The Biggest Force In Evolution.

Humans Have Become The Biggest Force In Evolution.


The Zoque people of Mexico hold a ceremony every year during which they grind up a poisonous plant and pour the mixture into a river running through a cave.

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Any of the river's molly fish that float to the surface are seen as a gift from the gods.

The gods seem to be on the side of the fish, though - the fish in the poisoned parts of the river are becoming resistant to the plant's active ingredient, Rotenone.

If fish can evolve in response to a small religious ceremony, can you imagine the effects of all the other changes we are making to the planet.
We are turning grassland and forests into fields and cities, while polluting the air and water. We are hunting species to the brink of extinction, as well as introducing new pests and diseases to just about every part of the world.

Species living today are likely to be wiped out over the next century or two as a result of this multiple onslaught,and what is now becoming clear is that few of the species that survive will live on unchanged.

Far from being a slow process,evolution can occur very rapidly when the environment changes,so,as we alter the planet faster and more drastically,we are becoming the main force driving evolution.

Stephen Palumbi of Stanford University in California,says
"The intensity of the ecological effects of man,is pretty obvious"

Some of the fastest rates of evolution ever measured in the wild are in plants and animals harvested by humans,the few populations for credible data, are on a average evolving 3 times as fast, as populations subjected only to natural pressures.


Hunting
Most predators target the young or the weak,Humans are different, we target the biggest and the best, or those with characteristics we desire,now combine this with our ability to kill in large numbers and the result is extremely rapid evolution of our prey.
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Many examples have emerged of how hunting can transform the hunted.

The targeting of large animals has resulted in a fall in the average size of Caribou in some areas, for instance, while trophy hunting has led to Bighorn Sheep in Canada and mouflon in France evolving smaller horns.

But the most dramatic example is the shrinking of tusks in Elephants, and in some even their complete loss.

In eastern Zambia, the proportion of Tuskless female elephants shot up from 10 per cent in 1969 to nearly 40% in 1989 as a result of poaching.

More dramatic rises in tusklessness have been reported in many parts of Africa, with some Bull elephants losing tusks too.

Ralph Tiedemann of the University of Potsdam in Germany suggest that female elephants preference for tuskers has partly counteracted the effect of hunting,and goes on to say
"even if all poaching stopped,it would still take a very long time for the percentage of tuskers to rise again."

Private Reserves in countries like Zimbabwe now have a policy,were they charge hunters a smaller Trophy Fee for shooting tuskless elephants,anywere from $3000 instead of the basic $12500 for a tusker.
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Synthetic Pesticides

The use of synthetic pesticides like DDT took off in the 1940s,Resistant Houseflies were discovered in 1946., and by 1948 resistance had been reported in 12 insect species, and then in 1966, James_F._Crow of the University of Wisconsin Madison reported that the count had exceeded 165 species.
He was noted at the time for saying.
“No more convincing examples of Darwinian evolution could be found than those provided by the development of resistance in one species after another”

Rats and mice around the world have become resistant to the Poison Warfarin, and in Europe some have even become resistant to warfarin’s replacement, SuperWarfarin

In Australia, meanwhile, rabbits are becoming resistant to the poison used to control their numbers, called Compound 1080.

Pesticide resistance has been studied far more closely than other kinds of ongoing evolution,and in many cases we know which mutations are involved, how they make organisms resistant and sometimes even how the mutations spread through populations.

Resistance arises due to mutations that alter the shape of proteins and prevent insecticides binding to their targets, were as DDT and pyrethroid compounds kill insects by opening sodium ion channels in nerve cells, but in the malaria-carrying mosquito Anopheles Gambiae, variants of the channels that cannot be opened this way have evolved on at least four separate occasions.

Other main mechanism of resistance involves enzymes that inactivate pesticides before they can kill,and some resistant strains of gambiae,produce large quantities of an enzyme called CYP6Z1 that can inactivate DDT.
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Pesticide resistance is becoming such a serious problem that strategies for preventing it evolving in the first place are taken increasingly seriously,and one approach is to alternate the type of pesticide applied, to try to avoid applying sustained selective pressure in one direction.

The pests seem to be evolving faster than we can develop new pesticides, and in one region of Burkina Faso, gambiae has become resistant to all four classes of insecticides used for malaria control.


Pollution Resistance

Between 1947 and 1976, two factories released half a billion kilograms of polychlorinated biphenyls called (PCBs) into the Hudson river in the north-east US. The effects on wildlife weren't studied at the time, but today some species seem to be thriving despite levels of PCBs, many of which are toxic, remaining high.
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At least one species, the Atlantic tomcod - an ordinary-looking fish about 10 centimetres long - has Evolved resistance.

