high school college prep biology evolution power point

1. EVOLUTION!!!

2. Charles Darwin, 1808-
1882
WHAT ABOUT HIM???
born into a wealthy family
medical school drop-out - thought surgery
was “brutal”
his father pushed him into becoming a
clergyman and dropped-out of this as well
eventually followed his interests in ecology,
geology and taxidermy
author of “On the Origin of Species” - 1859,
provided evidence for evolution by natural
selection

3. SOME OF DARWIN’S
INFLUENCES…
Charles Lyell, 1797-1875 - “Principles of
Geology”, described landforms as the result of
gradual processes over time (Darwin saw
evidence of this on his voyage - bands of coral
fragments in volcanic rock)
John Henslow, 1796-1861 - botanist/geologist,
Darwin’s mentor

4. SOME OF DARWIN’S
INFLUENCES…
Thomas Malthus, 1766-1834 - “An Essay on
the Principle of Population”, proposed that if
the human population continues to grow
“unchecked” it would soon reach carrying
capacity…then what???
"In October 1838, that is, fifteen months after I had begun my systematic inquiry,
I happened to read for amusement Malthus on Population, and being well prepared
to appreciate the struggle for existence which everywhere goes on from long-
continued observation of the habits of animals and plants, it at once struck me that
under these circumstances favourable variations would tend to be preserved, and
unfavourable ones to be destroyed. The results of this would be the formation of a
new species. Here, then I had at last got a theory by which to work".
Charles Darwin, from his autobiography. (1876)

5. DARWIN’S VOYAGE
was selected as an unpaid geologist/naturalist
voyaged on the HMS Beagle
purpose of voyage was to chart the coastline of
South America over 2 years
Darwin collected fossils and living organisms
and took many notes
unfortunately…he was seasick for most of the
trip

6. WHAT DID HE SEE IN THE
GALAPAGOS ISLANDS???
Galapagos Islands - volcanic islands west of
Ecuador in the Pacific Ocean (16 islands - 5
inhabited), some are still forming
observed birds (later determined to be finches)
- similar in appearance with differing beaks
since these were islands, all of the birds were
assumed to have one common ancestor
each bird was adapted to eating a particular
food - seeds, insects, etc.

7. DARWIN’S FINCHES

8. EVOLUTION BY NATURAL
SELECTION???Darwin's theory (yes, you need to know this!):
within a given species, more individuals are produced than
can survive due to limited resources (food, shelter, mates)
as a result, there is a struggle for existence/competition for
limited resources
individuals within a species show variation - no two
individuals are exactly alike
those with advantageous traits have a greater chance of
survival, and therefore of reproducing
individuals produce offspring that tend to resemble their
parents (inheritance)
advantageous traits that promote survival are inherited by
offspring, so individuals possessing those traits will become
more common in the population over successive generations
because they are more likely than individuals not possessing
those traits to survive and reproduce

9. HOW DO ORGANISMS
ACQUIRE
ADVANTAGEOUS
TRAITS???
GOOD QUESTION!!!

10. WHAT IS EVOLUTION BY
NATURAL SELECTION???
Simply stated:
in nature individuals compete for limited
resources and based on those resources, nature
selects the best suited for the environment =
natural selection
let’s look at an example…
and another…
and another…
and another…

11. INDUSTRIAL
MELANISM

12. More on Darwin…
Natural selection…less wordy
more organisms are produced than can survive
there is competition for resources
those with favorable traits (depending on what
the competition is over) win the resource(s)
these are the organisms that survive and
reproduce (and make more like themselves)
favorable traits are the result of differences
between organisms
differences are the result of random mutations

13. TERMS TO KNOW
adaptation - change in a species that makes it
better suited for its environment
natural selection - “nature” selects organisms with
better suited traits to survive and reproduce, over
time organisms become better adapted
isolation leads to the development of new species -
when organisms are isolated and cannot breed,
they become more different over time

14. EVIDENCE FOR
EVOLUTION1. fossils - show a pattern of development, all
organisms evolved from earlier life forms
FYI…there are few “missing links” or intermediate
forms or transitional species
archaeopteryx is one of the few “missing links” - it
has both reptile and bird-like features

15. 2. biological molecules - comparing proteins and
nucleic acid sequences can reveal a common
ancestor
for example - comparing differences in hemoglobin (a
protein that carries oxygen in your bloodstream) -
more distant ancestors have more differences

17. 3. comparing anatomy can reveal similarities
homologous structures -similar structures, although
they may have different functions/are adapted to
different environments

18. analogous structures – similar function, but
occur in unrelated species adapting to similar
environments

19. 4. biogeography – studies locations of organisms
around the world
 closely related organisms can be adapted to
different environments that are nearby (ex.
– Darwin’s finches)
 unrelated organisms can have similar
adaptations to similar environments that
are far apart (ex. – Australia’s mammals
that resemble mammals in similar
environments but are unlike in that they
are all marsupials)

21. 5. vestigial structures - structures that have less
important/no function as compared to related
organisms
for example - the human tailbone (coccyx), ear
muscles and the gene to make vitamin C
other vestigial structures - baleen whale pelvis and
femur, splint in horses, pelvis and femur in some
snakes

22. 6. comparing embryos - early in development
many organisms share similar characteristics

23. phylogeny – puts evidence together to show
relationships among organisms

24. GRADUALISM VERSUS
PUNCTUATED
EQUILIBRIUMgradualism - evolution occurs slowly over a long
period of time, organism changes many times
for example – human evolution…many small
changes occurred…larger brain size, bipedalism
punctuated equilibrium - major environmental
changes may cause evolution to occur in spurts,
rapid change followed by periods of no change
for example – species that show few “transitional
species” such as T. rex