Lecture 3 - Natural Selection

Lecture 3 - Natural Selection - BILD 3 4 April, 2008...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
BILD 3 4 April, 2008 Woodruff: Natural selection 1 1 LECTURE 3. EVOLUTION IN ACTION DARWINISM AND NATURAL SELECTION DESCENT WITH MODIFICATION = EVOLUTION TRANSMUTATION = SPECIATION STRUGGLE FOR EXISTENCE and SURVIVAL OF THE FITTEST = NATURAL SELECTION 2 SOURCES OF VARIATION MUTATION CROSSING OVER/RECOMBINATION/ SEXUAL REPRODUCTION AGENTS OF EVOLUTION MUTATION GENETIC DRIFT GENE FLOW NATURAL SELECTION DIRECTIONAL SELECTION DISRUPTIVE SELECTION BALANCING OR STABILIZING SELECTION SEXUAL SELECTION 3 DARWINISM 1. FAR MORE ARE BORN THAN CAN SURVIVE MALTHUS - GEOMETRIC GROWTH OF POPULATIONS YET MOST POPULATIONS REMAIN FAIRLY CONSTANT STRUGGLE FOR EXISTENCE 2. INDIVIDUALS ARE NOT ALIKE SOME VARIABLE TRAITS ARE INHERITED AND SOME INDIVIDUALS ARE BETTER ADAPTED THAN OTHERS SURVIVAL OF THE FITTEST or preferably: NATURAL SELECTION AND DIFFERENTIAL REPRODUCTION 3. THE ABOVE, PLUS NEW VARIATION LEADS TO ORGANIC EVOLUTION [HERITABLE CHANGE]. 4 GENOTYPE: UNDERLYING GENETIC CONTROL OF TRAIT PHENOTYPE: EXPRESSION OF THE GENOTYPE. MAY BE INFLUENCED BY THE ENVIRONMENT VARIATION WITHIN A POPULATION (GENE POOL) MONOMORPHISM DIMORPHISM POLYMORPHISM MORPHOLOGICAL GENETIC SEX-ASSOCIATED 5 NATURAL SELECTION DIFFERENTIAL SURVIVAL AND REPRODUCTION NUMBERS AA Aa aa N 0 400 640 320 N t 360 540 200 SURVIVAL RATE, 0.90 0.84 0.63 RELATIVE FITNESS, W 1.00 0.94 0.69 SELECTION COEFFICIENT, S = 1 - W 0.00 0.06 0.31 FITNESS (W) IS A PROPERTY OF A CLASS OF INDIVIDUALS NOT A SINGLE INDIVIDUAL 6 DARWIN’S MISSING EVIDENCE MELANISM IN THE ENGLISH PEPPERED MOTH Biston betularia MELANIC vs. TYPICAL MORPHS (CC, Cc) (cc) DIRECTIONAL SELECTION 1848 FIRST MELANIC 1895 95% MELANIC IN CENTRAL & EAST
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
BILD 3 4 April, 2008 Woodruff: Natural selection 2 7 HIGH FREQUENCIES OF MELANIC MORPHS IN PARTS ENGLAND LOW FREQUENCIES OF DARK MOTHS IN WEST AND NORTH. 8 DARK MORPH WAS CRYPTIC IN POLLUTED WOODS TYPICAL MORPH WAS CRYPTIC IN UN-POLLUTED WOODS BIRD PREDATORS WERE THE AGENTS OF NATURAL SELECTION RELEASED EQUAL NUMBERS OF MARKED DARK AND LIGHT MORPHS AND WATCHED THE BIRDS: UNPOLLUTED WOOD DARK LIGHT SPOTTED FLYCATCHER CAUGHT 81 9 MOTHS ROBIN 12 2 YELLOWHAMMER 20 0 ALL BIRDS 164 26 OF 190 MOTHS POLLUTED WOOD DARK LIGHT ALL BIRDS 15 43 OF 58 MOTHS ADAPTIVE ADVANTAGE WITH RESPECT TO VISUAL PREDATORS. 9 THIS IS A CASE OF INDUSTRIAL MELANISM MELANIC MORPHS OF THIS MOTH AND MANY OTHER INSECTS WERE FAVORED FOLLOWING THE POLLUTION OF THE DOWNWIND COUNTRYSIDE ASSOCIATED WITH THE INDUSTRIAL REVOLUTION. INTERESTINGLY SINCE THE GOVERNMENT ORDERED
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/19/2008 for the course BILD BILD 3 taught by Professor Woodruff during the Spring '08 term at UCSD.

Page1 / 6

Lecture 3 - Natural Selection - BILD 3 4 April, 2008...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online