"We could blast them with PCBs and dioxins with no effect," says Isaac Wirgin of New York Uninversity Scholl of Medicine.


Many of the ill effects of PCBs and dioxins are caused by them binding to a protein called the Hydrocarbon Receptor.
The Hudson tomcod all have a mutation in the receptor that stops PCBs binding to it,
Wirgin and colleagues reported earlier this year.
Isaac Wirgin also said,
"The mutation is present in other tomcod populations too,but the levels are a lot lower then those in the Hudson".

Pollution resistance in one species can have unexpected consequences for others.
The tomcod’s tolerance allows it to accumulate extraordinarily high levels of PCBs in its body,is a threat to animals higher up the food chain – IE: humans with a taste for fish.

The most famous example of evolution in action was a response to pollution, as the Industrial Revolution got under way, Cream coloured peppered moths in northern Britain turned black to stay hidden on trees stained by soot.
Most evolutionary changes in response to pollution seem to be invisible.

The spoil heaps of many old mines, are covered in plants that appear normal, but are in fact growing in soil with high levels of metals such as copper, zinc, lead even arsenic that would be toxic to most of these and other species.
The evolution of tolerance has occurred extremely rapidly in some cases, sometimes within just a few years of the soil being contaminated.

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Crusts of radiotrophic fungi fractalizing across the walls of Chernobyl’s blown out reactor core, cancer eating microbes drifting through the hyper-toxic waters of a lake full of mine tailings in Montana, the charred trunk of a ginkgo tree re-sprouting delicate leaves after the atomic blast at Hiroshima, Detroit’s feral houses and its ghetto pheasants – all these things indicate that despite the current ecological apocalypse, despite catastrophic climate change and the mass extinction of biota – nature itself isn’t going to go away any time soon.

No matter how much destruction we wreak, there are processes of regeneration lying in wait that are quietly evolving around us, or biding their time until we turn our backs. It’s as if the earth has a sentient biological field that sucks up our poisons and smothers the detritus of our civilization so that life itself can go on.

Though it’s quite likely that we will precipitate the extinction of our own species along with the countless others we have already wiped out, the bio-field will survive, as it must. It is the immune system of the planet and the signs of it are everywhere if you know where to look. Regular readers will know I’ve long been interested in ruderal ecologies, which evolve when we stop maintaining architectural landscapes and they gradually transform into habitat for a range of pioneering organisms such as ragweed, coyotes and Ailanthus trees.

Lately though, I’ve been tracking the absorption of various mass produced objects into the bio-field, some long discarded, others still in daily use.
The shiny, manufactured surfaces we so fetishize are little match for the relentless progression of slimes, films and crusts that soon moves in to obscure them. Yet there is something magnificent in these ancient, incremental processes. Life on earth has a future. And it’s far beyond us.

Source


Super Invaders


In 1935, the South American cane toad was introduced to Australia to control pests feeding on sugar cane, but the cane fields were not to the toad’s liking, but the rest of the countryside was.

The toad has spread aggressively at the expense of many native species.
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The highly poisonous animals are having a big effect on predators, such as the Australian black snake, who are developing resistance to cane toad toxins, also the red-bellied black snake and green tree snake, are changing in a surprising way – their mouths are getting smaller, and the only reason must be snakes with big mouths can eat large toads that would contain enough toxin to kill them.


The toads themselves are also changing, they are now colonising regions that were too hot for the founder population, suggesting that they are evolving tolerance to more extreme conditions.

The toads leading the invasion are becoming better colonisers as they have bigger front legs and stronger back legs than toads living in the areas already colonised.

Radio tagging has confirmed that these “Super Invader” toads can travel faster, as you might expect.

They are probably evolving because the first toads to reach new areas benefit from more food and less competition, and have more offspring as a direct result of this, and the changes are likely to be transient, once the toads stop spreading, the “super-invader” traits will gradually be lost i suspect.

In areas of the US that have been invaded by fire ants, native fence lizards have evolved longer legs, which can only suggest its to make it faster, as a dozen fire ants can kill a lizard in minutes.


Michael Kinnison of the University of Maine in Orono has been actively experimenting,and in one of his experiments, he moved juvenile chinook salmon from one river in New Zealand to another, and salmon were introduced to the country around a century ago, and Kinnison wanted to assess the extent to which they had adapted to conditions in individual rivers.

