7-evo of coop Flashcards
what are cooperative breeding systems?
systems where more than 2 individuals in group care for young
how many species cooperatively breed?
- fish
- mammals
- birds
- 20+
- 3%
- 4-9%
what are the 3 stages of emlen 1982 ecological constraints hypothesis?
- independent breeding constrained by no territory (ecological), no partners (demographic) or low chance of successful reproduction
- leads to delayed dispersal
- fitness benefits exceed those of not helping so helpers care for brood
in terms of the ecological constraints hypothesis what are:
- direct benefits
- indirect benefits
- increasing current or future reproduction
- increasing fitness of non descendant kin/kin selection
what happens when constraints are reduced?
reduced helping/cooperation
give 3 bird examples for intraspecific evidence for ECH + reference
- sociable weaver (covas et al 2004)
- red cockaded woodpecker (walters et al 1992)
- superb fairy wren (pruett-jones and lewis 1990)
what can the ECH explain?
breeding within species
what is there a strong component of for coop breeding
strong phylogenetic component to coop breeding
how many species of fairy wren are coop?
15 species
what % of australian corvidae are cooperative?
25%
how many independent evolutionary transitions are there to or from coop breeding in birds?
> 50
what are 4 hypotheses for evolution of coop breeding?
- ecology constrains breeding (ECH)
- Benefits of philopatry select for delayed dispersal
- life history traits predispose some lineages to cooperate
- coop breeding is associated with brood parasitism
to prove the ECH what did Rubenstein + Lovette 2007 discover about african starlings? (4)
- some coop and others not
- coop species live in savanna
- most non coop species in non savanna
strong association between habitat and social living - savana unpredictable environment
to prove the ECH what did Rubenstein + Jetz 2011 discover? (4)
- global level study to see if coop breeding associated with environment
- coop breeding rich in australia + sub saharan africa but not in polar regions
- within years/seasonality polar regions experienced more extreme temp
- support that coop breeding evolves in unpredictable environments + variable rainfall
to prove the ECH what did Lukas and Clutton-brock 2017 discover about mammals and unpredictable environments?
coop species live in more unpredictable environments in terms of rainfall and temp
in relation to ECH what did cornwallis 2017 discover?
could be coop breeding evolved first and group living means can colonise harsh environments
- the transition rate to colonise harsh environment from benign is greater for coop species
when is the ECH not as convincing?
across species
what is the hypothesis for the benefits of philopatry?
benefits of staying at home select for delayed dispersal rather than dispersal being constrained
why do siberian jays favour kin?
so they survive the winter better than non kin
in terms of the philopatry hypothesis what do benefits depend on? + example
resource wealth in natal territory
western bluebirds
what did Dickinson + McGowan 2005 discover about western bluebirds? (4)
- sons spend winter on natal territory + may help in following year
- mistletoe is key resource
- where mistletoe depleted less sons stayed behind on natal territory
- if benefits low for staying at home then will disperse
what did Hawn et al 2007 discover about green woodhoopoe? (2)
- both sexes stay home for several years before dispersing to breed
- F who stay home have higher LRS
what did Drobniak et al 2015 discover about the relationship between ECH and benefit of philopatry?
constraint on dispersal (ECH)= benefit of staying (philopatry)
- the hypotheses only differ in the emphasis placed on pros and cons of staying
what do slow life histories reduce?
the rate at which breeding vacancies arise
what 3 key traits did Arnold and Owens 1998 look at to test the life history hypothesis?
- longevity (longer survival > occupy territories longer > less breed vacancies)
- clutch size
- if migratory ot not
what did Arnold and Owens 1998 discover about the difference between families with slow or fast life histories ?
- slow: long lived, small clutch, coop when certain ecological conditions occur, tropical zones
- fast: short lived, large clutches, never coop, temperate zones
what is life history hard to distinguish from?
phylogeny and biogeography
why is the life history hypothesis discounted?
could just have slow life history as mainly live in tropical regions
what did Feeney et al 2013 discover for the coop breeding hypothesis for superb fairy wrens and Horsfields bronze cuckoo? (2)
- cuckoos should target coop groups where more individuals care for offspring
- good idea for wrens to live in groups as better defence
what did Feeny discover about the parasitism? ()
- parasites prefer coop breeders (heavier chicks, more likely to fledge as helpers provide extra food)
- parasitism selects for coop breeding
how does parasitism select for coop breeding? (3)
- small groups of wren parasitised at higher rate than large groups
- extra vigilance reduces the risk of being parasitised
- time spent mobbing the cuckoos greater in larger groups
what does global distributions of coop breeding match?
obligate brood parasitism
what are more likely to become coop breeders but what is uncertain?
hosts of brood parasites but direction of association uncertain
list 3 reasons for why predicting sociality is difficult
- diverse social systems: broad range of social organisation
- diverse constraints
- phylogeny, biogeography + life history traits co-vary
what are the 3 main social systems? + examples
> monogamy + non breeding helpers- florida scrub jay
polygamy + non breeding helpers- acorn woodpecker
coop polygamy- galapagos hawk + dunnock
what is an example of constraints that experiments can reveal?
proximate constraints on independent reproduction differ
what are the main constraints for each of these birds?
a) sociable weaver
b) red cockaded woodpecker
c) superb fairy wren
d) seychelles warbler
a) food
b) nest cavities
c) territory + mate
d) territory + food
why are phylogenetic analyses difficult?
- some taxa only in certain environments
- life history traits highly conserved within families so confused with phylogeny
what is the support for life history hypothesis?
- who support and who against
ambiguous
- support from beauchamp
- hatchwell + komdeur 2000 against: argued doesn’t matter what the source of constraint is
what did beauchamps argue? (4)
- similar ecological constraints allows for evolution of this strategy
- in worldwide sample of 81 species no association between max longevity + coop breeding
- supports high annual survival affecting evolution of coop breeding
- partial support for LH hypothesis
according to hatchwell and komdeur 2000 what was there a positive association between?
severity of ecological constraints + prevalence of coop
according to hatchwell and komdeur 2000 what may different coop systems be due to?
different selective pressures
according to hatchwell and komdeur 2000 what does philopatry mean for coop breeding?
can be found even in the absence of habitat saturation
according to hatchwell and komdeur 2000 what life history characteristics play a role in the evo of coop breeding?
high juveille and adult survival
according to hatchwell and komdeur 2000 in red cockaded woodpeckers what did the provision of new nest sites induce?
induced helpers to leave home + establish new breeding territories
according to hatchwell and komdeur 2000 what did the dense foraging habitat of non cooperative thornbills reduce?
benefits of group vigilance so more favour for non coop
according to hatchwell and komdeur 2000 what 2 other things does coop breeding link to?
habitat saturation + habitat characteristics
according to hatchwell and komdeur 2000 in Australia what % of all bird species breed cooperatively?
10%
according to hatchwell and komdeur 2000 what does ECH not provide?
model for evo of delayed dispersal
according to hatchwell and komdeur 2000 what is highly conserved in avian evolution and what does this mean?
LH traits
so phylogenetic bias in coop breeding consistent with LH hypothesis
according to hatchwell and komdeur 2000 what is a key factor causing certain avian lineages to coop breed?
low annual mortality
according to hatchwell and komdeur 2000 how is it likely that ECH and LHH act?
in concert, influencing rate of turnover of suitable breeding opportunities
according to hatchwell and komdeur 2000 what does the turnover and occupation of breeding territoires by helpers depend on?
breeder survival rate (LH trait) habitat saturation (EC)
