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ASSUMPTION : A breeding pause (BP) is common in Arctic Rangifer 1

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Figure 2, Output from 2 model runs. Cow weight. Calf weight. Breeding pause. Next steps: Simulate effects of breeding pause on calf life history pattern (age of first reproduction, FIG. 1). Influence of agents that synchronize pauses and that will affect populations (FIG 1).

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slide1
Figure 2, Output from 2 model runs

Cow weight

Calf weight

Breeding pause

  • Next steps:
  • Simulate effects of breeding pause on calf life history pattern (age of first reproduction, FIG. 1).
  • Influence of agents that synchronize pauses and that will affect populations (FIG 1).
  • 3. Simulate influence of winter diet on N recycling and on PTN dynamics.

Breeding

pause

NP

P

60 kg

BREEDING PAUSES IN ARCTIC RANGIFER: POTENTIAL PROGENITORSRobert G White, Colin J Daniel, Don E Russell, Ray D Cameron (Res & Grad Studies, UAA, Anchorage; Apex Res Mgmt Sol, Ottawa; Yukon College, Whitehorse, Institute Arctic Biology, UAF)

Cow fat weight

Cow Protein weight

Breeding pause

  • APPROACH: Use an energetics/protein model4:
  • simulate effects of a set of variables (Vx)
  • determine their consequences on:
    • fecundity,
    • birth weight,
    • five (5) weaning outcomes
    • [extended lactation]5
    • subsequent BP

Breeding pause

Base 3 calves non selfish

Base selfish

Calf weight

Cow weight

Extended

lactation

  • determine influence of selfish cow

ASSUMPTION: A breeding pause (BP) is common in Arctic Rangifer1

HYPOTHESIS: The BP is life-history response to seasonal protein limitation

PREDICTION: A major progenitor of the BP is the “selfish cow” syndrome2,3 that serves to minimize maternal mortality and optimize reproduction

Fig 1. Time series of pregnancy and pauses

of cow and offspring (P=pregnant; E=barren)

Cow fat weight

Cow Protein weight

FIG 1.

years

Simulations using winter conditions that result in 0 BW gain does not allow repeated reproduction and weaning. Mortality inferred as 0 FAT reserves in April of 2nd gestation. “Selfish cow” conserves PTN but results in lower weaning weight. Nutrition is the inferred progenitor.

1, Cameron 1994 J Mamm 75:10-13; 2, Russell et al 1996 Rangifer S I 9:255-257; 3, Russell et al 2005 CWS Tech Rep Ser 431 64pp; 4, Therrien et al 2007 Beha Ecol Soc 62:193-166; 5, Gerhart et al 1997 J Zool 142:17-30

slide2
Breeding pause

Breeding pause

NP

P

60 kg

Breeding pause

Breeding pause

Base 3 calves non selfish

Base selfish

slide4
Breeding pause

NP

Breeding pause

P

60 kg

Breeding pause

Breeding pause

Base 3 calves non selfish

Base selfish

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