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

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

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  1. 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

  2. Breeding pause Breeding pause NP P 60 kg Breeding pause Breeding pause Base 3 calves non selfish Base selfish

  3. Breeding pause NP Breeding pause P 60 kg Breeding pause Breeding pause Base 3 calves non selfish Base selfish

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