lecture 9 Flashcards
what is the purpose of natural selection?
to reduce variation to identify the most adaptive trait for the environment the individual is in
characteristic is passed on
how do traits show fitness, indicating adaptation?
fecundity
survivorship
what is fecundity?
the number of offspring an individual has
what is survivorship?
whether the offspring lives for long enough to reproduce
who proposed what sexual selection arises from?
Andersson, 1994
what does sexual selection arise from?
differences in reproductive success caused by competition for access to mates
what is the difference between inter sexual and intra sexual competition?
intersexual competition= competition between members to attract the opposite sex
intrasexual competition= members of one sex choose members of the other sex
what is directional selection?
favours traits which are overall positive, want more of that trait
what is stabilising selection?
want the mean level of the trait
extremes are selected against
what is disruptive selection?
extreme traits are favoured
what is heritability?
proportion of phenotypic variation in the population that is due to genetic variation
what is the formula for heritability?
h^2=Gv/(Gv+Ev)
what does Gv stand for?
genetic variation
what does Ev stand for?
environmental variation
is all genetic variance transmitted from one generation to the next?
no
who suggested three possible mechanisms for the evolution of personality?
Penke, Denissen and Miller, 2007
what are the three possible mechanisms for the evolution of personality?
selective neutrality
mutation selection
balancing selection
what is the most plausible mechanism for the evolution of personality?
balancing selection
what is selection neutrality?
mutations build up, but as these are removed by natural selection, they do not make significant contributions to variation within the species
how is reproductive success measured?
how many children people have
how many children live to age 5
these children’s bmi
what did Alvergne et al (2010) find out about personality and reproductive success in women?
greater reproductive success is linked to average levels of neuroticism
what did Alvergne et al (2010) find out about personality and reproductive success in men?
higher extraversion in men is linked to greater social status and more children
what is the mutation selection balance idea?
natural selection (decreasing trait variance) balances the effects of mutation (increasing trait variance)
everyone wants beneficial traits, but inbreeding doesn’t increase this trait
traits should be sexually attractive
is there evidence for assortive mating?
yes, but only for openness and conscientious personality traits
what is assortive mating?
individuals with similar traits are more likely to mate
what was found for husbands for assortive mating?
husbands who wanted kind, considerate wives got wives with high agreeableness and extraversion
what was found for wives for assortive mating?
didn’t match
wives who wanted kind, considerate husbands got husbands who were submissive, unmasculine and unsociable
what is balancing selection?
extremes of a trait are favoured to the same degree by different environments
what is environmental heterogeneity?
fitness varies across time and space
on average neutral across contexts
what is frequency dependent selection?
positive= favours traits with high frequency
negative= favours traits with low frequency
who investigated trade off models?
nettle, 2006
what are the issues we can see from trade off models?
as environment changes, associations between trait and behaviour change
so adaptibility of a trait depends on context
what does variable optima mean?
traits have an optimum fitness that varies across situations and time
what does it mean if traits are polygenic?
affected by multiple mutations at multiple different sites
what is quantiative trait loci?
specific parts of DNA linked to traits
help scientists understand which genes influence these traits
how can we investigate genetic and environmental influence?
twin studies
what are identical twins called?
monozygotic
what are non identical twins called?
dizygotic
what do twin studies assume?
share the same environment
gene environment correlation is minimal
twin scores are equivalent to population trait scores
mating occurs at random
zygosity
what is concordance?
degree of similarity between related individuals
what is the heritability for height?
.90
why is it nature and nurture not nature vs nurture?
genetic effects only emerge due to environmental exposure
what is an example of how genes and environment interact dynamically?
Wrasse fish
females turn into males
change in sex in response to how many of each sex there are
how does the environment impact gene expression?
gravitate towards environments which favour gene expression
what are behavioural reaction norms?
examine how people change their expression of behaviour according to the environment they are in
what is personality?
the average behavioural response across contexts
what is behavioural plasticity?
flexible expression of the trait
people have an average response, but vary behaviour depending on context
what is the density distribution approach?
traits reflect the accumulation of everyday personality states
describe the distribution of an individual’s traits and dynamic interaction with context
how does experience sampling methodology work?
assess people at different time points
use over time to calculate an average score for a person
what was the first finding for experience sampling methodology?
as much variation in personality within individuals as between individuals
what is the second finding for experience sampling methodology?
individuals have a mean personality state, which is very stable
(.8 to .9)
what is the third finding for experience sampling methodology?
stability in the amount of variability
.5
so variation is fairly stable and part of personality to be studied
how can phenotype and phenotypic expression be shown as a function of high and low trait scores?
scores from someone high in a trait can overlap with scores for someone low in a trait, but we should consider the average
who proposed the socio genomic model of personality?
Roberts and Jackson, 2008
what is the socio genomic model of personality?
integrates both social and genetic factors to understand complex behaviours and traits
social experiences and environmental factors interact with genetic predispositions to influence various outcomes
who investigated how personality can change over time?
Jackson et al, 2012
what did Jackson et al find out about changing personality over time?
looked at the impact of military training on personality
for the civilian community service group, compared to the military service group, their agreeableness levels increased over time
what is intersexual sexual selection?
the traits which make a mate more desirable
what is intrasexual sexual selection?
dominance hierachies and aggression
who proposed the two stage lens model?
Miller and Todd, 1998
what is the Two Stage Lens Model?
categorisation stage= individuals categorise incoming information into broader categories/dimensions, acts as a lense which allows them to interpret the information
integration stage= individuals integrate the categorised information to form a judgement/decision, consider how information from different categories interacts and influences their overall perception/evaluation
who investigated male generosity as a mating signal?
Iredale et al, 2008
how did Iredale et al, 2008 investigate male generosity as a mating signal?
participant plays economic games, and indicates how much they would like to donate to charity
either played on their own, or were watched by someone of the opposite sex
what did Iredale et al, 2008, find about male generosity as a mating signal?
women always give around 40-50% to charity
men gave more if there was a female observer
what do people look for in a relationship?
good genes- fitness indicators/low mutations
good partner- benefits for long term sexual relationships
good parents- traits for parental care
what is costly signalling theory?
animals may send honest signals about desirable personal characteristics and access to resources through costly biological displays, which would be hard to fake
eg) peacock’s tail
what does Darwin describe fitness as?
having children that live long enough to have children
