A new born baby enters the world and is at once corrupted, just like oceanic islands. Soon the migration on the island resembles the nearest mainland. The further away the island is from the mainland the harder it is for new plants and animals to arrive. A prime example is Krakatau, for it was an experiment in evolution that humans got to witness. Why were islands so beneficial to Darwin’s theory, and could you still use islands today to prove his theory? Is there any other models with which one can witness evolution instead of waiting around for a new island to form.
Islands are a good example of how genes will play an effective role within the first few generations. Large amount of genes will be lost, because their bearers can not successfully reproduce. This mishap causes a bottleneck effect, but eventually diversity will win and explode. However, the world has other islands such as rivers and lakes. It may seem that bodies of water are isolated when in fact they are not. Floods are a good example of how migration can happen, and many freshwater plants and animals have adapted ability to sufficiently travel. There are a few lakes that follow the same rules of an island. How is a lake able to stay isolated long enough in order to house distinct variety of life forms?
Why is it that islands exposed to the outside world, their life forms are driven to extinction? Shouldn’t the plants and animals living on the island be better adapted than the outsiders.
Humans themselves are great at exploiting a new territory. Soon many products of evolution will disappear. If all the products of evolution disappear on so-called islands of isolation, how would one be able to notice evolution?
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-Why is it that islands exposed to the outside world, their life forms are driven to extinction?
ReplyDeleteThis is most likely due to lack of genetic variation. Island populations have less genetic variation then the populations located on the nearest mainland (264). This increase in genetic variation allows for superior potential for alleles being present in invading population to allow for its individuals to adapt to the environment better, even better than those who have been present and adapting to island life for much longer. It would only be a matter of time.
-Humans themselves are great at exploiting a new territory. Soon many products of evolution will disappear. If all the products of evolution disappear on so-called islands of isolation, how would one be able to notice evolution?
I don't think that evolution's products will ever disappear and there will always be “islands of evolution” even if all current islands were literally to disappear. Bodies of water are an easy example to demonstrate both points. Large bodies of water, like oceans and seas, offer multiple barriers, including water temperature and depth, reefs and ridges, that prevent migration between different niches that these features help form. Oxbows in rivers are also constantly (albeit slowly) moving to isolate future lakes and islands. Islands, due to their isolation, make it easier to study evolution, but Jones provides numerous unconventional examples of evolution occurring all around us in the everyday world. His example of the alloy-resistant grass was particularly fascinating and very relevant to the question posed about humans exploiting new territory. Humans will eventually exploit every inch of the globe, or at least every inch that we deem worthy of exploiting, and this will force the globe to adapt, and therefore evolve, to our presence.
It seems to me that by exploiting every inch of the globe, we are in a sense creating one giant island that is highly specialized for human exploitation. Up to this point, we have been applying the laws of natural selection to only the inhabitants of Earth. Given all of the discoveries and advancements of our knowledge of life and its potential otherworldly "origins", what impact would such a specialized planet have on a much grander scale? Do humans have the ability to keep up with natural selection so that the globe will adapt to our "presence?"
ReplyDeleteI agree with Anthony on the idea that thre will always be new islands of evolution because humans, although we are still peaking out on our population, are very vulnerable to selective pressures. It is for this reason that humans stand the likely chance of losing their position on top of the pile. Just ask a teenager if they have ever used a screw driver or ever washed dishes by hand.
What hasn’t been explored here yet and is relevant for the creation and evolution of new forms on all our “islands” is the presence of some kind of barrier. Whether that exists as a body of water or climatic range or geological impingement, it is apparent that species are always on the move and will always find ways to do so when given the chance. If not, they will keep evolving or die. This, of course, explains why the rarest plants and animals are found in the remotest areas of the world. A breach of barrier will change an entire ecosystem. Another example we could use is the difference in the physical characteristics of humans. Enough time passed with human groups separated that alterations started to take place. What were are barriers? Without mass migration, innovation, and transportation, how different would we all look today?
ReplyDeleteIn continuing on Emily's discussion on barriers and diversity in remote areas, not just on islands, here is a relevant link to new species that have recently been discovered in the Greater Mekong of SE Asia:
ReplyDeletehttp://www.worldwildlife.org/who/media/press/2009/WWFPresitem13787.html?intcmp=208
The World Wildlife Fund does politicize the new findings by their relation to human-created climate change (and the subsequent disappearance of such new findings in the future) and it does bring up some interesting points about human agency in global climate change, as Anthony and Zach also bring up. Such natural barriers that have allowed these creatures (such as the fanged, bird-eating frog) to evolve unimpeded to where they are today are being dismantled due to climate change noted in the larger ecosystem in which they are a part of.
However, with climate change evident and looming extinction for these creatures with specialized ecological niches, does this allow for new adaptation to occur for these species in order to survive in new conditions? Or are such isolated pockets like this a relic of the past towards more a more homogenized world with species fulfilling specific niches based on our agency?
Building on what Anthony in regards to islands exposed to the outside world coming into contact with previously isolated islands. I think that alot of it may have to do with the introduction of new species onto an island and then leaving native species with no where to expand.
ReplyDeleteIf for example you consider invasive species that have been released onto Australia, such as rabbits, they are able to exploit the resources more effienciently than the natives, and coupled with an area that has no natural predators for a given species theire populations explode. This in turn drives the native species into extinction.
I think that this happens in many other ways as well, like Jones pointed out with his water way example, some species are just better adapted for their surroundings and given a chance will expand into new territory.
The problems that this pose for modern times i think has alot to do with Humans. The increase in trade and the constant need for capitalism to expand to new markets and exploit new resources means that it is easier for invasive species to travel, like the zebra mussels in the great lakes "hitching" a ride in ships.
Given that I think it may become increasing harder to find intact "islands" that clearly illustrate the processes of evolution the way that the Galapagos islands did for Darwin. However, I do think that this process still illustrates one of the major driving forces behind evolution, that of extinction. Be able to recognize that some species are just better adapted to a given set of conditions than a native species, in my mind, puts to rest the "theory" of intelligent design. When you really think about the way these processes play out there is no possible way that the species on earth were designed to fit perfectly into their given niche, if that was the case extinction would not occur because native species would be the best adapted for their own surroundings.
Returning to the topic of geographic distribution and it impact on evolution, I again think that Jones illustrates the point best when he discusses the barriers that are present within the natural landscape (swimming elephants....i didn't know they could even swim, let alone up to thirty miles....sorry side note), these barriers to me seem to represent a cage like effect. If you think about caged animals that are able to breed with one another within their own cage it descreases variablilty and selects for features that are most advantagous for that given area. However if he cage is opened whichever species is better equiped to handle the new landscape will ultimately be more successful reproducing and exploiting the areas resources.