Mating Systems

1
Mating Systems
2
Reproductive Strategies

• How do ecological and evolutionary factors affect
  fitness of individuals with different
  reproductive strategies?
• What is fitness?
• What is an ecological or evolutionary factor?
• Given diversity
• Waterfowl
• Habitats
• Behavior
• Should we expect a diversity of mating systems?

3
History

• Darwin (1871)
• Early writings about mate selection
• Classification
• Monogamy one mate at a time
• Polygyny more than one female mate at a time
• Polyandry more than one male mate at a time
• Promiscuity indiscriminate mating

4
Predictions

• What is best for each sex Is what is good for
  the goose, good for the gander?
• Male
• Can fertilize more than 1 female
• Success limited by access to females
• Monogamy not favored
• Females
• Reproduction costly (energetically,
  demographically)
• Why?
• Share cost with male
• Favor monogamy or polyandry

5
Other Considerations

• Who cares for the young?
• Ex. Emperor Penguins
• Spacing Patterns
• Food resources
• During different times of the year
• Breeding site availability
• Predation
• Lack of territorial defense may enhance
  non-monogamous mating system

6
What do we observe?

• Perennial Monogamy
• Anserini (true geese), Cygnini (swans), and
  Dendrocygna (whistling ducks)
• Male defends mate (and nest site)
• Male assists with brood care
• Male incubates (few species) or at least shields
  nest during female absence
• Low frequency of EPC and mate switching
• Male has big investment in young

7
What do we observe in most ducks?

• Annual Monogamy
• Anatini (dabbling), Aythyini (bay), and Oxyurini
  (stiff-tailed), Mergini (sea ducks) -? Poorly
  described
• New mate each year
• Range of duties
• Male defense of mate from conspecifics
• When does defense/pairing start?
• Territory defense (seasonally Buffleheads,
  Northern Shovelers)
• No incubation or brood care by males
• Forced copulation
• Some evidence of perennial monogomy

8
Other mating systems

• Polygyny
• Rare
• Magpie Goose
• Ruddy Ducks
• Polyandry is unknown

9
Why monogamy?

• Counter intuitive, at least for most male ducks,
  which have little investment in reproduction
• Young are highly precocial
• Males rarely participate in brood care
• Males rarely incubate
• Males are therefore free to be polygynous

10
Why not Polygyny?

• Why Monogamy?
• Polyandry
• Not feasible with female biased parental care
• Male biased sex ratio (not primary)
• Male-male competition
• Product or cause of mating system?
• Feedback
• Female biased philopatry (fidelity)
• Again, product or cause
• Feedback
• Default to monogamy
• No basis for polyandry
• No resource-defense polygyny on breeding areas

11
Some Exceptions

• Forced Copulation
• Mostly paired males
• Directed at fertilizable females, particularly in
  morning
• Female solicitation?
• Serial Monogamy
• Double Brooding
• Wood Duck
• Brood Parasitism
• Redhead and Canvasback