evolution revision Flashcards
when did darwin come up with his theory of evolution and what 2 problems did it solve
1859
- problem of history
- problem of design
problem of history
similarities between animals was confusing - appeared to be variations on a theme
example: cytochrome C - mre similar this protein more similar animals looks
need to think of animals as how closely related
relationship underpinned by time and common ancestor (descent with modification)
problem of design
animals appear well adapted
both adaptation and vestigial (appears no use) could be explained if there were slight changes in each gen, useful ones being more likely to be retained. ones with no harm stay for shits and gigs
define homologies and analogies
H - similarity between organisms due tpo common ancestry (human arm, horse leg etc)
A - similarities due to parallel selective pressures (share a selection pressure, such as adaptations for swimming, do not all share ancestors)
when were mendels peas discovered and what did he discover
1815
discovered principles of inheritence such as segregation and independent assortment
mechanisms for variation
mechanism definition
a system or structure that performs a function
who coined the term genes
wilhelm johannson, who found that theres particles of inheritence passed from parents to offspring to determine phenotypic characteristics
flow of genetics is:
one way
genes affect properties of proteins but proteins don’t affect properties of genes (seen in muscle mass differences father and son, may have a predisposition to build but is not automatic)
complete genome was first discovered in, and what we know about genome
1995 for bateria
first draft of a human completed in 2001
60% gemone + is non coding
exons make up 1%
non coding must be important (pufferfish have more coding regions than us)
psuedogenes
genes that haven’t been translated
polymorphism
variations at a locus between individuals
huntingtons disease
has late onset symptoms, due to allele on chromosome 4, codes for ill-surviving huntingtons protein
types of gene mutations
segmental changes - whole extra chromosomes
transposable element insertions - not always effect, chunks of sequences make copies of self
segmental duplications - important for evo, are extra copies og genes and this may have new mutations for new functions
deleterious genetic mutations often cause mendelian diseases - single gene, follow mendelian laws
how to find genetic basis of phenotypic characteristic (2 studies)
linkage: use big families where some members have/lack characteristic. when 2 genes are on same chromosome there will be some linkage. recomb can disrupt linkage
association study: large groups with/without trait to compare allele frequency
2 functions of genes
a - making more phenotype by mitosis
b - making more genotype via meiosis
modern synthesis
combination of mendels and darwins ideas tpo understand how genetic variatin and natural selection causes change
polymorphism
locus of 2 individuals have different sequences
can have single nucleotide polymorphisms
contribute to diversity
medels peas result from experiment 1 and 2
1: all f1 were yellow, f2 had 3/4 yellow and 1/4 green
2: had 9:3:3:1 ratio of yellow smooth to green wrinkly
this shows independent assortment
neutral theory
the amount of divergence between the DNA of any two populations reflects the time since their common ancestor
this is due to non coding changes and neutral mutations outside of natural selection
functionless molecular change
codominance vs incomplete dominance
C - both phenotypes are expressed such as AB blood
I - phenotype is an intermediate, e.g red and white carnation makes pink. NOT blended - these can still make pink or red, not a new allele
coefficient of relatedness
what proportion of genes are shared
falconars estimate of heritability
what proportion of the variation in the phenotype can be explained by variation in the genotype
in twins, can find gene responsibility by 2 x the correlation for MZ - the correlation of similarity for DZ)
heritability
estimates the degree of variation in a phenotypic trait in a population that is due to genetic variation (0-1)
this is not fixed and can change over population
heritability of walking on 2 legs is low
kallman syndrome
rare genetic disorder, gene identified is KAL-1 on the X chromosome. when this is faulty anosmin is not produced stopping sense of smell, libido, and gonad dev
but this phenotype can be expressed in different ways
MAOA gene and violence
MAOA gene varies - in no and also diff levels
more child abuse - low MAOA increases antisocial more than high MAOA does
both low and high MAOA have similar levels of behaviour without maltreatment
in rhesus monkey, MAOA has opposite effect
shows upbringing impacts behaviour
Tinbergens 4 questions
- what causes the behaviour right now (mechanisms and motivation)
- how does the behaviour develop in the individual (what processes shape)
- what is the function or adaptive value of the behaviour (why it exists)
- what is the evolutionary history of the behaviour across species (what species have this trait)
function of a sensitive period
lines up with synaptic pruning
we normally only acquire language once and early in our life (we can go and learn again as an adult but that is not primarily important for survival, at least not historically)
trade off
after acquisition we want to save metabolic costs by reducing neural tissue - would be wasting energy in adulthood
developmental induction
this where exposure to cues in early life induces a permanent change in the phenotype, e.g snail shells
waddingtons epigenetic landscape
represents the process of cellular decision-making during development
uses chanelling - possible routs for dev are constrained over time
may be self regulation - we compensate for shortcomings such as not driving in the rain
equifinality - many dev routes to the same end
baldwin effect
capacity to learn completes a gap in a genetically specified system, can promote the spread of underlying alleles
if cost of learning is low learning may still be involved
self regulation in development
modifying behaviour to compensate for environmental change. in general is about learning about the environment and responding adaptively
Hailman and chicks
investigating accuracy in laughing gull chicks
accuracy increased over time regardless of sight
element of maturation not just learning
how to read interactions is graphs
likely to interact when overlap/are not parrelel
contingency vs contiguity
contingency - how well the cs predicts the us
contiguity - closeness is time of cs and us
positive reinforcement + punishment
negative reinforcement and punishment
positive -> reward and add something bad
negative -> remove something bad, remove something good
planning for the future western scrub jays
make food provisions for future need - birds stored sig more of the “different” food than the “same” in each compartment relative to food in other compartment
will remember what they have cached, when, where and who watched
challenge bishof-kohler hypothesis - collecting on one day was controlled by the next days motivational state and daily resources
aggression - stags, motivation and purpose
S - will rut, roar, parallel walk them fight - aggression
motivation - hormones/season and aggression from other stag
function is to increase fitness and find mate
hamiltons rule
a behaviour can evolve if on average c<rb
cost is less than the benefit and relatedness
Bateman’s principle
benefit of extra mating is larger for a male than a female
due to carrying pregnancy and the size of the gametes (females want quality > quant)
sexy son runaway hypothesis and who is it by
females choose brighter males to get more attractive sons - male brightness increases and creates payoff
R A Fisher
life history theory
limited energy to be allocated between growth, care of self, care of existing offspring, and creation of new offspring
lifespan influences age of reproduction - earlier reproductive period for shorter lifespans
humans are unique in having long post reproductive time
trivers willard hypothesis
mother in good condition should produce high-quality offspring – more sons
because females are likely to find a mate no matter their phenotypic condition
