# Anyone good at population genetics?



## Poseidon (Oct 1, 2010)

Math!! *runs away* 


I would really love to help, but I lack the general mathematical processing genes most people have.


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## Peppy Barrel Racing (Aug 16, 2011)

Oh lord im having flash backs of college genetics class. I'm with Poseidon run away lol! I want to help you but even though I have a biology degree math is not my strong suit. I'm too scared I'd give you the wrong answer as its been a few years since I've had to look at that equation. Too bad my boyfriend is gone camping with a troup of boy scouts till Sunday he'd be the perfect person to ask that.


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## Chiilaa (Aug 12, 2010)

Bridgertrot said:


> So I'm having a bit of a brain fart on some extra credit work for genetics. I could ask the professor but she's not too nice and I already fought about horse colors with her before and she doesn't like me :lol:
> 
> It's with population genetics. To sum it up a fictitious herd of horses was abandoned to breed amongst themselves completely isolated. Original herd has one palomino paint stallion, one sorrel stallion, four sorrel mares, one palomino mare, and one sorrel paint mare. The herd has grown to 90 since then.
> 
> ...


The whole population starts as red, so assuming HWE remains, no new mutations appear, so every member of the final population will also be red. This narrows down how many genes you need to think about.

Are any of the questions to do with how many have inherited the pinto pattern? Because that is such a crappy way to run a genetics unit and not specify what pinto gene is there lol.

Ack this is the crappy lecturer that uses a different notation for cream, right? Which does she use to denote dominant and which for recessive?


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## Poseidon (Oct 1, 2010)

No, that was mine, Chiilaa, but that's the same notation that doesn't make any freaking sense. Last time I checked, there was one "c" in the word "cream".


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## Chiilaa (Aug 12, 2010)

So, I am going to delve into this for you a bit. It's the first time I have ever looked at population genetics, so forgive me while I learn and make mistakes. I do, however, want to point out that HWE could not be established in this herd - inbreeding negates the "random mating" part of HWE, and with only 8 horses as your starting pop, it is inevitable they are inbred.


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## Chiilaa (Aug 12, 2010)

Ok, I cheated, but I have numbers!

I don't want to do your assignment for you, so PM if you need more help. However, your 0.34 frequency for cremello is off - that would be 34% of the population, and 11 is not 34% of 90.


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## Faceman (Nov 29, 2007)

Chiilaa said:


> So, I am going to delve into this for you a bit. It's the first time I have ever looked at population genetics, so forgive me while I learn and make mistakes. I do, however, want to point out that HWE could not be established in this herd - inbreeding negates the "random mating" part of HWE, and with only 8 horses as your starting pop, it is inevitable they are inbred.


Very true...the whole proplem is rather far fetched. The initial population is waaaay too low for Hardy-Weinberg to come into play, and 11 cremellos out of 90, considering the initial population, is rather absurd and totally negates "random" breeding. The problem can still be solved, but it is such a stupid problem it is beyond hypothetical...a professor ought to be able to come up with a more realistic problem than that...


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## Reno Bay (Jul 8, 2012)

Faceman said:


> Very true...the whole proplem is rather far fetched. The initial population is waaaay too low for Hardy-Weinberg to come into play, and 11 cremellos out of 90, considering the initial population, is rather absurd and totally negates "random" breeding. The problem can still be solved, but it is such a stupid problem it is beyond hypothetical...a professor ought to be able to come up with a more realistic problem than that...


Yeah the entire thing is far-fetched...too many variables as well.

How many of those 82 new horses came directly from the first 8? How many of them came from the second generation breeding and so forth? You can't possibly determine the exact number and color of foals each horse produced (though since they're all red-based that would make it only slightly easier, but there's still the question of who bred who and what came out of it).

