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Help me with some questions pls :)

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Help me with some questions pls :)

Postby vomer » Mon Jun 30, 2008 11:28 pm

Hi guys,

I am new here but really like the good helping community so far... I have a few questions to ask

My first question is

Bipedalism in humans when compared to quadrupedalism in the great apes represents ?

a convergence
ORRRRR
a derived trait

I personally think it is a derived trait but I need that confirmed with someone :)

My next question is :

Based on this diagram I need to answer some questions :

Image

1) name the outgroup.... I think that would be FISH?
2) Draw a solid line around a monophyletic clade....I am having trouble with this one...
3)List the shared derived characters in order of evolution leading to humans.
Would it be : leg, metabolism, hair/fur, thumbs,tail loss, bipedal ???

4)Name 2 organisms showing analogy or convergent evolution and explain your reasoning.

Would it be cheetha and manx cat? i am not sure if it is that and how to explain it...

Well thats all the questions i have for now :oops: Kindly help me out...im trying to learn as we go :)
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Postby MrMistery » Tue Jul 01, 2008 10:30 am

right on the first question
on the second
1) right
2) should include a common ancestor and all its descendants.
3) right
4)should be 2 organisms showing the same trait but which has evolved independently in both
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Re: Help me with some questions pls :)

Postby vomer » Thu Jul 03, 2008 6:00 pm

so for

2) I draw a solid line around the common ancestor and fish?

and for

4) would it be minx cat and monkey because of tail loss? Sorry i am not sure about these two

Lemme know please :)

Thanks
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Postby mith » Thu Jul 03, 2008 6:08 pm

Living one day at a time;
Enjoying one moment at a time;
Accepting hardships as the pathway to peace;
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Re: Help me with some questions pls :)

Postby DrD » Thu Jul 03, 2008 7:18 pm

Dear Vomer,

First, congratulations: only a true-to-the-bone biologist would take the name of a bone as a pseudo :D

Now lets get down to business :

vomer wrote:so for

2) I draw a solid line around the common ancestor and fish?

and for

4) would it be minx cat and monkey because of tail loss? Sorry i am not sure about these two

Lemme know please :)

Thanks


2) No, sorry.

A monophyletic group (also known as Clade, which means that "monophyletic clade" is a pleonasm) contains a common ancestor and ALL of its descendants.

If you take the deepest ancestor in this tree but only fish then you create a paraphyletic group (a common ancestor and PART of its descendants)

4) Trust Mr Mystery, he gave you the correct definition of convergent evolution. And trust yourself too. If you apply the definition he gave you (which you have done), then why doubting your answer ?

Another remark on this tree (which is obviously outdated but that is not your fault it is that of the manual) is that neither FISH nor REPTILES are monophyletic groups. Fish are now notoriously polyphyletic (they are a hodgepodge drawn from several different clades) and reptiles are paraphyletic, otherwise birds would have to be included in reptiles.

Since you do not mention your study level, please excuse me if I go too far in my explanations and please do not challenge your teacher about the paraphyly of reptiles, he/she does the best he/she can with the manuals you have to use.

Cheers

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Postby MrMistery » Fri Jul 04, 2008 9:40 pm

most books now incorporate birds into reptiles. Some differentiate between reptiles and the Sauropsida(reptiles+birds)

@Vomer
I gave you the definition of a monophylectic group. I said take A common ancestor, not what is listed there as "common ancestor". For example, if you take monkey, gorilla and human on your drawing you would provide a correct answer.
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Postby vomer » Sat Jul 05, 2008 1:32 am

thanks guys, explinations espicially helped a lot!
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Re: Help me with some questions pls :)

Postby Quasarsphere » Thu Oct 30, 2008 10:33 pm

DrD wrote:A monophyletic group (also known as Clade, which means that "monophyletic clade" is a pleonasm) contains a common ancestor and ALL of its descendants.


Sweet, now I get what a clade is! Cheers! :)
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