MT Prep - Friction is a Force

The topic of our text today is F.R.I.C.T.I.O.N --

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Remember with a pencil - take notes!

Comments on the Finches + GAME at the end of the post

"A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question. "

Charles Darwin

 So let's think about our experiment in class yesterday--modelling natural selection with spoons and scissors and macaroni and toothpicks and a bunch of other stuff.  What did it mean, and also what did it not mean?
Here is a shortened version of an article from this site, Truth in Science, which you or your parents might appreciate for a fuller discussion.

Darwin's Finches

Galapagos finches showing different beak shapes

On the Galapagos Islands in the Pacific Ocean, close to the equator, there are a variety of different finches, which vary in the shape and size of their beaks. It appears that the  finches colonised the Islands from mainland South America, and then diverged in form. The distance between the islands meant that the finches on different islands could not interbreed, so the populations on the different island tended to become distinct. Different populations also became specialised for different food sources, birds with thin, sharp beaks eating insects and birds with large, sturdy beaks eating nuts.

Darwin collected some of these finches when he visited the Galapagos Islands, and it is often stated that the finches were key to the development of his theory of evolution. They are used as evidence for his theory in many textbooks.

Were the Finches important to Darwin in formulating his theory?

When he was on the Galapagos Islands, Darwin did not notice that different islands had different finches. Neither did he realise that the finches were closely related despite their differences in beak shape. He did not match different beak shapes to different diets. Even after his return to London, Darwin's biographers note that he "remained confused by the Galapagos finches...unaware of the importance of their different beaks...He had no sense of a single, closely related group becoming specialized and adapted to different environmental niches." (p. 209, Darwin - A. Desmond and J. Moore).

So all Darwin did was speculate that the different finches had descended from a common ancestor and had changed to be able to do different things. He was never sure that the different species were from different islands. He certainly never came up with the detailed theory for how the finches diversified which the BBC suggests. ...


What do the Finches demonstrate about evolution?
Though the finches were not important in the work of Charles Darwin, they do tell us something about evolution. In particular, over the past few decades, two scientists have done an excellent long term study on the finches on one of the Galapagos Islands. This is accurately described by the textbook Advanced Biology. (Jones, M., and G. Jones. 1997. Cambridge University Press) The authors recount how from 1977 to 1982 there was a drought on one of the Galapagos Islands, and due to natural selection the average finch beak size became larger…

However, this proved not to be the end of the story. If it continued in this way, the average beak size of G. fortis would continue to get larger and larger. But this has not happened (p. 153)

This cumulative change does not occur for two reasons. (1) There are disadvantages to having a large beak, especially when a bird is young. This can outweigh [no pun intended!] the advantages. (2) The selection pressure on the island fluctuates. In 1982 the drought stopped and there was selection for birds with small beaks.

It can therefore be argued that the study shows natural limits to evolutionary change. Variation in a species is a good thing, as it gives them the ability to cope with environmental change, but variation does have limits.

Many textbooks do not go into such detail, and simply describe the finches as a good example of a range of species evolving from a common ancestor.

The Galapagos finches afford an excellent example of adaptive radiation. It is assumed by evolutionists that a stock of ancestral finches reached the islands from the mainland and then, in the absence of much competition, evolved to fill many of the empty ecological niches occupied on the mainland by species absent from the islands.” (p. 725) Advanced Biology. Roberts, M., M. Reiss, and G. Monger. 2000. Nelson

Conclusion
The Galapagos finches were not as important to Darwin as is often claimed, but they are a good example of micro-evolution. They show us that finches can vary in their morphology [shape], and that natural selection has a role in this.

This study does not give evidence for macro-evolution, and does not prove that natural selection and random mutation could produce the living world as we know it from simple single-celled ancestors.

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So here is a fun interactive that sums up what natural selection is--NOT NECESSARY to AGREE or to draw a conclusion--simply to understand the idea.
Who Wants To Live a Million Years? Game click here
Read, and then play the game until you can consistently win.

Biodiversity, Current Events, and (ouch!) Natural Selection

Biodiversity Research Project - from last week - If you didn't do this yet, compete it now, and be ready to share on Thursday. (for instructions, look at last blog)

Other than that, here is a 10 minute video you might find fascinating; it is about wooly mammoths, and the possibility of un-extincting them by reconstructing their DNA.  How cool would that be!  (?)

