The debate about density dependence – a polemic

Haak, Christian

doi:10.1046/j.1365-2311.2002.00424.x

Cited by 4 publications

(3 citation statements)

References 35 publications

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“…Method 5: results with different letters in superscript denote significant differences and rank for best fitting curve (a definition. While the debate on the consequences of density dependence for host population dynamics continues (Godfray & Hassell 1997;Haak 2002;Berryman 2003), the statistical definition and quantification of densitydependent relationships remain fundamental to the field.…”

Section: Discussionmentioning

confidence: 99%

Spatially explicit analyses unveil density dependence

Veldtman

McGeoch

2004

Proc. R. Soc. Lond. B

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Density-dependent processes are fundamental in the understanding of species population dynamics. Whereas the benefits of considering the spatial dimension in population biology are widely acknowledged, the implications of doing so for the statistical detection of spatial density dependence have not been examined. The outcome of traditional tests may therefore differ from those that include ecologically relevant locational information on both the prey species and natural enemy. Here, we explicitly incorporate spatial information on individual counts when testing for density dependence between an insect herbivore and its parasitoids. The spatially explicit approach used identified significant density dependence more frequently and in different instances than traditional methods. The form of density dependence detected also differed between methods. These results demonstrate that the explicit consideration of patch location in density-dependence analyses is likely to significantly alter current understanding of the prevalence and form of spatial density dependence in natural populations.

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Section: Discussionmentioning

confidence: 99%

Spatially explicit analyses unveil density dependence

Veldtman

McGeoch

2004

Proc. R. Soc. Lond. B

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“…However, uncertainty has prevailed elsewhere and particularly in insect species, where little evidence for density dependence has been observed in field populations (Andrewartha & Birch, 1954;Dempster, 1983;Stiling, 1987Stiling, , 1988. The lack of empirical support for density dependence in insect species culminated in long-standing debates between entomologists in the late 1980s and mid-1990s (Andrewartha & Birch, 1954;Dempster, 1983;Gaston & Lawton, 1987;Stiling, 1987Stiling, , 1988, appearing to end with an 'agreement to disagree' (Wolda et al, 1994;Haak, 2002). Some authors deduced that density dependence does not occur in insect populations (Dempster, 1983;Stiling, 1988).…”

Section: Introductionmentioning

confidence: 99%

Nutritional availability and larval density dependence in Aedes aegypti

Heath

Paton

Wilson

et al. 2020

Ecological Entomology

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1. Density dependence is the effect of density on population growth. Density dependence is an aggregate term for a suite of complex interactions between animals and their environment. 2. Mechanistic studies of density dependence in mosquito ecology are sparse, and the role of environmental factors is poorly understood. 3. Two empirical study designs were compared to consider the interaction between nutritional availability and density in Aedes aegypti. First, larvae were fed per capita. Second, larvae were fed a fixed amount of food unadjusted for the number of individuals; therefore, at higher densities, individuals received less per capita. 4. Survivorship, wing length, and development rate were lower at high densities when larvae were fed a fixed, unadjusted amount of food. The opposite was observed when food was adjusted per capita, suggesting that high densities may be beneficial for larval development when per capita nutrition is held constant 5. These results demonstrate that negative associations between Ae. aegypti larval density and larval development are a manifestation of decreased per capita nutrient uptake at high densities. 6. Population regulation is a proportional response to environmental variability in Ae. aegypti. Increased survivorship at high densities when larvae were fed per capita demonstrates that nutritional availability is not the only mechanism of density dependence in mosquitoes. Further studies should characterise density dependence in mosquitoes by using mechanistic study designs across diverse environmental conditions.

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“…In actuality, the observed populations are regulated about some mean level and this leads to a stationary probability distribution of population densities ( Turchin, 1995 ) where the variance of population density is bounded. Haak (2002) has argued that ecological density dependence is not a necessary or required concept and that due to methodological developments only statistical density dependence is of importance. Here, the role of statistical density dependence has been evaluated; this provides evidence that the populations are regulated.…”

Section: Discussionmentioning

confidence: 99%

Density dependence and noise determine the long‐term dynamics of two species of lady beetle (Coleoptera: Coccinellidae: Epilachninae) in the Indonesian tropics

Bonsall

Hasan²,

Nakamura

2006

Ecological Entomology

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1. The long-term dynamics of two beetles ( Epilachna vigintioctopunctata and Epilachna enneasticta ) from Indonesia are analysed using descriptive time-series statistics and mechanistic time-series models.2. Statistical analysis of the time series reveals that the dynamics of E. vigintioctopunctata are underpinned by a second order density-dependent [AR(2)] process, which is consistent between sites. Similarly, the dynamics of E. enneasticta are also described by a second order density-dependent [AR(2)] process. The predicted dynamics from these statistical models are stable dynamics.3. Mechanistic models of the density dependence predict that in the absence of noise the dynamics of the populations should also be stable. Inclusion of the stochasticity in the models of density dependence allows a more accurate description of the population dynamics of each species to be determined.4. Correlation analyses reveal that the fluctuations between species are a function of both the density dependence and the environmental conditions experienced by each species. Under low environmental variance it is predicted that the dynamics could be synchronised but under high variance in environmental noise, the dynamics may not be synchronised and species respond idiosyncratically to the environment.5. The study highlights the value of long-term population dynamic time series for exploring the structure of population regulation and fluctuations in insect populations. Entomology, 32, 28-37 y ¼ a 0 1 a 1 Á x h1 t 1 a 2 Á x h2 t21 30 Michael B. Bonsall, Nusyirwan Hasan and Koji Nakamura

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The debate about density dependence – a polemic

Cited by 4 publications

References 35 publications

Spatially explicit analyses unveil density dependence

Spatially explicit analyses unveil density dependence

Nutritional availability and larval density dependence in Aedes aegypti

Density dependence and noise determine the long‐term dynamics of two species of lady beetle (Coleoptera: Coccinellidae: Epilachninae) in the Indonesian tropics

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