1. Evolution and Biodiversity
APES
Chapter 5
Ms. Miller

2. Key Concepts Origins of life Evolution and Evolutionary processes
Ecological niches
Species formation
Species extinction

3. Origins and Early Evolution of Life
Chemical evolution—evolution on Earth before life (evolution of organic molecules and chemical reactions)
Biological evolution—evolution of living organisms from single cell to multicellular organisms
Fig. 5-2 p. 88

4. Evolution and Adaptation
Macroevolution—long-term, large-scale evolutionary changes by which new species form and others go extinct
Microevolution—small genetic changes that occue in a population
Gene pool—collection of genes or genetic resources potentially available to a population’s offspring
Mutation—random changes in the structure or number of DNA molecules in a cell
Natural selection—when individuals have genetic traits that increase their chance of survival and fitness

5. Natural Selection
Natural selection is a relatively simple theory that involves five basic assumptions. The theory of natural selection can be better understood by identifying the basic principles on which it relies. Those principles, or assumptions, include:
Struggle for existence - More individuals in a population are born each generation than will survive and reproduce.

6. Variation - Individuals within a population are variable
Variation - Individuals within a population are variable. Some individuals have different characteristics than others.

7. Differential survival and reproduction - Individuals that have certain characteristics are better able to survive and reproduce than other individuals having different characteristics.

8. Inheritance - Some of the characteristics that influence an individual's survival and reproduction are heritable.

9. Time - Ample amounts of time are available to allow for change.
It took thousands of generations to get to this

10. The result of natural selection is a change in gene frequencies within the population over time, that is individuals with more favorable characteristics will become more common in the population and individuals with less favorable characteristics will become less common.

11. Differential reproduction—selection that enables individuals to leave more offspring than other members of a population

12. Adaptive trait—any heritable trait that enables organisms to better survive and reproduce
Anthropologist Nina Jablonski, Ph.D. theorizes that variations in human skin are adaptive traits that correlate closely to geography and the sun’s ultraviolet radiation, not race.

13. Coevolution—a back and forth adaptation duel between two interacting species in which one species gains a temporary advantage over the other
The relationship between flowering plants and their pollinators can offer a classic examples of coevolutionary relationships. Flowering plants rely on pollinotors to transport pollen among indivudla plants and thus enable cross-pollination.

14. Ecological Niches and Adaptation
Fundamental niche
Habitat
Realized niche
Fig. 5-4 p. 91

15. Broad and Narrow Niches
Generalist species—organisms with a broad niche that can live in many places, eat a variety of food and can tolerate wide range of environmental conditions
Refer to Spotlight p. 92: cockroaches

16. Specialist species—organisms with a narrow niche that live in one type of habitat, use one or a few food sources and can tolerate a narrow range of climate and environmental conditions

17. Speciation, Extinction, and Biodiversity
Speciation—process of forming two species from one
Fig. 5-7 p. 94

18. Geographic isolation—earth feature blocks interactions of a population thus forming new species
Reproductive isolation—long-term geographic separation of members of a species

19. Allopatric Speciation: Parent population of a species is physically separated and spatially isolated.
Each population then takes on a slightly different traits and can, at times, cause such great differences that if the barrier is removed, they can’t interbreed.

20. Allopatric speciation of squirrels in the Grand Canyon .
The canyon is a barrier to dispersal by small mammals, and as a consequence the isolated populations can diverge.

21. Parapatric Speciation: Population isn’t spatially segregated ; occurs more in plants.
Spontaneous genetic abhorations which changes over time and diverge (mutations which survive and reproduce). Ex: number of chromosomes

22. Reproductive Isolating Mechanisms: work by preventing mating from occuring. The end result if EXTINCTION…not speciation
1) Ecological/Spatial Isolation: individuals are separated physically and unable to breed

23. 2) Temporal Isolation: Species have different periods of sexual reproduction
Example :
Drosophila persimilis - breeds in early morning
Drosophila pseudoobscura - breeds in the afternoon

24. 3) Behavioral Isolating Mechanisms: Incompatible behaviors prevent mating from occuring.

25. 4) Mechanical Isolation: Size differences, different reproductive tracts prevent mating from occuring.

27. 5) Mating occurs but offspring are not viable
5) Mating occurs but offspring are not viable a) die young or before birth b) are sterile

28. Liger: male lion and female tiger Tigon: female lion and male tiger

29. Extinction
Background extinction—when local conditions change and species disappear at a low rate (annual extinction rate of one to five species for each million species on earth)
Mass extinction—a significant rise in extinction rates above the background level; widespread event 25-70% of species wiped out
Mass depletion—when extinction rates are higher than normal but not high enough to classify as a mass extinction
Adaptive radiation—periods of recovery after a mass extinction
Human Impacts—human activities are decreasing the earth’s biodiversity and are leading towards a mass extinction

30. Human Impacts on Evolution
Artificial Selection—process by which humans select desirable genes of a population (selective breeding); used in agriculture
Genetic Engineering—(gene splicing)—techniques used to isolate, modify, multiply and recombine genes from different organisms
Concerns about Genetic Engineering—unpredictable process and raises concerns in ethical, legal and environmental practices