And 11/90 cremello. I'm assuming they're all solid cremello in the hypothetical problem, since the question didn't mention cremello pinto. Assuming that only the original 8 produced 82 new foals, that would mean the palomino pinto stallion would have had to breed with the palomino mare at _least_ 11 times and successfully genetically combined for cremello foals. Ugh. This class would hurt my brain.


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## Bridgertrot (Dec 2, 2011)

Chiilaa said:


> The whole population starts as red, so assuming HWE remains, no new mutations appear, so every member of the final population will also be red. This narrows down how many genes you need to think about.
> 
> Are any of the questions to do with how many have inherited the pinto pattern? Because that is such a crappy way to run a genetics unit and not specify what pinto gene is there lol.
> 
> Ack this is the crappy lecturer that uses a different notation for cream, right? Which does she use to denote dominant and which for recessive?


-sigh- Yep...the same one. She does the CcrCcr (but the cr in superscript) for two cream, CCcr for one, and CC for none. Same one that still seems to think homozygous dominant roans are lethal. 

There's more parts to the question (part A, part B, etc) it's just the first one that's asking about the cremello. I figure if I figure one out I can get the rest. One section asked about what red genes, creme genes, and tobiano genes are present. That's why I'm assuming all the "paints" have only tobiano. Plus that's the only one she put in her powerpoint "horse color instructional guide" for the students who don't know about horse colors. Just annoys me how she's teaching all these people the wrong things...though a large majority are horticulture people so they probably don't care anyway. :lol:

I'll probably PM you some more Chiilaa, just won't get around to working on it again until Sunday. 

She is more into plant genetics so probably explains why this is so complicated. I might just try and fill it out and at least get some points for trying lol


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## Reno Bay (Jul 8, 2012)

One thing that's bugging me...this teacher is using "paint" as a color term when it is a breed. Pinto is the proper term when dealing with color. *facepalm*


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## FrostedLilly (Nov 4, 2012)

Do you mind if I ask what class you are taking? Unfortunately, I am a Commerce student, so I can't help you with population genetics, but I'm just curious about the class and the program this is part of. Is it Vet. science, or just biology with horses being the subject?


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## Bridgertrot (Dec 2, 2011)

Glynnis said:


> Do you mind if I ask what class you are taking? Unfortunately, I am a Commerce student, so I can't help you with population genetics, but I'm just curious about the class and the program this is part of. Is it Vet. science, or just biology with horses being the subject?


It's just a regular into level genetics class, it just so happens she picked horses to put on this extra credit.


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## FrostedLilly (Nov 4, 2012)

Thanks! I wish you luck!


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## Bridgertrot (Dec 2, 2011)

Thanks everyone for the help. I managed to get 13 extra credit points at least which will be helpful.

One last thing I'm wondering. One of the questions is "In the gene pool for the original small herd, what alleles were present at:

a) the E (black/red) locus?
b) the C (color dilution) locus?
c) the To (paint) locus?

I -thought- I had it right but she took some points off and circled "alleles" in the question.

I put that there were 8 with ee (sorrel) on A. 2 CCcr (palomino) and 6 CC (no cream) on B. and that there were 2 TO? and 6 toto for C.

Is that not right? I thought those were alleles...unless she wanted me to actually write out color names...I only wrote "ee" and such but it seems like she would have known anyway.


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## FrostedLilly (Nov 4, 2012)

I'm pulling out the dusty biology memories from way back, but doesn't an allele only refer to one of the letters? (forgive my lack of technical jargon) Like for example, one chestnut parent will contribute one "e" allele and the other will also contribute one "e" allele making the foal "ee"? I could be totally off, but I vaguely remember something surrounding that.


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## Reno Bay (Jul 8, 2012)

Bridgertrot said:


> Thanks everyone for the help. I managed to get 13 extra credit points at least which will be helpful.
> 
> One last thing I'm wondering. One of the questions is "In the gene pool for the original small herd, what alleles were present at:
> 
> ...


"Original herd has one palomino paint stallion, one sorrel stallion, four sorrel mares, one palomino mare, and one sorrel paint mare."

