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Biology - Week 7

Terms in this set (24)

What is evolution?
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What is microevolution?
a change of allele frequencies within a population.
What is macroevolution?
Changes that result from an accumulation of microevolutionary (small) changes over time. This results in speciation where a new species is formed.
Determine episodes of evolutionary radiation (increase in taxonomic diversity and morphological disparity) and mass extinctions from an evolutionary timescale of life on Earth (approximately 3.5 billion years).
You just need to determine from a graph where mass extinction occurs (when there is a sleep decline or die off in a graph) and when there is an evolution (when there is a steep shoot in a graph).
Interpret data (i.e. degree of DNA similarity) to reveal phylogenetic relationships with an understanding that comparative genomics involves the comparison of genomic features to provide evidence for the theory of evolution.
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What do speciation and macroevolutionary changes result from?
An accumulation of microevolutionary changes over time.
Name the four patterns of diversification between species?
Divergent
Convergent
Parallel
Coevolution
What is the pattern of divergent diversification look like between species?
The evolution of 2 completely different species from a common ancestral species.
A common ancestor that spreads apart as the 2 species evolve differently.
e.g. Galapagos finches - different food types = divergent evolution, adaptive radiation.
What is the pattern of convergent diversification look like between species?
Evolution through natural selection of similar features in unrelated groups of organisms. Where 2 species are very different but start to look the same probs from the same selection pressures.
e.g. Echidna and porcupine
What is the pattern of parallel diversification look like between species?
2 species that diverge, then develop similar adaptations in similar environments in different locations.
What is the pattern of coevolution diversification look like between species?
Where one thing influences the other. e.g. prey getting faster than the predators so the predators can't keep up and eventually have to adopt a faster speed to survive.
What are the modes of speciation?
Allopatric
Sympatric
Parapatric
Describe the mode Allopatric
- geographical barriers divide population.
- spatial isolation prevents interbreeding between populations.
- different selection pressures result in accumulation of differences that eventually prevent the two populations from interbreeding.
- Gene flow is completely stopped.
Describe the mode Parapatric
- besides/near
- populations are not geographically isolated, but there is significant variation in habitat conditions (i.e. niche habitats).
- Gene flow is reduced but not completely stopped.
- e.g. same species of snail living together along the beach but different colours.
- clinal variation is present - allele variation across a geographic range and phenotypic variation.
Describe the mode Sympatric
- With/together
- often the result of disruptive selection
- more common in plants than animals
- Preventing them from breeding together but not physically isolating them.
- - Gene flow is reduced but not completely stopped.
- living in the same area
What are the different mechanisms of isolation that influence gene flow?
- Geographic
- reproductive
- spatial
- temporal
Describe geographic isolation
Can be done 3 ways:
- Separates populations by physical and geographical barriers, like oceans, deserts, mountain ranges etc...
- environmental disasters can immediately reduce the number of individuals within a population or across populations depending on the size of the disaster.
- habitat fragmentation portions habitats and reduces the range of individuals, potentially creating localized populations.
Describe reproductive isolation
pre-zygotic -
- Behaviour (e.g. wolf would eat rabbit instead of breed with it).
- Temporal (species bredding in warmer compared to colder months/spatial
- structural (e.g. elaphent and mouse)

Post-zygotic - fertilization can occur but doesn't allow the organism to survive e.g. dog and wolf
- hybrid inviability
- hybrid sterility (chromosome numbers don't match up e.g. horse and donkey = mule)
Describe spatial isolation
separation in space/area
Describe temporal isolation
separation in time
e.g.
Explain how populations with reduced genetic diversity (i.e. those affected by population bottlenecks) face an increased risk of extinction.
Do we just define bottleneck effect or do we have to say something about natural seleciton
Interpret gene flow and allele frequency data from different populations to determine speciation.
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What is speciation?
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Answering evolution question
1. state that variation exists
2. the variation is inherited
3. The variation provide a survival advantage/disadvantage.
4. answer actual question
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