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Questions and Answers
What was the historical understanding of heredity before the development of modern genetics?
What was the historical understanding of heredity before the development of modern genetics?
- The concept of natural selection
- The blending of traits between parents (correct)
- The inheritance of acquired characteristics
- The role of mutations in variation
What was the focus of Morgan's research in genetics?
What was the focus of Morgan's research in genetics?
- The investigation of natural selection
- The study of biometrics
- The analysis of mutations in fruit flies (correct)
- The exploration of continuous variation
What was the significance of the white-eyed fly in Morgan's research?
What was the significance of the white-eyed fly in Morgan's research?
- It showed the relationship between genetics and cell biology
- It exhibited a sex-linked gene (correct)
- It represented a continuous variation
- It demonstrated the concept of natural selection
What was the contribution of Fisher's work in genetics?
What was the contribution of Fisher's work in genetics?
What is the result of recurrent mutation and selection against variation?
What is the result of recurrent mutation and selection against variation?
What is the term for the loss of genetic variation in a population over time?
What is the term for the loss of genetic variation in a population over time?
What is the role of selection in maintaining genetic variation in a population?
What is the role of selection in maintaining genetic variation in a population?
What was the focus of the Biometricians in the early days of genetics?
What was the focus of the Biometricians in the early days of genetics?
What was the significance of Morgan's choice of fruit flies in his research?
What was the significance of Morgan's choice of fruit flies in his research?
What was the historical context of the development of modern genetics?
What was the historical context of the development of modern genetics?
What is the result of faster mutations and stronger selection against them?
What is the result of faster mutations and stronger selection against them?
What is the advantage of being a heterozygote?
What is the advantage of being a heterozygote?
What is the result of negative frequency-dependent selection?
What is the result of negative frequency-dependent selection?
What is the result of gene flow between two populations?
What is the result of gene flow between two populations?
What is the characteristic of a sharp cline?
What is the characteristic of a sharp cline?
What is the result of fluctuating selection?
What is the result of fluctuating selection?
What was the importance of the discovery of isozymes in 1957?
What was the importance of the discovery of isozymes in 1957?
What is the main argument against the genetic load argument?
What is the main argument against the genetic load argument?
What is the prediction of the neutral theory?
What is the prediction of the neutral theory?
What is the result of very slow evolution?
What is the result of very slow evolution?
What was the primary focus of the Biometricians in their research?
What was the primary focus of the Biometricians in their research?
What was the significance of Morgan's choice of fruit flies in his research?
What was the significance of Morgan's choice of fruit flies in his research?
What was the primary contribution of Fisher's work to the field of genetics?
What was the primary contribution of Fisher's work to the field of genetics?
What is the result of recurrent mutation and selection against variation?
What is the result of recurrent mutation and selection against variation?
What is the main effect of genetic drift on a population?
What is the main effect of genetic drift on a population?
What is the main effect of selection on genetic variation in a population?
What is the main effect of selection on genetic variation in a population?
What was the significance of Aristotle's work in the historical development of genetics?
What was the significance of Aristotle's work in the historical development of genetics?
What was the significance of Morgan's research on fruit flies?
What was the significance of Morgan's research on fruit flies?
What is the effect of combined effects of several genes on continuous variation?
What is the effect of combined effects of several genes on continuous variation?
What is the effect of genetic variation on the adaptation of a population?
What is the effect of genetic variation on the adaptation of a population?
What is the primary factor that determines the amount of variation expected in a population under the neutral theory?
What is the primary factor that determines the amount of variation expected in a population under the neutral theory?
What is the consequence of very fast evolution in a sequence?
What is the consequence of very fast evolution in a sequence?
What is the role of heterozygote advantage in maintaining genetic variation?
What is the role of heterozygote advantage in maintaining genetic variation?
What is the outcome of gene flow between two populations with different adaptations?
What is the outcome of gene flow between two populations with different adaptations?
What is the consequence of a sharp cline in allele frequency?
What is the consequence of a sharp cline in allele frequency?
What is the primary problem with the genetic load argument?
