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Lecture notes - Feb. 3

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York University
BIOL 1500
Alexander Mills

BIOLOGY 1001 Lecture: February 3, 2014 Question: In a population, sperm and eggs each exhibit a 34% likelihood of carrying the B allele. The other allele in the population is the b allele. What is the likelihood of a male and female, drawn at random from the population, mating to produce a heterozygous offspring? Answer: 45% correct answer! Draw a punnet square and add the 2 Bb squares! *** Answer on moodle! ^ p^2 + 2pq + q^2 = (.34*.34) + (2*.34*.66) + (.66*.66) = .1156 + .45 + .44 = 1 The normal Distribution  COD FISHES: Directional Selection Question: Distinguish Darwinian Evolution from evolution Answer:  Darwinian evolution proceeds by Natural selection  Accordingly Darwinian Evolution results in adaptation  DE: change in a population allele frequencies over time due to natural selection Question: Polygenic Traits: more than one gene for a trait. Example: AABBCC * aabbcc =ABC * = abc = AaBbCc Example of corn having: DISRUPTIVE AND POLYGENIC due to many genes ^ It would have been directional IF there was a constant slope going one direction and not two Side Trip: Selection sub-category  Countervailing selection as a fitness trade off  Directional Selection: tends to reduce genetic diversity  If directional selection continues over time: favoured alleles eventually reach a frequency of 100%  ^ they are said to be fixed  Stabilizing Selection: intermediate variants are favoured  ^ The mean trait value doesn’t change  Pattern during periods of stability  Purify Selection: Any type of selection where variation is reduced  ^ making population less variable  Disruptive Selection: favours indication at both ends of the phenotypic range  ^ Occurs when 2 different opportunities are available  ^ Ex. Intermediate individuals are less efficient in consuming either source (large or small.. so birds need either large or small.. not in between to feed on those seeds)  Which pairs will likely have greatest fitness? BOTH SMALLAND LARGE BEAKED! LECTURE: February 7, 2014 –Lecture #5a Misunderstanding Natural Selection  P-prims: phenomenological primitives - AKA folksy knowledge, common knowledge  Fallacy A: somebody is in charge  Anthropomorphic Thinking  Fallacy B: The needs of an organism generate evolutionary solution  Teleological thinking  Fallacy C: the process drives towards complexity and perfection -- > Progressive thinking  Fallacy D: AN entire population transforms uniformly as it adapts  typological thinking Fallacy A  Example: mother nature  Language  Darwin and Wallace had a dispute about understanding each other’s concepts about natural selection Fallacy B  Organisms evolve traits as they need them  P-prim: when we need something, we design it and build it  Organisms evolve traits when they need them  Ex. Antibiotic resistance - As microbes evolve, they adapt to their environment  true if they do evolve - They may evolve new mechanisms that resist - Avoid any argument that uses “in order to”  Lamarck “ the guy who was wrong”  Use and Disuse - Individuals sends messages to gametes and gets them to change  Vestigial Traits - Population - Common ancestors - Mutations accumulate because there is no fitness consequence Fallacy C  Life has become more complex over time, but there is nothing about natural selection that requires that  P-prim: we are at the end-point Fallacy D  Pre-evolutionary view: - Species have essences and members of a species must have all criteria required to achieve that essence - Within a species, variation represents non-essential aspects of the species  You can’t point to one generation where a mother gives birth to a child of a different species  Mostly gradual change over thousands of years  All species are transitional  NO MISSIN
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