BIO NOTES
CHAPTER 11 - DARWINIAN EVOLUTION
The thumb makes us human
What is evolution? “Change over time”
**Fossils are remains of extinct organisms**
Jean Baptiste de Larmarck: Inheritance of acquired traits
July 1, 1858 - Charles Darwin & Alfred Russel Wallace: evolution occurs through natural
selection(It is NOT survival of the fittest)
- Tracks (fittest) of a children or genes down to offspring
Natural Selection: the differential survival and reproductive success of individuals whose traits
are best adapted to the environment
To operate it needs:
- Variation in traits(genetic diversity)
- Variation in traits that must affect survival and reproduction
- Variation must be inheritable
An adaptation is a heritable trait that aids in survival
There were criticisms of Darwin’s natural selection theory
- “The Ant and the Peacock”
Sexual Selection: traits that aid in mating only
Criticisms:
- Another problem was the mechanism for inheritance
- DNA was unknown
Where does genetic diversity come from?
- Mutation(random changes in DNA that occur when replication happens): this mechanism
can create new alleles, but most mutations are neutral or negative
- Migration: individuals enter a population and introduce new alleles into subsequent
generations through breeding
Modern synthesis and the Four Major Mechanisms of Biological Evolution(ON TEST)
- Natural Selection
- Mutation
- Migration
- Genetic Drift(biggest driver of evolution; occurs randomly)
Patterns of Evolution:
Divergent evolution: two species evolve in different directions(chimps and humans; similar but
look different)
, Convergent Evolution: similar phenotypes evolve independently(cacti; look the same but no
common ancestor)
Analogous Structures: similar function but not related evolutionary or common descent
Homologous Structures: same patterns because all mammals share a common ancestor; due to
common descent
Homoplasies: similarity not due to common descent at all(antenna of a beetle and the tail of a
scorpion; both inject venom, not evolutionarily descent)
Microevolution: The generation-to-generation changes in frequencies of alleles within a
population is called microevolution. Its evolution on the smallest scale.
Mechanisms:
- Natural Selection
- Sexual selection
- Artificial selection
- Genetic Drift
- Gene flow
- Small-scale
- Few generations
- Within species/population
- Small evolutionary changes
- Observable
- Less controversial
Macroevolution: Major patterns and changes among living organisms over long periods of time.
The evidence comes from 2 main sources:
- Fossils
- Comparisons between living organisms
- Large-Scale
- Longer Time period
- at/above level of species
- Extended microevolution
- Not directly observed
- More controversial
Micro Vs. Macro
Miscro: Beetle population
Macro: Dinosaurs; birds are dinosaurs/reptiles
Population Genetics
- How genes affect population is call “population genetics”
- Gene Pool: all the alleles from a population
- Allele Frequency: the % of any allele present
CHAPTER 11 - DARWINIAN EVOLUTION
The thumb makes us human
What is evolution? “Change over time”
**Fossils are remains of extinct organisms**
Jean Baptiste de Larmarck: Inheritance of acquired traits
July 1, 1858 - Charles Darwin & Alfred Russel Wallace: evolution occurs through natural
selection(It is NOT survival of the fittest)
- Tracks (fittest) of a children or genes down to offspring
Natural Selection: the differential survival and reproductive success of individuals whose traits
are best adapted to the environment
To operate it needs:
- Variation in traits(genetic diversity)
- Variation in traits that must affect survival and reproduction
- Variation must be inheritable
An adaptation is a heritable trait that aids in survival
There were criticisms of Darwin’s natural selection theory
- “The Ant and the Peacock”
Sexual Selection: traits that aid in mating only
Criticisms:
- Another problem was the mechanism for inheritance
- DNA was unknown
Where does genetic diversity come from?
- Mutation(random changes in DNA that occur when replication happens): this mechanism
can create new alleles, but most mutations are neutral or negative
- Migration: individuals enter a population and introduce new alleles into subsequent
generations through breeding
Modern synthesis and the Four Major Mechanisms of Biological Evolution(ON TEST)
- Natural Selection
- Mutation
- Migration
- Genetic Drift(biggest driver of evolution; occurs randomly)
Patterns of Evolution:
Divergent evolution: two species evolve in different directions(chimps and humans; similar but
look different)
, Convergent Evolution: similar phenotypes evolve independently(cacti; look the same but no
common ancestor)
Analogous Structures: similar function but not related evolutionary or common descent
Homologous Structures: same patterns because all mammals share a common ancestor; due to
common descent
Homoplasies: similarity not due to common descent at all(antenna of a beetle and the tail of a
scorpion; both inject venom, not evolutionarily descent)
Microevolution: The generation-to-generation changes in frequencies of alleles within a
population is called microevolution. Its evolution on the smallest scale.
Mechanisms:
- Natural Selection
- Sexual selection
- Artificial selection
- Genetic Drift
- Gene flow
- Small-scale
- Few generations
- Within species/population
- Small evolutionary changes
- Observable
- Less controversial
Macroevolution: Major patterns and changes among living organisms over long periods of time.
The evidence comes from 2 main sources:
- Fossils
- Comparisons between living organisms
- Large-Scale
- Longer Time period
- at/above level of species
- Extended microevolution
- Not directly observed
- More controversial
Micro Vs. Macro
Miscro: Beetle population
Macro: Dinosaurs; birds are dinosaurs/reptiles
Population Genetics
- How genes affect population is call “population genetics”
- Gene Pool: all the alleles from a population
- Allele Frequency: the % of any allele present
