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#312541 - 07/25/07 09:28 AM Texas DNA Parentage Study
grundsow
4 Point


Registered: 04/03/01
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Loc: Berks County, PA

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http://www.huntamerica.com/wwwthreads/showflat.php?Cat=0&Number=777705&an=0&page=0#777705
What do you make of this? Some buck outperforming others at successfully producing offspring, some not producing at all. All this DESPITE a lousy 1:3 buck to doe ratio, and an extremely high deer density (over 120 deer per sq. mi. on the West Pasture). What gives?








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#312575 - 07/25/07 10:06 AM Re: Texas DNA Parentage Study [Re: grundsow]
Wes Parrish
16 Point


Registered: 06/12/02
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Loc: Knoxville-Dover-Union City, TN

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I would take this study with a huge dose of salt.
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#313978 - 07/26/07 08:01 AM Re: Texas DNA Parentage Study [Re: Wes Parrish]
BSK
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Registered: 03/11/99
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grundsow,

The very best DNA parentage studies (and the best is from the King Ranch and a high-fenced military reservation in Oklahoma) indicate that breeding is spread far more evenly through the male population than what was assumed to be occurring. In addition, some bucks--even mature bucks--appeared to be responsible for no successful breedings throughout their entire lifespan.

Antler size has been shown to have no relationship to breeding success. In fact in every large-scale study I've seen the most prolific breeders DO NOT have large antlers. Obviously, Nature DOES NOT select for large antlers, only human hunters do.

Yearling bucks make up a percentage of successful breedings in every herd studied, but in herds with advanced buck age structures they rarely make up more than 10-20% of successful breedings. When you consider that yearling bucks are the largest single age-class of bucks present in any herd, that indicates they are successful breeders far less often than older bucks.

However, there are two caveats to that breeding yearling buck data. In all of the studies to date, they have collected the data from skewed sex ratio herds (usually in the 2.0 to 2.5 does per buck range). What would the results be from a balanced sex ratio herd? In addition, I had a chance to see the King Ranch data broken down by week. At the front and tail-end of the breeding process, when the least number of does were in estrus, all of the successful breedings were done by bucks 3 1/2 years old or older. Only during the peak of breeding, when the maximum number of does were in estrus at one time did yearlings produce any successful breedings. This suggests that when competition for estrus does is high (few does in heat), older to mature bucks conduct most if not all of the breedings. Yearling bucks only have the opportunity to breed when many does are in heat at one time (competition is lowest). In a truly balanced sex ratio herd, I strongly suspect yearling bucks would produce fewer successful breedings.
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"There is no reasoning someone out of a position he has not reasoned himself into." --Clive James

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#314010 - 07/26/07 08:16 AM Re: Texas DNA Parentage Study [Re: BSK]
BSK
Jerkasourous of the non-typical kind
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A point I've been trying to get across for years is that Natural Selection works differently for white-tailed deer than for other herd animals. In most herd species, males will compete for dominance and then the dominant male collects a "harem" of females that only he breeds. This is Nature's way of ensuring that a male large enough and healthy enough (has expressed his genetic potential and his genetic characteristics have allowed him to win dominance battles) does the majority of the breeding.

White-tailed deer work differently. When herd dynamics are as Nature intended (balanced sex ratio and advanced buck age structure [50% of the male population 3 1/2 or older]), the majority of females will enter estrus over a short period of time (10-14 days). Since so many females are in heat at the same time, it is physically impossible for a few dominant males to breed all those does in that short of a time-span (a buck will spend 24-48 hours with an individual doe during the mating ritual). This ensures that the breeding is spread between a much larger number of males than in a "bull and harem" species. In fact, within a single doe social unit--where all the members are realted on the female side (they are all sisters, cousins, aunts, mothers, grand-mothers, etc.)--all of these does will enter estrus at about the same time, guaranteeing that each must be bred by a different buck and ensuring maximum genetic diversity within the offspring of that group (all the fawns from a single doe social unit for a given year will have different fathers--and studies confirm that is the case).

Why is this important? Because the white-tailed deer appears to have developed high genetic diversity within localized populations as a primary species survival mechanism. White-tailed deer thrive in an amazingly wide variety of environments; from the tropical rainforests of Central America, to the deserts of northern Mexico and the American Southwest, to the swamps of south Florida to the boreal forests of Canada. They are able to do this because of their extremely diverse genetics. No matter what conditions they are faced with, some animals in every population will by shear genetic chance be adapted to that new environment. Just the unique way Nature has produced for that particular species' survival.

