9- Evolution of Personality Traits

Flashcards reviewing the evolution of personality traits.

What are the main questions regarding the evolution of personality traits?

Evolution selects for the most adaptive traits, and we need to understand why traits like extraversion and neuroticism remain in the population and why there's variation in these traits.

According to Darwinian mechanisms, what does trait fitness indicate?

Traits have fitness, which indicates adaptation in terms of fecundity (number of offspring) and survivorship (living long enough to reproduce).

What is sexual selection, according to Darwinian mechanisms?

Sexual selection arises from differences in reproductive success caused by competition for access to mates, including inter-sexual (mate competition) and intra-sexual (competition).

What 5 factors are required to maintain a genetic equilibrium according to the Hardy-Weinberg Principle?

Random mating, no mutations, population isolation, infinite or large populations, and no natural selection.

What is Copy Number Variation (CNV)?

Individual differences in repetition of DNA segments may be due to replication/duplication errors.

What is Single Nucleotide Polymorphism (SNP)?

Replication errors via base pair substitution.

Describe directional, stabilizing, and disruptive selection.

One variation is most adaptive (greater fitness) and is selected for. Extremes are selected against and is common in stable environments.

What is genetic heritability?

Proportion of total phenotypic variation in the population that is due to genetic variation (h2).

According to Penke, Denissen, & Miller (2007) what are three possible mechanisms for the evolution of personality?

Selective Neutrality, Mutation-Selection, and Balancing-Selection.

Describe Selection Neutrality.

Fitness neutral mutations build up and lead to increased genetic variation in the trait and is only affected by genetic drift.

Describe Mutation-Selection-Balance.

Natural Selection (decreasing trait variance) balances the effects of mutation (increasing trait variance).

What should traits do in Mutation-Selection-Balance?

Traits should be sexually attractive and show assortative mating.

Describe Balancing-Selection.

Extremes of a trait are favored to the same degree by different environments; includes Environmental Heterogeneity and Frequency-Dependent Selection.

Explain the Trade-off model.

Variable Optima is when any traits will have an optimum fitness that varies across situations and time and environmental heterogeneity occurs when, as the environment changes, then associations between trait and behavior change.

Describe behavioral genetics.

All traits are polygenic (affected by multiple mutations at multiple sites); Twin Studies (MZ, DZ) are used to estimate the degree of genetic and environmental influence on a trait

What are the assumptions of twin studies?

MZ and DZ share the same environment, Gene-environment correlation is minimal, Twin scores are equivalent to trait scores in the population, and Mating occurs at random.

What about the environment?

Genetic Effects also influence environmental exposure

Nature vs Nurture

There is NO such thing as Nature versus Nurture IT IS Nature And Nurture.

What are the GE Correlations?

Active, Passive, Evocative

Trait Expression

People should have a preferred way to express their trait (their average score on a personality trait) but also be able to express aspects depending on context.

What two terms are found in behavioral reaction norms?

Personality is defined in a BRN as the average behavioral response across contexts. and Behavioural plasticity represents the flexible expression of the trait.

Describe the Density Distribution Approach.

Traits reflect ‘accumulation of everyday personality states’: Personality and Describe the distribution of an individual traits and dynamic interaction with context (contingencies): Behavioural Plasticity.

How do use experience sampling methods (ESM).

Assess people at multiple time point (4-8 times a day)

Finding 1: Behavioural Plasticity

Individuals vary as much from moment to moment (with variation) as they do between each other (between variation).

Finding 2 & 3: Personality

Individual have a central tendency (mean) and these are very stable (correlation of .80 and .90) and There is also stability in the amount of variability (.50) – therefor variation is fairly stable and a part of personality to be studied.

Describe the Socio-Genomic Model (Roberts & Jackson, 2008)

This implies that both the expression of behaviors associated with trait and the mean level of the trait can vary as a function of (1) the influence of the environment via biological factors (route A) and (2) the dynamic interaction of environment, states (emotions, values, beliefs), biology and the trait. (route B).

What were Miller & Todd’s (1998) two key parameters we may use to identify a good mate?

Personality and intelligence.

What are you looking for?

Good Genes, Good Partner, Good Parents

Costly Signaling Theory

Hard to fake indicators of an animal’s fitness

Preferences and Trait Expression Should Show a Genetic Correlation

Preference for a trait (e.g., openness) and the trait itself should be correlated not only in terms of responses but also at a genetic level.