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