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
what is dunbars number and an explanation
~150 is group number that human brain size predicts
because group size leads to better predation, allowing late production and long lifespan (for bigger brains). food resources also play role
how many different kinds of learning have been identified
over 40
all underpinned by an experience that results in a relatively permanent change in the state of the learner
why do we learn
- tinbergen’s 4 qs answer this
- faster than mutations - associations means that better mates are chosen
- in humans, we can also unlearn problems
mere exposure effect and who is it by
by zajonc
repeated unreinforced expose is enough to enhance attitudes towards it (like attraction due to proximity)
types of non associative learning
mere exposure
liking
imprinting
reversed facial image (we prefer mirror images)
habitiuation (and dear enemy phenomenon)
observational
song learning
conditioned physiological responses in drug use
when using substances, environment becomes part of the CS
response secretes NTs that counteract effects
new setting - conditioned stimulus is different and the compensatory physiological conditioned response is absent or decreased
high/second order condtioning
when a conditioned stimulus becomes associated with a new unconditioned stimulus
stimulus can create a response of what it may lead to - money
pavlov and learning
- excitatory association: increases likelihood of response
- inhibitory association: decreases likelihood of response
- when activity in one area is closely followed by another - neural connects strengthen
extinction occurred from a new inhibitory centre
schedules of reinforcement
determines rules of reinforcement
continuous - everytime after desired behaviour
interval - based on time elapsed since reinforcement
ratio - based on how many responses have been made
intermittent reinforcement is more resistant to extinction than continuous reinforcement
instrumental conditioning
behaviour is modified by its consequences - we learn associations and their consequences
thorndike
learning as a mechanism
software - rules it follows
hardware - neural mechanisms
cognitive view of conditioning - and examples for diabetes
conditioning is achieved through predictability
knowledge is an intervening variable between stimulus and response
in diabetes - insulin (US) decreases blood sugar (UR) but the conditioned response to the injection results in CS of more blood sugar in compensatory reaction
compensatory reaction - body prepares for a unnatural stimulus to reduce effect
premack principle
neutrality of reinforcers
can find an activity that an individual prefers then use that to reinforce a non-preferred one
contingency in rescola’s rats - tone and shock
when tone and shock appeared randomly next to/at same time rats don’t press the bar as fear of shock is stronger than wish for food
is contingency
latent inhibition definition
conditioning takes longer because there is already information about the tone/CS that exists, and is not a reliable predictor
existing info interferes
kamins experiment on blocking
rats have more suppression when have light-tone-shock condition before just light
light is a blocker in tone-shock and tone-light-shock - appears redundant
new associations are learned more quickly
tolmans contributions
deatour learning - when one route is blocked they have cog map to choose next most efficient
instrumental conditioning
learning without reinforcement
reinforcement vs learning in colwill and rescorla
nausea was paired with sucrose solution and given 20 min extinction trial
rat avoided sucrose and preferred food - experience leads to learned act-outcome association. rat combines the pull chain to nausea and deduces that pulling chain lead to sickness - cognition
garcia effect
taste is a prepared stimulus for association with illness - evolutionary elements of CC
token economy
can reduce driver speed
learned behaviours usually not maintained once reinforcement is discontinued (glynn)
over justification effect - rewards when not needed means that behaviour has inherently less motivation
social reinforcers
smiles, praise touch etc
variable for individuals
are not universal - events are relatively reinforcing based on a number of factors
however can be more effective and continue after a programme ends
cognitive behaviour modification in smoking
in smoking
- 2 groups with one told they were improving due to their own willpower and other was due to treatment
- long term, the willpower group showed better long term improvement
what kind of behaviour does intelligence describe
behaviour not readily explained by associative learning
hayes and hayes chimp vicki
showed that non human apes cannot learn human language as they do not have the vocal apparatus - could make a few sounds such as mama or cup but were not english like sounds
pigeon self-concept, mental rotation and intelligence
SC - can discriminate videos that reflect movement with 5-7s delay
MR - similar or better than humans, could discriminate natural concepts
I - epstein et al used box to reach banana using insight (ps was sudden, direct, continuous)
bischof kohler hypothesis
idea that only humans can detach from current motivation and act for future needs
chimp washoe
taught asl with human signer and moulding
could sign appeals, location, action etc
chimp nim
sign meaning was ambiguous
19,000 utterances
equivalent to 2-word utterances of children 18-24m
struggled with linguistics like turn taking
sign stimuli - types and stickleback example
can be visual, auditory or chemical (pheromones)
stickleback - males attack model that imitate them (slim/swollen and red, but will court or avoid female looking)
gaping responses in birds
- presented chick with different shapes that mimics the outline of beaks
- chicks directed gaping behaviour was directed at angled beak shapes
- preference for proportionate body/beaks
- sign stimulus impacted the fixed action pattern
definitions: reproductive success, fitness, reproductive restraint
RS - number of decedents left by indvidual
F - strictly a property of an allele. It is the change in frequency of an allele over the generations. related to average RS
RR - when food is scarce, birds lay less eggs because it would create too much competition.
