1. Patterns of Evolution
Chapter 17
Section 4

2. 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.

3. Macroevolution/Microevolution
Both involve changes in allele frequencies in gene pools
The difference is largely one of approach and scale
Each offers different insights into the evolution process

4. 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
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

5. Macroevolution/Microevolution
5. Observable
6. Evidence produced
by experimentation
7. Example: Bacterial
resistance to
antibiotics
Macroevolution
5. Has not been
directly observed
6. Evidence based on
remnants of the past
7. Example: Birds from reptiles

6. Macroevolution/Microevolution

7. 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. 

8. 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

9. Mass Extinctions
Many types of living things became extinct at the same time. 
Disrupted energy flow caused food webs to collapse
Species disappeared.
Left habitats/niches open
Resulted in burst of evolution of new species in new habitat

10. Mass Extinctions Possible causes Asteroids hitting earth
Volcanic eruptions
Continental drift
Sea levels changing

11. Adaptive Radiation (divergent evolution)
The evolution of an ancestral species, into many diverse species, each adapted to a different habitat
Many new species diversify from a common ancestor .
The new species live in different ways than the original species did.

12. Adaptive Radiation

13. Adaptive Radiation Hawaiian honeycreepers
Variation in color and bill shape is related to their habitat and diet

14. Convergent Evolution
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, and bats all serve the same function and are similar in structure, but each evolved independently

15. Convergent Evolution

16. Convergent Evolution

17. Convergent Evolution Hummingbird Hawkmoth
Hummingbird Hawkmoth

18. Convergent Evolution
Similar body shapes and structures have evolved in the North American cacti...and in the euphorbias in Southern Africa

19. Coevolution 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

20. Coevolution

21. Coevolution A fly and an orchid--can influence each other's evolution

22. Coevolution
Bumblebees and the flowers the they pollinate have co-evolved so that both have become dependent on each other for survival.

23. Coevolution Clown Fish and Sea anemone

24. 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.

25. 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

26. Gradualism

27. Gradualism

28. Punctuated Equilibrium
Stable periods of no change (genetic equilibrium) interrupted by rapid changes involving many different lines of descent
Opposite of gradualism
Rapid events of branching speciation

29. Punctuated Equilibrium

30. Gradualism or Punctuated Equilibrium

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

32. Lamb born with seven legs
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

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

34. Hox Genes Determine where limbs and other body segments will grow in a
developing fetus
or larva

35. Hox Genes
They are general purpose in the sense that they are similar in many organisms
It doesn’t matter if it’s a mouse’s head or a fly’s head that is being built, the same gene directs the process

36. (a) normal fruit fly (b) Antennapedia mutation
Hox Genes
Small changes in such powerful regulatory genes, or changes in genes turned on by them, could represent a major source of evolutionary change
Fruit fly head showing the effects of the Antennapedia gene. This fly has legs where its antennae should be.
(a) normal fruit fly (b) Antennapedia mutation

37. Hox Genes Most insects have two pairs of wings
However, flies have one set of flying wings and one set of small balancing wings
A single mutation in the gene will result in a fly with two complete sets of flying wings
This mutation results in an organ appearing in the wrong place.

38. Hox Genes
Hox Genes control development 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.

39. Hox Genes
Hox genes determine the form, number, and evolution of repeating parts, such as the number and type of vertebrae in animals with backbones.
In the developing chick (left), the Hoxc-6 gene controls the pattern of the seven thoracic vertebrae (highlighted in purple), all of which develop ribs. In the garter snake (right), the region controlled by the Hoxc-6 gene (purple) is expanded dramatically forward to the head and rearward to the cloaca.

40. Patterns of Macroevolution
Species
Flow Chart
that are
Unrelated
Related
form in
under
under in in
Intense environmental pressure
Inter-relationships
Similar environments
Small populations
Different environments
can undergo
can undergo
can undergo
can undergo
can undergo
Convergent evolution
Punctuated equilibrium
Adaptive radiation
Coevolution
Extinction