PARENT SESSION
Oral Session # 42: Mammal Ecology: From Mice to Elephants.
Presiding: H Howe
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 104.
Yellow-bellied marmot population dynamics: Demographic mechanisms of growth and decline.
Oli, Madan*,1, Armitage, Kenneth2, 1 Dept of Wildlife Ecology, Gainesville, FL, USA2 Dept of Ecology and Evolutionary Biology, Lawrence, KS, USA
ABSTRACT- Multiple environmental factors may act synergistically to influence demographic characteristics, and ultimately the dynamics, of biological populations. Using prospective and retrospective analyses of demographic data from a 40-yr study of individually-marked animals, we investigated the demographic mechanisms of the temporal and spatial dynamics of a yellow-bellied marmot (Marmota flaviventris) population. Prospective elasticity analyses indicated juvenile survival rate would have the largest relative influence on the projected population growth rate. Relative magnitudes of elasticities did not differ between years characterized by positive and negative population growth. However, retrospective analyses of life table response experiment (LTRE) revealed that changes in age at first reproduction, followed by fertility rate, made the largest contributions to observed annual changes in population growth rate. Changes in age at first reproduction made the largest contributions to annual declines in population growth rate most frequently, whereas fertility rate made the largest contributions to increases in population growth rate most frequently. Population dynamic differences among marmot colonies were due primarily to spatial variations in age at maturity and juvenile survival rates. Broader implications of our findings to population ecological studies are discussed.
Key words: sensitivity analysis, yellow-bellied marmots, population dynamics, analysis of life-table response experiments