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Reproduction & Survival. Reproduction & Survival. Nutrition is of interest to ecologists and managers because it has the potential to affect demographic processes Many stages of reproductive cycle may be affected by nutrition. Reproduction & Survival. Fig. 1 Kirkpatrick 1988. males vs.

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reproduction survival
Reproduction & Survival
  • Nutrition is of interest to ecologists and managers because it has the potential to affect demographic processes
  • Many stages of reproductive cycle may be affected by nutrition
reproduction survival3
Reproduction & Survival
  • Fig. 1 Kirkpatrick 1988

males vs.

females?

reproduction survival4
Reproduction & Survival
  • To understand data, need a quick primer on a few aspects of reproductive physiology

Figs. 4 and 7 of Wildlife

Techniques Manual

reproduction survival5
Reproduction & Survival
  • Placental scars – Formed when placenta tears out of the uterus during birth. Formed from a deciduous placenta
    • Insectivores
    • Lagomorphs
    • Rodents
    • Carnivores Fig. from JWM 60:432
reproduction survival6
Reproduction & Survival
  • Age at first reproduction
    • Young animals sensitive to nutritional condition
  • Most birds, breeding by yearlings the norm
  • Waterfowl and raptors
    • Some evidence puberty advanced by nutrition
  • Puberty could change in long lived species
  • Some evidence of earlier puberty in small mammals
  • Lagomorphs / squirrels – Earlier puberty, esp. if adults breed earlier in year. Young breed later that same year (4-9 months old)
reproduction survival7
Reproduction & Survival
  • Carnivores
    • Lynx: Hare high  99% yearling lynx breed

low  5% yearling lynx breed

see Table 4 from Mowat et al. 1996. JWM 60

reproduction survival8
Reproduction & Survival
  • Carnivores
    • Lynx: Hare high  99% yearling lynx breed

low  5% yearling lynx breed

    • Fox: yearlings seem to breed every year
    • Coyotes: Abundant prey  65-83% yrl breed

Scarce prey  0-23% yrl breed

    • Bears: Good food conditions can advance puberty 3-5 years (e.g. 3 years old vs. 8)
reproduction survival9
Reproduction & Survival
  • Artiodactyls – Most work on wt deer
  • Table 1 from Kirkpatrick 1988
reproduction survival10
Reproduction & Survival
  • White-tailed deer (Abler et al. 1976)
    • 9 of 11 fawns on high energy diet cycled
    • 0 of 8 fawns on low energy diet cycled
    • protein in diet (9.6 vs. 18.2) had no effect
    • body weight of cycling and non-cycling fawns not dramatically different

Table 26 from Elk of North America (1982)

reproduction survival11
Reproduction & Survival
  • Length of the breeding season
    • For species that can reproduce >1 time/yr, breeding season length may vary
    • Many small mammals will have >1 litter/yr if nutrients are sufficient
    • Quail in S. Texas will nest >1 if conditions are good (not clear that nutrition is driving force)
    • Snowshoe hares w/ feed had up to 4 litters/yr. Hares w/o feed had ≤3. % hares w/ 2 and 3 litters greater in areas w/ feed
reproduction survival12
Reproduction & Survival

Table 4, Kirkpatrick 1988

reproduction survival13
Reproduction & Survival
  • Proportion of adults breeding
    • In waterfowl, galliforms, and raptors, fewer adults breed when food resources are poor
    • Have been manipulative studies done with raptors and turkeys
reproduction survival14
Reproduction & Survival
  • Proportion of adults breeding
    • In small mammals, can have fewer adults breed when nutrition is poor, but not consistent

Fig 7 from Kirkpatrick 1988

reproduction survival15
Reproduction & Survival
  • Table 14 from Kirkpatrick 1988
reproduction survival17
Reproduction & Survival
  • Proportion of adults breeding - Carnivores
    • Fewer adult lynx breed if prey are scarce
reproduction survival18
Reproduction & Survival
  • Proportion of adults breeding - Carnivores
    • Bears are very sensitive to food resources. Why would bears be particularly sensitive?
    • 33, 44, and 59% adult black bears had cubs following years of scarce, moderate, and abundant mast crops
    • In good habitats, adult black bears produce every other year. In poor habitats, produce every 3-4 years.
reproduction survival19
Reproduction & Survival
  • Proportion of adults breeding - Carnivores
    • Fox and coyotes ovulate every year
    • Ovum may not implant if female is in poor condition
  • Artiodactyls
    • Cycling in adult females can be altered if in poor condition
reproduction survival20
Reproduction & Survival
  • Table 2 from _____ (collared peccary reproduction)
reproduction survival21
Reproduction & Survival
  • Clutch Size
    • Arctic nesting geese

Data from Ankney

and Macinnes (1978)

reproduction survival22
Reproduction & Survival
  • Table 15 Kirkpatrick 1988
reproduction survival23
Reproduction & Survival
  • Litter Size - Small mammals
    • Effect found in some studies but not all
    • Litter size affected by nutrition in snowshoe hares, but not necessarily in cottontails
  • Carnivores
    • Litter size varies with prey abundance
    • Bears have 1-2 cubs in poor habitat conditions and 3-4 in good conditions
reproduction survival25
Reproduction & Survival
  • Litter Size – Artiodactyls
    • Nutrient restriction through breeding will cause a decline in litter size. Affect due to energy
reproduction survival26
Reproduction & Survival
  • Survival of young