breeding systems and reproductive strategies of mammals
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BREEDING SYSTEMS AND REPRODUCTIVE STRATEGIES OF MAMMALS. BREEDING SYSTEMS: COMPETING INTERESTS OF MALES AND FEMALES. Description of mating behavior and parental care by both sexes Parental care & potential rate of reproduction of each sex

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breeding systems competing interests of males and females
BREEDING SYSTEMS: COMPETING INTERESTS OF MALES AND FEMALES
  • Description of mating behavior and parental care by both sexes
  • Parental care & potential rate of reproduction of each sex
  • If males contribute no parental care (many mammals), they have high potential rate of reproduction; fitness limited by access to females; males most competitive sex
slide3

Reynolds. 1996. Animal Breeding Systems. TREE

OSR = operational sex ratio = ratio of available adult females to males

*Time budget for males = competition for mates and/or advertisement – not choosy

*Females invest in gametes & care (lower rate & resource limits) – choosy females

****What if males contributed to parental care?

breeding systems competing interests of males and females1
BREEDING SYSTEMS: COMPETING INTERESTS OF MALES AND FEMALES
  • Are the result of a “battle” of competing interests between the sexes
    • opportunities & constraints set by environment
common types of breeding systems in mammals
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Monogamy

(<10% of mammals)

Some canids, primates, prairie voles, beavers

  • facultative
    • low density
  • obligate
    • delayed maturity
    • assisted rearing
common types of breeding systems in mammals1
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Polygamy

  • Mating 1 sex with >1 individual

of opposite sex

common types of breeding systems in mammals2
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Polygamy

  • Polyandry = 1 female and several males
    • unknown except possibly in pine voles (but mainly facultative monogamy)

???

common types of breeding systems in mammals3
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Polygamy

  • Polygyny = 1 male with several females
    • Not promiscuity
    • >80% of mammals
    • 2 types
      • Female (harem) defense polygyny
      • Male dominance polygyny
common types of breeding systems in mammals4
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Polygamy

  • Polygyny
    • Female (harem) defense
      • males control access to females directly (gregarious females)
common types of breeding systems in mammals5
COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS

Polygamy

  • Polygyny
    • Male dominance
      • males sort out dominance hierarchy among themselves
      • some ungulates with lek mating systems
breeding system and development at birth
BREEDING SYSTEM AND DEVELOPMENT AT BIRTH
  • Lactation believed to precede evolution of parental care
    • females benefit from monogamy
    • predict larger litters, shorter gestation
  • Review of 500 placental species indicates:
    • Monogamy

1) large litters

2) altricial young

3) short gestation

breeding system and development at birth1
BREEDING SYSTEM AND DEVELOPMENT AT BIRTH
  • Polygyny

1) small litters (<2)

2) precocial young

3) longer gestation

4) greater maternal investment before parturition

breeding system and size of males and females
BREEDING SYSTEM AND SIZE OF MALES AND FEMALES
  • Monogamous
    • monomorphy
  • Polygynous
    • sexual dimorphism
breeding system and juvenile dispersal

M

F

F

Mom

M

BREEDING SYSTEM AND JUVENILE DISPERSAL

Natal Dispersal in Mammals is Male-Biased

  • frequency & distance
  • Females philopatric
  • Why?

F

breeding system and juvenile dispersal1
BREEDING SYSTEM AND JUVENILE DISPERSAL

The Inbreeding-Avoidance Model

What’s the critical assumption?

breeding system and juvenile dispersal2
BREEDING SYSTEM AND JUVENILE DISPERSAL

Effects of Inbreeding on Mammals

  • inbreeding depression
    • decrease in fitness of offspring
  • Homozygosity
    • deleterious, recessive alleles
breeding system and juvenile dispersal3
BREEDING SYSTEM AND JUVENILE DISPERSAL

Effects of Inbreeding on Mammals

  • field studies
    • white-footed mice
    • island releases of matings from siblings
    • lower survival
slide18

Effects of Inbreeding on Mammals

golden lion tamarin

  • No offspring survive
  • Father-daughter mating
  • Sibling mating
  • 80% outbred survive
breeding system and juvenile dispersal4
BREEDING SYSTEM AND JUVENILE DISPERSAL

Fit of the Inbreeding-Avoidance Model?

  • Father present: do females disperse?
breeding system and juvenile dispersal5
BREEDING SYSTEM AND JUVENILE DISPERSAL

Fit of the Inbreeding-Avoidance Model?

  • Monogamy: sex bias in dispersal?
    • 11 of 12 monogamous species studied show similar female vs. male dispersal
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