1. UNIT 3 Chapter 4 Evolution and Biodiversity
The Earth is 6 billion years old.
Life is 3.7 billion years old.

2. ORIGINS OF LIFE
1 billion years of chemical change to form the first cells, followed by about 3.7 billion years of biological change.
Figure 4-2

3. What factors make EARTH a perfect place for life to exist?

4. Temperature range
Orbit distance from sun
Rotation
Size and gravitational mass
Ozone
Diversity which sustains life!

5. Background for Evolution from Biology
Evolution is the change in a population’s genetic makeup over time.
All species descend from earlier, ancestral species- theory of evolution
Can species evolve in one generation?
Darwin video

6. Evolution cont.
Microevolution describes the small genetic changes that occur in a population over time.
Over time, a population’s gene pool changes when mutations in DNA molecules are passed on to offspring. There may be several different forms (alleles) of a single gene.
Example: Alleles for eye color might be B (brown) and b (blue)
Homozygous vs. heterozygous
Genotype vs. phenotype
Dominant vs. recessive

7. Genetic Diversity leads to Evolution
Sexual reproduction leads to random recombination of alleles from individual to individual.
Crossing over
Recombination
Mutations causes genetic variability in populations due to random changes in structure/number of DNA molecules in a cell.
Errors in transcription, translation, or replication
Exposure to radiation (x-rays, UV light, radioactivity, mutagens (specific chemicals) can cause genetic variations
Are all mutations harmful?

8. In order for evolution to occur by natural selection there must be…
Genetic variability
Different traits to exist in the population
Ex. Fur color
Traits must be heritable
Fur color depends on parents fur color
Trait must lead to Differential reproduction
Trait allows those individuals to have more reproductive success
Video

9. What is coevolution?

10. Limits of adaptation through Natural Selection
The only genetic traits that can be selected for are those already in the gene pool.
Genetically diverse species that reproduce quickly, can often adapt quickly.
Populations that reproduce slowly take a long time to adapt through natural selection.
Population’s GENE POOL
RATE OF REPRODUCTION

11. Evolution Myths Survival of the fittest= the strongest survive
Organisms develop through the traits they NEED
Evolution follows a plan of nature to create the perfect species

12. How did each event affect Evolution?
Tectonic plates
Volcanoes
Earthquakes
Climate change
Asteroids

13. Fundamental vs. Realized Niches
The niche includes the members’ adaptations; its range of tolerance for physical and chemical conditions, its interactions with other components of the ecosystem, and its role in energy flow and matter recycling.
The fundamental niche is the full potential range of conditions and resources a species could potentially use.
Its realized niche is the part of the potential niche that allows a species to survive and avoid competition with other species for the same resources.
Video example insert!

14. Generalist vs. Specialist Species
Broad Niches
Specific niches

15. Specialized Feeding Niches
Resource partitioning reduces competition and allows sharing of limited resources.

16. Rainforest and specialist species

17. Speciation- creation of a new species
Most species take thousands-millions of years to evolve and create new species.
What about fleas, ticks, roaches?

18. Evolutionary Divergence
Each species has a beak specialized to take advantage of certain types of food resource.

19. Speciation occurs due to:
Hybridization
Gene Swapping
Isolation
Geographic isolation- physical separation for long time periods.
Reproductive isolation-The gene pools are so changed that members become so different in genetic makeup that they cannot produce fertile offspring.
Behavioral isolation- individual
doesn’t pick up mating cue

20. Extinction: Lights Out
Extinction occurs when the population cannot adapt to changing environmental conditions.
The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate.

21. Species and families experiencing mass extinction
Bar width represents relative
number of living species
Millions of
years ago
Era
Period
Extinction
Current extinction crisis caused
by human activities. Many species
are expected to become extinct
within the next 50–100 years.
Quaternary
Today
Cenozoic
Tertiary
Extinction 65
Cretaceous: up to 80% of ruling
reptiles (dinosaurs); many marine
species including many
foraminiferans and mollusks.
Cretaceous
Mesozoic
Jurassic
Extinction
Triassic: 35% of animal families, including many reptiles and marine mollusks.
180
Triassic
Extinction
Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites.
250
Permian
Carboniferous
Extinction
345
Figure 4.12
Fossils and radioactive dating indicate that five major mass extinctions (indicated by arrows) have taken place over the past 500 million years. Mass extinctions leave many organism roles (niches) unoccupied and create new niches. Each mass extinction has been followed by periods of recovery (represented by the wedge shapes) called adaptive radiations. During these periods, which last 10 million years or longer, new species evolve to fill new or vacated niches. Many scientists say that we are now in the midst of a sixth mass extinction, caused primarily by human activities.
Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites.
Devonian
Paleozoic
Silurian
Ordovician
Extinction
500
Ordovician: 50% of animal families, including many trilobites.
Cambrian
Fig. 4-12, p. 93

22. Natural Selection takes a LONG time…
Man has used artificial selection to change the genetic characteristics of populations for years.
We use selective breeding to obtain specific desired traits. (plants, domestic animals) but this takes many generations also.
Humans have turned to the
GENE REVOLUTION

23. Genetic Engineering
Genetic engineering/gene splicing are techniques that isolate, modify, multiply and recombine genes from different organisms.
Genes from different species that would never interbreed in nature are being transferred to each other.

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

25. Genetic Engineering
Genetically modified organisms (GMOs)/transgenic organisms are the results of this gene splicing.
Glowing tobacco ng_tobacco_plant.jpg

26. Do you agree with cloning?
Cloning plants, animals, humans, pets?
Video of golden retriever cloned insert!!!