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Unit 4 Topic 2
Continuity of Life on Earth
| Question | Answer |
|---|---|
| Define evolution | Evolution is the change in the genetic composition of a population during successive generations, which may result in the development of new species. |
| Define microevolution | Microevolution is small-scale variation of allele frequencies within a species or population, in which the descendant is of the taxonomic group as the ancestor. |
| Define macroevolution | Macroevolution is the variation of allele frequencies at or above the level of species, over geological time, resulting in the divergence of taxonomic groups, in which the descendant is in a different taxonomic group from the ancestor. |
| What is evolutionary radiation? | an increase in taxonomic diversity or morphological disparity |
| What is genetic drift? | A change in the gene pool of a population as a result of chance; usually occurs in small populations |
| What is the bottle-neck effect? | when a catastrophic event or a period of adverse conditions drastically reduces the size of a population. |
| What is the founder effect? | a type of gene flow that occurs when a few individuals that have become isolated from a larger population do not carry all the alleles that were present in the original population. |
| What is viability? | capability of living |
| What is fecundity? | a measure of fertility, the capacity to reproduce |
| What are 5 examples of selection pressures? | 1. competition between species for food/territories 2. predator-prey relationships 3. competition within species for food/water 4. competition within species for territories/nesting places 5. sexual selection -selection of traits that attract males |
| What are the three main types of phenotypic selection? | 1. stabilising selection 2. directional selection 3. disruptive selection |
| What is stabilising selection? What does this look like on a graph? | A form of selection that tends to advantage organisms similar to their parents; this usually occurs when the environment is very stable and unchanging, and selects against extremes of phenotypes. Peak narrows - mean does not change. |
| What is directional selection? What does this look like on a graph? | a form of selection that selects against one of two extremes and leads to a change in a trait over time. Mean/peak shifts |
| What is disruptive selection? What does this look like on a graph? | a form of selection that operates in favour of extremes and against intermediate forms. Two peaks form |
| What is gene flow? | gene flow is the transfer of alleles that results from emigration and immigration between populations. |
| What is descent with modification? | Descent with modification is Darwin's terminology indicating that life today has descended and evolved from common ancestors that were generally different from their modern descendants. |
| What is reproductive isolation? | Reproductive isolation is the separation of populations that are unable to interbreed because of changes that produce physical, biological or behavioural barriers. |
| What is a pre-reproductive isolating mechanism? | a mechanisms that prevents organisms from being able to interact to reproduce. |
| What are 4 examples of pre-reproductive isolating mechanisms? | Geographical mechanisms temporal mechanisms behavioural mechanisms morphological mechanism |
| What is a post-reproductive isolating mechanism? | a mechanisms that prevents fertilisation occuring or an embryo developing into viable offspring if reproduction does occur. |
| What are 3 examples of post-reproductive isolating mechanisms? | gamete mortality zygote mortality hybrid sterility |
| What are the three modes of speciation? | 1. allopatric 2. sympatric 3. parapatric |
| What is allopatric speciation? | Speciation due to physical or geographic isolation. |
| What are some examples of things that can cause allopatric speciation? | 1. water 2. mountains 3. continental drift 4. rising sea levels 5. climate change |
| What is sympatric speciation? | speciation that occurs without physical or geographic isolation. Generally arises from reproductive isolation instead. |
| What is parapatric speciation? | Speciation that occurs when populations are separated by an extreme change in habitat: populations may interbreed in bordering areas (hybrid zone) |
| What are the four patterns of evolution? | 1. Divergent 2. Convergent 3. Parallel 4. Co-evolution |
| What is divergent evolution? | a process whereby related species evolve new traits over time, away from the common ancestor, to give rise to new species. eg. koalas, Tasmanian devils and marsupial moles. |
| What is convergent evolution? | a process whereby unrelated organisms evolve similar adaptations in response to similar environmental pressures. Eg. anteaters, echidnas, pangolins etc. |
| What is parallel evolution? | a process whereby unrelated organisms evolve similar adaptations in response to the same environmental pressure. eg. sugar glider and flying squirrel |
| What is coevolution? | a process whereby an evolutionary change in one species influences the evolution of another species. |
Created by:
Caitlyn_01
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