Behavioral Development Genes (Innate/Nature) Environment (Learned/Nurture) DNA is both inherited and environmentally responsive The ability to learn is influenced by genes
Environmental differences lead to behavioral variation
Phenotypic plasticity: multiple alternative phenotypes within a species whose differences are induced by key differences in the environments experienced by members of this species Reaction norm – Reaction norms provide graphical representations of phenotypic plasticity—the ability of a genotype to produce different phenotypes across an environmental gradient
2 forms of tiger salamanders
Phenotypic plasticity is favored when conditions are ____________ a)variable/unpredictable b)constant/predictable
Resolution of the Nature vs. Nurture Debate Contemporary view –No behavioral trait is ‘genetically determined’ nor ‘environmentally determined’ –Rather, behavioral development is an interactive process between genes and the environment –differences in phenotype may be due to genetic and/or environmental differences among individuals Both genes and environment are 100% important in the development of all behavior. (Donald Hebb)
Individual Variation is Important
Overall Success YesNo Exploration Diversity Successful hyenas display a wider array of behaviors in 1 st trial Logistic regression results: * = p < 0.05 Exploration diversity: # of exploratory behaviors used Digging, investigating, biting, flipping or dragging the box
Individual variation in exploration diversity Likelihood ratio test: Hyena ID: P < Generalized linear mixed model: Success: P < Least Diverse Most Diverse Mean exploration diversity score per individual Hyena ID
Personality Differences/ Behavioral Syndromes Consistent long-term behavioral differences among individuals across time and context may be heritable may be affected by individual and social learning -especially when learning occurs early in development Behavioral syndrome: a suite of correlated behaviors reflecting between-individual consistency in behavior across multiple situations. Within the syndrome, individuals have a behavioral type (i.e. less aggressive or more aggressive) - Sih et al Behavioral consistency, both within and between individuals
Behavioral Syndromes Aggression in contests Aggression in feeding Aggression in mating Parental care behavior Boldness with predators present Good territory High feeding rates Sexual coercion Poor parenting DEATH
Personality Is Often Heritable A recent review of temperament and personality in nonhumans found evidence for heritability in twenty species (Reale et al 2007, 2010).
Boldness and Shyness Psychologists have long proposed that where a person falls on the continuum from very shy to very bold behavior is one of the most stable personality variables studied. Boldness = the tendency to take risks in both familiar and unfamiliar situations Shyness = the reluctance to take risks, or even a reluctance to engage in unfamiliar activity at all.
Barnacle geese - consistent leaders (bold risk takers) and consistent followers (Kurvers et al. 2009; 2011) costs to leaders - increased predation/injury benefits to leaders - first access to food
Predator Inspection in Guppies
Q: Why do some guppies exhibit high predator inspection behavior? H1: Guppies inspect predators to protect vulnerable offspring P1: Only guppies with an active nest nearby should exhibit high predator inspection behavior
H1: Guppies inspect predators to protect vulnerable offspring Level of Analysis? A.Phylogeny B.Mechanism C.Function D.Ontogeny
Q: Why do some guppies exhibit high predator inspection behavior? H1: Guppies exhibit high predator inspection behavior due to activational effects of testosterone, which causes guppies to be more aggressive and more willing to take risks P1: Guppies that exhibit high predator inspection behavior have higher circulating testosterone levels than guppies that exhibit low predator inspection behavior
Level of Analysis? A.Phylogeny B.Mechanism C.Function D.Ontogeny H1: Guppies exhibit high predator inspection behavior due to activational effects of testosterone, which causes guppies to be more aggressive and more willing to take risks
Q: Why do some guppies exhibit high predator inspection behavior? H1: Predator levels during development trigger predator inspection behavior in adult guppies. P1: Guppies that develop in environments with a high concentration of predators will exhibit higher predator inspection behavior than guppies developed in environments where predators were absent
Level of Analysis? A.Phylogeny B.Mechanism C.Function D.Ontogeny H1: Predator levels during development trigger predator inspection behavior in adult guppies.
Also tested the ability of males guppies to learn an association Treatment 1: males evaluated on boldness and then given a learning task Treatment 2: males given a learning task and then evaluated on boldness Results: Bolder guppies in treatment 1 learn more quickly than behaviorally inhibited guppies. This result did not hold for treatment 2. Predator inspection may prime bold fish to learn better, or it may have a negative effect on learning in behaviorally inhibited fish. This may be due to higher levels of stress hormones in the behaviorally inhibited fish after seeing a predator. Predator Inspection in Guppies
What behavioral observation method did Sih et al. use? a. ad libitum sampling b. scan sampling c. focal animal sampling d. critical incident sampling
Bold and shy sunfish
Personality in Great Tits
Photo by K. van Oers Slow birds take longer to explore an environment spend more time learning about each aspect of a new environment and vary their foraging routine often
Personality in Great Tits Photo by K. van Oers Fast birds take less time to explore an environment spend only a short time in any particular area but are unlikely to change established foraging patterns
Photo by K. van Oers Used marked birds in a natural population in the Netherlands. measured the reproductive success of slow and fast birds in different types of environments found that reproductive success was greatest when pairs of bird had similar personalities slow-slow and fast-fast pairings led to the production of the healthiest chicks Does personality affect fitness?
Photo by K. van Oers Found that females paired with males that had a personality type similar to their own had the highest rates of extrapair matings increase behavioral variation among offspring?
slow-slow and fast-fast pairings led to the production of the healthiest chicks In small groups, come up with two hypotheses to explain this result. Why do these pairings result in the healthiest chicks? Each hypothesis has to be at a different level of analysis State the level of analysis for each hypothesis, and give a very brief (one sentence) explanation for your answer