Population Numbers Count: Tools for Near‐Term Demographic Analysis

Fox, Gordon A.; Gurevitch, Jessica

doi:10.1086/303387

Cited by 99 publications

(133 citation statements)

References 19 publications

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“…Apart from threeyear olds, the age structure of our captured population was approximately similar to that during Afton's study (1984). While age structure has strong potential to affect scaup demography (Afton 1984) and shortterm population dynamics (Fox and Gurevitch 2000), we do not believe age structure was responsible for the low reproductive success of scaup in 1999 and 2000 at Erickson.…”

Section: Discussionmentioning

confidence: 64%

Have Lesser Scaup, <em>Aythya affinis</em>, Reproductive Rates Declined in Parkland Manitoba?

Koons

Rotella

2003

Can Field Nat

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Long-term surveys indicate that the scaup populations have declined over the past 20 years, and that this is probably the result of decreases in Lesser Scaup (Aythya affinis) rather than Greater Scaup (Aythya marila) numbers. To identify factors possibly related to the decline, we estimated demographic parameters for a local population of Lesser Scaup at Erickson, Manitoba, that was well studied before declines occurred and compared these estimates to historic rates. On average, nests were initiated later than in the past, and recent estimates of nesting success and duckling survival were lower than historical estimates. Breeding-season survival of adult females was estimated as 72.6%, with most (83%) mortality occurring during nesting. Current estimates of demographic rates at Erickson are too low to maintain a stable local population, and suppressed reproductive rates might be the proximate cause of the local population decline.

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Section: Discussionmentioning

confidence: 64%

Have Lesser Scaup, <em>Aythya affinis</em>, Reproductive Rates Declined in Parkland Manitoba?

Koons

Rotella

2003

Can Field Nat

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“…How frequently this assumption is adequately met is unclear (Bierzychudek 1999, Williams et al 2011, as are the implications of deviances from SSD in model applications (Ezard et al 2010, Johnson et al 2010. Consequently, there has been an increasing focus on analyzing the short-term, transient dynamics that result when populations are not at SSD (e.g., Fox and Gurevitch 2000, Caswell 2007, Stott et al 2011. To date, these methods have focused on the effect of a single initial disturbance, or departure from SSD, on a constant, deterministic matrix (e.g., Neubert and Caswell 1997, Caswell 2007, Townley et al 2007, Townley and Hodgson 2008, Stott et al 2010.…”

Section: Introductionmentioning

confidence: 99%

The role of transient dynamics in stochastic population growth for nine perennial plants

Ellis

Crone

2013

Ecology

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Abstract. Most populations exist in variable environments. Two sets of theory have been developed to address this variability. Stochastic dynamics focus on variation in population growth rates based on random differences in vital rates such as growth, survival, and reproduction. Transient dynamics focus on short-term, deterministic responses to changes in the stage distribution of individuals. These processes are related: demographic variation shifts stage structures, producing transient responses, which then contribute to the overall variability of population growth rate. The relative contributions of vital rates vs. transient responses to stochastic dynamics, and the implications for transient analyses, are unclear. This study explores the role of transient responses in stochastic dynamics of nine perennial plant species. Across the species, transient responses contributed more on average to variability in annual population growth rates than did variation in vital rates alone. Transient potential of an average matrix was indicative of the contribution of transient dynamics, although these metrics varied greatly across years. Transient responses were often in the opposite direction as demographic variation, suggesting that transient dynamics may at times have a buffering effect on populations. Overall, transient dynamics had an important role in modulating environmental variation, with implications for both processes in understanding stochastic dynamics.

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“…Thus, an understanding of the dynamics of populations in variable environments consequently requires an understanding of the transient dynamics (Hastings 2001(Hastings , 2004. This is true both in the short term, when predicting how a population may respond numerically to a particular perturbation, and in the long term, as the perturbations may alter the selection pressures on the life history, leading to evolutionary change (Coale 1972;Benton and Grant 1999b;Fox and Gurevitch 2000;Koons et al 2006;Caswell 2007;Tuljapurkar et al 2009;Ezard et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Population Responses to Perturbations: The Importance of Trait-Based Analysis Illustrated through a Microcosm Experiment

Özgül

Coulson

Reynolds

et al. 2012

The American Naturalist

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Environmental change continually perturbs populations from a stable state, leading to transient dynamics that can last multiple generations. Several long-term studies have reported changes in trait distributions along with demographic response to environmental change. Here we conducted an experimental study on soil mites and investigated the interaction between demography and an individual trait over a period of nonstationary dynamics. By following individual fates and body sizes at each lifehistory stage, we investigated how body size and population density influenced demographic rates. By comparing the ability of two alternative approaches, a matrix projection model and an integral projection model, we investigated whether consideration of trait-based demography enhances our ability to predict transient dynamics. By utilizing a prospective perturbation analysis, we addressed which stage-specific demographic or trait-transition rate had the greatest influence on population dynamics. Both body size and population density had important effects on most rates; however, these effects differed substantially among life-history stages. Considering the observed trait-demography relationships resulted in better predictions of a population's response to perturbations, which highlights the role of phenotypic plasticity in transient dynamics. Although the perturbation analyses provided comparable predictions of stagespecific elasticities between the matrix and integral projection models, the order of importance of the life-history stages differed between the two analyses. In conclusion, we demonstrate how a trait-based demographic approach provides further insight into transient population dynamics. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. Here we conducted an experimental study on soil mites and investigated the interaction between demography and an individual trait over a period of nonstationary dynamics. By following individual fates and body sizes at each life-history stage, we investigated how body size and population density influenced demographic rates. By comparing the ability of two alternative approaches, a matrix projection model and an integral projection model, we investigated whether consideration of trait-based demography enhances our ability to predict transient dynamics. By utilizing a prospective perturbation analysis, we addressed which stage-specific demographic or trait-transition rate had the greatest influence on population dynamics. Both body size and population density had important effects on most rates; however, these effects differed substantially among life-history stages. Considering the observed trait-demography relationships resulted in better predictions of a population's response to pert...

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Population Numbers Count: Tools for Near‐Term Demographic Analysis

Cited by 99 publications

References 19 publications

Have Lesser Scaup, <em>Aythya affinis</em>, Reproductive Rates Declined in Parkland Manitoba?

Have Lesser Scaup, <em>Aythya affinis</em>, Reproductive Rates Declined in Parkland Manitoba?

The role of transient dynamics in stochastic population growth for nine perennial plants

Population Responses to Perturbations: The Importance of Trait-Based Analysis Illustrated through a Microcosm Experiment

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