What determines a particular phenotype Nature versus Nurture

What determines a particular phenotype? Nature versus Nurture All behavior is the product of an inextricable interaction between heredity and environment during development, so the answer to all nature-nurture questions is “some of each. ” -Steven Pinker 1

5/15/08: Development of Behavior Lecture objectives: + ? Behavior 1 Behavior 2 ? 1. Understand that behavior is a product of gene-environment interactions 2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences 3. Understand features of development and the adaptive value of learning 2

Behavior is a complex product of gene-environment interactions Environment influences expression of genes (protein production) Genes encode information Development unfolds over time 3

Example (pgs. 56 -59): Gene-env interactions underlie the development of honeybee foraging Gene 1 Gene 2 Gene 3. . Gene n Nurse Forager (young) (old) Nurse (old) Forager (young) Effect of social environment: When foragers (old bees) are scarce, young bees will rapidly become foragers 4

Example cont: Gene-env interactions underlie the development of honeybee foraging Concentration of JH + nurse forager 5

Even learning has a genetic contribution Gene-environment interactions Example: Different species show different imprinting tendencies Learning Blue tit Great tit 6

What determines a particular phenotype? Nature X versus Nurture All behavior is the product of an inextricable interaction between heredity and environment during development, so the answer to all nature-nurture questions is “some of each. ” -Steven Pinker Info in genes is only expressed Development & learning require the 7

Lecture objectives: + ? Behavior 1 Behavior 2 ? 1. Understand that behavior is a product of gene-environment interactions 2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences 3. Understand features of development and the adaptive value of learning 8

Members of the same species often differ in behavior Black-capped chickadee: caching behavior What underlies differences in development/behavior? - differences in genetic info? - differences in environmental inputs? - both? 9

Differences in development/behavior can arise from environmental differences Idea: Environment A Behavior/Phenotype 1 Environment B Behavior/Phenotype 2 10

Example: social behavior differences in paper wasps arise from early olfactory experiences Demonstrated by manipulating Can experience shape a wasp’s tendency to tolerate unrelated wasps (nonkin)? Home nest Foster nest I don’t fight with my sisters! Tendency to fight Sister wasps Foster wasps 11

Differences in development/behavior can arise from genetic differences Idea: Genotype A Behavior/Phenotype 1 Genotype B Behavior/Phenotype 2 12

Example: “Good mommy” behavior differences in mice arise from genetic differences Demonstrated by a fos. B Expression is “knocked out” 13

Example: Slug-eating behavior differences in tiger snakes arise from genetic differences Demonstrated by a X 14

Example: Cotton collection differences in mice arise from genetic differences Demonstrated by an x ? x x 15

You suspect that the difference in food-caching ability of these two bird populations has a genetic basis, but there hasn’t been much work done on this question before. You only have 2 years of funding for the project. How will your research team go about investigating this question? 1. Come up with a project plan that seems feasible – write/draw your experimental design 2. List why you chose that design over the other possible designs you could have chosen 3. List your predictions for the hypothesis that the trait difference has a genetic basis Black-capped chickadee: caching behavior 16

Lecture objectives: + ? Behavior 1 Behavior 2 ? 1. Understand that behavior is a product of gene-environment interactions 2. Be able to figure out whether differences in a behavior arise from genetic and/or environmental differences 3. Understand features of development and the adaptive value of learning 17

“Normal” development is often robust, even under adverse genetic or environmental conditions Gene knockouts Genetic system likely has high informational redundancy Rhesus monkeys develop normal social behavior with only 15 minutes of socialization/day 18

Sometimes there is more than one form of “normal” development ( >1 discrete phenotype) Proximate: what env. cues activate a different developmental pathway? Ultimate: what fitness benefits do animals gain from being able to “choose” how to develop? 19

There are costs and benefits to learning Adaptive modification of behavior based on experience Costs: Benefits: 20

Natural selection favors investment in learning when the ability to learn confers reproductive advantages Benefits > Costs Yoohoo! Where is my Romeo? Something isn’t quite right here… The ability to learn would probably be beneficial for male thynnine wasps. 21

An animal’s ability to learn certain associations or solve certain problems often makes biological sense Example: Rats have an easy time learning certain associations and a hard time learning others 22

An animal’s ability to learn certain associations or solve certain problems often makes biological sense Example: Sex differences in spatial learning ability are linked to home range size 23

Summers' remarks on women draw fire By Marcella Bombardieri, Globe Staff | January 17, 2005 “The president of Harvard University, Lawrence H. Summers, sparked an uproar at an academic conference Friday when he said that innate differences between men and women might be one reason fewer women succeed in science and math careers. Summers also questioned how much of a role discrimination plays in the dearth of female professors in science and engineering at elite universities. ” What is your reply to the following assertions? Explain your answers. • • • Genes determine the ability of women to succeed in science. Upbringing and culture determine the ability of women to succeed in science Differences in the abilities of men and women to pursue scientific careers might arise from genetic differences Differences in the abilities of men and women to pursue scientific careers might arise from cultural differences There is a gene or group of genes that determines scientific ability. 24