Lecture 5: dunnock and alpine accentor Flashcards
who studied dunnocks:
Nick Davies in Cambridge 1980
dunnock’s mating system
v variable:
- monogamy
- polygyny
- polygynandry
- polyandry
polygynandry
multiple females looked after by multiple males
mean female territory sizes in monogamous, polygynous and polyandrous
mono & polygyny = 0.25ha
polyandry = 0.55 ha
–> F range size drives variation in mating system
Female _____ drives variation in mating system
range size
experiment to see food resource on f & m territory sizes and mating systems
food available = female = smaller territories
male territories unaffected
-when female territories large sig more polyandry occurring
alpine accentor live?
above 2000m
alpine accentor mating system =
polygynandrous
-typical 3 females and 3 males in one territory (alpha, beta and gamma male)
alpine accentors vs dunnocks territory ranges
dunnocks = 0.2-1 ha female and 0.2-2ha male
aa = 6- 30 ha females and 9- 38ha males
aa a lot bigger! as their habitat = temporal unpredictability
- larger habitat = sure of access to resources
Variation within & between species depends on the distribution of resources which in turn determines ___ dispersion which determines ___ dispersion
Female then male
Accentor breeding biology:
- female builds nest
- lay 3-5 blue eggs
- F incubates
- both sexes feed chicks & fledglings
- pair often have 2 broods her year
monogamy in dunnocks
- M guards F
- F solicits (exposes cloaca)
- M pecks cloaca, female ejects sperm from earlier matings
- copulate 1-2 times per hour
- male monopolises matings –> 100% paternity
- males share chick feeding equally w the female
polygyny in dunnocks
- males guard and copulate with 2 females
- M either invest in brood of one F but not the other, or they divide their investment
- f fertility staggered, they’re ok
- if f fertility at same time, hard work for M
- f get reduced assistance in looking after chicks
polyandry in dunnocks
- M compete to copulate
- alpha M gets most
- f male sneak off with beta M
M parental care varies
- alpha males always care
- -beta male sometimes do nothing, but may work as hard as alpha-male, more likely to feed young if they have paternity
- in polyandry, paternity is often shared between males
polyandrous dunnock experiment
- 28 alpha males removed from territory
- beta males allowed to mate w females
- beta males showed more care (feeding)
alpine accentors; parental investment is related to
mating access
–more time spent mating w female, more chance they’ll help feed brood
Accentor breeding biology:
- -Males compete to mate w females
- -variable mating success reflected in paternity
- variable male paternity care explained by paternity
Dunnocks competition among females:
Fighting between females -loser often deserts eggs --highest in polygyny (39%) as females competing -monogamy 20% polyandry 8%
In dunnocks polyandry: Female should copulate with ___ in her group to gain their parental investment
both males, should aim for 50:50 share of matings with alpha & beta
F behaviour in alpine accentor
- to convince males they have some paternity females copulate up to 1000 / clutch
- males have huge testes (8% body weight) and a large cloacal protuberance
- females solicit with bright red cloaca
- Females compete by singing
Dunnock reproductive succes:
more male help by male reduces starvation and means more fledglings can be produced
Alpine accentor reproductive success
more care provided by males, the better the condition of chicks when they fledge
Male reproductive success different mating systems in dunnocks
polygyny is highest, monogamy then polyandry (alpha then beta)
Female reproductive success different mating systems in dunnocks
polyandry is highest, monogamy then polygyny
males compete for __ and females compete for ___ care
matings & paternal care