For an explanation of Natural Selection,  an 8-minute video by Stated Clearly.  I appreciate that the narrator makes a distinction between "descent with modification" and "common descent"--something I will go over  next class--and the difference between facts  and conclusions. If  you or your parents are concerned about this topic, I understand people have strong feelings about this, and I respect that. This subject requires much thought and discernment.

If you would rather skip the video, do another short report like the last (see Thursday's blog)

 

New Subject: Biodiversity, Meaning LOTS & LOTS of different kinds of animals!

What did I say an ADAPTATION was? --an inherited trait which enables an organism to "fit" into its environment.  It could be camouflage (spell that!) or long legs or sneezing salt, or something much weirder.  Here is an animal that is so crazy I cannot even imagine what all those features are for--the mantis shrimp--Why the Mantis Shrimp Is My New Favorite Animal       


Anyway, here's the real homework:

1.Read the handout from class (one page) 

2. A short research paper: Choose a small animal, like an ant, a frog, a barnacle, a beetle, etc. Research it on the Internet.  These are the questions you should answer:

1. How many different species of [ants,beetles,frogs...] are there in the world?  (Just Google the question, How many species of ant are there in the world?)

2. And where are they found? What types of habitat?

3. Find pictures of 5 of the species.  Copy and paste them onto a Word document.  (Ask your older brother or sister to help.  Or your mom...)

4. Find examples of adaptations that those species have which enable them to fit or survive in their own environment.  For example, of the 10,000 different species of ants, one kind of ant, called a citronella ant is brilliant yellow and emits a strong lemony odor which is expelled from a gland in its head to warn nestmates and drive off enemies.  They are nearly blind and live underground.

Citronella ant

 

Digging Deeper with DNA

How do pirates make proteins?  With Aaaarrrh-NA.  (just a little Harmon family humor.) Get it???

OK< Class was fun; good work on your models. On to the homework: more videos:)

Brainpop.com >>>  pcshome / ilearnathome
Just movie, quiz and FYI

http://www.brainpop.com/health/bodysystems/immunesystem/

http://www.brainpop.com/health/diseasesinjuriesandconditions/vaccines/

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But wait, there's more!

Self-Assembly: The power of organizing the unorganized


And....More Pirates...
RNAi Discovered

RNAi Therapy

 

Viruses: Little Bits of Pirate DNA

Next class we will be making models of viruses, which are little bits of rogue DNA or RNA surrounded by a protein coat which wiggle their way into cells.  They hijack the machinery of the cells to make copies of themselves, then they blow up the cells and escape to infect more cells, and so on and so on.  So for background, here is some Brain.pop to clue you in:


First, a review of RNA:
login:  pcshome   ilearnathome
http://www.brainpop.com/science/cellularlifeandgenetics/rna/
Print/copy out activity page (vocabulary) and either write down what the words mean or draw it.  Watch the movie, take the quiz and read FYI.

Then, the Virus:
http://www.brainpop.com/health/diseasesinjuriesandconditions/viruses/  Print/copy out activity page (vocabulary) .  Watch the movie, take the quiz and read FYI.

A few shorties: 

 

 

By the way, I just wanted to say how much I respect the level of attentiveness and seriousness this class generally gives to their studies--I loved the reports I got to watch.  HOWEVER, PLEASE DISCOVER THE PENCIL POUCH, AND NEVER AGAIN TELL ME YOU DON'T HAVE A PENCIL!  (pens are cool too.)

You Knit Me Together...

  Now that we have extracted DNA from strawberries, split peas and broccoli, can you agree with me that DNA is amazing and beautiful?  How about just amazing??  Every living thing has DNA, which stores the information to copy itself, to make new proteins and to direct the activities of the cell.

On Monday we will finish our unit on DNA by watching some videos that will put it all together for us--DNA in ACTION!  And we'll take a look at how our technology has been revolutionized by the discovery of Watson & Crick  back in 1953, when they walked into a bar and said, "We've found the secret of life!"

Homework is to complete the Chapter 4 review (not section review, but the questions at the end of the chapter.) 

By the way, has anyone seen my copy of the textbook? It  has "teacher" written on the sides.