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Lecture 8

BIOB51H3 Lecture 8: Lecture 8 note


Department
Biological Sciences
Course Code
BIOB51H3
Professor
Maydianne Andrade
Lecture
8

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Lecture 8
Bipedal organisms using feathers for thermoregulation
o Move to arboreal environment feathers are aerodynamic to aid in leaping
Elaborated feathers that allow for parachuting
New generations with larger feathers can glide
o Evolve to have powered flight
In arboreal environment, more elaborate feathers are favored
o Post selection range of variation selection becomes directional
This change in trait value over generations required 3 things:
o Selection
o Phenotypic Variation
o Heritability
Polymorphism = # of options, what alleles you can have in a gene pool at that locus
Mean Heterozygosity = # of individual heterozygotes per locus
Polymorphism is hand in hand with adaptability genetic capacity to adapt
Genetic Variation and Fitness
Fixed allele only allele present at a given locus
Deleterious alleles lost by selection
Neutral mutations are maintained, lost, or fixed by chance
Beneficial mutations are maintained or fixed by selection
o As compared to the wild type
Neutral Mutations
1. Silent site (synonymous) substitution
a. Point mutation that has no amino acid change
2. Replacement (non-synonymous) substitution
a. Changes amino acids to another amino acids with same properties
C. elegans great lab model system, can engage in sexual reproduction
o No natural selection, 74 lines of reproduction, ideal conditions
o Randomly pick one to be new parent for each generation
o 74 mutation accumulation lines”
o Had control lines where competition occurred and selection has operated
Better competitors are new parents for next generation
o Found from experiment that most mutations are mildly deleterious
Increased mutations
Decreased fitness by 0.5% per generation
o Took mutation accumulation group and allowed selection to occur
Low fitness population have beneficial mutations occur
Can recover rapidly
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