Decoupling of component and ensemble density feedbacks in birds and mammals

Salvador Herrando-Pérez, Steven Delean, Barry Brook, Corey Bradshaw

    Research output: Contribution to journalArticle

    15 Citations (Scopus)

    Abstract

    A component density feedback represents the effect of change in population size on single demographic rates, whereas an ensemble density feedback captures that effect on the overall growth rate of a population. Given that a population's growth rate is a synthesis of the interplay of all demographic rates operating in a population, we test the hypothesis that the strength of ensemble density feedback must augment with increasing strength of component density feedback, using long-term censuses of population size, fertility, and survival rates of 109 bird and mammal populations (97 species). We found that compensatory and depensatory component feedbacks were common (each detected in ;50% of the demographic rates). However, component feedback strength only explained ,10% of the variation in ensemble feedback strength. To explain why, we illustrate the different sources of decoupling between component and ensemble feedbacks. We argue that the management of anthropogenic impacts on populations using component feedbacks alone is ill-advised, just as managing on the basis of ensemble feedbacks without a mechanistic understanding of the contributions made by its components and environmental variability can lead to suboptimal decisions.

    Original languageEnglish
    Pages (from-to)1728-1740
    Number of pages13
    JournalEcology
    Volume93
    Issue number7
    DOIs
    Publication statusPublished - Jul 2012

    Keywords

    • Compensation
    • Conservation
    • Density dependence
    • Depensation
    • Fertility
    • Management
    • Mortality
    • Population regulation
    • Recruitment
    • Survival

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