Wednesday, September 12, 2007

Natural selection

Hi guys, yesterday in class we learned about natural selection. Well what is natural selection? It is the process by which favorable traits are inherited and passed down from generation to generation. In other words, it helps them to survive better, hence the phrase "survival of the fittest." Well natural selection is helpful in predation, physiology, and sexual selction.



Predation selection

The preying mantis is a perfect example of predation selection. The preying mantis has blended in with the leaves. This enables it to remain hidden so it can catch prey easier. Isn't that amazing!!




The fastness of a cheetah is also due to natural selection. By running fast, it is able to catch its prey. The extremely long legs also help it to run fast enough.


Physiological selection
When the Antarctic ocean had frozen over, some of the fish had developed an anti-freeze like chemical in their body. This helped them to survive in the cold waters of the Antarctic Ocean. This anti-freeze like, ice-binding chemical was then passed on to the next generation.


Sexual Selection
This is the ability to attract mate and maintain a successful rearing of offspring. Males in the animal kingdom show spectacular displays to attract female mates. Lets have a look:





Ever wonder what a lion's mane is for? It for attracting females duh!!








The peacock is another example. The peacock is using his beautiful display of feathers to attract mate. Its so beautiful!!




This was yesterday's lesson. Well if you guys have any questions feel free to ask me!!

3 comments:

KB Foglia said...

Good job, Muskan!

I have one clarification & some questions for the class.

CLARIFICATION
Rather than saying "...natural selection is helpful in predation, physiology, and sexual selection" it is more accurate to say "natural selection can be classified by what facet of a creature's life it is acting on." Remember, there are two parts to evolutionary success: survival & reproduction. So any trait that gives an individual an advantage in either has the potential to be a selecting agent:

predation selection -- includes any trait that allows you to escape predation or to capture prey better

physiological selection -- includes any trait that enables the body to work more efficiently or more successfully, like making energy more easily or surviving disease better.

sexual selection -- includes any trait that allows you to reproduce more like attracting mates more or rearing healthy young more.

QUESTIONS
1. Does a male lion know a darker, longer mane attracts more females?
2. Does a female lion know a darker, longer mane is a good measure of fitness in a male?

Ryan said...

hi, nice job, i did my homework!..this part atleast

Dan said...

1. Does a male lion know a darker, longer mane attracts more females?

No. Natural selection has nothing to do with what the organisms want. Instead, the male lions who happen to be born with longer darker manes will attract more females, and have a better chance to reproduce more often. Therefore, the trait for a longer and darker manes show up in population more as generations pass.
2. Does a female lion know a darker, longer mane is a good measure of fitness in a male?

No. As stated in the previous answer, natural selection has nothing to do with what the organisms want. The traits that control a female lions "desires" may happen to make one individual mate with a lion with a darker and longer mane. Therefore, their offspring survive more often because of the protection from their Papa, and the future generations will have a greater frequency of lions with this selective trait.