Evidence for Evolution II: contemporary Lecture Contemporary evidence for evolution Natural...
-
date post
15-Jan-2016 -
Category
Documents
-
view
218 -
download
0
Transcript of Evidence for Evolution II: contemporary Lecture Contemporary evidence for evolution Natural...
Evidence for Evolution II: contemporary
LectureContemporary evidence for evolution
Natural selection, theoretical problems, and new evidence
GoalSummarize how molecular and developmental biology support evolution; what new discoveries convinced scientists of natural selection
Problem for Darwin I: Lord Kelvin and the age of the earth
Estimating the age of the earth
Problem for Darwin II: absence of transitional fossils
Archaeopteryx:
Ancestors of whales
Ambulocetus natans – 50 mya.
Problem for Darwin III: plausibility of Natural Selection
Contemporary evidence for evolution: Molecular genetics
Arbitrary nature of genetic code
Developmental Biology
see figure 3.15
Pax6 controls eye development in all triploblasts!
Embryological experiments: the same gene can function in multiple
organisms
Evidence for evolution: historical constraints
Evolution in Natural PopulationsHuman Immunodeficiency Virus (HIV)
Sequence Evolution in six childrenHuman Immunodeficiency Virus (HIV) – Ganeshan et al. 1997
Why are branches longer in children D-F?Human Immunodeficiency Virus (HIV) – Ganeshan et al. 1997
•A brief interlude for some genetics review
•Mutations within a gene can be classified as:
– Synonymous (silent)
– Non-synonymous
Evolution in Natural PopulationsHuman Immunodeficiency Virus (HIV) – Ganeshan et al. 1997
Distinguishing selection from mutation
Effect of mutation
Not selected (neutral)
Selected against(deleterious)
Selected for(favorable)
Relative probability of mutation remaining in population
• Studied weedy, wind-dispersed plants located on the islands off the west coast of Vancouver Island
• Censused the plant populations of 200 islands and a region of the mainland over a 10-year period
• Extinction and recolonization events occurred frequently on the islands.
Evolution in Natural PopulationsDispersal in island plant populations – Cody & Overton
1996
Evolution in Natural PopulationsDispersal in island plant populations – Cody & Overton
1996
•Studied two species:– Hypochaeris radicata– Lactuca muralis.
William S. Justice @USDA-NRCS PLANTS Database
© Markku Savela
Evolution in Natural PopulationsDispersal in island plant populations – Cody & Overton
1996
•Both are Asteraceae (composites).
•Both produce achenes consisting of a feathery pappus and a seed.
Evidence of selection on dispersal
Speciation and selection?
Provisional definition:Species – An interbreeding group of
organisms that is reproductively isolated from (does not interbreed with) other
groups of organisms
• Flies choose
– lightness or darkness (left vs. right) – selection for phototaxis
– up or down – selection for geotaxis
– acetaldehyde (white vial) or ethanol (black vial) – selection for chemotaxis
• Experimenters choose time period: early (E), middle (M), and late (L) – selection for development time
Selection and speciation?Habitat selection in Drosophila – Rice & Salt 1988,
1990
• Flies mated within the maze
• Control lines: 120 females chosen randomly
• Selected lines – 60 females each from:
Selection and speciation?Habitat selection in Drosophila – Rice & Salt 1988,
1990
• dark, up, acetaldehde, early (5E)• light, down, ethanol, late (4L)
• Experimental larvae were mixed and placed together in the maze to start the next generation.
• Controls were run through the maze separately.
• Offspring of mothers collected from 5E and half of the controls were raised on a chemical that turned their eyes brown.
Evolution and Artificial SelectionHabitat selection in Drosophila – Rice & Salt 1988,
1990
Selection and speciation - outcome
Habitat selection in Drosophila – Rice & Salt 1988, 1990
5E
5E4L
Dotted line: 5E
Solid line: 4L
Selection and speciation: summary
Habitat selection in Drosophila – Rice & Salt 1988, 1990
Contemporary evidence: new species
Hedylepta
New species: Tragopogon mirus
More creationist / ID arguments
I believe that, as a result of media bias, there seems to be total ignorance of new scientific evidence against the theory of evolution. Such evidence includes (1) race formation (microevolution), which is not a small step in macroevolution because it is a step towards a reduction of genetic information and not towards its increase. It also includes formation of (2) geological strata sideways rather than vertically, (3) archaeological and palaeontological evidence that dinosaurs coexisted with humans, (4) a major worldwide catastrophe in historical times, and so on.
Dr. Maciej Giertych, Polish member of European parliamentPhD in tree physiology, U Toronto.
Letter to the editor, Nature, December 2006.
Readings and study questions• Chapter 2 in Freeman and Herron (3rd or 4th edition)• Questions 2 and 4 at end of chapter 2
SourcesCody and Overton. 1996. Short-term evolution of reduced dispersal in
island plant populations. J. of Ecology 84:53-61.Ganeshan et al. 1997 Human immunodeficiency virus type 1 genetic
evolution in children with different rates of development of disease. J. of Virology 71:663-677
Giertych, M. 2006. Letter to editor. Nature 444:265.Ownbey, M. 1950. Natural hybridization and amphiploidy in the genus
Tragopogon. American Journal of Botany 37:487-499.Rice, WR and Salt, GW. 1988. Speciation via disruptive selection on
habitat preference – experimental evidence. American Naturalist 131:911-917.
Rice, WR and Salt, GW. 1990. The evolution of reproductive isoation of a correlated character under sympatric conditions – experimental evidence. Evolution 44:1140-1152.