Transcript Ch 22 (Biogeography)-ppt

Lines of Evidence
for Evolution:
Remember: In science,
one line of evidence in
and of itself is not
sufficient. All evidence
must work together and
support a theory.
1. Biogeography: geographic distribution of species
*closely related species tend to be found in the same
geographic region, whereas the same ecological niches in
distant regions are occupied by very different (though
sometimes similar-looking) species
*this is what 1st suggested evolution to Darwin
-Example: Australia is home to a group of mammals
(marsupials)that are distinct from another
group of mammals (eutherians) that live
elsewhere on Earth
Australia: sugar glider is superficially
similar to flying squirrel (N. America)
 sugar glider has characteristics that
define it as distinctly marsupial
*These external superficial similarities are an
example of CONVERGENT EVOLUTION (not
homologous structures & therefore, not evidence of
evolution)
Because the continents drifted over time the
mammal distribution has changed dramatically
–Monotremes and marsupials developed in
Gondwanaland 165 million years ago before the three
southern continents were separated.
–Placental mammals (developed life young) developed
later 135 million years ago and replaced almost all of the
monotremes (egg laying mammals) and marsupials
(undeveloped young born into pouches) in the other
continents.
–Australia was separated from the other continents. This
is why marsupials and monotremes are now found only
on Australia. Monotremes and marsupials have evolved
to fit the niches within the Australian environment and
there are no placental mammals. This is simply because
of geography not because Australia is unfit for placental
mammals.
In order for an organism to have a high
level of fitness, what must be true?
A.
B.
C.
D.
It must be really strong
It must be really fast
It must have a lot of offspring
It must be smarter than others in the population
What is the difference between common
descent and a direct descendant?
A. Common descent: parents children; direct
descendant: having a common ancestor
B. Common descent: having a common ancestor;
direct descendant: parents children
C. There isn’t a difference; both mean the same thing
In Darwin’s Theory of Natural
Selection, evolution is acting on
A.
B.
C.
D.
a population
a species
an individual
a community
What are vestigial structures?
A. Structures that are essential for survival
B. Structures that have never served a useful purpose
C. Structures that are similar in function but not in
internal form
D. Structures that no longer serve a purpose but did
at one time
Which of the following is not a homologous structure?
A. Fin of a goldfish and the fin of a whale
B. The hemoglobin protein in humans & chimps
C. A cat’s leg and a bat’s wing
D. They are all homologous structures
What are analogous structures?
A. Structures that are formed using the same DNA
instructions
B. Structures that seem to serve a similar purpose
C. Structures that are similar in function but not in
internal form
D. Structures that no longer serve a purpose but did
at one time