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Because humans can shape their environment, they are not subject to pressures of natural selection in the same way as other organisms. While they may adapt and evolve, evolution will probably happen more slowly. For example, humans with very fair skin can now live in very hot, sunny environments: shelter, clothing, and sunscreen all help to protect their skin from the sun, so that they will have as much reproductive success as people with darker skin who are naturally adapted to such environments. Convergent evolution is when two species develop the same traits or features independently, even though their last common ancestor did not have this trait. An example of convergent evolution would be the opposable thumb of opossums, which is also found in primates but not in common ancestors. Divergent evolution is when a single species diverges to form two or more related species due to evolutionary pressures that cause different features to develop, or when two related species become more and more dissimilar. An example of this would be the red fox and the kit fox. The kit fox is adapted for a desert environment, with a sandy color for camouflage and large ears to dissipate heat. The red fox’s color helps it to blend in with trees and dirt. Adaptive radiation happens when a species colonizes a new area with many unfilled niches. The species quickly adapts to form many subspecies with different traits that allow the species to survive across many areas of the ecosystem. For example, in Lake Victoria, a very deep lake in Central Africa, cichlids evolved from one species to 300 in about 15,000 years (“Adaptive radiation”, n.d.). Co-evolution is the change in one species in response to a change in another. For example, the garter snake, a predator, has evolved a resistance to nerve toxins that the Rough-skinned newt (Taricha granulosa) produces in its skin. The newt, in response, has adapted more and more toxic poisons (“Co-evolution”, n.d.). An impact of adaptive radiation for future humans is that human destruction of species and environments may open up new niches, or introduce species to ecosystems they did not previously occupy. Previously non-invasive species may adapt to become invasive and may over time become as damaging as current invasive species such as kudzu and fire ants. For example, in Hawaii, there is a crisis of invasive species, and Hawaii, as an island chain, is the perfect environment for adaptive radiation to take place. As the invasive species crowd out native species, niches will be left unfilled (Loope & Canfield, 2000). The invasive species may then adapt to fill the niches even more effectively. Adaptive radiation. (n.d.). Retrieved December 13, 2008, from Wikipedia: http://en.wikipedia.org/wiki/Adaptive_radiation Co-evolution. (n.d.). Retrieved December 13, 2008, from Wikipedia: http://en.wikipedia.org/wiki/Co-evolution Loope, L. & J. Canfield. (2000, July/August). Hawaii: A model for addressing invasive species. People, Land, & Water. Retrieved December 13, 2008, from http://www.usgs.gov/invasive_species/plw/hawaii01.html