Deer University - Culling

[Mexico]

So if I could knowingly kill every dink 4 or 5yr old "cull" on my 5k acre lease and allow only 160" plus deer to breed for 10yrs I would see no genetic improvements in horn size?



Another 5k acre place not killing culls will have the same results as me?



I respectfully call BS ,Even a half attempt at this would make improvements as has for many many ranches for many yrs.

If you "only" let 160 plus deer breed you're in a controlled environment. You just contradicted yourself. There is no way to "only" let your trophies breed in an open environment.

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[TXDUCKCUTTER]

Ok.
I will start with something that I wrote for members of my lease several years ago

In an effort to explain whether culling can alter the genetics of a wild population, I wanted to explain a little about selection and how it works in a wild population. Although it may not appear to be, the example I present is an over simplified model. The actual biology of a natural population is a lot more complex. I am using gene and allele interchangeably to eliminate some of the genetic jargon.
Selecting for or against antler traits in a wild population will not reduce or eliminate a gene(s) from the population. Since antlers are only exhibited on half of the population, selection for/against the characteristic is only occurring on 50% of the population (assuming a 1:1 buck:doe ratio, the percentage is actually less when there are more does). Let’s assume that the deer population is 200, the frequency of a gene that is to be selected for/against is around 10%, the characteristic is easy to identify and there are only 2 genes. The actual population size is actually a lot higher, the gene frequency is probably lower, the trait is not displayed the same in all individuals, and there are probably 10 plus genes in a population. In addition, the development of antlers is influenced by a lot of genes, and not just one gene. The more genes that contribute to a trait, the more complex the problem becomes.
If this is the case, there are around 40 individuals (20 bucks and 20 does) per year that carry the allele (I’ll spare you the mathematical calculation on why it isn’t just 10% of 200 or 20). Annually, at least 20 individuals (does) are carrying the gene, but you can’t select against the trait because they do not produce antlers. This leaves 20 individuals that are male and carrying the gene that you desire to remove. In a given year, let’s assume that one can do a good job of culling the gene in question, and you remove 15 of the 20 individuals. One can assume that you also culled at least 10 other bucks, and 30 does. Of the does that were harvested 10% of the does contained the gene in question. After culling you would have a total of 32 deer that have the gene and 113 deer that do not carry the gene in the population after a yearly harvest. This leaves 32 non-favorable genes and 290 total genes in the population. Each individual carries two genes (145 individuals x 2 alleles). To calculate the gene frequency after harvest divide 32 by 290, this equals .11 or 11%. Although one attempted to selectively remove an unfavorable gene from the population, the end result is that the gene frequency actually remained the same. Several of the assumptions that I made are not realistic regarding a low-fenced population (i.e. population size, number of genes, , etc).
Antler characteristics are a phenotypic characteristic (a characteristic you can see or measure). These traits are the result of genotype (genetics), environment, and the interaction between genotype(genetics) and environment
Phenotype = genotype + environment + geneXenviro
Since we cannot alter the gene frequencies in a low fenced natural population, let’s examine the environmental component. The environmental component is comprised primarily of age and nutrition. We can control parts of this component with supplemental protein and allowing bucks to mature. Obviously, we cannot control the amount of annual rainfall or mortality of a specific deer.
However, post-rut mortality can be minimized by supplemental feeding (and praying for rain).

Thank you,Ill look further into this.

[Aggie PhD]

So if I could knowingly kill every dink 4 or 5yr old "cull" on my 5k acre lease and allow only 160" plus deer to breed for 10yrs I would see no genetic improvements in horn size?

Another 5k acre place not killing culls will have the same results as me?

I respectfully call BS ,Even a half attempt at this would make improvements as has for many many ranches for many yrs.

Assuming equal nutritional resources, equal buck:doe ratios, equal harvest, and the same population size.

You still would not effect the genetics frequencies in the population. The effects of genetic drift has a greater influence on the frequency of alleles in a population than you would through minimal selection (harvest/cull) of a few bucks.

https://en.wikipedia.org/wiki/Genetic_drift

In a low fence population, how does one select for antler characteristics in half the population that doesn't exhibit antlers?

There are A LOT of factors in play, and most of them are random chance. The amount of pressure that one thinks they are helping is washed out by randomness.

[TXDUCKCUTTER]

If you "only" let 160 plus deer breed you're in a controlled environment. You just contradicted yourself. There is no way to "only" let your trophies breed in an open environment.

