Chapter 17
Section 4

Macroevolution/Microevolution
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Macroevolution- One genus or family evolves into another….due to large scale changes that take place over long periods of time.
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MicroevolutionSmall scale changes within a species to produce new varieties or species in a relatively short amount of time.

Macroevolution/Microevolution
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Both involve changes in allele frequencies in gene pools
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Both work through the same basic processes
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The difference is largely one of approach and scale

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
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.

Macroevolution/Microevolution
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Macroevolution has never been observed in any breeding experiment.
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Theories…?
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The controversy still exists
 http://evolution-facts.org/Newmaterial/Microevolution.pdf
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Patterns of Macroevolution
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29+ Evidences for Macroevolution
"Evidences"?
Copyright © 1999-2003 by Douglas Theobald,
Ph.D.
http://www.talkorigins.org/faqs/comdesc/evide nces.html

Patterns of Macroevolution
Much written in the support of macroevolution

Patterns of Macroevolution
These are theories/models of evolution
A. Mass Extinctions
B. Adaptive Radiation
C. Convergent Evolution
D. Coevolution
E. Gradualism
F. Punctuated Equilibrium
G. Developmental Genes

Mass Extinctions
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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
Believed to result 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
 Believed to be an on-going process

Adaptive Radiation
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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

Diversity in anoles is most striking in the
Caribbean islands
Adaptive Radiation

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
All are believed to descend from a common ancestor…Totally theoretical!!

Convergent Evolution

Convergent Evolution

Convergent Evolution ocotillo (left) from the American Southwest, and in the allauidia (right) from Madagascar

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
Totally theoretical

Coevolution

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. Theoretical!!

Coevolution
Clown Fish and Sea anemone

Gradualism

The evolution of new species by gradual accumulation of small genetic changes over long periods of time
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Emphasizing slow and steady change in an organism
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Occurs at a slow but constant rate
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Over a short period of time it is hard to notice

(Theoretical) Gradualism

Gradualism

Gradualism

Punctuated Equilibrium
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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

Developmental Genes

Development is a progressive process
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There are a variety of certain developmental genes that regulate the timing of certain events

Developmental Genes

Hox genes – are master control genes

Some alter the position of an organ

Others alter when things happen
Lamb born with seven legs

Hox Genes
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Determine body plans

Function in patterning the body axis
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Provide the identity of particular body regions

Hox Genes
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Small changes in such powerful regulatory genes, or changes in genes turned on by them, are thought to be a major source of evolutionary change
Fruit fly head showing the

Hox Genes
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Hox Genes control development of central nervous system and are common to most organisms.
Four groups of similar Hox
Genes, shown in color, appear to control related regions of the human body and the fly.
Each box represents a single Hox Gene.
Illustration by Lydia Kibiuk, Copyright © 1994 Lydia Kibiuk.

Patterns of Macroevolution
Species Flow Chart that are form
Interrelationships
Does this equal
Coevolution
Unrelated Related in
Similar environments under
Intense environmental pressure under in
Small populations can undergo
Convergent evolution can undergo
Extinction
Do they undergo
Punctuated equilibrium in
Different environments
Do they undergo
Adaptive radiation