Transcript 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.
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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.
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Evolution is simply species changing.
 Sometimes its gradual (GRADUALISM).
 Sometimes its fast (PUNCTUATED
EQUILIBRIUM).
 It is always GENETIC!
 The 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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Who Is This Darwin Dude?
Well, he was a naturalist who made some
cool observations (remember those) in 1831
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,
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He hypothesized that geographic
separation had prompted these critters
to change over time as a response to
the environment in which they lived.
 How? Well…Natural Selection…which
we’ve discussed (Overproduction,
Variation, Competition, & Selection).
 He didn’t know about
genetics…Mendel took care of that
piece of information in the 1840’s.
 We now have modern evolutionary
biology.

Natural Selection…da KEY!
This is the process that explains how beneficial traits accumulate within
populations and speciation* takes place.
Speciation: When one species splits into two new species…that called
speciation. That’s a really simplified version, but…just go with it for
now…okay?
Four Mechanisms of Natural Selection:
1.
Overproduction-Within a population, more individuals will be
“born” than will survive to reproduce.
2.
Variation-Within a species, not all individuals are identical (look
around).
3.
Competition-organisms within populations compete for limited
resources (nutrients, water, space, and mates).
4.
Successful Reproduction-indivuduals with beneficial traits will
compete more successful for resources and will have a better
chance for reproductive success…passing these beneficial traits to
the next generation.
Geographic (aka Allopatric) Speciation- This happens
when a population is split and develops in different
places with different conditions. The traits beneficial in
one place may not be helpful for survival in the other
place…over time…the beneficial traits accumulate. One
set in one place…another set in the other place.
Eventually the two groups differ enough so as to no
longer be considered the same organism.
There are other types…check ‘em oat iffin’ you wanna…
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Peripatric Speciation
Parapatric Speciation
Sympatric Speciation
Reproductive Isolation
Cospeciation
See? There’s way more to this than we could possible learn in a couple of
weeks!
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.
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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.