BIO220-Slides-Lecture1-W2012(1)

BIO220-Slides-Lecture1-W2012(1) - Locke Rowe PhD (UBC)...

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Unformatted text preview: Locke Rowe PhD (UBC) Professor, and Chair, EEB Canada Research Chair in Evolutionary Ecology Evolutionary Ecology • The evolution of developmental strategies • Early life effects on late life outcomes • The causes and consequences of coevolution between the sexes 1 Genomes to Ecosystems in a Changing World Sexual Differences Prof. Locke Rowe Social Evolution Evolutionary Medicine Prof. Asher Cutter Ecological genomics Conservation genetics Genetics of exploited populations Applied ecology Prof. James Thomson Human impacts on climate & on biogeochemical cycles 2 Sexual Interactions & The Evolution of Sexual Differences Lecture 2 - Sexual Selection and Male Competition Lecture 3 - Female Choice 3 Cooperation & Conflict 4 - Social Behaviour 5 - Parent-Offspring Conflict 4 Aging (Senescence) Lecture 6 - Costs of Reproduction and Aging 5 The Evolution of Disease Lecture 7 - Drug Resistance Lecture 8 - Virulence Lecture 9 - Emerging Disease 6 Early Life Effects on Development & The Institute for Human Development Lecture 10 - Dr. Fraser Mustard 7 Genes, Environment and Behaviour • Genes, environment and the phenotype • Phenotypic plasticity & reaction norms • The evolution of behaviors General background reading in Ricklefs: Evolution and adaptation, pp 113-119 Assigned reading: Phenotypic plasticity, pp 124-130 8 Two classes of scientific questions How/What? Why? • How an individual manages to carry out an activity? • Why an animal has evolved the behaviour? • How mechanisms within an animal work to produce a particular behaviour? ULTIMATE CAUSES PROXIMATE CAUSES Tinbergen 9 What is the causal relationship between the animal’s genes and its behaviour? Copyright © 2005 Rick Cameron Why has this behaviour evolved and how has it changed over evolutionary time? 10 What is the hormonal basis of infanticide? Copyright © George B. Schaller Why has it evolved: what is the adaptive value of infanticide to both males and females? 11 Have you noticed that bees and wasps behave oddly in the fall? They are a little bit drunk •What? Reaction to ethanol •How? Feeding on over ripe fruit •Why? An adaptation for locating ripened fruit. 12 •What? Reaction to ethanol •How? Feeding on over ripe fruit •Why? An adaptation for locating ripened fruit. Broad-leaved helleborine Plants produce ethanol to attract bees. 13 “Nothing in biology makes sense except in the light of evolution” Theodosius Dobzhansky, 1973 General background reading in Ricklefs: Evolution and adaptation, pp 113-119 14 Genetic and Environmental and Variation Identical twins: • Same genetic make-up • Even slight differences in environment lead to variation in behaviours But – it’s difficult to conduct experiments on humans 15 Phenotypes reflect both genetic and environmental effects Z=G+E phenotype genes environment 116 6 The Rover-Sitter Polymorphism Marla Sokolowski locomotion courtship foraging movement in food media larva learning & memory olfaction geotaxis adult sleep circadian rhythms 17 Within Population Variation in a Behaviour: Rover/Sitter Polymorphism • Yeast is food, and is spread on agar, a non-food media • Within food patches, rovers move much more than sitters • Rovers and sitters move more often, and for similar distances in the absence of food no food, two classes move the same. so the movement is related to food 18 Rover/Sitter Polymorphism • Rovers move much greater distances than sitters when food is patchy • This means that rovers are off food patches more often, but also are more likely to find new patches Rover Sitter 19 Natural variation in the frequency of rovers and sitter larvae Sitter, 30% Rover, 70% 20 Genetic Analysis Sitter males Rover females All rovers F1 F2 3 rovers: 1 sitter rover gene is dominant Track length (cm) 21 What do these foraging alleles produce? rover gene produce PKG PKG - an enzyme involved in cell signaling - located in nervous system, and the gut l(2)09230 Hindgut Stomach Brain 22 Rover/sitter transgenics insert rover gene into larvae We can insert the “rover” allele in “sitter” larvae Then measure the effects of that allele on foraging 23 Both foraging behaviour and PKG activity in transgenic flies resembles “rover” type more than “sitter”. Strain Foraging Behaviour PKG activity (cm traveled) (pmol min-1mg-1 ) 9.2 11.2 transgenic sitter hosting a rover allele 8.9 Behavior much closer to rover 11.3 sitter (host) 10.0 rover 4.6 24 Phenotypes reflect both genetic and environmental