Download evolution 1415 - Cobb Learning

Evolution…Whatz Up Wit Dat?
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Evolution is change. Galaxies, languages, and
political systems all evolve.
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Biological evolution- change in the properties of
populations of organisms that transcend (are
bigger than) the lifetime of a single individual.

Individual organisms do not evolve…they can
change…that’s different. Species evolve.
Evolutionary Changes are…changes in
populations that are inheritable through
passing of genetic material from one
generation to the next.
 Can be minor or BIG.
 Everything from slight changes in the
amounts of different alleles within a
population, all the way up to…
 …changes that led from the earliest life
forms to worms, fish, lions, and tulips.

Evolution is simply species changing.
 Sometimes it’s gradual (GRADUALISM).
 Sometimes it’s fast (PUNCTUATED
EQUILIBRIUM).
 One mechanism of evolution is natural
selection (cause and effect...right?).
Natural selection causes species to evolve
(just like tectonic activity causes
continental drift).
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Applying Natural Selection
1.
2.
Discuss the relationship among genetics,
natural selection, and evolution.
Construct a scenario wherein a
population of organisms (any type you
want) is acted upon by natural selection.
Be sure to discuss all four mechanisms.
Yeah…I know it’s hard; you’re gonna
have to actually think.
Who Is This Darwin Dude?
Well, he was a naturalist who made some
cool observations (remember those) in 1835
while visiting the Galapagos Islands (off the
western coast of South America…Ecuador
to be specific).
 He saw that certain flora (plants) and fauna
(animals) in the islands were slightly
different than those on the mainland.
 Examples: Finch beaks, Tortoise shell
shapes,

He hypothesized that geographic
separation had prompted these critters
to change over time as a response to
the environment in which they lived.
 He didn’t know about
genetics…Mendel took care of that
piece of information in the 1840’s.
 How? Well…Natural Selection…which
we’ve discussed (Overproduction,
Variation, Competition, & Selection).
 We now have modern evolution.

What is Natural Selection?
Ok…we have this concept called
NATURAL SELECTION…right?
 That states that critters that are better
equipped for survival have a better chance
of…(you tell me)?

 That’s
pretty straight forward isn’t it?
I mean, imagine you’re in a soup
eating contest (just do it ok!). You
have a fork and your buddy has a
spoon…you ain’t gonna win that
contest.
 Natural
selection works in the
same way only the winner lives,
and the loser…well…I don’t
wanna talk about it.
 Let’s
look at what affects this process.
1.
Overproduction: This refers to the way
many organisms produce waaaay more
offspring than can survive.
2. Competition: Food and other resources
are limited, right? Offspring compete for
this stuff to survive. Competition is
usually indirect (they don’t
have…like…ultimate cage matches for
food), and only a few offspring survive
long enough to reproduce.
3. Variation: members of a species
differ from one another with regard
to certain traits. Differences
between individuals of the same
species is called VARIATION.
4. Selection: Some variations make
certain individuals better adapted to
their environment. Those individuals
are more likely to survive and
reproduce.
Ok, so its like this…When the individuals
that are better adapted reproduce, their
kids may inherit the allele for the helpful
trait (ok…plants don’t have “kids,” but you
get the idea).
 The kids, will be more likely to survive and
reproduce…cuz they gotz the good genes
(alleles) for the good traits right?
 The kidz can pass on the allele to their
kidz.

 After
a bunch of generations, more
organisms within the species will
have the helpful trait.
Over a long period of time, natural
selection can lead to evolution.
 How? Beneficial variations gradually
build up within a species, while
unfavorable ones disappear.
 This lab we do on Monday will
demonstrate how this happens.

Darwin…did he act alone?
Well…he did but there was another
dude acting alone at the same
time…Alfred Russel (don’t call me
Russell) Wallace.
 Wallace was an admirer of Darwin and
texted him to say that he figured out
the whole natural selection thing.
 And then Darwin was all like…oh no
you didn’t 
 Yes…he did!

More Darwin Stuff
So anywaze…Darwin and Wallace
presented their findings on the same day
at the same meeting.
 Darwin wrote a book though (1859): On
the Origin of the Species by Means of
Natural Selection…so he got the cred.

Darwin’s Galapagos Vacation

The Galapagos Islands.
It was a balmy Friday afternoon on September the
twentysomethingteenth, 1835…ok…I have no idea
what day it was or whether it was balmy or if
porcupines were falling from the sky…although that
would’ve been pretty cool IMHO.


Anyway…October 1835…Darwin lands on the
Galapagos Islands (which are where…?).
He spends five weeks there. Nice! So, besides
windsurfing, parasailing, and shopping…he’s
doing the naturalist thing. You know…one of
those eco-tour things. Not nearly as trendy in
1835.
Darwin’s Finches
Whilst doing the naturalist thing
(actually…when he got home), Darwin
collected some birds (called finches). He
thought that they were the same, but
although they were closely related, they
were actually different. This catalyzed his
development of the principle of natural
selection.
 What Darwin had observed was…

Speciation



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Changes in closely related organisms that result
in enough of a difference to be classified as a
separate species.
This happens when populations of one species
are geographically isolated and each must adapt
to its new environment.
Speciation that occurs in this way is called
ADAPTIVE RADIATION.
In the case of the finches, their beaks developed
differently depending upon the food sources
available in their specific geographic location.
Peppered Moths
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First you’ll need 3 lbs of moths with wings
2 Tbs Olive Oil
¼ cup lemon or lime juice
4 Tbs coarsely ground black pepper
…but seriously folks…we’re now
discussing INDUSTRIAL MELANISM
 This is an example of
Polymorphism…whhaaaa? Relax…it’s a
big word that means many forms.
So…when a species is found in two
distinctly different groups (but is still the
same species), that’s polymorphism.

The peppered moth has changed its
appearance since the beginning of the
industrial age.
 In the 1800's, soot would collect on the
sides of buildings from chimneys and
factories and make the buildings darker in
color.
 The moths were originally light colored
and were pretty easy to see…happy,
happy birds (if you like to eat
moths…happy you)!
 A mutation which caused darker coloration
occurred and it was beneficial…if you
blend in, you’re tougher to find and eat.
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