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Understanding Mammal Breeding Systems and Reproductive Strategies

Explore the fascinating world of mammal breeding systems, from competing interests of males and females to different types of mating behavior and parental care. Discover common breeding systems, the effects of parental care on fitness, and the dynamics of juvenile dispersal in mammals.

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Understanding Mammal Breeding Systems and Reproductive Strategies

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  1. BREEDING SYSTEMS AND REPRODUCTIVE STRATEGIES OF MAMMALS

  2. 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

  3. 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?

  4. 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

  5. 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

  6. COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS Polygamy • Mating 1 sex with >1 individual of opposite sex

  7. COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS Polygamy • Polyandry = 1 female and several males • unknown except possibly in pine voles (but mainly facultative monogamy) ???

  8. 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

  9. COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS Polygamy • Polygyny • Female (harem) defense • males control access to females directly (gregarious females)

  10. COMMON TYPES OF BREEDING SYSTEMS IN MAMMALS Polygamy • Polygyny • Male dominance • males sort out dominance hierarchy among themselves • some ungulates with lek mating systems

  11. 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

  12. BREEDING SYSTEM AND DEVELOPMENT AT BIRTH • Polygyny 1) small litters (<2) 2) precocial young 3) longer gestation 4) greater maternal investment before parturition

  13. BREEDING SYSTEM AND SIZE OF MALES AND FEMALES • Monogamous • monomorphy • Polygynous • sexual dimorphism

  14. M F F Mom M BREEDING SYSTEM AND JUVENILE DISPERSAL Natal Dispersal in Mammals is Male-Biased • frequency & distance • Females philopatric • Why? F

  15. BREEDING SYSTEM AND JUVENILE DISPERSAL The Inbreeding-Avoidance Model What’s the critical assumption?

  16. BREEDING SYSTEM AND JUVENILE DISPERSAL Effects of Inbreeding on Mammals • inbreeding depression • decrease in fitness of offspring • Homozygosity • deleterious, recessive alleles

  17. BREEDING SYSTEM AND JUVENILE DISPERSAL Effects of Inbreeding on Mammals • field studies • white-footed mice • island releases of matings from siblings • lower survival

  18. Effects of Inbreeding on Mammals golden lion tamarin • No offspring survive • Father-daughter mating • Sibling mating • 80% outbred survive

  19. BREEDING SYSTEM AND JUVENILE DISPERSAL Fit of the Inbreeding-Avoidance Model? • Father present: do females disperse?

  20. 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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