1. How are evolution and ecology related?
Ecology involves understanding of relationships of organisms with each other and with their environment
Evolution involves changes in species in response to interactions with each other and with their environment…

2. Evolution: ‘unfolding’ – process by which species are altered
Species change over generations
New species appear
Species become extinct

3. Contributions to Modern Evolutionary Thought “Malthusian catastrophe”
Thomas Malthus – economist, social philosopher – populations of all organisms eventually out-grow available resources

4. Gregor Mendel (1822-1884): concepts and patterns of inheritance

5. Catastrophism Vs Uniformitarianism.
Catastrophism- he Earth’s surface has been scarred by catastrophic natural disasters
Charles Lyell: theory of uniformity – surface of earth has gradually changed, earth much older than previously recognized
"The Present is the Key to the Past"

6. Fig. 2.3
Darwin’s Voyage
Charles Darwin: synthesis of theory of evolution based on natural selection

7. Out of this study grew several related theories:
one, evolution did occur;
two, evolutionary change was gradual, requiring thousands to millions of years;
three, the primary mechanism for evolution was a process called natural selection; and
four, the millions of species alive today arose from a single original life form through a branching process called "speciation."

8. Forces driving evolution: over-reproduction genetic variability
selective pressure
environment –(food, temperature, etc.)
disease
predators
survival and reproduction of organisms best suited to their environment

9. Review articles
Scot Norris’ paper Evolution's "Driving Force" Shifts Based on Behavior, Study Says
Jonathan Losos' paper "Adaptation and speciation in Greater Antillean anoles"

10. Genetics and Evolution
Trait: appearance/ability to carry out some process
Phenotype: appearance of an organism due to a specific trait or combination of traits
Gene: genetic information (region on a chromosome) which codes for a specific trait.
Allele – variant form of a gene

12. Figure 2.7bc

13. Natural selection can favor, disfavor, or conserve the genetic make-up of a population:
Stabilizing Selection
Directional Selection
Disruptive Selection

14. Stabilizing Selection- also known as ‘Purifying Selection’
Stabilizing selection acts to impede changes in a population by acting against extreme phenotypes and favoring average phenotypes.- prevents divergence from form and function but genetic diversity decreases

15. Directional Selection
Directional selection leads to changes in phenotypes by favoring an extreme phenotype over other phenotypes in the population. Increase frequency independent of dominance

16. Disruptive Selection- also called ‘Diversifying selection’
Disruptive selection creates bimodal distributions by favoring two or more extreme phenotypes over the average phenotype in a population.- driving force of sympatric speciation- (Finch population Darwin)

18. ‘Ecosystems’ ability to absorb shocks and disturbances
Fig. 2.18
‘Ecosystems’ ability to absorb shocks and disturbances

19. Species evolve to fill different niches
What is a species?
‘A group of similar appearing organisms which share the same gene pool’
Species evolve to fill different niches
Example: Finch evolution in Galapagos Islands
Result: Radial Evolution
Single ancestral form
Many generations  unique species for different niches

20. Speciation of Finch on Galapagos Islands- C. Darwin
Fig. 2.10
Speciation of Finch on Galapagos Islands- C. Darwin

21. How do new species arise?
Sympatric speciation
Allopatric speciation

22. Sympatric speciation:
occurs as a species fills different niches within the same habitat or geographic area
Spread of species into new areas
Founding population in isolated location
Geologic changes – gradual process

23. Allopatric speciation:
spatial isolation – occurs due to geographic isolation
Genetic changes (as ploidy levels in plants)
Disruptive selection: divergent genotypes favored

24. Geographic Variation Within Species
Cline: measurable, gradual change in a trait over geographic region
Ecotype: Population adapted to particular local environment
Geographic isolate: reproductively isolated populations
subspecies

25. competative exclusive principle
Gause’s Law-
competative exclusive principle
Georgii Frantsevitch Gause
a theory which states that two species competing for the same resources cannot stably coexist, if the ecological factors are constant. Either of the two competitors will always have an advantage over the other that leads to either the extinction of the inferior competitor or its evolutionary shift towards a different ecological niche.

26. Geographic Isolation of Ensatina escholtzii populations in CA
‘ring species’ – geographically isolated populations surround uninhabitable area
Adjacent populations can interbreed
Reproductively incompatible at extremes (black)
Figure 2.16

27. Local E.escholtzii

29. Changes within a species are due to changes in its gene pool – causes:
Selective pressures
Genetic drift and bottleneck effects
Isolated populations
Effect greater in small populations

30. Variation Within Populations
Variation in Plant Populations
Many plant species differ dramatically in form from one elevation to another.
Clausen et.al. found evidence of adaptation by ecotypes to local environmental conditions in Potentilla glandulosa.
Distinctive ecotypes- distinct entity of animal or plant or organism closely linked to its ecological surroundings

31. Variation in Plant Populations
Molecular and Morphological Information
Hansen et. al. used randomly amplified polymorphic DNA (RAPD) along with morphological data to support separation of three species of Potentilla.

32. Ecotypes – Potentilla glandulosa – sticky cinquefoil
Alpine
Midelevation
lowland

34. How genetically different are ecotypes?
Work with Potentilla nivea (a species complex)
Morphological (appearance) observations suggest three species
Molecular analysis via RAPID study supports morphological species distinction

35. Fig. 8.6

36. Summary:
Organisms become ‘tailor made’ for their role niche within an environment by processes of evolution
New species arise from preexisting species
New species arise as organisms become reproductively isolated
Reproductive isolation may often result in genetically different populations

37. Questions
How do we know that a species is a species if we do not directly observe whether it can interbreed with other organisms? 
If one population is the ancestor to another, how do we decide if they are more than one species? 
Does extinction imply mistakes by an "intelligent designer"?
How, in terms of Gause's law, does a catastrophic event influence subsequent evolutionary events.
Which (and why) are more likely to become extinct, a highly specialized species extremely well adapted to a particular niche, or a less specialized generalist?