to learn about this issue!
people like you need to exist more
Outstanding! Thank you so much for sharing!
you really helped me with these topics.
always such well done videos. thank you
Wouldn't the example about pingelap island be a bottleneck effect because it was a natural disaster that wiped out most of the population?
When genetic drift was first used or created? How this process was developed?
...? genetic rift wasn't created it was discovered
I'm a little confused on the difference between the bottleneck and founder effects....can you explain please?
Bottleneck @4:32, Northern Elephant Seal Bottleneck effect @7:07, (consequences of tribalism) Human version @9:24
What a great presentation!!
Question, did anyone actually find this playlist of ap bio helpful on the ap exam?
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
Hi Mr Andersen, I still don't understand the way you say genetic drift are due to chance, what do you mean by chance?
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?
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.
oh wow this helped a lot a lot :D wonderful! thank you so much! you are a gem!
Your videos are really amazing sir
A population bottleneck may also cause a founder effect even though it is not strictly a new population.
I am confused on gene pool! Is a gene pool all the genetic material in a population?
+Kaylia Williams Yep! It's the sum total of genetic information in a population at a given time.
+Luke Hebert Thanks.
+Countless Productions Thanks
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This was very helpful, my notes are not very good on this. Thank you
wow this was insanely helpful!! thank you!
Really your a great hero of universe.
Thanks for the help!
Great video! Thank you!
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?
good presentation
@bozemanbiology Can you share the web adress that you used @ 02:55?
I didn't see much difference between the bottleneck effect and the founder effect.
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
That was the point of the example....
what is the simulator you used?
Seriously, your videos are why I'm passing AP Bio...
What is the website of the simulator
you are amazing .... thanks a LOT
This is really good thank you!
can someone say me the source of the simulator?
You also have genetic mutations that alter the behavior imprinting.
this was helpful. Thanks!
does anyone know the site for that simulator?
I'm actually studying Mr.Veres!
incredible
Thank you !!
no founder implys there is migration involved and an exploitation of multiple new niches.
This "proves" or is "related" to "evolution" .. How ?
thanks, the founder effect kinda bugged me
wow this is really nice
So you better do Erawesome :) this is a good video :)