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Lecture 2

ANTA01 - SUMMER 2012 - LECTURE 2 - MODERN EVOLUTIONARY THEORY

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Department
Anthropology
Course
ANTA01H3
Professor
Carolan Wood
Semester
Summer

Description
LEC 2 – ANTA01 – MAY 17, 2012 DARWIN (NS) + MENDEL (GENETICS + MOLECULAR BIO) = MODERN EVO TH  DARWIN AFTER BEAGLE  WALLACE  DARWIN’S “ORIGIN OF SPECIES BY MEANS OF NS”  DARWIN’S COMMENT ON HUMAN EVOLUTION  DARWIN/WALLACE CONTRIBUTIONS  CONCEPT OF NS (DIVE) – WALLACE/DARWIN  MECHANISM OF NS – MENDEL  MENDELIAN GENETICS  EXPERIMENT  INDEP ASSORTMENT  ALLELE COMBOS  NON-MENDEL INHERITENCE  POLYGENIC  PLEIOITROPHY  VARIATION BY  MUTATION  MEIOSIS  EVO IMPORTANCE  GENE REDISTRIBUTION BY:  GENE DRIFT/FLOW  ADAPTATION DARWIN AFTER BEAGLE  1838 – D reads Malthus “Population” Essay  1944 – D puts EVO TH BY NS  Scared to publish, feared reprisal  Huxley supported D (His representative and homie) WALLACE  Huxley’s Friend  Same conclusion as D (collecting specimen in Indonesia)  1858 – sent D manuscript named “Tendency of Varieties to Depart Indefinitely from Original Type”  1858 – D present paper to Royal Linnaean Society (RLS) – quick, no peer edit 1859 – BOOK = “ORIGIN OF SPECIES BY MEANS OF NS”  Malthus’ “Population” essay = “organisms potential for pop growth outstripping food supply”  M (Human), D (Species) = Struggle for Existence  In nature, populations are relatively STABLE  Observation: Nature has lots of variation, some favoured and some not = NS DARWIN’S COMMENT ON HUMAN EVOLUTION = Humans have evolved LEC 2 – ANTA01 – MAY 17, 2012  Went against Church = God made everything perfect, no need for change  African Great Apes = Closest Human Relative  Africa = Earliest member of human lineage DARWIN/WALLACE CONTRIBUTIONS  NS = From existing variations, nature selects species best adapted to their envi  Adaptive traits inc/time  Evo = No direction (more like being at the right place/time)  Selection acts on existing variation (variation already w/in a pop)  Diff pop, diff envi, diff selective pressures  SPECIATION: when pop becomes so distinct. Therefore species can’t interbreed  Organisms best adapted to envi have highest chance of surviving/reproducing successfully CONCEPT OF NS 1. VARIATION IS SHOWN B/W INDIV FOR EACH TRAIT a. NS operates on variation, does not need to be expressed (can be gene coded) 2. INHERITED = TRAITS (from parents to offspring) 3. ENVI = FILTER (pressures NS to act) 4. DIFFERENTIAL REPRODUCTIVE SUCCESS a. Frequency of adaptive traits increase as you’re better adapted to envi NB. NOT ALL TRAITS COME FROM NS  I.e. NS does not account NEUTRAL TRAITS (originate from random processes i.e. gene drift/flow)  Darwin/Wallace = “We need variation for NS!” MECHANISM OF NS (MENDEL )= “I know where variation comes from!” EXPERIMENT (pea plants)  Took notes on types and proportion of hybrids, testing blending of inheritance  1 Breed of Green and Yellow = got ALL YELLOW  2 Gen = YELLOW:GREEN (3:1)  Conclusion =  traits must be passed on using discrete units – either 0 or 1 – no intermediates)  some traits will be dominant over recessives (yellow over green)  Dominant = gene/allele will ALWAYS be expressed phenotypically  Recessive = phenotypic expression suppressed (only expressed with 2 together)  Genotype = genetic makeup  Phenotype = physical expression  Conclusion: NS works by HEREDITY (advantageous variations are passed down) MENDELIAN GENETICS  HERITABLE VARIATION = BASIS OF EVO LEC 2 – ANTA01 – MAY 17, 2012  Genes = Units of inheritance, occur in pairs for each trait  1 unit per parent  PRINCIPLE OF INDEPENDENT ASSORTMENT  Genes coding for diff traits = inher indep of one another (eg. 1 trait for blue, 1 for brown, brown usually dominant)  ALLELE = 1 unit of gene pair (eg. Dad’s blue allele, mom’s green allele) codes diff version of trait  ALLELE COMBO  Homozygous (2 identical genes/alleles) in corresponding locations on a chromosome  Heterozygous (2 diff genes/alleles) in corresponding locations on chromosome  F1 Generation – Ss and Ss = 3 Smooth and 1 Wrinkle  9:3:3:1  9 yellow smooth, green smooth, yellow wrinkle, green wrinkle NON MENDELIAN INHERITANCE  POLYGENETIC INHERITANCE = continuous phenotypic expressions (bellcurve)  Vs DISCRETE  Ctrl’d by 2+ genes  Traits often influenced by envi  MENDELIAN: Gene  Effect (1:1)  POLYGENIC: Many Genes  Effect (+1:1)  PLEIOTROPHY: Gene  Effects (1: +1) (eg. Disease that might be sex linked)  POLYGENIC AND PLEIOTROPHY: Many Genes  Effects GENETICS  GENES: DNA segments found on chromosomes w/in nucleus  CHROMOSOMES: always show in pairs.  Alleles for traits found in same location on pairs of chromosomes  Cell structures made up of DNA wrapped around prote
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