Transcript Patterns of Evolution

Patterns of Evolution
Macroevolution/Microevolution
Both involve changes in allele frequencies
in gene pools
 Both work through the same basic
processes
 The difference is largely one of approach
and scale
 Each offers different insights into the
evolution process

Macroevolution/Microevolution
 Macroevolution-
One genus or family
evolves into another….due to large
scale changes that take place over
long periods of time.
 Microevolution- Small scale changes
within a species to produce new
varieties or species in a relatively
short amount of time.
Macroevolution/Microevolution
Macroevolution
Microevolution
1. Large-scale changes
in gene frequencies
2. Occurs over a longer
(geological) time
period
3. Occurs at or above
the level of species in
separated gene pools
4. Consists of extended
microevolution
1. Small-scale changes
in gene frequencies
2. Occurs over a few
generations
3. Occurs within a
species or population
in same gene pool
4. Refers to smaller
evolutionary changes
Macroevolution/Microevolution
Macroevolution
Microevolution
5. Has not been
directly observed
6. Evidence based on
remnants of the past
7. More controversial
8. Example: Birds from
reptiles
5. Observable
6. Evidence produced
by experimentation
7. Less controversial
8. Example: Bacterial
resistance to
antibiotics
Macroevolution/Microevolution
Macroevolution/Microevolution

Dog Variability When bred
for certain traits, dogs
become different and
distinctive. This is a common
example of microevolution—
changes in size, shape, and
color—or minor genetic
alterations. It is not
macroevolution: an upward,
beneficial increase in
complexity.
Patterns of Macroevolution
These are theories/models of evolution
A.
B.
C.
D.
E.
F.
Mass Extinctions
Adaptive Radiation
Convergent Evolution
Coevolution
Gradualism
Punctuated Equilibrium
Mass Extinctions
Event in which many types of living things
became extinct at the same time.
 Period in which huge numbers of species
disappeared.
 Whole ecosystems were wiped out
 Left habitats/niches open
 Resulted in burst of evolution of new
species in new habitat
 Disrupted energy flow throughout the
biosphere and caused food webs to
collapse

Mass Extinctions
 Possible
–
–
–
–
causes
Asteroids hitting earth
Volcanic eruptions
Continental drift
Sea levels changing
Mass
Extinctions
 Is
an on-going
process
Adaptive Radiation
The evolution of an ancestral species,
which was adapted to a particular way of
life, into many diverse species, each
adapted to a different habitat
 Many new species diversify from a
common ancestor .
 The branching out of a population through
variation.
 The new species live in different ways
than the original species did.

Adaptive Radiation
Adaptive Radiation
Adaptive Radiation
Diversity
in anoles
is most
striking
in the
Caribbean
islands
Adaptive Radiation
 Hawaiian
honeycreepers
 Variation in
color and bill
shape is
related to
their habitat
and diet
Convergent Evolution
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

Opposite of divergent evolution (adaptive
radiation)
Unrelated organisms independently evolve
similarities when adapting to similar
environments, or ecological niches
Analogous structures are a result of this process
Example: penguin limb/whale flipper/fish fin
The wings of insects, birds, pterosaurs, and bats
all serve the same function and are similar in
structure, but each evolved independently
Convergent Evolution
Convergent Evolution
Convergent
Evolution
Convergent Evolution
ocotillo (left) from the American Southwest,
and in the allauidia (right) from Madagascar
Convergent Evolution
Hummingbird Hawkmoth
Convergent Evolution
Similar body
shapes and
structures
have evolved
in the North
American
cacti...and in
the
euphorbias
in Southern
Africa
Coevolution
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The mutual evolutionary influence between two
species
When two species evolve in response to
changes in each other
They are closely connected to one another by
ecological interactions (have a symbiotic
relationship) including:
– Predator/prey
– Parasite/host
– Plant/pollinator
Each party exerts selective pressures on the
other, thereby affecting each others' evolution
Coevolution
Coevolution
A fly and an orchid--can influence
each other's evolution
Coevolution
Bumblebees and the flowers the they pollinate
have co-evolved so that both have become
dependent on each other for survival.
Coevolution
Coevolution between the
yucca moth and the yucca
plant. (right) A female
yucca moth pushing pollen into the stigma
tube of the yucca flower
while visiting the flower
to deposit her eggs.
Yucca moth larvae (left)
feeding on seeds in
the yucca fruit.
Coevolution
Clown Fish and Sea anemone
Coevolution
Praying Mantis simulates plant to protect itself
from predators and eats pests that are attracted
to and feed on the plant, so it protects the plant.
Coevolution
Shrimp cleaning
Titan triggerfish
in Pacific Ocean
Gradualism
The evolution of new species by gradual
accumulation of small genetic changes
over long periods of time
 Emphasizing slow and steady change in
an organism
 Occurs at a slow but constant rate
 Over a short period of time it is hard to
notice

Gradualism
Gradualism
Current living zebras (top), extinct quaggas (bottom)
Gradualism
Gradualism
Punctuated Equilibrium
Stable periods of no change (genetic
equilibrium) interrupted by rapid changes
involving many different lines of descent
 Opposite of gradualism
 It is rare, rapid events of branching
speciation
 Characterized by long periods of virtual
standstill ("equilibrium"), "punctuated" by
episodes of very fast development of new
forms

Punctuated Equilibrium
 Horseshoe
crabs have change little since
their first appearance in the fossil record.
 They are in a state of equilibrium
Punctuated Equilibrium
Punctuated Equilibrium
Gradualism or
Punctuated Equilibrium
Patterns of Macroevolution
Flow Chart
Species
that are
Unrelated
form
Related
in
under
under
Interrelationships
Similar
environments
Intense
environmental
pressure
can undergo
can undergo
can undergo
Coevolution
Convergent
evolution
Extinction
in
Small
populations
in
Different
environments
can undergo
can undergo
Punctuated
equilibrium
Adaptive
radiation