effects Z=G+E phenotype genes environment 225 5 Environmental effects on foraging • Adults were deprived of food for 4 or 24 hrs • Assayed for foraging behaviour in patchy environment Adult foraging behaviour (cm traveled) Food Deprivation Rover Sitter 4h 24 h 36.17 25.60 22.38 16.20 environmental effect rover after 24h food deprivation is like sitter after 4h deprivation 26 Summary: rover - sitter story • A single major gene underlies the rover/sitter polymorphism • The rover allele is dominant to the sitter allele • Both larval and adult behaviours are effected by these alleles • Elements of the environment (e.g. food deprivation) also effect these behaviours • Homologous genes occur in bees, mice and humans 27 Genes, Environment and Behaviour • Genes, environment and the phenotype • The evolution of behaviors • Phenotypic plasticity & reaction norms 228 8 Phenotypic plasticity: an environmental effect on the phenotype genotype effect Food Deprivation Rover Sitter 4h 24 h 36.17 25.60 22.38 16.20 environment effect 29 genotype effect Food Deprivation Rover Sitter 4h 36.17 22.38 24 h 25.60 16.20 environment effect 30 genotype (G1) rover Phenotype (Z) cm traveled genotype (G2) sitter 10 4 24 Environment (E) hours of food deprivation rover and sitter both have phenotypic plasticity 30 Use of Refuge (phenotype) Behavioural Response to Predators (Plasticity) No predator Predator big fish refuge (environment) 31 Helmet (phenotype) Morphological response to predators (plasticity): Daphnia helmet No predator Predator (environment) 32 Plasticity can be dramatic mouth part is facing down Non-cannibal Cannibal little tadpole grows up with shrimps massive jaws to consume shrimps Spadefoot Toad 33 Reaction Norms: Visualizing G and E • Environmental effects on trait values can be described as plasticity • The influence of genes and environment can be visualized with plots of the reaction norm • The reaction norm describes the effect of some environmental variable on the phenotype of a single genotype. a reaction norm 30 genotype (G1) rover Phenotype (Z) cm traveled genotype (G2) sitter 10 4 24 Environment (E) hours of food deprivation 334 4 Reaction Norms: Visualizing G and E Reaction norms describe the effect of an environmental variable on the phenotype of a single genotype. phenotype G1 G2 A • Genetic differences no environmental differences B • Genetic and environmental differences A B environment You can learn a lot from reaction norms G1 phenotype G2 • large genetic effects, small environmental effects • small genetic effects, large environmental effects steep slope • complex gene environment interactions environmental effect on one genotype is different than on another genotype environment 36 Helmet size Evolution of reaction norms blue is maladaptive, blue genotype is lost red will do better than green. No predator Predator (environment) 37 Genetic variation and evolution of reaction norms Daphnia tends to display phototactic behaviour - They are attracted to or repelled by light Genotypes can easily be isolated all offsprings are clones of the parent Phototaxis can be quantified in the lab Food is in the light, but fish are visual predators - There is a trade-off. Assayed 30 genotypes from 3 lakes (G) Tested with and without fish smell (E) The lakes had different predator ake (selection)histories llake with lots of predators, force of selection is strong with less predators, weaker force of selection 38 Evolution of reaction norms Phototactic behaviour Increasing attraction to light Selection History Many Fish Few Fish No Fish not responding to the smell of fish extent of plasticity differs among the 3 lakes C F C F C F Fish scent treatment (environment) 3 reaction norms 39 Evolution by natural selection... • Variation in a trait individuals differ • Variation in fitness for the trait • Genetic basis for the trait Evolution of behaviour… • Behaviours have great variation • Different behaviours have different fitness • Behaviours have a genetic basis 40 Summary • Genes and environment influence phenotypes • Environmental effects on trait values can be described as “plasticity” • The influence of genes and environment can be visualized with plots of the “reaction norm” • Natural selection shapes the reaction norm • Natural selection shapes behaviours Bring both lecture 2 and 3 to next lecture 41 ...
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This note was uploaded on 04/03/2012 for the course EEB BIO220 taught by Professor Locke during the Spring '12 term at University of Toronto.

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