Of War, Tusks & Genes

[Hank2211]

This is the title of an article in the most recent issue of Science, the magazine of the American Association for the Advancement of Science. I have added a link below, but it may be behind a paywalls and I can't copy the article. What follows is pretty nerdy but, at least for nerds, may be of some interest. Having said that, this research may also have an impact on hunters.

The gist of the article is that tusklessness in female African elephants is clearly a genetic matter (long known) but that it may also be an evolutionary adaptive response to certain types of harvest.

The researchers focused on elephants in Mozambique over a 28 year period, 15 years of which involved civil war. During that war, combatants, to raise money, poached elephants for their ivory (as one might expect). This "intensive selective killing" of tusked females caused a rapid increase in the proportion of the population which was tuskless. So far, this is simple math, and wouldn't be unexpected. The interesting aspect of the research was that the frequency of tuskless female births after the war ended was also higher than before the conflict, and beyond the numbers which would normally be expected, which they argue suggests an evolutionary response as well as the expected genetic response. Of course, there could be other explanations for this, but the scientists' modelling showed that the increase in tuskless female births after the end of the civil war was extremely unlikely to have been caused by genetic factors alone.

I will leave a critique of the statistical and genetic modelling to those who are more knowledgeable than I am, but it is interesting to think that hunting could provoke an evolutionary response away from the traits favoured by hunters, particularly in such a short period of time (evolutionarily speaking).

Of course, this argument has been raised against hunting for decades in North America, where many argue that by targeting males with the largest horns/antlers, hunters are 'degrading' the gene pool and that eventually, only animals with small horns/antlers will be left. And in fact, the article makes just this connection. Of course, anyone who reads or follows the record books knows that this is demonstrably not the case, at least not in North America.

Perhaps one reason is that the numbers of animals harvested from North American populations is strictly controlled and quite small in comparison to overall populations. This clearly wasn't the case during the Mozambique civil war, where tusked elephants of both sexes were hammered (a scientific term!). This provides support for the argument that well-regulated hunting, including what we call trophy hunting (a term I hate), doesn't have a negative impact on the physical traits of hunted populations.

In fact, it might be interesting to study the effects of well-regulated hunting on the genetic diversity of hunted populations. Given that many male animals hunted are likely breeding males (such as in elk herds in North America of zebra, impala, blesbok, etc. herds in Africa), is it possible that hunting, by allowing males to breed which wouldn't otherwise have had that opportunity, increases rather than decreases genetic diversity?

The link is https://www.sciencemagazinedigital....021002&utm_content=gtxcel&pm=2&folio=394#pg26

 

[Newboomer]

This is the title of an article in the most recent issue of Science, the magazine of the American Association for the Advancement of Science. I have added a link below, but it may be behind a paywalls and I can't copy the article. What follows is pretty nerdy but, at least for nerds, may be of some interest. Having said that, this research may also have an impact on hunters.

The gist of the article is that tusklessness in female African elephants is clearly a genetic matter (long known) but that it may also be an evolutionary adaptive response to certain types of harvest.

The researchers focused on elephants in Mozambique over a 28 year period, 15 years of which involved civil war. During that war, combatants, to raise money, poached elephants for their ivory (as one might expect). This "intensive selective killing" of tusked females caused a rapid increase in the proportion of the population which was tuskless. So far, this is simple math, and wouldn't be unexpected. The interesting aspect of the research was that the frequency of tuskless female births after the war ended was also higher than before the conflict, and beyond the numbers which would normally be expected, which they argue suggests an evolutionary response as well as the expected genetic response. Of course, there could be other explanations for this, but the scientists' modelling showed that the increase in tuskless female births after the end of the civil war was extremely unlikely to have been caused by genetic factors alone.

I will leave a critique of the statistical and genetic modelling to those who are more knowledgeable than I am, but it is interesting to think that hunting could provoke an evolutionary response away from the traits favoured by hunters, particularly in such a short period of time (evolutionarily speaking).

Of course, this argument has been raised against hunting for decades in North America, where many argue that by targeting males with the largest horns/antlers, hunters are 'degrading' the gene pool and that eventually, only animals with small horns/antlers will be left. And in fact, the article makes just this connection. Of course, anyone who reads or follows the record books knows that this is demonstrably not the case, at least not in North America.

Perhaps one reason is that the numbers of animals harvested from North American populations is strictly controlled and quite small in comparison to overall populations. This clearly wasn't the case during the Mozambique civil war, where tusked elephants of both sexes were hammered (a scientific term!). This provides support for the argument that well-regulated hunting, including what we call trophy hunting (a term I hate), doesn't have a negative impact on the physical traits of hunted populations.

In fact, it might be interesting to study the effects of well-regulated hunting on the genetic diversity of hunted populations. Given that many male animals hunted are likely breeding males (such as in elk herds in North America of zebra, impala, blesbok, etc. herds in Africa), is it possible that hunting, by allowing males to breed which wouldn't otherwise have had that opportunity, increases rather than decreases genetic diversity?

The link is https://www.sciencemagazinedigital....021002&utm_content=gtxcel&pm=2&folio=394#pg26


View attachment 432608

I doubt genetics could change that rapidly. Historically for a species to change, adapt, evolve, etc, it usually requires several generations over several hundreds or thousands of years. In evolutionary terms this quick a change is almost instantaneous which scientifically is nearly impossible. But maybe they are on to something.

 

[mark-hunter]

I know, that in my country, Croatia, regulated hunting continuously exist for more then 100 years.
But since the end of World War 2, there are record books of trophies, kept by national hunting association.
When I dig up somewhere record books, I can post more details.

