1. Evolution and Biodiversity
Chapter Four

2. Evolution: All species
descended from earlier
ancestral species.
Changing genetic make-
up in a population over
time.
Accepted scientific
explanation of how
animals adapt and
survive

3. Evolution and Adaptation
Macroevolution – long term, large scale changes
Microevolution – small genetic changes
Gene pool – all genes in a population
Mutation – random change in structure of DNA. Every so often, a mutation is beneficial for survival.
Natural selection – individuals that have traits that benefit survival.

4. Natural Selection
Microevolution is changes in the gene pool of a population over time that result in changes to the varieties of individuals in a population such as a change in a species' coloring or size.
Macroevolution If the changes are over a very long time and are large enough that the population is no longer able to breed with other populations of the original species, it is considered a different species.

5. Evolution and Adaptation
Microevolution
Macroevolution

6. Natural Selection Three things must happen:
1. Genetic variability in a trait within population
2. Trait is heritable
3. Differential reproduction – must enable individuals with the trait to leave more offspring than others without the trait.
Adaptive (heritable) trait helps survival and reproduction under current conditions

7. Speciation, Extinction, and Biodiversity How Species Evolve
Speciation: A new species can arise when member of a population become isolated for a long period of time.
Genetic makeup changes, preventing them from producing fertile offspring with the original population if reunited.
Fig. 5-7 p. 94

8. Geographic Isolation
…can lead to reproductive isolation, divergence of gene pools and speciation.
Figure 4-10

9. Reproductive Isolation
a category of mechanisms that prevent two or more populations from exchanging genes
The separation of the gene pools of populations, under some conditions, can lead to the genesis of distinct species.
Reproductive isolation can occur either by preventing fertilization, or by the creation of a degenerate or sterile hybrid, such as the case with the common mule and the hinny.
Basically, organisms have a barrier such as unfavored genes that don't allow them to mate.

10. Extinction Background extinction – slow rate
When Environmental changes occur, species must evolve to adapt. If not…
Background extinction – slow rate
Mass extinction – quickly, large groups
Mass depletion – higher than mass (Ice Age)
99% of species that have existed on earth are now extinct.
Changes in Earth’s biodiversity – has leveled off during the last 1.8 million
Years. Is this due to human influence?

11. Extinction
Adaptive radiation – after mass extinctions, numerous new species evolve to fill vacated niches. Takes 1-10 million years for adaptive radiation to rebuild biodiversity.
Human impacts – accelerated extinction

12. Human Impacts on Evolution
Artificial Selection – artificially selecting superior genetic traits
Agriculture
Hatcheries
pets
Genetic Engineering
Gene splicing
Species creation in laboratories
Takes less time than artificial selection
Concerns about Genetic Engineering
Many failures (1% success rate)
Lead to more abortions? Only for the wealthy?

13. GENETIC ENGINEERING AND THE FUTURE OF EVOLUTION
We have used artificial selection to change the genetic characteristics of populations with similar genes through selective breeding.
We have used genetic engineering to transfer genes from one species to another.
Figure 4-15

14. Genetic Engineering: Genetically Modified Organisms (GMO)
GMOs use recombinant DNA
genes or portions of genes from different organisms.
Figure 4-14

15. Identify and remove portion of DNA with
Phase 1
Make Modified Gene
E. coli
Genetically
modified
plasmid
Insert modified
plasmid into E. coli
Cell
Extract
Plasmid
Extract DNA
Plasmid
Gene of
interest
DNA
Identify and remove portion of DNA with
desired trait
Remove plasmid
from DNA of E. coli
Insert extracted
(step 2) into plasmid
(step 3)
Identify and extract gene with desired trait
Grow in tissue
culture to
make copies
Figure 4.14
Genetic engineering: steps in genetically modifying a plant.
Fig. 4-14, p. 95