assumes altruism - but in reality being selfish and still laying as many eggs as possible is more effective
evolutionary stable strategy
behaviour that once common in a population cannot be out-competed by any alternative behaviour
kin selection in prairie dogs and cells
PD - when offspring are present - the most alarm calling closely followed when siblings or parents are present
C- cells such as blood, nerve, heart or small intestine cells will never have full reproduction, however will continue to work in order to allow reproduction with gametes
intragenomic competition
suppressing competition between genes
arises when genes favour own interest over bigger picture
transposable elements in humans - jumping genes that move to different segments, can help us survive and adapt but should not always be used
isogamous vs anisogamous sex
I - 50/50 energy,
A - unequal gamete size, usually females (more energy for equal genome) . applies in cases of sequential (changing sex) or simultaneous hermaphroditism
dioecious definition
have male and female gametes in separate individuals
two fold cost of males
john maynard smith
the cost of sexual reproduction
asexual females will have both more children and viable grandchildren with all genes
many animals still take part in anisogamy bc recombining genetics gives more adaptability and change, red queen hypoth
red queen hypothesis
“takes all the running you can do to stay in the same place”
keep adapting and changin to fight off parasites - they will always evolve and become stronger
bananas - sexually reproducing ones better and surviving
parasites evolve to keep up with snails and snails live better when cohabitating
intrasexual and intersexual competition examples
(seals, humans, peacocks, swallows)
intra - same sex
seals invest in size to compete with men and win females
peak reproduction - men are 3x more likely to die (nore risk taking and aggression)
inter - other sex
peacocks -tail cost/flying
swallows - prefer males with artificially longer tails - have less mites in nest
explain senescence, disposable soma hypoth and extrinsic mortality
S is aging - accumulation of unrepaired damage to body
extrinsic mort - sets pace of life history, faster when death rate is high
DS h - energy is a limited resource we use bc of EXM, organisms senesce but are capable of reproduction in earlier life
lack curve explanation
more children you have - harder it is to feed and care
have to balance output again own and child survival
parental care costs
paternity uncertainty - males invest more in children that look like them
chimaeras - offspring is a mix of different mates so more paternal care (% DNA)
stepfathers have much higher rate of killing children - are less attached
costs of being in a group
most important - sharing food/resources
diseases
predator detection
types of social systems
asocial - promiscuity
monogamy - 1 + 1
polygyny - one male several females
polyandry - one female multiple males
multiple males multiple females has various systems
social brain hypothesis
monogamous pairs have larger brains (watching each other)
monkeys and apes have larger neocortex when increasing group size
larger groups = more predation = larger brains
human society
we are ultrasocial
monogamy and polygyny
wives move to husbands family - virilocality
husbands move - uxorilocality
altruism in cooperation
behaviour benefits another individual but is detrimental to the actor
evolves when the two involved are related - by helping you are letting genes live on
direct vs indirect reciprocity
d- tit for tat, actor cost < recipient benefit. increases probability of repetition - but need to keep interacting and recognise
i - A helps B, C then helps A. control mechanism is reputation . actor cost < recipient benefit X probability of correct info about partners rep
social learning and culture
social learning can produce cultural traditions - bird songs/washing food
cultural vestigial characteristics - previously useful but maintaining
founder effect - first and stayed
cultural traditions and humans
humans heavily rely on social learning
only human cultural traditions are cumulative
biological naming systems, who made and the order, what are they for
carl linneus
genus, then species
to classify animals and understand offspring
what are ring species
similar species may successfully breed with each other but cannot reproduce with other wide of ring - differences to large
monophyletic vs paraphyletic groups
M - group of organisms that are classified in the same taxon and share a most common recent ancestor - not strictly valid
p - group of animals which contains a common ancestor and some, but not all, of the descendants.
what are transposable elements in animals
elements that mammals can share will split at different parts - best seen on phylogeny trees
classification of apes and relation to humans
great apes: orangutans, chimps, gorillas and humans
african apes: chimpanzees, gorillas, humans
also have lesser apes and gibbons
we originated from hominins
how did anatomically modern humans come about and what chnages occurred
mostly replacements, some admixture
did NOT come from chimps - we split from chimp vs hominins
bipedalism - pelvis structure allowing running and walking on 2 legs
meat eating - nutrient density
brain size
tool use
life history
learning niche (social learning and long childhood)
human behaviour and environment of evolutionary adaptedness (EEA)
human behaviour has a mismatch hypothesis - behaviour is adaptive only when environment is still similar
assumes our behaviour is determined and has low phenotypic flexibility
in reality which are much more plastic
human behaviour ecology
difference between populations are evoked culture
we have fast and plastic adaptation
cultural evolution thinking
behaviours determined by cultural norms and social learning
norms are adaptive to environment
phenotypic gambit
theoretical approach focusing on the relationship between phenotype and fitness in
evolutionary processes
definitions: hereditary, redundancy, false dichotomy
H - passing on characteristics
R - extra genetic material that can perform the same function as another gene
FD - presenting two answers when 2+ exist
hebb’s analogy
neurons that wire together fire together
fixed action pattern
predictable series of actions triggered by a cue, sometimes called the key stimulus
