Spatiotemporal variation of age-specific survival rates in a yellow-bellied marmot metapopulation.
Ozgul, Arpat*,1, Oli, Madan1, Armitage, Kenneth2, 1 Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL2 Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS
ABSTRACT- Spatiotemporal variation in age-specific survival rates can profoundly influence population dynamics, but few studies of vertebrates have thoroughly investigated both spatial and temporal variability in age-specific survival rates. We used 28 years (1976 -2003) of mark-recapture data from 17 locations to parameterize an age-structured Cormack-Jolly-Seber model, and investigated the significance of spatial and temporal variation in age-specific survival rates of yellow-bellied marmots (Marmota flaviventris). Yellow-bellied marmot survival rates varied both spatially and temporally during our study. Spatial variation in survival was the highest in the younger age classes. Among the environmental correlates, the altitude and the slope direction of the natal site accounted best for the observed spatial variation in young survival rates. Average group size influenced the survival of older age-classes, but not of young animals. Temporal variation was observed only in young survival rates. Adult survival rates were less variable, both over space and time, compared to survival of younger age classes. High spatiotemporal variability in young survival rates and high sensitivity of population growth rate to variation in these rates are likely to be important determinants of the substantial temporal fluctuations and spatial variation observed in local dynamics of yellow-bellied marmots and other mammals with similar life history characteristics.
Key words: age-specific survival, Cormack-Jolly-Seber model, yellow-bellied marmot, demography
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