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My point is that with selective culling you should be able to control it a lot more than not doing so.Thanks for you comments,if there is a better way that's what I'm always after.

[kyle1974]

we shouldn't build the wall because some illegals will still get in.

[TXDUCKCUTTER]

Assuming equal nutritional resources, equal buck:doe ratios, equal harvest, and the same population size.

You still would not effect the genetics frequencies in the population. The effects of genetic drift has a greater influence on the frequency of alleles in a population than you would through minimal selection (harvest/cull) of a few bucks.

https://en.wikipedia.org/wiki/Genetic_drift

In a low fence population, how does one select for antler characteristics in half the population that doesn't exhibit antlers?

There are A LOT of factors in play, and most of them are random chance. The amount of pressure that one thinks they are helping is washed out by randomness.

I see what your saying,what I'm saying is shouldn't we be able to eliminate some of that guesswork on the does side just by selection on the bucks side over time?

I don't have all the answers, but I know what ive seen in the positive identifiable genetic traits passed on within our herd,and what seems to be the negative effects of certain inferior bucks being allowed to breed.

[Aggie PhD]

I see what your saying,what I'm saying is shouldn't we be able to eliminate some of that guesswork on the does side just by selection on the bucks side over time?

I don't have all the answers, but I know what ive seen in the positive identifiable genetic traits passed on within our herd,and what seems to be the negative effects of certain inferior bucks being allowed to breed.

There is not enough selective pressure through buck harvest to make a difference. If you only had a small number of deer then you may make a difference (like on an island, or in a breeder pen). But on a low fence or larger high fence population, the random forces of population genetics will overpower your selective pressure

[Muygrande]

Seems like some of the old timers at TPWD will defend the “massacre all spikes” 1960s Kerr study to the bitter end. Hard for me to understand.

[Aggie PhD]

Seems like some of the old timers at TPWD will defend the “massacre all spikes” 1960s Kerr study to the bitter end. Hard for me to understand.

I have a diatribe about that one too that I sent to members of my lease.
I may have found some of their raw data in an old publication, and reanalyzed it myself......

[lovemylegacy]

So if I could knowingly kill every dink 4 or 5yr old "cull" on my 5k acre lease and allow only 160" plus deer to breed for 10yrs I would see no genetic improvements in horn size?

Another 5k acre place not killing culls will have the same results as me?

I respectfully call BS ,Even a half attempt at this would make improvements as has for many many ranches for many yrs.

When you remove "dinks", that void doesn't stay a void. The possibility of another "dink" to take his place is high. Or how about a nocturnal "dink" that you never laid eyes on? Or your neighbors "dinks"? Or doe that carry "dink" qualities, that you cannot see?


I understand your argument, but there to many variables and I just gave you five times as many as you gave me that go against the "cull" theory. The biggest being buck recruitment. When a buck dies or is taken, usually a buck will take his place and there is no control of what quality of animal that will be.

[JonW]

When you remove "dinks", that void doesn't stay a void. The possibility of another "dink" to take his place is high. Or how about a nocturnal "dink" that you never laid eyes on? Or your neighbors "dinks"? Or doe that carry "dink" qualities, that you cannot see?


I understand your argument, but there to many variables and I just gave you five times as many as you gave me that go against the "cull" theory. The biggest being buck recruitment. When a buck dies or is taken, usually a buck will take his place and there is no control of what quality of animal that will be.

The study identified a negative feedback loop that I think probably happens regularly in heavily culled herds. Late born fawn population increased when culling increased. Late born fawns were more likely to meet culling criteria, so more bucks were culled which resulted in reduced breeding and more late-born fawns.

Another think they were able to learn in the study is that late born fawns that met culling criteria would catch up to the rest of their age class by the third or fourth year in the control group.




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[Javelin]

I just love how some people continue to not believe what the experts who have studied this for 40 plus years with tons of money thrown out are saying. Every study out there says culling does not change genetic makeup in an uncontrolled environment, yet so many on here and elsewhere think they can do what the experts and science can't

[kyle1974]

I just love how some people continue to not believe what the experts who have studied this for 40 plus years with tons of money thrown out are saying. Every study out there says culling does not change genetic makeup in an uncontrolled environment, yet so many on here and elsewhere think they can do what the experts and science can't

Is there a study related to culling?


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[Javelin]

Is there a study related to culling?


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Are you joking and being sarcastic? Or are you serious.

[kyle1974]

Are you joking and being sarcastic? Or are you serious.

If you have a link to studies specific on culling I’d like to read them.


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