Unit 2: Evolution Flashcards
Catastrophism
The idea that catastophies periodically destroy species living in a region, allowing species from neighboring regions to repopulate the area.
- Georges Cuvier
Uniformitarianism
The theory that geological processes operated at the same rate in the past as they do today and that changes result from the action of continuous and uniform processes. Slow and unperceivable change. (gradualism)
- Charles Lyell
Mass Extinction
Over 50% of all species become extinct in a short time (usually about 2 years)
Fossil Record
Traces and remains of past life found in sedimantary rock.
- Shows species alive and history
- helful for finding ancestors of species
Mutable
Changing
Transitional Fossils and Trace Fossils
A fossil that shows links between groups of organisms and shares characteristics common to two now seperate species (links from past to present). Trace fossils are fossils of a trace of an animals but not the animal itself.
Vestigial Structure
A structure that is a reduced version of one functional in the organisms ancestors.
Biogeography
The study of past and present geographical distribution of species populations.
homologous Structures
- different funtion
- same structure
- common ancestor
(evidence of divergent evolution)
Divergent Evolution
Species with a common ancestor change to become more different over time.
Convergent Evolution
Species with no ancestral similarities changing to develope similar characteristics.
Analagous Structures
- same function
- different structure
- no common ancestor
(evidence of convergent evolution)
Microevolution
Changes in characteristics within a species (smaller changes). Changes in allele frequency.
Macroevolution
Evolution that creates a new species (large changes).
Adaptation
A change where a species becomes better suited to its environment.
Species and “the species problem”
A group of similar individuals capable of exchanging genes. The species problem in the debate over how to define the word species and how to identify species.
Mutation
A random alteration in the nucleic acis (structure of genes) causing a variant form which may be passed to future generations.
Variations
Every individual is not the same as every other individual.
Background Extinction
Species going extinct based on non human factors at a normal rate.
Selective Advantage
Any characteristic which gives an organism a greater chance of survival.
Selective Pressures
Environmental conditions which select for certain characteristics of an individual and select against others.
Fitness
An organisms ability to survive and reproduce offspring which will survive and reproduce.
Natural Selection
The process where charateristics of a population change over generations due to organisms with heritable traits surviving and passing on these traits to their offspring.
Allele
A version of a gene. A variation in a sequence in a gene.
Allele Frequency
The precent of a specific trait in a certain population. Changes in allele fruency is microevolution.
Adaptive Advantage
A favourable trait for a particular environment.
Stabalizing Selection
Natural selection that favours the middle ground phenotypes (not extremes). Medium length flowers.
Directional Selection
Natural selection which favors one extreme phenotype. Long OR short length flowers. (selective pressure).
Disruptive/diversifying Selection
Natural selection which favors both extremes. Long AND short length flowers.
Sexual Selection
Natural selection for mating based on competition between males and choices made by females.
5 Fingers of Evolution
Thumb - Natural selection
Pointer - Gene flow/ genetic drift
Middle - Mutation
Ring - Non-random mating
Pinky - Small populaton size
5 Fingers - Natural selection
Thumb - The idea that characteristics of a population change over time. Some alleles live and some don’t which changes allele frequency.
5 Fingers - Gene flow/genetic drift
Pointer - Gene flow is the movement of alleles from one population to another due to migration. This can cause new alleles in a population.
Genetic drift is the random change in genetic variation. This changes allele frequency. Affects small populations more as one random mutation is a larger part of the population.
5 Fingers - Mutation
Middle - The randomly produced changes caused by changes in the nucleic acid in an individuals genes that can cause new phenotypes and traits. Mutation can change allele frequency.
5 Fingers - Non-random mating
Ring - Mating based off of particular phenotypes. Does not affect allele frequency but increases the amount of paired individuals with shared alleles.
Absolute Dating
The actual age of a fossil estimated by the rates of radioactive decay.
Relative Dating
The age estimated by a fossils position in the sediment.
Founders Affect
Individuals of a species go off in a small group and create a new isolated population.
Bottleneck Affect
Population is rapidly decreased which reduces genetic variation and diversity.
Machanisms of Evolution
Pre-zygotic:
- Behavioral - Mating
- Ecological - Seperated geologically
- Mechanical - Structural reproductive differences
- Gametic - Gamates fail to fertalize
- Temporal - Timing differences
Post-zygotic:
- Zygote mortality - zygote is not viable
- Hybrid inviability - offspring is weak and often dies
- Hybrid infertility - Offspring lives but can not reproduce
Types of Speciation
Allopatric Speciation - Populations are split up and isolated
Sympatric Speciation - Variation within characteristics causing diversion
Buffon
Life is mutable - earth is over 6000 years olf
Evidence for Darwins Ideas
- Fossils
- Homologous structures
- embryology
- biogeographic distribution
Anning
Helped discover the first specimens of an ickthyosaur and plesiosaur. Highly skilled paleantologist.
Lyell
- Uniformitarianism - gradualism, slow and inperceivable change.
Malthus
Carrying Capacity - species produce more offspring than the environment can sustain.
Lamarck
Theory of Aquired Characteristics - Individuals of a species change in their lifespan and pass the aquired traits to their offspring.
Curvier
Catastrophism - Catastrophies would occasionally come and destroy a regions population causing species from other regions to repopulate it.
Vertebrate paleantology
Wallace
Had the same ideas as Darwin. Had the idea of natural selection.
