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REPRODUCTIVE PATTERNS

REPRODUCTIVE PATTERNS. LIFE HISTORY. POPULATION DYNAMICS. REPRODUCTION. STRONGLY SEASONAL. Peromyscus. SEMI-SEASONAL. ASEASONAL. Seasonal patterns (latitude gradient). Seasonal reproduction in the tropics. Cebus capucinnus ARGENTINA.

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REPRODUCTIVE PATTERNS

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  1. REPRODUCTIVE PATTERNS LIFE HISTORY POPULATION DYNAMICS

  2. REPRODUCTION STRONGLY SEASONAL Peromyscus SEMI-SEASONAL ASEASONAL Seasonal patterns (latitude gradient)

  3. Seasonal reproduction in the tropics Cebus capucinnus ARGENTINA

  4. REPRODUCTION Differential response to seasonal environments Costa Rica – savannah (wet & dry seasons) (seasonal) (aseasonal) Marmosa Zygodontomys

  5. WEANING Seasonal reproduction Artibeus jamaicensis

  6. Reithrodontomys megalotis(seeds) RAIN DROUGHT Microtus californicus (grass) Seasonal reproduction Coastal California

  7. birth normal development resumes post-implantation delayed development 6-9 months ovulation Seasonal reproduction Delayed development and Reproductive synchrony Haplonycteris fischeri (Philippine pygmy fruit bat) 1 litter per year births are synchronous within local populations implantation

  8. Synchronized births in BOTH age groups 2 litters per year no delay up to 6 month delay Synchrony established Initial asynchrony Seasonal reproduction Delayed development and Reproductive synchrony Ptenochirus jagori (Philippine fruit bat) 1 litter per year

  9. SPERM STORAGE (MALE) SPERM PRODUCTION BIRTH ACTIVE (SEXES SEGREGATED) FERTILIZATION SPERM STORAGE IN UTERUS COPULATION HIBERNATION HIB. Sperm storage and delayed fertilization Antrozous pallidus (Pallid bat)

  10. Fertilization Delayed implantation of blastocyst (1 month) Implantation Gestation and birth Delayed implantation of blastocyst (8+ months) Delay of more than 9 months Seasonal delayed implantation (Mustelidae)

  11. Peromyscus maniculatus Litter size and latitude Reproductive patterns How many young? How often? ITEROPARITY-- repeated production of offspring at intervals throughout the life cycle Mean litter size = 8 Mean litter size = 2

  12. 5.6 5.0 4.4 4.0 Reproductive patterns Litter size and elevation Peromyscus maniculatus Decreasing season length and increasing litter size with increasing elevation The increase in litter size increase with both latitude and elevation reflects the same basic life history trend: Immediate reproductive expenditure increases with declining probability of future reproduction (in harsh environments where adult survival is low)

  13. Reproductive patterns What if the likelihood of future reproduction drops to near zero? SEMELPARITY-- a single act of reproduction duringan organism's lifetime. Also known as: “BIG-BANG” Semelparity is common in plants and invertebrates, but rare in vertebrates

  14. Dasyuridae Northern Quoll Dasyurus hallucatus Didelphidae Gray short-tailed opossum Monodephis domestica Semelparity in male marsupials Seasonal, promiscuous breeding Males compete for mating opportunities during a very brief mating season Males fast during mating, and have high levels of androgen and glucocorticoids Brown antechinus Antechinus stuartii Extreme physiological stress Complete male die-off following mating period Dasyuridae Does NOT apply to females (may live multiple years)

  15. 2-year-old male at emergence in his first breeding season 26 April 2002 Same male 3 weeks later 16 May 2002 “PARTIAL” SEMELPARITY Seasonal heterotherm (winter torpor) Promiscuous breeding immediately following emergence Intense male-male competition for mates Females breed as yearlings Males delay reproduction until 2nd spring Arctic ground squirrel (Spermophilus paryii) 26% loss of mass Numerous wounds (died ca. 23 May 2002)

  16. Traditional stone & ivory Inuit harpoon points (from recently killed animals) Maximum longevity Bowhead whale (Balaena mysticetus) Longest-lived mammal? Maturity: 15-25 years Gestation: 13-14 months Birth interval: 3-4 years Maximum longevity: more than 200 years?

  17. Maximum longevity

  18. Passerine birds & non-hibernating bats Non-passerine birds Placentals (excluding bats) Body size & Longevity

  19. Body Size and Life History Traits -- (artiodactyls)

  20. AGE AT MATURITY MAXIMUM LIFE SPAN LIFESPAN AND AGE AT MATURITY

  21. Body Size and Life History Traits -- (artiodactyls)

  22. ENTIRE SAMPLE PRECOCIAL ALTRICIAL Body Size & Length of Gestation (Placentals)

  23. Body Size Underlying influence of metabolic rate

  24. Hibernating bat species Passerine birds & non-hibernating bats Non-passerine birds Placentals (excluding bats) 3-fold increase Body size & Longevity Insight from heterotherms

  25. Fast track to longevity Mouse study shows molecular connections between caloric restriction and lifespan extension March 7, 2005 The Scientist October 2004 The Longevity Gene A gene that releases stored fat may be the key to a longer life. THE SEARCH FOR A UNIVERSAL LONGEVITY GENE

  26. Maximum longevity

  27. Logistic population growth K = carrying capacity Population dynamics Exponential growth

  28. Growth determined by r Growth limited by K Population dynamics – logistic growth

  29. r & K selection theory

  30. Population dynamics Sheep (Tasmania) “K-selected” Peromyscus “r-selected”

  31. Population fluctuations Ord’s kangaroo rat (Dipodomys ordii) New Mexico Multimammate mouse (Mastomys natalensis) South Africa

  32. Population cycles Multi-annual “cycles” Brown lemming (Lemmus sibiricus) Alaska

  33. Canada (Hudson Bay Co.) Predator – prey cycles Lynx canadensis Population cycles Lepus americanus

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