17-4 Patterns of Evolution Download

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17-4 PATTERNS OF
EVOLUTION
I. Extinction
1.
Macroevolution large-scale
evolutionary patterns
& processes that
occur over long
periods of time.
2.
Six important topics in
macroevolution are:
a)
b)
c)
d)
e)
f)
extinction
adaptive radiation
convergent evolution
coevolution
punctuated
equilibrium
changes in
developmental genes
3.
4.
Over 99% of all
species that have ever
lived are now extinct
Mass extinctions have:
a)
b)
provided ecological
opportunities for
organisms that survived
resulted in bursts of
evolution that
produced many new
species
II. Adaptive radiation
1.
Adaptive radiation the process of a
single species or a
small group of
species evolves into
several different
forms that live in
different ways.
Adaptive Radiation of Mammals
Artiodactyls
CetaceansPerissodactyls TubulidentatesHyracoids Sirenians Proboscideans
Ancestral Mammals
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2.
The evolution
mammals is an
example of adaptive
radiation b/c many
species of mammals
evolved from one
ancestral species
III. Convergent evolution
1.
Convergent Evolutionprocess whereby
organisms not closely
related independently
evolve similar traits as a
result of having to
adapt to similar
environments or
ecological niches.
a)
Ex: the similar nature of
the flight/wings of
insects, birds, pterosaurs
(flying reptiles that are
now extinct), and bats.
IV. coevolution
1.
2.
Coevolution- A
process that takes
place with two species
evolve in response to
each other as time
passes.
Ex: Predator/prey
and parasite/host
Some Central American Acacia species have hollow
thorns and pores at the bases of their leaves that secrete
nectar (see image at right). These hollow thorns are the
exclusive nest-site of some species of ant that drink the
nectar. But the ants are not just taking advantage of the
plant—they also defend their acacia plant against
herbivores. berkeley.edu
v. Punctuated equlibrium
1.
Gradualismevolutionary
change is slow
and steady
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2. Punctuated
equilibrium- a pattern
of evolution in which
long stable periods are
interrupted by brief
periods of more rapid
change.
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vi. Developmental genes & body
plans
1.
2.
3.
Scientist believe changes in genes for growth and
differentiation during embryological development
could produce changes in body shape and size.
Small changes in the activity of control genes can
affect many other genes to produce large changes
in adult animals.
Small changes in the timing of cell differentiation
and gene expression can make the difference
between long legs and short ones.
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Evolution of Wings in Insects
Ancient Insect
Two Types of Modern Insects
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