Patterns of variance in stage-structured populations: Evolutionary predictions and ecological implications
TL;DR: The results suggest that variable life history stages tend to contribute relatively little to population growth rates because natural selection may alter life histories to minimize stages with both high sensitivity and high variation.
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Abstract: Variability in population growth rate is thought to have negative consequences for organism fitness. Theory for matrix population models predicts that variance in population growth rate should be the sum of the variance in each matrix entry times the squared sensitivity term for that matrix entry. I analyzed the stage-specific demography of 30 field populations from 17 published studies for pattern between the variance of a demographic term and its contribution to population growth. There were no instances in which a matrix entry both was highly variable and had a large effect on population growth rate; instead, correlations between estimates of temporal variance in a term and contribution to population growth (sensitivity or elasticity) were overwhelmingly negative. In addition, survivorship or growth sensitivities or elasticities always exceeded those of fecundity, implying that the former two terms always contributed more to population growth rate. These results suggest that variable life history stages tend to contribute relatively little to population growth rates because natural selection may alter life histories to minimize stages with both high sensitivity and high variation.
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TL;DR: This formula reveals the major qualitative and quantitative effects of the average life history, fluctuations, and temporal autocorrelation on fitness of the age-structured population in a temporally fluctuating environment.
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Evaluating Management Alternatives for Red-Cockaded Woodpeckers: A Modeling Approach
TL;DR: A male-only, stage-based matrix model is presented to assess potential effects of various management techniques used to enhance red-cockaded woodpecker populations and predicts the population-level effects of 5 proposed management techniques that affect stage-specific survival, growth, and fecundity.
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DEMOGRAPHIC AND GENETIC MODELS IN CONSERVATION BIOLOGY: Applications and Perspectives for Tropical Rain Forest Tree Species
TL;DR: The main conclusions of deterministic demographic models are the key importance of species' longevity in determining susceptibility of population growth rate to harvesting of individuals at different life-stages, the critical effect of patch dynamics, and the importance of density-dependent mechanisms at least for abundant species.
Life history and population dynamics of rare and common mariposa lilies (Calochortus Pursh: Liliaceae).
TL;DR: Rarity in populations of three mariposa lilies appears rather idiosyncratic, and few generalizations should be drawn across taxa or conspecific populations.
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How to keep fit in the real world: elasticity analyses and selection pressures on life histories in a variable environment
Tim G. Benton,Alastair Grant +1 more
TL;DR: In this article, the authors investigate the impact of environmental variability on selection pressures (elasticities = proportional sensitivities) on a range of life histories and find that the impact is influenced significantly by the amount of variability an organism experiences (more variability affects selection pressures more), the correlations between variations among the vital rates, and the life history in question (shorter life histories are more affected).
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