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Reproductive Biology / Reproductive Strategies

Reproductive Biology / Reproductive Strategies. Factors Influencing Timing of Breeding. Male Reproductive Cycle. Testes : Permanently scrotal – primates, canids, felids, ungulates Withdrawn into body seasonally – rodents, insectivores. Year-round breeders

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Reproductive Biology / Reproductive Strategies

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  1. Reproductive Biology / Reproductive Strategies

  2. Factors Influencing Timing of Breeding

  3. Male Reproductive Cycle • Testes: • Permanently scrotal – • primates, canids, felids, • ungulates • Withdrawn into body • seasonally – • rodents, insectivores • Year-round breeders • Long-day breeders • Short-day breeders

  4. Female Reproductive Cycle • Estrous cycles vs. Menstrual cycles

  5. Ovulation

  6. Reproductive Strategies • “Normal Development ” from conception • to parturition • Delayed Fertilization • Delayed Implantation • Delayed Development

  7. “Normal Pattern of Breeding and Pregnancy” Breeding Breeding Ovulation Blastocyst Formation Fertilization Embryonic/Fetal Development Implantation Parturition Anestrus Suckling Post-partum estrus - Reproductive Tract - Bicornuate

  8. White-tailed deer (Odocoileus virginianus) Short-day breeder Copulation Parturition Anestrus Nov./Dec. Mid-late May Total gestation = ~ 200 days Eastern spotted skunk (Spilogale putorius) Long-day breeder Copulation Parturition Anestrus April Late May/June Total gestation = ~ 55-65 days

  9. Elk (Cervus elaphus) Estrus October Parturition Mid - June Anestrus (8.5 mo.) (3 - 4 mo.) John Morrison (1960): 17 hr. estrus / 21.2 day estrous cycle Early October / Late October / Mid-November / Early December [August – Nov/Dec] [Sept – Dec/Jan]

  10. Western Big-eared Bat Corynorhinus townsendii Delayed Fertilization Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. May June Spermato- Testes Copula- Ovulation Viable embryos genesis regress tion Fertilization develop depending Implantation upon ambient temperature Sperm Sperm stored in stored in epididymis uterus Delayed Development • Gestation 56 – 100 days in length • Breeding occurs before hibernation

  11. Delayed Implantation • Obligate delayed implantation– • Facultative delayed implantation

  12. Black Bear Ursus americanus Foresman and Daniel (1983). Journal of Reproduction and Fertility 68:235-239.

  13. 1 - 2 mm Grizzly Bear Blastocyst

  14. Black Bear Plasma Proteins Molecular Weight Protein Molecular Weight Date Date Pregnant Non-pregnant

  15. Short-tailed weasel • Mustela erminea • Breeds May – July • 10 – 11 mo. Obligate delay • Parturition April – May • Post-partum estrus • Northern fur seal • Callorhinus ursinus • Breeds 26 June – 5 August • 1 Estrus lasting 1 day • 3 – 5 mo. Obligate delay • Total gestation = ~ 360 days

  16. Facultative Delayed Implantation Red Kangaroo Estrus Parturition Parturition Breeding Day 0 33 235 Post-partum Post-partum estrus estrus Resumption in devel. ~ 30 d prior to exit of pouch young 200 day delay due to suckling 200 day delay 1 2 3

  17. Lactational Anestrus Eastern Gray Kangaroo Western Gray Kangaroo Red Kangaroo Swamp Wallaby Tammar Wallaby Quokka Ovulation Lactational Quiescence Seasonal Quiescence Seasonal Anestrus Parturition

  18. Swamp Wallaby – Macrotus bicolor Parturition Parturition Lactational Quiescence Ovulate, breed and conceive ~ 2 days prior to parturition

  19. Environmental Influence on Reproduction • Field observations suggested that short-term • fluctuations in temperature and rainfall affect the • reproduction of prairie deer mice (Peromyscus • maniculatus bairdii); • Females exposed to unusally warm spring temperatures • had 0.4 more young / litter; female embryos negatively • affected; • Females exposed to warm temperatures in the autumn • had 0.5 fewer young / litter; male embryos negatively • affected;

  20. Myers, P.L., L. Master, and R. A. Garrett. 1985. Ambient temperature and rainfall: an effect on sex ratio and litter size in deer mice. J. Mammal. 66, 289-298. Field conditions: Noted temperatures on days when field-caught mice were in early pregnancy; If max. temp. fell into the upper 5% of average observed maximums = “HOT” If min. temp. fell into the lower 5% of average observed minimums = “COLD”

