Answer the questions below by writing five to ten sentences for each question. 1

Question

Answer the questions below by writing five to ten sentences for each question.

1. The ancestor of penguins was a bird that could fly. Based on the habitat that penguins are living in today, how would you expect selection to have modified phenotypic traits in the lineage leading to penguins? What are traits evolution may not have been able to change? What are traits that may not have needed to change? Why?

2) In class, we discussed how whales are aquatic, despite having terrestrial ancestors. One evolutionary constraint that they face is having to breathe air. Think of another organism and an example of an evolutionary constraint that limits their adaptation to their habitat. (Choose any habitat except the ocean!). What is the constraint? How does it limit them in that habitat? What is another species that doesn't face that constraint?

3) Environments around the world are changing rapidly due to humans' effects on the planet. What is an example of a way that a species could be evolving in response to human-mediated environmental change?

Explanation / Answer

1. It is suggested that distant ancestor of modern day penguins could fly. It is found from research that as the ancestor of modern day penguins saw that more food was found in sea than in the sky, they slowly adapted to dive. Their wings became shortened and flap shaped and the feather coat became denser than before. So, the wings slowly modified in the Penguin lineage. This adaptation ocurred to suit in the aquatic marine environment. Since, they are birds complete loss of wings was not possible. Presence of a beak need not change, since it would help them to catch animals.

2. Whales have to come to the surface of water to breathe. As they are placental mammals, so possibly they could not develop gills like the fishes and mammals are higher in evolutionary cascade than whales. One example of limiting adaptation is that of the hens and cocks which can not fly much and so sometimes it becomes difficult for them to escape from cats and dogs. Most of the other birds do not face this problem. There is no constrain for them.

3. One example could be the evolution in mosquitoes which have developed the resistance to many mosquito repellants. As their, generation time is very short compared to humans, excessive use of mosquito repellant have induced changes in their resistant power.

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