Definition of Evolution:
Change in allele frequency of a population over time
Do species of individuals develop traits?
Individuals develop traits (such as going from a zygote to a human)
Development of traits does NOT equal evolution
Aristotle/Plato
- Essentialism (Things have set characteristics and should be categorized
- Typology (study of types)
- Believed there was a hierarchy in the animal Kingdom
- Thought discrete forms were unchanging and that variations were do to accidental imperfections)
Linneas
- Founder of Modern Taxonomy (created binomial nomenclature)
- Set to classify gods creations
- Systema Naturae: Classification based on ranking (still a scale of nature)
Georgies Cuvier
- First real paleontologist
- Discovered many distinct species and explained strata in rocks
- Established the idea that organisms change overtime.
Superposition:
Location in sedimentary rock (the higher, the newer)
- Gives RELATIVE age
Marie Curie
Discovered radioisotopes which help us find the exact age of fossils
(carbon dating is only good up to 10,000 years)
Hutton's Uniformitarianism
- Father of modern geology
- Geological processes occurred in the past the same as rates observed in the present.
Lamark
- Believed everything arose via spontaneous generation
- Some organisms acquired traits due to different need and children inherited those traits
- Created the "Principle of Inheritance of acquired traits"
- Believed animals can move through the hierarchy
Charles Lyell
Wrote the Principles of Geology, which offered evidence to show that the earth had formed over millions of years ago
(combined uniformitarianism and superposition)
Charles Darwin
- Studied pigeons
- Suggested traits could be blended
- Discovered Natural Selection/ Differential fitness (it has no future purpose)
*
Below are 4 postulates that must occur for Natural Selection to take place
*
- Variation exist among individuals alread
Thomas Malthus
- Wondered why life was so bad in Europe
- Populations change because not everyone survives to be part of the next generation
Alfred Wallace
- Wrote an essay describing Darwin's theory
- Arrived at his ideas independently (even though they matched darwin's)
Three reasons why the Theory of Evolution via Natural Selection was revolutionary
- It overturned the idea that species are unchanging
- Replaced typological thinking (populations change not individuals)
- It was scientific and could be proved by experiments
The Modern Synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution.
Post-synthesis
- The genomic revolution(molecular evolution) supports Darwin's theory
- DNA described by Watson, Crick, Wilkins and Franklin
- Neutral theory of Molecular Evolution - Motoo Kimura
- Kin-selection & Macro-evolution
Darwin & Wallace presented these ideas:
1. Common Ancestry
- All life is related. Homology: when 2 things share a trait due to ancestry
2. Natural Selection
- Differential fitness (best will survive)
Transitional feature
A trait that is intermediate between an ancestor and new one (a missing link (?))
Vestigial traits
Traits that were useful in ancestors that are inherited today, but that have lost their original use.
The pattern of evolution:
- Similar species are found in the same geographic areas
- Phylogenies are made using homology
Phylogenic Tree
A branching diagram that shows how organisms are related through evolution (just a hypothesis)
Homology
Shared ancestral traits
If phylogenies made from each of these three levels agree... We have confidence that we are looking at actual evolutionary relationships.
1. Genetic homology (similar DNA)
2. Developmental homology (similar embryo structure)
3. Structural homology (Similar bone structure)
Evidence of homology
Inserted genes in one organism (e.g.mice genes) can be read in another organism
Using homology in Medicine
- We can test the effects of possible carcinogens (cancer causing chemicals) on other organisms because DNA repair enzymes are homologous
- Drugs can be tested in other mammals, if the proteins targeted are homologous to our own, And we can determine if t
Evidence of evolution
1. Species change through time
2. Species are related and not independent
Acclimation vs Adaptation
Acclimation: acquired through physiological change (cant be passed down)
Adaptation: genetic and can be passed down
Evolution is not progressive
There is no such thing as progress
Gene pool
All of the alleles in a population
Genotype frequencies
A1A1, A2A1, A2A2
Allele frequencies
P and Q factors of H-W equations
Assumptions of H-W
Describes a population that is not evolving
1. There is no selection.
2. No mutation
3. No migration
4. Random mating (genetic drift not a factor)
5. population is diploid
6. Population reproduces sexually
inbreeding depression
A reduction in fitness resulting from breeding among relatives causing homozygosity of deleterious recessive mutations.
- Many genes function best when paired with a different allele because of stabilizing selection
4 Different modes of selection
Genetic Drift
When allele frequencies change at random (without respect to fitness, could just be luck)
- Reduces genetic variability
Founder Effect
A branch of genetic drift ;
Immigrants establish a new population (random, not based on fitness)
Bottleneck effect
Natural disaster, where the allele that survives is random
Gene Flow
movement of alleles from one population to another (random with respect to fitness)
Types of Mutations
- Point (single nucleotide substation)
- Chromosomal (big change to chromosomal structure)
- Lateral gene transfer (movement of genes between species)
Uhm
sorry
umm
sorrie