GGR Week 5
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What is a cline, and give an example.
- Cline - geographical gradient of genetically controlled trait.
- Ex: Yarrow in California, whose height is thought to be determined by elevation. In fact it was found that difference in height is due to genotypic differences, and thus represent genetically distinct races.
What is Allopatric Speciation? Name and describe the two types of Allopatric Speciation.
- Allopatric Speciation is when a species that separates and becomes so distinct that they become different.
- Vicariance - When say a land mass get split, and a species get separated. The new separation thrusts them into new habitats and eventually they grow to become distinct species.
- Jump Dispersal - When migration or displacement of a certain species results in a new species in the new area.
Jump dispersal may lead to two types of effects. Name and describe these effects.
- Founder Effect - When a species lands in a new area, the genetic variation in the group is a new base from which future generations begin. This new combination in addition to the new habitat may result in a new species.
- Bottleneck - The effect of those who did not migrate or leave the old habitat. This remaining gene pool is the new base from which future generations evolve from.
Describe the two types of Sympatric Speciation.
- Parapatric - When species begin to utilize other parts of a habitat and eventually become their own species. This is often found with plant-host insects. A group of insects who usually eat grass A may change and eat grass B, and eventually form a new species. Another good example are cichlids in Africa, who live in lakes and each exploit a different part of them.
- Peripatric - Certain organisms from a species may seek out and slowly push how far they will go to get food. This increases the range, as well as what they eat. In time this may result in a new species being formed.
Explain Adaptive Radiation in finches.
In Darwin's finches, we can see adaptive radiation where each finch has a distinct type of beak depending on what its main food source is.
Explain and give an example of a Ring Species.
A ring species is when a certain species can be found in a ring shape. They are believe to have started at one point in the ring and eventually evolve, differing slightly as you travel around the ring, so much so that those found at the end of the ring (close to the start) cannot successfully mate with each other.
What is Convergent Evolution?
When we can find animals on different continents that exploit the same resources and resemble each other, however have no common ancestor (placentals and marsupials).
What is parallel evolution?
Similar to convergent evolution, however these species do have a common ancestor, and so similar habitats have distinct groups which resemble each other and can be traced back. An example of this are the tree lizards which reside in the Caribbean islands.
What is Local extinction? Global extinction?
- Local extinction is when a certain species or taxonomic group cannot be found in a certain area anymore.
- Global extinction is when a certain species or taxonomic group cannot be found anywhere in the world.
What is a tropic cascade?
When the extinction of one animal leads to the extinction of another because of a loss of a food source.
What is phyletic extinction, and give an example.
Species goes extinct but genetic material remains through descendants. Example is a horse.
Explain phyletic graduation.
Phyletic graduation is an evolutionary theory which proposes that species evolve slowly over time, and gain characteristics that make their survival more successful. Those who gain these favourable attributes slowly increase their numbers due to this and are what we see today.
Explain punctuated equilibrium.
Punctuated equilibrium is the competing theory of evolution which suggests that evolution happens quickly, in a burst. For example, a species may have some members with a randomly mutated gene which becomes so prevalent that it dominates and is what we see today.
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