But since the end of ww2, the strongest trophy of brown bear, roe deer, red deer, mouflon are harvested in last 20 years, and it indicates that regulated hunting and planned game management is improving the quality and gene pool for game. At one time, president Tito was the most prominent hunter and his trophies were displayed on international CIC exibitions, as best at the time.
Now, latest records are better then this, 50 years later.

With continuously applied such game management program, we have increased population of bear, increased population of boar (one the biggest populations of bear in Europe), steady population of roe and red deer. Increase of population of wolf.
We had successful reintroduction of beaver (soon expected to start hunting on them but population is increasing to more then huntable numbers. Beaver was locally extinct by the beginning of XX century). predatory birds, still protected but looks like steady and healthy population.
At this moment, we have programs for reintroduction of cappercaille, which numbers are dropping in the wild, and european lynx, who is being reintroduced for last 20 years (numbers unknown, but sightings are reported)

 

[mark-hunter]

Following my earlier post, I found the records, so will give the years when top trophies were taken in my country:
red deer, 2003, CIC 261.81
fallow deer, 2004, CIC 212.34
Axis deer, 2012, CIC 342.70
Chamois, 2007, CIC 120.13
Mouflon, 2008, CIC 237.15
Boar, 1995, CIC 149.25
Bear (scull), 2009, CIC 63.8
Fox, 2013, CIC 25.81
Badger, 2013, CIC 23.73
Jackal (scull), 2011, CIC 27.96

So, all top trophies from record book, are taken recently.
Indicates improvement of gene pool, in last decades.

 

[Hank2211]

I doubt genetics could change that rapidly. Historically for a species to change, adapt, evolve, etc, it usually requires several generations over several hundreds or thousands of years. In evolutionary terms this quick a change is almost instantaneous which scientifically is nearly impossible. But maybe they are on to something.

I tend to agree with you about evolution happening that rapidly.

My reading of the article - and this is a layman's interpretation - is that the researchers' conclusion is based on a statistical model which evidences the influence of something other than just genetics at play. The researchers then look at what those other influences could be, eliminate those that aren't applicable, and adaptation is what's left.

 

[WilhelmM]

Highly unlikely for a large mammal to evolve that quickly. The only organisms that can adapt and change in such a short period of time are invertebrates. That, and the idea that selective hunting is damaging to the gene pool is contradictory to existing evidence of increasing "trophy quality" in places like Botswana.

 

[375Fox]

I’m not sure I can believe there is evolution occurring in that short time, but selectively poaching tusked elephants, leaving a higher proportion of cows carrying the tuskless trait that will have more tuskless calves seems seems very predictable to me.
Trophy traits can change pretty quickly in response to hunting/breeding. In my own experience. Pennsylvania started antler restrictions on deer in 2002. My area most 1.5 year old bucks had 4 points to a side, maybe 30% of the deer fell into something less than this, and near zero spikes. The first year following this “huge” bucks were taken because some actually made it to 2.5 years old. I believe the harvest statistic was previously 90% of 1.5 year old bucks. The buck to doe ratio was terrible because of the high buck harvest and none making it to any age. Three to four years later I would put the less than 4 points to a side percentage at greater than 70% and spikes became common. The 1.5 year old bucks with 4 points to a side had short tines because more difficult to count quickly and got to live to breed. We did start getting older bucks and a much better buck to doe ratio though. Only in the last few years has this finally recovered with less hunters and more people looking to take a trophy buck instead of the first legal buck that walked by. The genetics are recovering to what they once were.
South African breeding is another example. If they can intentionally breed huge buffalo and sable greater than 50 inches in just the last 25 years with selective breeding, the opposite can easily happen by hunting all the prime trophy animals and leaving the shorter horned animals to breed particularly if inside a fenced area. Similar examples would be New Zealand and Texas.

 

[375Fox]

Highly unlikely for a large mammal to evolve that quickly. The only organisms that can adapt and change in such a short period of time are invertebrates. That, and the idea that selective hunting is damaging to the gene pool is contradictory to existing evidence of increasing "trophy quality" in places like Botswana.

See what happens inside a fenced area when you selectively take out trophy kudu and impala that flare out. It can happen quickly. There are many properties where impala will only turn in and kudu will barely or not exceed 50” mark. It doesn’t take long to eliminate certain genetics especially if new blood can’t naturally come in or owner can’t afford new blood. Free range hunting with too high of a quota isn’t much different. Free range and a low quota of post breeding males will have no effect. While many hate the price structure of European hunts, it has really protected their genetics by incentivizing people to harvest management trophies and not just top trophies like people try to hunt in the rest of the world.

 

[mark-hunter]

@375Fox,
I never shot a buck in CIC medal, exactly for that reason. Too expensive.

 

[WilhelmM]

See what happens inside a fenced area when you selectively take out trophy kudu and impala that flare out. It can happen quickly. There are many properties where impala will only turn in and kudu will barely or not exceed 50” mark. It doesn’t take long to eliminate certain genetics especially if new blood can’t naturally come in or owner can’t afford new blood. Free range hunting with too high of a quota isn’t much different. Free range and a low quota of post breeding males will have no effect. While many hate the price structure of European hunts, it has really protected their genetics by incentivizing people to harvest management trophies and not just top trophies like people try to hunt in the rest of the world.

Good point

 

[R.M.C.]

I don't doubt its some kind of natural response. I've always heard coyotes can "adjust" the size of the pup litters they have due to over or under population of coyotes in their particular area. I realize coyotes might have been doing this for millennia but the individual yearly shift is interesting.

 

[thi9elsp]

I would believe that reducing the percent of cows and bulls with the tusk trait and leaving a larger proportion of the population with the tusk-less trait would result in the findings. To me, that is not evolution simply the changing of the gene pool in a certain area. Remove all tusk-less animals and I suspect that the population will revert back to a more balanced proportion.