Predictors of early survival in Soay sheep: cohort-, maternal- and individual-level variation

Authored by OR Jones, MJ Crawley, JG Pilkington, JM Pemberton

Date Published: 2005

DOI: 10.1098/rspb.2005.3267

Sponsors: Biotechnology and Biological Sciences Research Council (BBSRC) Wellcome Trust United Kingdom Natural Environment Research Council (NERC) Scottish Natural Heritage National Trust for Scotland

Platforms: R

Model Documentation: Other Narrative

Model Code URLs: Model code not found

Abstract

A demographic understanding of population dynamics requires an appreciation of the processes influencing survival-a demographic rate influenced by parameters varying at the individual, maternal and cohort level. There have been few attempts to partition the variance in demography contributed by each of these parameter types. Here, we use data from a feral population of Soay sheep (Ovis aries), from the island of St Kilda, to explore the relative importance of these parameter types on early survival. We demonstrate that the importance of variation occurring at the level of the individual, and maternally, far outweighs that occurring at the cohort level. The most important variables within the individual and maternal levels were birth weight and maternal age class, respectively. This work underlines the importance of using individual based models in ecological demography and we, therefore, caution against studies that focus solely on population processes.

Tags

Climate Evolution Dynamics Weather Mortality growth Density Bighorn sheep Population fluctuations Ovis-aries