Topic 5 & 6 Flashcards
Darwin’s book and 2 main points
On the Origin of Species by Means of Natural Selection
- Descent with modification (evolution) from common ancestors
- Natural selection is the mechanism for “descent with modification”
Georges Cuvier
Pre-Darwin thinker who observed that fossils found in older strata were different from living organisms. He did not believe in evolution, but catastrophism, where catastrophes cause local extinctions and new species moved into the area
Jean-Baptiste Lamarck
Pre-Darwin thinker who hypothesized that the apparent disappearance of species was due to one species evolving into another. He opposed extinction and proposed that characteristics were inherited
Jean-Baptiste Lamarck
Pre-Darwin thinker who hypothesized that the apparent disappearance of species was due to one species evolving into another. He opposed extinction and proposed that characteristics were inherited
Natural Selection
the mechanism for descent with modification (evolution) that gives rise to adaptation and speciation
Genotypic Variation
heritable difference in DNA among individuals in a population
Phenotypic Variation
Differences in organisms’ observable characteristics (phenotype). It is determined by the interaction of environmental factors and genotype
Selective Agents
Environmental factors action on populations that effect the survival and/or reproduction of individuals in the populations.
Selection Pressure
when a selective agent consistently causes differences in survival and/or reproduction, which leads to a directional change in a population
Evidence of Evolution
- Direct observations of evolutionary change Ex) pesticide-resistant insects
- Homologies
- Fossil Record
- Biogeography
Homologies
Anatomical, molecular, and embryonic similarities
Chronological sequence of the Fossil Record
The order in which different groups of taxa appear in the fossil record aligns with heir evolutionary relationships
2 Biogeography aspects that contribute to the Theory of Evolution
- Isolated populations
- Continental patterns of species distribution
Allopatric speciation
Occurs when there is a geographic barrier between populations
Sympatric speciation
Occurs when any reproductive barrier that is not geographical appears including sexual selection, change in diet, or change in habit.
2 Ways that new genetic mutations are introduced into a population
Mutation and Gene flow (an outsider moves in and reproduces)
2 Ways that Alleles can change frequency in a population
Generic drift and selection
Phylogenetics
How we represent history of speciation over time through phylogenetic trees
Where on phylogenetic trees do speciation events occur?
After a node where two taxa split
Parsimony
The principle that says that organisms that require fewer changes or speciation events/nodes on a phylogenetic tree are generally better than those involving multiple
Molecular Clock Hypothesis
When a population splits in two, the two populations accumulate different mutations over time. The continuous build up of mutations can be used to estimate how long ago the ancestors of currently living species split.