He found drastic differences in survival, even though the fish appear identical
he said
“When a population was locally adapted, it performed twice as well”
Kinnison suspects that lots of small changes can add up to make a huge difference to a population’s success.
“Contemporary evolution may be relatively modest on a trait-by-trait basis, but its overall contribution to the performance of populations may be immense”

These findings explain why there is often a lag between the introduction of new species and their rapid spread,when a newly arrived species is likely to find itself in an environment that is not ideal, and its population is very small, meaning there is little genetic diversity, and in these circumstances, a species will spread only slowly, if at all.

As the population begins to adapt to local conditions, maybe via invisible changes such as mutations in immune genes it is likely to start to grow and spread.
Because more mutations occur in larger populations, it will then evolve faster, enabling it to spread quicker and further, but if this turns out to be common place in nature, it could only mean bad news, as it suggests that many introduced species that seem to be behaving themselves could yet start spreading explosively and cause serious problems.

reply to post by TheMaverick


Such a wonderful and valuable thread on a topic that doesn't get the attention it deserves.

I hope this thread is the wake up call people need.

Why can't it be??????


Star and Flag people PLEASE.

Plants are changing too, as when seeds collected from field mustard plants (Brassica rapa) in California in 1997 and 2004 were grown in identical conditions, but the 2004 strains flowered 9 days earlier on average (National Academy of Sciences Vol 104).
The change was a result of drought the plants have evolved to reproduce before they run out of water.

It also seems the faster organisms evolve, the less able they are to evolve further,and this may be because fast change occurs when only a small proportion of each generation manages to reproduce, resulting in a dramatic loss of Genetic diversity which is clearly the fuel for further evolution, and in many cases, the size of populations will also plummet, rendering them vulnerable to extinction.

Also what intrigues me,is are these changes happening in humans as well,as certain populations decrease,and some increase.

So developing an immunity to a poison is "evolving"? Really? Plenty of humans have developed poision immunities as well. If anything it's adaptation but even then it's stretching it.

reply to post by TheMaverick


Yeah, well, if the scientists in the 80's were right, the poodle would have become extinct by 2004.

SeraphNB

reply to post by jjkenobi


Clearly you have not read the thread,or you wouldn't of posted your pointless comment...thanks for your highly intelligent response.


reply to post by seraphnb

So your sarcasm suggests you believe these scientific findings are wrong,please enlighten me on your explanation on why these clear scientific findings are wrong ?..or is it because your religious,and refuse to accept facts ?

reply to post by TheMaverick


One would think that the most resistant fish would survive, thus reproducing. The surviving fish would have babies some with the same resistance to the poison as their parents they would grow up and have babies of their own. Eventually the fish born with the best resistance would thrive since all the competition would be dead. . It would seem like the simplest answer.

The hunting scenario seems pretty much the same. People kill the stuff with biggest size/horns. That leaves smaller size/horned males to reproduce with females. Eventually the largest and medium sized males are gone only to be left with the small males. None of witch requires a changing of any ones DNA. Kill all the dogs with white spots in the world and you wont have any dogs with white spots....... seems pretty straight forward.

The mosquito article is pretty impressive. However it still seems not to pass the smell sniff test. Mosquitoes that are not resistant die immediately. Then the ones that already have resistance to it "the ones that didnt die in the first place" have babies and pass their DNA and pesticide resistance to them. You limit the gene pool and only the not dead mosquitoes are having babies with each successive poison used on them. Same would go for the rats and bunnies.

The little fish in the next article would read like the first article. The fungi in the radioactive zones same principle. In a normal state the fungi would have too much competition and not be able thrive like it does in these places. A strain of fungi happened to be resistant it of course survived and became dominant in this special environment. Plants as well. The peppered colored moth is a silly example if ive ever seen one. The whiter moths were more likely to be eaten by predators. The predators could see them easier thereby eating all the whiter moths lowering the amount white genes in the population. To the point were they were eaten out of the gene pool.

Same goes for the frog eaters. The snakes the lizards etc etc.

Little mind experiment. Say a disease starts to spread that only can get in through sweat glands. People are dying all around us except for a select few with a rare mutation. Ectodermal dysplasia is very real and detrimental to a typical human in a normal environment. I know 2 brothers that have it actually. In this scenario all us normal cats are dead and these lcuky....er lucky mutants survive and pass their odd gentic disorder onto their children. Eventually the disease would be eradicated not due to people evolving but a few lucky mutants that in any normal circumstance would in the the lesser mammal kingdom die before they could pass on their genetics.

Cool article though.