lecture 6 ecology Flashcards
behaviour – appropriate behaviour
those with more appropriate behaviour pass on MORE genes
what does it mean ‘appropriate behaviour’
suited to biotic asnd abiotic enviornment (interactions, temp…) – more likely to survive and reproduce
we explain behaviour in terms of what
affect on individual fitness – likelihood of animal passing genes.
benefit of individual
if fitness is increased – more likely to survive and pass on genes
costs of individual
if fitness is decreased – opposite, mire likely to die, have lower fitness, and puts individual at risk
terms to remember
fitness, actor, recipient
fitness defintion
refers to evolutionary fitness – how likely an individual is to pass on its genes
actor definition
the animal performing the behaviour
recipient definition
is/are other animals invovled
- altruism
behaviour where an individual helps at cost to theirselves to benefit survival and reproduction of other individuals / relatives.
social behaviour costs vs benefits table
cooperative (both +)
Selfish (actor+ recipient -)
altruistic (actor - recipient +)
spiteful (both -)
cooperative examples
packs (i.e wolves) – defense and hunting – they hunt in a pack, therefore cam bring down larger prey.
defense – individuals aggregate together in group therefore less picked on by predators
selfish behaviour examples
actor = + recipient = -
territorality – individuals defends / preserves a territory not allowing other individuals to come in – benefit ffor actors as they get all of the resources, but not beneficial to the recipients who do not get those resources.
spiteful
negatyive for both – surplus killing?
altruistic – why does this non beneficial behaviour persist – give example
pikas – they live in rocky mountains/slopes
they live in small groups,
- have an alarm call they use to ward off predators
– the alarm is loud therefore it makes the pika calling it at a higher risk – allows predators to hone in on the alarm caller (actor) rather than the others in the group (individual)
why is benefit not greater than cost in altruistic example
you havce to look at the inclusive fitness
what is inclusive fitness
concept that there is more going on in terms of passing on genetic material than just in an individual and their direct offspring (relatives)
what two things have affect on number of genes passed on (or affect on likelihood)
`1. producing offspring
2. Aid relatives to produce more offspring – you share some genes w relatives – therefore indirectly, if relative reproduces, some og your genes will be present,
kin selection
framework we look at for inclusive fitness – selection for an act that enhances a relatives reproductive success.
Hamiltons rules
natural selection (evolution) favours an act if C < r*B
what does C represewnt
cost of altruist (actor) – lost reproduction
what does r represent
relatedness (fraction of genes shared)
what does B represent
benefit to recipient (increase reproduction)
Scenario 1 – does it increase (evolutionary) fitness to save a sibling if you will die in the process
no, it will not increase inclusive fitness because C>r*B which does not follow Hamilton’s rule
Scenario 2 – does it increase (evolutionary) fitness to save a sibling if you MAY die in the process (risk)
risking dying does increase inclusive fitness – depends on the cost because B and r do not change.
Pikas behaviour, cost, benefits
Pikas – altruistic behaviours are evolutionary benefical/fit
the cost of the alarm is small – yes it increases risk of being predated but it is not at 100%.
the benefits is that they live in groups (family groups) so there is high relatedness, and more chance that their genes will be passed on
reciprocal alturism
tit for tat – return the favour – why such stable social groups
– chimps grooming each other in hopes for favour rwturned in future
group living and social organization – when is it worth it to live in a group (benefits and costs)
benefits - cooperative feeding, defense of group
costs - disease/parasite transmission because living in close proximity
– restricted reproduction
why do animals stay in social groups
because benefits outweigh the costs
restricted reproduction two types/examples
cooperative feeding, eusocial societies.
cooperative feeding; restricted reproduction
individuals may delay their own reproduction to stick around and help raise other offs[ring (two examples are packs, and scrub jay)
eusocial societies; restricted reproducton
division of animals into different castes (soldiers, workers, queen) [two examples are army ants and naked mole rats]
cooperative feeding example in depth (packs)
dominance hierarchies – some animals live in packs/groups – some older and more mature (dominance) – they limit the reproduction of other indiviuddals – only the dominant individuals breed
– the helpers in the packs stay because of kin selection and inclusive fitness – offspring survive better in packs
individual fitness – get stronger, more experience, and more likely to survive when they leave pack – higher lifetime of reproduction
cooperative feeding example (florida scrubjay) think of habitat, male, female, benefits,
live in patchy habitat (scrub oak) – small family group – they arebsurrounded by other habitats that are nottt substantial for the scrub jay
– breeding pair – build nest, incubate eggs
mature young stay on territory to feed yonger siblings, defend territory, and warn off predators
juvenile males help more than females
– this is because scrub oak habitat is limited so often patches are already occupied therefore they have a small change of them finding teritory to call their own
bUT – when parent dies, juvenile male inherits family territory fully or divided amongst other males (partitioned)
juvenile female never inherits family territory – stick around to gain experience in child raising – leads to longer lifetime of reproduction
benefits – kin selection
individual fitness – male only – ingerit territory in future.
Eusocial societies restricted reproduction examples (insects; army ants)
often seen in insects – euoscoail insects –division of labour and behaviour into reproductive and nonreproductive castes
army ants – reproduction caste – queen and severale males queen is only female that reproduces.
non-reproductive castes – all workers are sterile females – defend, foraging, care of young. – relatedness is slightly higher in sisters, instead of r=.5 it is r=.75
benefit - kin selection - sibling survival vewry high
individual – none but kin selection iss worth it `
euosical societies example (mole rats )
live in harsh environments – dry habitats
colonies live in underground burrows
workers are male and female – they dig tunnels, gather food, and nest material for young
soldiers – many die to defend burrow (altruistic behaviour as they are putting themselves at risk)
reproduction - 1 female (queen) and 1-3 males –
– queen supresses reproduction in conlony (coercion) by behaviou (aggressive, attacks/kills any females attempting to reproduce)
also by chemical cues – hormone control
why dont the rats leave – because of harsh environment – food is very limited – they cannot survive in small groups or on own
if leave fitness = 0
if stay fitness >0 be\
benefits = kin selection but no individual benefits
what does environment influence
cost and benefits of group living
group living evolves where
total fitness for staying in group > independent reproduction
it pays to give up your delay in independent reproduction if
– chance of independent reproduction is low
– survival is difficult (naked mole rate)
– opporunities for reproduction are few ( limited habitat – scrub jay)
– a delat increases future reproduction potential (pack animals)
Types of mating systems
monogamous, polygamous, promiscuous
monogamous mating
single pair bond – 2 individuals / parents - typically evolves where there is heavy parental investments (prairie vole)
polygamous mating
two types – polygynous (elks) and polyandrous (spotted sandpiper)
polygynous
one male and multiple females – male is bigger because they compete for female
polyandrous
one female and multiple males – female is bigger because they compete for males
promiscuous ``
no strong mating bonds – australian magpipe – no parental sticking around
polyandry in spotted sandpipers
females are first to arrive to breeding grounfs – they are competing for males so they are bigger – once theyve found male, they breed, lat eggs and leave – they have time to reproduce wqith another male – they let the male tale care of eggs and chicks
whats the reason for the female spotted sandpipers leaving their nests
the environmental conditions – there is enough food that only one p[arent is needed to raise the chicks – females produce only a few eggs at a time so if they have the opportuity to mate again they take it to increase number of offspring. season is long enough for more than one clutch of eggs.
