BIOL 290 Lecture 5: Other Factors that Effect the Population

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Published on 21 Sep 2018
Other Factors that Effect the Population
Friday, September 21, 2018
9:14 AM
Pairing of homologous chromosomes during meiosis
Humans have 23 pairs of chromosomes, and humans have 46 all together
People will use the "proof" that we have different numbers of chromosomes than other primates,
we can't be related to them
Telomeres & centromeres; telomeres are protective caps, and centromeres are in the middle; they
fuse together at the telomeres; and some scientists say that’s why we have 46, while other
primates have 48
Random Genetic Drift
Random subsampling of populations
Ex: brown rabbits reproduce faster than white rabbits, in the second generation there will be
more brown, third all brown
Random event; wipeout, natural disaster, etc.,
Gene Flow:
Movement of alleles, genes, gametes between populations
Happens through immigration/emigration, and migration
Hybridization: two species interbreed and give rise to a new hybrid species with different genetic
Two species interbred and gave rise to a new species
Populations are units of evolution
o A population is a group of individuals of the SAME species living in the SAME place at the
SAME time
o A species: made up of a group of populations whose individuals have the potential to
interbreed and produce fertile offspring
Individuals do not evolve
Evolution is a process; that has many mechanisms
o Evolution by natural selection is a genetic change in a population that occurs between, or
over the course of generations
Evolution acts on existing heritable (genetic) variation
Involves changes in the frequency of particular traits due to differential success
among individuals
Natural selection does not cause mutation; variations are ALREADY there; it just
selects the best variation
1. Natural selection involves individuals trying to adapt to current environmental conditions: FALSE
2. What is evolution?: Process
3. How can we depict evolution: Evolution is a gradual branching of lineages
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