Lecture 8 study Guide
What are the 3 criteria for natural selection?
- Trait variation in populations (Differences among individuals that can be passed down) - Heritability (Are the traits able to be passed down) - Differential Reproductive success (Do certain traits make your reproductive success more likely)
What was the Modern Evolutionary Synthesis?
Combines Darwinian Selection and Mendelian Genetics in order to explain genetic changes in populations over time
What were the two theories being combined at the heart of the Modern Evolutionary Synthesis?
Darwinian Natural Selection and Mendel's Genetics
Why weren't Mendelian genetics readily accepted following their rediscovery?
Davenport and Bateson discovered that Mendelian traits cannot explain continuous traits (Like quantitative traits)
Regression towards mean
Decrease in variance for traits that makes mean more likely by natural selection
Darwin's Pangenesis
Each body part has little particles (gemmules) that develop each organ
Did the hole in Darwinian theory mean science did not accept evolution had occurred?
Evolution and natural selection was not fully accepted for 40 years
Why do we talk about Mendel's Laws AND Gene Theory?
Gene theory explains Mendel's Laws.
What's the difference between genotype and phenotype? How are they related?
Genotype is the genetic makeup; Phenotype refers to the physical characteristics
Who contributed to the Modern Evolutionary Synthesis? What is so special about this time in the history of science?
Julian Huxley, Dobzhansky, Mayr This time was important because all fields are coming together as the modern evolutionary synthesis
What are Mendel's Laws? Are they Laws?
Law of Segregation: predicts ratios of traits (3:1 ratio from a hybrid cross); each parent is making an equal contribution (Law is a established pattern so yes) Law of Independent Assortment: inheritance of different traits is independence
Does blending result in gain or loss of variance
Loss of variance
Why are mutations important to evolutionary theory?
Mutations may be harmful or beneficial, but they are important because they introduce trait variance
What is it called when phenotypic plasticity result in discontinuous variation occurs?
Polyphenisms
What is recombination and why is it important from an evolutionary perspective?
Recombination is the combination of two alleles (typically seen in meiosis); It is importance because it introduces variance of traits
Who are its founders (population genetics)?
Sewll Wright, J.B.S. Haldane, [Sir R.A. Fisher]
What would happen to variation in populations if no new variants were generated?
Variation would decrease because selection decreases variance
Is phenotypic plasticity adaptive?
Yes
If these three conditions are met, will evolution occur? What kind of reasoning
Yes; because of deductive reasoning.
What is a mutation?
any change in the DNA sequence
What alternative to Mendelian genetics was promoted and held off complete acceptance of natural selection for 40 years?
blended inheritance
discontinuous traits
controlled by variation in one gene (ex. All or nothing traits)
continuous traits
determined by multiple genes (polygenic), such as height or hair color
What was the "hole" in Darwin's theory?
heritability was explained by the theory of blending inheritance. There was no Mendelian genetics to help explain how traits were inherited.
What was the first principal contribution of the field of population genetics?
polygenic model: most traits are influenced by many genes (Mendels only applied to individual loci)
What is phenotypic plasticity?
the ability of an organism to change its phenotype in response to changes in the environment.
What is population genetics?
the study of how populations change genetically over time
