ANTA01H3 Lecture Notes - Lecture 2: Bighorn Sheep, Bowerbird, Porphyria

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Published on 5 Jul 2012
School
UTSC
Department
Anthropology
Course
ANTA01H3
Professor
Lecture 1 September 12, 2011
Evolution does not rely solely on a particular mechanism or praceess
Smallest unit of time in which evolution occurs is a generation
Niche: role of a species in its environment
o (eg) Galapos Island
Evolutionary Processes
Selection:
o Natural selection
o Artificial selection
Selection by humans for favorable traits
o Sexual selection
Selection on feathers or behavior associated with mating
Generally takes two forms:
Male-male competition (eg. Bighorn sheep headbutting)
Female choice (eg. Female bower bird inspecting a bower)
Male choice is not very important because sperm is CHEAP.
o Non-random mating more associated with humans
Example: Inbreeding: Charles II of Spain
Mutation: “A change in DNA can refer to change in DNA bases as well as changes in chromosome # or
structure
o It’s the ultimate source of variation
Genetic Drift:
o Random changes
o Not due to selection
o Mostly affects small population
o Gametic Sampling: Changes in the genetic material passed on the next generation just as a
result of random chance in which variants get passed on.
o Fission effect: changes in the frequency of variants in a population as a result of subdivision
Could be the first step in process of speciation
o Founders effect: differences in the frequency of variants in a population as a result of random
chance in which members start a new population
Ex. One outcome of founders effect can be the increase in the relative frequency of a
rare type (eg. A gene for a disease such as porphyria)
Ex. Jansz family carried genes for porphyria
o Bottleneck effect: restriction in genetic variability w a decrease in population size
Decrease in population because something catastrophic (eg. Tsunami)
Population that have less variability are more likely or at risk of extinction
150 000 years ago, humans underwent bottleneck effect
o Geneflow: exchange of genes between population
Reduction of gene variability (WHY?)
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Document Summary

Evolution does not rely solely on a particular mechanism or praceess. Smallest unit of time in which evolution occurs is a generation. Niche: role of a species in its environment (eg) galapos island. Selection by humans for favorable traits: sexual selection. Selection on feathers or behavior associated with mating. Female choice (eg. female bower bird inspecting a bower) Male choice is not very important because sperm is cheap: non-random mating more associated with humans. Mutation: a change in dna can refer to change in dna bases as well as changes in chromosome # or structure. Could be the first step in process of speciation: founders effect: differences in the frequency of variants in a population as a result of random chance in which members start a new population. One outcome of founders effect can be the increase in the relative frequency of a rare type (eg. a gene for a disease such as porphyria)

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