Now that I've got your attention, let's talk about another invasive group; the Europeans and their take over of the Americas, after all Mexicans are indigenous descendants of the Aztecs(but even Aztecs are from "south of the border" you say? I know!). JUST KIDDING! I won't be talking about People this post.
But really this isn't about people, or indigenous people (or is it?). This is about plants(and animals if you so wish). So what is an invasive species? Wikipedia claims there are three definitions. The first being:
The first definition expresses the phrase in terms of non-indigenous species (e.g. plants or animals) that adversely affect the habitats they invade economically, environmentally or ecologically.
The second:
broadens the boundaries to include both native and non-native species that heavily colonize a particular habitat.
The third:
is an expansion of the first and defines an invasive species as a widespread non-indigenous species.
Most people, when talking about invasive species are talking about the first one. But, there are those that argue that there is no such thing as an invasive species. Let's refer to Darwin, let's go back to evolution. Survival of the Fittest!
Most argue that invasive species take over already established ecologies, choke out existing species and possibly cause extinction. But hasn't that always been happening? Hasn't that been happening for billions of years? Where are the dinosaurs? where are the Saber Toothed Tigers!? Evolution occurs when one species becomes extinct in favor of another. So where does that put invasive species?
Humans can very well be considered invasive, not just to each other but also to other environmental issues. An article I just read, states that (while human induced evolution has always been known) trophy hunting is also speeding up the process, causing some animals to reproduce sooner and remain smaller. Humans are also known to bring plants and animals from for away lands that are invasive.
But then there is the natural process, it's a very grey area. for example, I did a post a while back about California Fan Palms and Mexican Fan Palms in Pomona. Mexican Fan Palms are considered invasive, they take over California Sycamores' natural breeding grounds. However, Mexico is RIGHT NEXT DOOR! Wouldn't birds naturally bring seeds over during migration patterns? Absolutely! At some point the evolutionary process would eventually bring the MFP's all the way up to California anyways, the border is just an imaginary line!
Confusing? Well, I am definitely confused, I am in no way making an official stance on invasive species. Invasive species affect already established ecological systems. but maybe it's part of the evolutionary process. who knows!? I sure as hell don't!
In Australia the removal of one invasive species allows for the explosion of another even MORE invasive species. Maybe if we allow all the invasive species to move in to this tiny island, it would balance itself out? If one goes deep enough into it, it becomes a can of worms. I'm going to stay on the surface for now.
Sunday, January 18, 2009
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4 comments:
There is a rule when hunting dear that the buck must have more than one point on its antlers. This has been an indication of age in the past. A hunter friend of mine has recently spotted large mature bucks with single point antlers.
Around here there is an invasive species of grass growing in the sand dunes on the beach. They spend tons of money ripping it out in specified areas. Then they "let" the native species try to grab a foothold. Whats stupid about it is that the dunes look like a wasteland after they pull out the "invasive grass." The native grass cannot get a foothold because the dunes are now barren and the sands shift more without any plants in them. What they should do is just thin out the invasive plant and gradually let the native plant take over. But, hey, what do I know? I'm sure plenty of biologists came up with the plan and are patting themselves on the back. Meanwhile, the beach looks like crap.
Interesting post!
Although I'm not a biologist, I wonder if part of their concern with non-native species has to do with ecological diversity. The problem with human populations is our propensity to induce very rapid changes in our local ecology. Although you might be right that the mexican palms would overtake the sycamores, the time necessary to wipe out the species without human involvement may allow the sycamores the opportunity to evolve and thrive. When we're talking about losing ecological diversity, we're really talking about a loss of genetic material.
Thanks for encouraging us to think a little bit.
Huck, there are some who say that loosened soils attract invasive species because the soil is foreign and would otherwise not enjoy it as much, so if left to it's own demise it might go away!
Ed, I think you are right, I'm sure the sycamores left to defend themselves would probably be able to defend their territory. and ecological diversity is ultimately good for evolution and life system survival
Well said. More on this topic here:
http://www.invasionbiology.org/
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