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speciation
the evolutionary process by which new biological species arise
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allopatric speciation
- different places
- isolated populations (geographically)
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sympatric speciation
same place
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parapatric speciation
adjacent populations with some overlap
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peripatric speciation
one large population withsome small isolates at the perimeter
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Mayr's biological species concept
"Species are groups of actually or potentially interbreeding populations, which are reporductively isolated from other such groups
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premating isolating mechanisms
- prevents union of gametes -> zygote
- 1. mates do not meet (seasonal or habitat isolation)
- 2. mates meet but do not mate (ethological or behavioral isolation)
- 3. mates meet but no sperm transfer (mechanical isolation)
- * can have pre and post simultaneously
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post-mating isolating mechanisms
- 1. sperm transfered but dies before fertilization
- 2. zygote dies
- 3. zygote produces an F1 adult that has reduced viability (survival)
- 4. hybrid is viable, but partially or completely sterile (fecundity) or the F2 is deficient
- *can have both pre and post simultaneosly
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cline
the gradual change in certain characteristics exhibited by members of a series of adjacent populations of organisms of the same species
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In the Mimulus (monkeyflower) speciation study, what traits did Schemske and Bradshaw find to be attractive or repulsive to bee and hummingbird pollinators
- Bees prefer large flowers and avoid flowers with carotenoids
- Hummingbirds prefer large nectar loads
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neofunctionalization
- one copy of a duplicate gene is under selection to retain its original function, and the other copy is free to evolve a new function
- if this process occurs in regulatory genes, then this could lead to the evolution of new developmental pathways and new bauplans (blueprints)
- *deleterious mutations are more common than beneficial)
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subfunctionalization
- regulatory genes often have multiple functions (pleiotropy).
- Gene AB -> Copy1 AB, and Copy2 AB
- Copy1 loses function A and retains B, Copy2 unchanged
- Copy2 loses function B and retains A (it has pressure to retain A and can afford to lose B)
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silverswords vs tarweeds
- they are close relatives
- two regulatory genes and 1 structural gene exist as single copies in the tarweeds, but as duplicate copies in the silverswords
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regulatory genes vs structural genes
- regulatory genes evolved faster than structural genes in silverswords (suggesting the regulatory gene is controlling the macroevolution in silverswords)
- regulatory genes evolved faster in silverswords than in tarweeds
- (regulatory genes are "master control" genes; they tell other genes to talk or shut up)
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adaptive radiation
rapid evolution and diversification of a lineage into a wide array of species (ex: almost all mammals in Austrialia are marsupials, very few placentals)
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nonsynonymous vs synonymous point mutations
- non / s
- high number means rapid evolution and vise versa
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