Just going to say first that your notation of cream confuses me (I use 'n' for absence of one allele...so one dose of cream would be nCr).

Palomino Tobiano (stallion) = ee nCr TT/nT
Sorrel (stallion) = ee
Sorrel (mares x4) = ee
Palomino (mare) = ee nCr
Sorrel Tobiano (mare) = ee TT/nT

a) the E (black/red) locus? *ee* (all horses, 8)
b) the C (color dilution) locus? *nCr* (2 horses)
c) the To (paint) locus? *TT or nT* (2 horses)

You are correct. Your teacher has an obviously limited understanding of this subject. She shouldn't even include something like this if she has no idea what she's talking about, IMHO.


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## Chiilaa (Aug 12, 2010)

No, she is right. There are 8 horses with ee alleles, meaning a total of 16 e alleles. 2 Cr (or whatever dominant cream is for her mutant program). 14 cr (recessive cream). TO is the harder one - were they homozygous or not?


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## Bridgertrot (Dec 2, 2011)

The cream format I'm using is not mine, it's how she likes it, I hate it too. :lol:

I think I'm going to fight it because I did exactly that and a lot of other people I've asked feel the same way about it.


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## Reno Bay (Jul 8, 2012)

Chiilaa said:


> No, she is right. There are 8 horses with ee alleles, meaning a total of 16 e alleles. 2 Cr (or whatever dominant cream is for her mutant program). 14 cr (recessive cream). TO is the harder one - were they homozygous or not?


I actually just notice. The teacher said nothing about how _many_ alleles there were. She only asked what the alleles were...


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## Bridgertrot (Dec 2, 2011)

Reno Bay said:


> I actually just notice. The teacher said nothing about how _many_ alleles there were. She only asked what the alleles were...


Friend of mine had the same answers without the numbers listed and she got the same points off. Plus I don't see why (even if that was the problem) she would take any off as I was only stating how many of each were in the gene pool.


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## verona1016 (Jul 3, 2011)

Seems like it's at least worth going to the prof during office hours and asking for an explanation of what she was looking for.


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## Bridgertrot (Dec 2, 2011)

Alright...this seems totally silly IMO. Here's a direct quote from the answer sheet.

"A) the E/e (black/red) locus? 
None of the orignal or present day horses is black or any derivative of black (bay, buckskin etc). so only the red allele e was present at this locus.

b) the C/Ccr (color dilution) locus?
The original herd included sorrel (CC) palomino (CCcr) and cremello (CcrCcr) so both the C (colid color) and Ccr (diluter) alleles are present at this locus.

c) the To/to (paint) locus?
One of the original stallions and one of the original mares was a paint (white patches) and the rest of the herd was non-paint, so both the dominant paint allele To and the recessive non-paint allele to were present.

NOTE: ee, CCcr, Toto etc. are GENOTYPES NOT ALLELES. The gene pool does NOT contain geneotypes."

So in other words...I got points marked off because I didn't mention what colors were present. But colors are mentioned in the directions right above it so why would I need to repeat that? And any person that knows about horse genetics would be able to figure out the colors from the genotypes. My friend had our TA look at hers (who wrote the same stuff) before she turned it in and she said it was correct.

-headdesk-


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## Reno Bay (Jul 8, 2012)

Bridgertrot said:


> Alright...this seems totally silly IMO. Here's a direct quote from the answer sheet.
> 
> "A) the E/e (black/red) locus?
> None of the orignal or present day horses is black or any derivative of black (bay, buckskin etc). so only the red allele e was present at this locus.
> ...


Um...there were no cremellos in the original 8...not to mention using Paint as a color.
Your teacher is an idiot.


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## Bridgertrot (Dec 2, 2011)

Reno Bay said:


> Um...there were no cremellos in the original 8...not to mention using Paint as a color.
> Your teacher is an idiot.


Mother. of. God.

Email time! :lol:


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