How are evolution and ecology related? Ecology involves understanding of relationships of organisms with each other and

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…

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. Darwin’s Voyage Fig. 2.3 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 http://news.nationalgeographic.com/news/2006/11/061116-lizard-evolution.html • Jonathan Losos' paper "Adaptation and speciation in Greater Antillean anoles" http://biosgi.wustl.edu/%7Elososlab/losos.2004.adaptivespeciationbook.pdf

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

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

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

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

22. 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 Sympatric speciation:

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

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. Georgii Frantsevitch Gause a theory which states that two speciescompeting 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. Gause’s Law- competative exclusive principle

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)

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 3 ecotypes: 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?