This system would appear to produce no "Natural Selection" of the fittest male fathers, yet again, if you look at the DNA parentage studies, many bucks--even mature bucks--are doing no breeding at all. This means there is some selection at work, but it is not as intense of a selective process as that which occurs in "bull and harem" species. Now exactly what Nature is selecting for is unknown, but it is suspected to be large body size, resistance to disease, and aggressive personality.
_________________________
"Know where you stand, and stand there" --Jesuit Father Daniel Berrigan

"There is no reasoning someone out of a position he has not reasoned himself into." --Clive James

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#314093 - 07/26/07 09:09 AM Re: Texas DNA Parentage Study [Re: BSK]
TOW
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Registered: 06/29/05
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Excellent read BSK...

"Obviously, Nature DOES NOT select for large antlers, only human hunters do."

Most hunters think of great genetics as a large racked buck when in the deer community he could be a complete dork.






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#314298 - 07/26/07 10:47 AM Re: Texas DNA Parentage Study [Re: TOW]
Wes Parrish
16 Point


Registered: 06/12/02
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I have much "antidotal" evidence that many of the oldest bucks in many hunting areas (and these bucks are typically the ones with the largest antlers of the areas simply because they're also the oldest bucks) are the particular bucks that are the least aggressive, do the least breeding, and the least tree rubbing.

Think about it:

If a particular older buck didn't rub trees, fewer hunters would realize he lived.

If a particular buck didn't chase does (or didn't pursue them as aggressively), he would be more likely to live older.

Consequently, I think it's no accident that many older bucks in a particular hunting area may be of relatively small body weights. The larger body weight bucks may tend to be more aggressive (more dominant) and more likely to be killed at a younger age. That leaves proportionately more of the less aggressive bucks to become older, but they're not necessarily doing so much to spread their genes.

Also, hunters tend to most aggressively target the younger bucks that have the largest antlers and the largest body weights, further fueling the fire of leaving more of the smaller body-weight bucks to become older. But should note that body weights have little to do with antler size. The fact that many of these older bucks may have smaller than expected antlers (for their ages) is in large part to hunters selectively targeting the largest antlered younger bucks, not allowing those to become extremely large antlered older bucks.

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#314310 - 07/26/07 10:52 AM Re: Texas DNA Parentage Study [Re: Wes Parrish]
Wes Parrish
16 Point


Registered: 06/12/02
Posts: 19199
Loc: Knoxville-Dover-Union City, TN

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There is also much evidence that antler gentics come more from a buck's momma than his daddy.
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#314341 - 07/26/07 11:07 AM Re: Texas DNA Parentage Study [Re: BSK]
grundsow
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Registered: 04/03/01
Posts: 284
Loc: Berks County, PA

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Thanks for the insight BSK.

A 1:3 buck-doe ratio and roughly HALF the buck in each pen did NOT produce offspring? Does that sound right?

How much of that is due to competition among buck, and how much is instead due to doe health (120 dpsm)? Anyone know the fetus to doe ratio?

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#315262 - 07/26/07 09:58 PM Re: Texas DNA Parentage Study [Re: grundsow]
Chris Tripp
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Registered: 10/20/05
Posts: 3762
Loc: Brush Creek, TN

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that study is way outdated
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#315476 - 07/27/07 06:47 AM Re: Texas DNA Parentage Study [Re: Chris Tripp]
BSK
Jerkasourous of the non-typical kind
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Registered: 03/11/99
Posts: 65056
Loc: Nashville, TN

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A 1:3 buck-doe ratio and roughly HALF the buck in each pen did NOT produce offspring? Does that sound right?

Yup. Even in a skewed sex ratio herd there is some Natural Selection going on.


How much of that is due to competition among buck, and how much is instead due to doe health (120 dpsm)? Anyone know the fetus to doe ratio?

Most of it will be due to buck competition. Even in an unhealthy herd, fetal numbers will average around 1.3 to 1.4 per doe. In a healthy herd it will run around 1.6 per doe.
_________________________
"Know where you stand, and stand there" --Jesuit Father Daniel Berrigan

"There is no reasoning someone out of a position he has not reasoned himself into." --Clive James

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