Succession_and_Naturalization

Week 3 CheckPoint: Succession and Natural Selection 1. View the succession of the ecosystem in the Succession Animation. Is it primary or secondary succession' Explain your answer. The succession of the ecosystem in the Succession Animation is both primary and secondary succession. I say primary succession because primary succession is when development begins on an area that has not been previously occupied by a community, such as a newly exposed rock or sand surface, a lava flow, glacial tills, or a newly formed lake such as when the beavers damned up the stream. By doing this, the beavers caused a pond to form thus killing out the trees and old vegetation. As time progressed new vegetation formed, then trees, which eventually caused the pond to dry up and become a stream once again. I say secondary succession because secondary succession arises on sites where the vegetation cover has been disturbed by humans or animals (an abandoned crop field or cut-over forest, or natural forces such as water , wind storms, and floods), such as when the beavers cut down the trees to make the beaver damn. Secondary succession is usually more rapid as the colonizing area is rich in leftover soil, organic matter and seeds of the previous vegetation. As the Succession Animation video progressed new plant life replaced old plant life which came from the organic matter and seeds left from the previous vegetation. 2. Although most salamanders have four legs, the aquatic salamander shown below resembles an eel. It lacks hind limbs and has very tiny forelimbs. Propose a hypothesis to explain how limbless salamanders evolved according to Darwin's theory of natural selection. For my proposed hypothesis to explain how limbless salamanders evolved according to Darwin’s theory of natural selection, I chose the variation method. I chose this method for my hypothesis to explain how limbless salamanders evolved because the variation method shows how species become reproductively isolated from each other by adapting to their different ecological environments and eventually become a separate species. According to the variation method, by adapting to their environment, the aquatic salamanders had an advantage in staying alive long enough to successfully reproduce and pass on their traits to the next generation. As their traits became more common, the population of the aquatic salamanders evolved.