  21. Laboratory Conditions and Experimental Design: • Paired males and females at age 40 – 60 days • and left until successful pregnancy; Removed • offspring (female exhibits post-partum estrus); • Day of birth of one litter (Day 0) = Day of • conception of next litter (Day 23); • Exposed females to 12 h of high temperature: • 33 – 35o C; Exposure occurred at either: Day 23 (n = 12) Controls held at 22 – 26o C Day 21 (n = 26) Day 19 (n = 28) Day 17 (n = 7) Day 15 (n = 12)

  22. Measured: • Total number of young • Number of male and female offspring • Sex ratio of litter • Average weight of offspring

  23. Total number young/litter Number of young/litter Decreased litter size Increased female mortality Implantation Males/ Females Increased male mortality

  24. Differential sensitivity of male and female • embryos in utero How do you think that this would affect the results of demographic studies?

  25. Nutritional Influence on Reproduction Cheatum, E. L., and C. W. Severinghaus. 1950. “Variations in fertility of white-tailed deer related to range conditions.” Trans. 15th N. A. Wildl. Conf. Poor range Poorest range Best range Good range Poor range

  26. 1943 De Bar – heavy harvest (bucks/ does); Moose River – relatively in- accessible; little doe harvest De Bar Moose River De Bar – heavy buck/doe harvest; Increased logging; Shaded areas are antlerless deer seasons

  27. Fertility Indices recorded for 911 does: embryo counts/number of corpora lutea as index of ovulations 1939 – 1943 No. Pregnant Does Avg.Young/doe De Bar 57.1% 0.71 Moose River 90.7% 1.00 1947 – 1949 De Bar 100% 1.78 Moose River 68.8% 1.00

  28. Conclusions:

  29. Verme, L. J. 1965. Reproduction studies on penned white-tailed deer. J. Wildl. Mgmt. 29:74-79.

  30. Verme (1965). Dietary Group: I – II Excellent diet III Moderate diet IV Poor diet

  31. McClure, P. A. 1981. Sex-biased litter reduction in food- restricted wood rats (Neotoma floridana). Science 211,1058-1060. • Polygynous mating • system • No difference in cost • to female to produce • male or female • offspring • Mother in poor health • should increase • investment in • female offspring

  32. Experiment Design: • Bred woodrats • Assigned females to control or food-retricted • groups • Control: • Food ad libitum • Food restricted: • 70 – 90% of maintenance requirement of • non-reproductive female • Experiment lasted 21 days (normal time to weaning)

  33. Control litters Restricted litters Parturition

  34. M F Controls M F Restricted

  35. Conclusions

  36. - Trivers & Willard Hypothesis -

  37. Roe deer:Clutton – Brock; 15 years of data on Roe deer; Coypu (Nutria): Females in good condition abort small litters of predominantly female embryos; - Large litters and small male litters are retained; Possums: Females given more food produce significantly more males 1.4/1.0 M/F; Old females are in poor condition 1.8/1.0 F/M;

  38. Verme, L. J. 1965. Reproduction studies on penned white-tailed deer. J. Wildl. Mgmt. 29:74-79.

  39. Verme, L. J., and J. J. Ozoga. 1981. Sex ratio of white-tailed deer and the estrus cycle. J. Wildl. Mgmt.45:710-715. • Bred does 15 – 95 h after the start of estrus • behavior; • Ovulation occurs 12 – 14 h after estrus • teminates; Ovulation 0 Duration of estrus – hrs. 100 Hours Post-copulation 13 – 24 25 – 36 37 – 48 49 – 96 % Males:

  40. Social Contraception

  41. Bruce effect: Pregnancy blockage Whitten effect: Estrous synchronization Lee-Boot effect: Induced estrus

  42. “Pheromone-induced reproductive inhibition in young female Peromyscus leucopus.” Haigh, G. R. et al. 1985. Biol. Reprod. 33, 271-276. • Adult Male + Juvenile Female White- • footed mice (Peromyscus leucopus) Floor • All pairs maintained until juvenile • female littered, or for 150 days; Bedding Controls: • Clean bedding • H2O sprayed on bedding Experimentals: • Soiled bedding from Ad Female’s cage • (direct contact - no floor) • Soiled bedding from Ad Female placed • under floor (no contact – olfactory) Ad Male/Juv Female • Urine from Ad Female sprayed on bedding • (no contact – olfactory)

  43. M = Adult Male olf = olfactory (soiled bedding y = juvenile female under floor) cb = clean bedding u = urine (under floor – olfactory) H2O = water in contact F = presence of adult female sb = soiled bedding in contact Parous = pregnant Nulliparous = non-pregnant

  44. Delay of reproductive maturation last 24-92 days. M = Adult male y = juvenile female 0 – 24 = hours of contact with Adult female Parous = pregnant Nulliparous = non-pregnant

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