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Why Alien Species Thrive
planux writes "The Sacramento Bee has an interesting article about why invasive animal species thrive, pushing out native species -- sometimes to the point of extinction. Kevin Lafferty, a U.S. Geological Survey marine ecologist at the Western Ecological Research Center in Santa Barbara says "Invasive species end up with about half the parasites, or diseases, they had at home." Animals with an average of 16 parasites on their home turf typically bring about three of the parasites with them to new locations. And only about four new parasites will typically adapt to attack the invading species. Net gain: 9 fewer parasites!"
Makes sense. That's why the colonists came to America. Damned European parasites.
Sunlit World Scheme. Weird and different.
A species new to an area has no known predators in that area. Hence, they may thrive and continue to do so until they have wiped out the population of the prey in that area. By that time overpopulation fixes itself because of a shortage in food supply. (or, think long term the development of resistence - if the given species feeds on plants, eventually they will start to taste bad to the species.
Basically, this is a built-in function of nature. It's just like life. When things are new and great you're happy, but you will adapt to your enviroment and will be bitchin about something soon - I promise.
Don't mess with nature, I suppose.this reminded me of an older paper that tried to rationalize why optimal growing conditions does not seem to favor rapid evolution of a species. That is what scant evidence there is, it appears that evolutionary diversity and advancement occurs under not the optimal growing conditions but rather in the harshest. e.g. at the highest altitude, hottest temperaures or any place life struggles to survive.
While its obvious that harsh conditions by themselves impose evolutionary pressure this does NOT promote diversity--after all that pressure only is placed on genes that govern adaptation to the environment, and even there there is generally a narrowing of the gene pool not an expansion.
No instead the diversity arises because you have left your old balanced environment and predators, and thus have LOST the finely honed evolutionary pressure on those genes. thus you can evolve semi randomly with little selective pressure, leading to diversity. Another factor leading not to diversity but to rapid differentiation is that when these new traits that have nothing to do with survival get chromosomally linked to the features that enhance a species survival in the harsh environment, they get amplified.
some people call this the poker hand effect. You dont need a royal straight flush to win. all you have to do is beat your opponents. Or to put it another way if you are trying to live in a chemical wasteplant out flow, you dont have to generate a a very good enzyme for digesting plastics, anything that is better than your competitors is good enough for now. You can evolve it more later.
this explanation is perhaps the simplest and best answer to creationists who want to insist that life is too complex a process to spring into existance fully developed (.e.g. behe's mouse trap argument). The answer is that being adaptive can beat being the best.
anyhow its interesting that a species poised to exploit an opportunity will evolve faster than one that dominates its native environment.
Some drink at the fountain of knowledge. Others just gargle.
On my native network where the domiant boxen is Windows, I have found that non-indiginous boxen such as Solaris, Linux, and Mac are slowly taking over one part of my network. They often don't fall victum to the numerous virus and dipshit users. Either by design or just from complexity built into thier mutated form. I have also noticed a cross pollonation that has caused a raise in stability in our fringe windows boxes that are protected by the Alien unix and linux boxen.
It is all just nature at work, I one day hope to see all my boxeb being some kind of freakish hybrid of windows and unix/linux....or maybe the dominate boxen will take over the whole network.
Neck_of_the_Woods
#/usr/local/surf/glassy/overhead
Most species are going to have predators pleased to greet them, as most plants and animals are edible. What's important is the edge, a relative rather than absolute advantage over native species.
A couple of examples are kudzu and zebra mussels -- they don't complain about much. Our local favorite is the Asian "tiger" mosquito. But there are serious bad effects from monoculture -- one disease can destroy everything in its path. Think Windows desktops and a nasty virus.
Nature will tend to reach an equilibrium, or oscillate wildly, or the newcomers either exterminate the old, or vice versa. There are equatios for estimating equilibrium. Only in a really catastrophic situation does shortage of food supply rein in the invader. But evolution, as opposed to natural selection, is slow, so an alien species can easily exterminate native species before they have a chance to develop defenses, even to the point of suicide. Hawaii is suffering significant losses of species diversity because of newcomers. It takes thousands or millions of years for a new species to develop, yet perhaps the blink of an eye to perish.
I hate seeing natural selection described as some sort of moral quest for the "best," when it's just a way of explaining natural phenomena (I'm not saying you're doing that, but lots of people do). Darwin didn't judge was was "best," just tried to predict which species would do better under given circumstances. Nature doesn't care about the outcome, or become improved as a result. Species diversity is often the preferable situation.
Maybe I'm being clueless, but I'm hazy on your relevance to "devil's weed," slang for pot (which does grow quite nicely in the wild).
If you're somewhere that has access to Nature's archives, you can read the two original articles this one was based off of:
Release of invasive plants from fungal and viral pathogens and
Introduced species and their missing parasites
I am only half joking when I say that. With all the debate nowadays about the value of manned space flight, this is actually a very good argument for putting people out there. Space is harsh and there are many perils that we have to learn to deal with out there. But, those are the equivalent to the new parasites in any new environment.
For a little idea of how many paraites we would bring with us just look at the Earth similar ailments that astronauts get. They rarely get sick and never get into car accidents.
It just goes to show that getting into space and staying there might not be as daangerous for the log stay as just visiting is.
Is this the end yet?...How 'bout now...how 'bout now...how 'bout now?
I just checked, and marijuana (from the hemp plant) apparently was cultivated thousands of years ago in central asia (yes, China), then made its way west to Europe. It was imported (alien species!) to the New World very around 1600, as the hemp provided valuable fiber. I saw the stuff growing wild many feet tall in Asia, which was kind of startling. The varieties grown for drug use has been refined to have many times the THC of the wild variety. The US prohibits growing low-THC hemp for the idiotic reason that it makes law enforcement look bad. Soem argue it does have economic value.
Don't ask me to connect pot and natural selection....
Sickle cell is oh-so-nasty, and even the heterozygotes show some mild symptoms. Yes, I learned the same thing sickle cell and malaria. Only a fraction (8-45% by region) of Africans have the trait, so probably people with it simply survive somewhat more often. I guess it was a glitch at some point that helped, but was not do-or-die essential to survival.