What is the primary problem with the genetic load argument?
What is the result of fluctuating selection on genetic variation?
What is the result of fluctuating selection on genetic variation?
What is the significance of the discovery of isozymes in 1957?
What is the significance of the discovery of isozymes in 1957?
What is the prediction of the neutral theory regarding the evolution rate?
What is the prediction of the neutral theory regarding the evolution rate?
What is the role of mutation in shaping genetic variation under the neutral theory?
What is the role of mutation in shaping genetic variation under the neutral theory?
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Study Notes
Historical Background of Genetics
- Genetics is the study of heredity and variation
- Aristotle and the Western scientific world thought in terms of blending of traits/bloods between parents, and sometimes inheritance of acquired characteristics
Early Developments in Genetics
- Thomas Morgan worked on mutations and how they were inherited, which was initially seen as evidence against Darwin
- There were two factions: Medalists (mutation is the important process) and Biometricians (variations in characters like height/milk yield)
- Morgan chose fruit flies and made connections between genetics and cell biology
- Flies around the world are still descended from his original population
Understanding Variation
- Mutations and variations were carefully catalogued, crossed, and observed
- A fly with white eyes had a sex-linked gene
- Fisher's work brought the two factions together, showing that continuous variation could be due to combined effects of several genes
Factors Affecting Variation
- Recurrent mutation and selection can lead to a situation where mutation creates rare alleles, and selection removes them
- Heterozygote advantage maintains variation at a locus, making it better to be Aa than AA or aa
- Negative frequency-dependent selection can occur, where the rarer alleles have rarity value
- Gene flow can maintain variations between areas with different environments
- Fluctuating selection can maintain variation by favouring different alleles in different generations
Advances in Molecular Genetics
- 1957: discovery of isozymes and development of molecular genetics
- Protein sequencing and DNA sequencing showed even more variation, including at silent sites
- The genetic load argument suggests that the explanation of variation being maintained by selection is implausible
Neutral Theory
- Kimura calculated the evolution rate, which equals the mutation rate, if all variation is neutral
- The amount of variation expected in a population depends on mutation rate and population size
- The neutral theory gives us a null hypothesis
- Very slow evolution is called sequence conservation or purifying selection, or sometimes negative selection
- Very fast evolution might mean the sequence is currently adapting
Historical Background of Genetics
- Genetics is the study of heredity and variation
- Aristotle and the Western scientific world thought in terms of blending of traits/bloods between parents, and sometimes inheritance of acquired characteristics
Early Developments in Genetics
- Thomas Morgan worked on mutations and how they were inherited, which was initially seen as evidence against Darwin
- There were two factions: Medalists (mutation is the important process) and Biometricians (variations in characters like height/milk yield)
- Morgan chose fruit flies and made connections between genetics and cell biology
- Flies around the world are still descended from his original population
Understanding Variation
- Mutations and variations were carefully catalogued, crossed, and observed
- A fly with white eyes had a sex-linked gene
- Fisher's work brought the two factions together, showing that continuous variation could be due to combined effects of several genes
Factors Affecting Variation
- Recurrent mutation and selection can lead to a situation where mutation creates rare alleles, and selection removes them
- Heterozygote advantage maintains variation at a locus, making it better to be Aa than AA or aa
- Negative frequency-dependent selection can occur, where the rarer alleles have rarity value
- Gene flow can maintain variations between areas with different environments
- Fluctuating selection can maintain variation by favouring different alleles in different generations
Advances in Molecular Genetics
- 1957: discovery of isozymes and development of molecular genetics
- Protein sequencing and DNA sequencing showed even more variation, including at silent sites
- The genetic load argument suggests that the explanation of variation being maintained by selection is implausible
Neutral Theory
- Kimura calculated the evolution rate, which equals the mutation rate, if all variation is neutral
- The amount of variation expected in a population depends on mutation rate and population size
- The neutral theory gives us a null hypothesis
- Very slow evolution is called sequence conservation or purifying selection, or sometimes negative selection
- Very fast evolution might mean the sequence is currently adapting
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