The example on where varies places grapes can grow would seem that alternate places can, given the chance, will support identical forms of life. However, grapevines that produce wine may look and taste the same, but are in fact distinct. Why does evolution drive species to be distinct even if the land regions are identical? Are there certain barriers, past or present, that have influence distinct species, and if so are they the major driving force behind natural selection? Are there ways to get around a barrier? Do you think humans can influence the laws of life in order to produce the same species in identical land regions?
Why do you think there are twice as many left shoes as right shoes washed ashore in Holland?
Water is affected by climate change, which in turn affects migrations of plants and animals. Throughout the history of the planet there have been several cooling phases and warming periods. Today a few of the environmental issues are the green house effect and depletion of the ozone layer. It has been manifested that humans and their pollution have affected the ozone layer, causing further warming of the planet. Do you think that human involvement is affecting the outcome? Or is Earth following its usual course of moving between warming and cooling periods.
“There is a striking parallelism in the laws of life throughout time and space: the laws governing the succession of past times being nearly the same as those governing at the present time the differences in different areas (2360.” Why does the southern beech tree of South America have close kin in Australia, in South Africa, Antarctica? The land itself is on the move rather than the ocean. The information on the theory of Pangaea can be found on the first two websites.
http://library.thinkquest.org/17701/high/pangaea/
http://pubs.usgs.gov/gip/dynamic/historical.html
The following link talks about Pangaea today. This is their mission statement: In a world where people are often divided by borders, difference, and conflict, it's easy to lose sight of what we all have in common. Pangea Day seeks to overcome that and to help people see themselves in others through the power of film.
http://www.pangeaday.org/
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Jones talks about plants being confined to their native habitat because the are constrained by geological barriers that prevent them from exploiting other similar ecological niches. There for the other indigenous life forms have to opportunity to adapt to the changes in their own habitat. The genetic makeup retains it uniqueness because it has no influx from other species competing for a similar niche. The surface traits are similar because it is a response to what the environment or selective pressures call for. For instance, if a plant is selected for having spiny branches, and it is within its genetic capabilities, different regional ecotones will reflect similar pressures and as a result those species will arrive to similar traits.
ReplyDeleteHumans have the ability to create artificial ecotones, but as the Biosphere experiment suggests, there are many variable that contribute to the delicate balance of an ecosystem. If a single species is even reduced in population to a point where they can no longer hold their own, other species are more than willing to take control and dominate. Take the Western United States for instance. Most people today view the Northwest as a lush, green region full of Ponderosa Pines, Firs, and other coniferous trees. Prior to Western influence much of the region was recorded in early ethnographic documents as a region of oak stands and rolling valleys dominated by grass meadows occasionally punctuated by conifers. It wasn't until the area was exploited that it allowed for the balance to be upset and conifers invaded and capitolized on the change in pressures. This is also an example of human influence on the selective forces.
The earth's record does indicate periods of warming and cooling. On the other hand, the industrial revolution and the last hundred years in particular have without a doubt changed the environment in which we live. It is not to say that other species haven't drastically affected global climate change, but what we do have is the rate of change that humans have enacted upon the landscape. Just as we have artificial selection as a counterpart to natural selection, we also have artifical forces changing the environment that we have become so adapted to. What new adaptations will humans have, or will we create them artificially to retrofit our now obsolete bodies? I am voting for robot legs and x-ray vision myself.