Lecture 1:
Introduction to Evolution
Evolution = change in allele frequencies in a population
Great, is class over now?
No (sigh), because the process & results are interesting &
important to our understanding of biology
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Introduction to Evolution - Evolution - Lecture Slides, Slides of Theory of Evolution
Introduction to Evolution, Allele Frequencies, Adaptations Perfect, Benefits from Adaptation, Spontaneous Generation, Geographic Variation, Darwin Conclusion, Origin of Species are the key important points of lecture slides of Evolution.
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Lecture 1:
Introduction to Evolution
Evolution = change in allele frequencies in a population Great, is class over now? No (sigh), because the process & results are interesting & important to our understanding of biology
Questions in evolution
WHY is life on earth diverse? (we’ll get to this later)
HOW is life adapted? (questions leading to more questions)
BD : Before Darwin
- Orthodoxy – species as fixed, designed by God
- Bible = literal truth
- variation = imperfection
- BUT, even before Darwin this was questioned
- Idea of changeable/old Universe, allowed idea of
changeable life on earth (geology & paleontology)
- Enlightenment – fossils: spontaneous generation,
transmutation
Lamarck
- spp. change into new spp. over time
Transformism: Acquired Characters:
-no branching e.g. Giraffe’s neck
-no extinction
So, Darwin had somewhere to start…
Darwin’s conclusion
- ‘Struggle for existence’ only some survive
- Expect favourable variations to survive
= Natural Selection
- Mechanism = most important aspect of theory
- Poor Alfred Russel Wallace – same conclusions
on a much smaller budget
- Co-presented the idea but Darwin is remembered because of The Origin of Species
Darwin’s Dangerous Idea
The Origin of Species (1859)
Theses:
- Descent with Modification from Common
Ancestors (Evolution)
- Natural Selection is main agent of Evolution
- Individuals vary
If competition for resources then only favourable variants survive to reproduce
- Most of the variation is inherited
(e.g. domestic species – sexual repro:diversity)
Favourable variants have more offspring & increase in
frequency = Change in the population over time
Plus lots about pigeons…
Deduction
Descent with modification via natural selection Testable???
Predictions
Fossil Record
Comparative Anatomy
Comparative Embryology Geographic Distribution
Behaviour
Evolution is a bush not a ladder
Fish
Amphibians
Birds
Mammals
Humans
Reception
“Evolution” generally accepted but:
1. Viewed as progressive (towards a goal)
2. Natural selection rejected
- No theory of heredity (how characteristics passed on)
- Problem of uncrossable “gaps” in evolution
- Back to transmutation
Tenets of Modern Synthesis
- Populations have variation from random, not adaptively directed, mutation & recombination
- Populations evolve through changes in gene frequency by drift, gene flow & N.S.
- Change is gradual because most genetic variants have slight effects on phenotype
- Diversification (speciation) is due to gradual reproductive isolation among populations
- Overtime, changes give rise to new taxa
Genetics…more important than
Darwin?
- After Darwin, many accepted the idea of
evolution as change in species over time
- BUT, much argument against NS
- Genetics forced the rejection of evolution as