Biology: Evolution (Package 1)
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What is evolution?
The process in which significant changes in the inheritable traits of a species occur over time.
What is necessary to prove evolution?
Two organisms must have a common ancestor.
Changes must be _______.
6 Evidences for macroevolution
- 1. Fossils
- 2. Biogeographic relationships
- 3. Homologous structures
- 4. Vestigial structures
- 5. Embryological development
- 6. Similarities in DNA
Who started palaeontology and when?
Baron Georges Cuvier in the 18th century
How do Cuvier's observations imply the idea of common descent?
Cuvier's observations imply the idea of common descent because he revealed that many fossils were of extinct species and that different sedimentary rock layers contained distinctive fossil species. His evidence challenged the view that all fossils were of currently living species.
What is macroevolution? Name 3 examples.
Pertains to large-scale evolutionary changes. Examples: Pigeons to Dodo birds, Eohippus to Equus, Archaeopteryx.
What is microevolution? Give 3 examples.
Pertains to small-scale evolutionary changes. Examples: humans becoming darker in skin (allele frequencies), genetic drift in cheetahs in which the population was drastically reduced to a few individuals because of the same alleles, and members of an Amish community all had short limbs because one of the founders had the recessive allele for short limbs
What two observations did Cuvier make?
- 1. Fossils of simple organisms could be found at all depths of sedimentary rock, but more complex forms were found at shallow deposits.
- 2. Fossils contained in shallower deposists were more likely to resemble currently living species.
What is Archaeopteryx?
A famous intermediate fossil that serves as a link between groups. Archaeopteryx has both bird and reptilian features. Such a fossil allowed scientists to deduce this line of descent.
What is biogeography?
The study of the distribution of plants and animals throughout the world, study of which species live where, and why.
Define the term homologous structure and give an example.
Body parts with similar anatomical features but different functions. Example: Human arm and whale flipper.
Define the term analogous structure and give an example.
Body parts with similar functions but different anatomical features. Example: Bird and butterfly wing.
Define the term vestigial structure and give two examples.
Anatomical features that are fully developed and functional in some organisms, but are undeveloped and have no function in others. Examples: Appendix in humans, wings in flightless birds.
How does biogeography imply the idea of common descent? Give an example.
Biogeography can imply the idea of common descent becuse if one studies an organism's environment, they may figure out which species had previously once lived there to explain why the organism turned out the way it did. An example of this would be the thought that flightless birds (dodo birds) are descendants of migratory birds that could fly- they settled on islands and lost their ability to fly b/c it was a disadvantage to do so.
What is the significance of homologous and analogous structures in common descent? Example.
Organisms with homologous structures are more closely related than organisms with analogous structures, because they share a more recent common ancestor. Example: Humans are more closely related to birds than butterflies are to birds.
What is the most important factor in the process of evolution?
Change in environment and allele frequencies.
What is a notochord?
A supporting rod located to the back of the embryo of all vertebrates. Eventually forms the spinal column.
What are pharyngeal pouches?
Structures that, in humans, eventually form eustachian tubes.
Who is Charles Darwin? What did he do?
He was a naturalist and geologist, who came up with the theory of natural selection that supported evolution.
What does the term survival of the fittest mean?
Only the organisms that are best adapted to the environment will survive and thus pass on its genes to future generations.
Who is Ernst Haeckel? What did he do? What was his problem?
Ernst Haeckel was a zoologist who examined the embryos of various organisms and drew pictures illustrating them to be almost identical to one another. His problem was that he falsified his drawings of such embryos so that they matched his beliefs that embryological forms of vertebrates were similar.
What is population?
All members of a single species occupying a particular area at the same time.
What does the Hardy-Weinberg law state?
As long as certain conditions are met, allele frequencies in a sexually reproducing population can come to an equilibrium that is maintained generation after generation.
The Hardy-Weinberg law predicts that:
Sexual reproduction alone cannot alter the allele frequencies in a population.
Why is the Hardy-Weinberg law inaccurate?
Because in real life, the conditions needed to maintain an equilibrium of allele frequencies from generation to generation are impossible to abide by. The allele frequencies in a gene pool naturally do change over time, so evolution is inevitable.
What are the five conditions that can cause evolutionary change? (Also known as evidence of microevolution)
- 1. Mutations
- 2. Gene flow
- 3. Genetic drift
- 4. Non-random mating
- 5. Natural selection
What are the 5 basic types of mutations?
- 1. Deletion
- 2. Duplication
- 3. Inversion
- 4. Insertion
- 5. Translocation
What is gene flow?
The movement of alleles from one population to another through movement of individuals and/or gametes.
Gene flow tends to _______ differences between populations.
Non-random mating occurs when...
Individuals pair up, not by chance, but by according to their genotypes or phenotypes.
What is inbreeding?
Incest; mating to relatives.
What are the two types of genetic drift?
- Founder effect
- Bottleneck effect
What is genetic drift?
Changes in allele frequencies in a gene pool due to chance. These changes are more pronounced in a small population.
What is the founder effect?
Genetic drift that results when small numbers of individuals separate from th original population and find a new population.
What is the bottleneck effect?
A dramatic, often temporary reduction in population size usually resulting in significant genetic drift.
What is natural selection?
Process by which heritable traits that make it more likely for an organism to survive and reproduce become more common in a population.
What is fitness in natural selection?
How reproductively successful you are.
4 things that evolution by natural selection requires:
- 1. Variation - members of pop'n differ from one another
- 2. Inheritance - many of said differences can be inherited
- 3. Differential Adaptedness - some of said differences affect how well an organism is adapted to its environment
- 4. Differential Reproduction - individuals that are better adapted to their environment are more likely to reproduce, and their fertile offspring will make up a greature proportion of the next generation
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