Succession and Natural Selection

2.     CheckPoint: Succession and Natural Selection

 

         View the Ch. 6 Succession animation located under the Week Three Materials section of your student Web page.

         Post a total of 200- to 300-words in response to the following items:

 

o    View the succession of the ecosystem in the Succession animation. Is it primary or secondary succession? Explain your answer.

o    Respond to question 9 under the Critical and Creative Thinking Questions in Chapter 6 of the text. Review Ch. 6 on natural selection to help you with your response. If you need additional help with your hypothesis, refer to the following article to see an explanation of how evolution could have occurred in a population of mussels: http://evolution.berkeley.edu/evolibrary/news/060901_mussels

9.  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(158).

The succession featured in the animation is an example of secondary succession. Primary and secondary succession differ in that primary succession is a change in species composition that takes place where there was no soil or vegetation present; Secondary succession is a change in species composition due to some disturbance that destroys existing vegetation and that takes place where there was soil present. The animation showed an already existing forest and small river where beavers made a damn in order to create a pond for their home. This caused a pond to form, the trees to die and new vegetation to grow. With a bog mat forming across the top of the pond and peat growing on the bottom of the pond, over time trees begin to grow again. The end of the animation shows a bog forest and stream where the forest and stream existed before the beavers built their damn. This shows secondary succession, the change to the forest was because of the beavers building their dam.

Darwin’s theory of natural selection basically says the more capable or better equipped species will survive. This includes the same species with genetic differences. The salamander probably lived near water for generation, then a mutation happened and that salamander was better equipped at handling the water in his surroundings. So it prospered and reproduced, his offspring had the same mutation and they prospered. Being better equipped than other salamanders without the mutation, he would beat out the others of his species to food and shelter. This allowed him to live and his offspring to prosper.