scholarly journals Density‐dependent age of first reproduction as a key factor for population dynamics: stable breeding populations mask strong floater declines in a long‐lived raptor

2021 ◽  
Author(s):  
Jakob Katzenberger ◽  
Eckhard Gottschalk ◽  
Niko Balkenhol ◽  
Matthias Waltert
Keyword(s):  
Population Dynamics ◽  
Density Dependent ◽  
Breeding Populations ◽  
First Reproduction ◽  
Key Factor

POPULATION DYNAMICS OF LEPTINOTARSA DECEMLINEATA (SAY) IN EASTERN ONTARIO: III. MAJOR POPULATION PROCESSES

1971 ◽  
Vol 103 (7) ◽  
pp. 1049-1061 ◽  
Author(s):  
D. G. Harcourt
Keyword(s):  
Population Dynamics ◽  
Leptinotarsa Decemlineata ◽  
Food Resource ◽  
Weather Conditions ◽  
Density Dependent ◽  
Natural Agents ◽  
Potato Beetle ◽  
Key Factor ◽  
Leptinotarsa Decemlineata Say ◽  
Population Processes

AbstractAn appraisal of population processes in the Colorado potato beetle, Leptinotarsa decemlineata (Say), on its principal host plant showed that the insect has no natural agents that act in a manner that prevent it from overshooting its food supply. It is little affected by weather conditions or predators, and its only parasite, the tachinid Doryphorophaga doryphorae (Riley), is inversely density dependent in its action. Once the beetle has exploited its food resource, the larvae starve and the adults emigrate in quest of other hosts.The analysis of age interval survivals showed that populations are both regulated and disturbed by the principal key factor, adult migration, which is density dependent but overcompensating. A predictive model based on density relationships explained 94% of the variance in population trend.

An analysis of the population dynamics of the Jamaican sugar-cane pest Saccharosydne saccharivora (Westw.) (Hom., Delphacidae)

1972 ◽  
Vol 62 (1) ◽  
pp. 73-85 ◽  
Author(s):  
J. R Metcalfe
Keyword(s):  
Population Dynamics ◽  
Selective Breeding ◽  
Population Analysis ◽  
Graphical Analysis ◽  
Leaf Nitrogen ◽  
Mortality Factor ◽  
Agricultural Practice ◽  
Mortality Factors ◽  
Density Dependent ◽  
Key Factor

The Varley & Gradwell method of population analysis is applied to data on populations of Saccharosydne saccharivora (Westw.), comprising 51 generations from 21 fields, obtained in Jamaica in 1961–62. Populations were estimated at five points in each generation, namely, maximum potential natality, and numbers of eggs laid, instar 1, peak instars 3–5, and of normal reproducing adults. Taking maximum potential natality as the first point in each life budget, graphical analysis showed that the key factor was mortality between instar 1 and reproducing adults or between peak instars 3–5 and reproducing adults. Reduced fecundity, due to submaximal leaf nitrogen, was density independent or possibly inversely density dependent; one egg parasite, Tetrastichus sp., was inversely density dependent while another, Anagrus flaveolus Waterh., and an undetermined egg mortality factor were density independent; parasitism of nymphs and presumably adults also by Stenocranophilus quadratus Pierce was density dependent, and was Considered to be the only regulating factor. The key factor was density independent, and it is concluded that, of the separate mortality factors contained within it, dispersal of adults is the most important. This itself depends on crop characters which could be altered by selective breeding or agricultural practice.

scholarly journals Individual-based modelling of resource competition to predict density-dependent population dynamics: a case study with white storks

Oikos ◽  
2014 ◽  
Vol 124 (3) ◽  
pp. 319-330 ◽  
Author(s):  
Damaris Zurell ◽  
Ute Eggers ◽  
Michael Kaatz ◽  
Shay Rotics ◽  
Nir Sapir ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Resource Competition ◽  
Density Dependent ◽  
White Storks

scholarly journals Population dynamics of the species Plantago major L. and Poa annua L. in a replacement series experiment

2009 ◽  
Vol 61 (4) ◽  
pp. 819-825
Author(s):  
A. Mijovic ◽  
N. Stavretovic ◽  
Zorica Popovic
Keyword(s):  
Population Dynamics ◽  
Specific Interaction ◽  
Growth Dynamics ◽  
Bare Soil ◽  
Poa Annua ◽  
Plantago Major ◽  
Ontogenetic Changes ◽  
Replacement Series ◽  
Density Dependent ◽  
Study Results

Population dynamics of the species Plantago major L. and Poa annua L., typical representatives of ruderal vegetation, was analyzed in a replacement series experiment. The analyzed species were sown in an area with meadow vegetation, where the vegetation present had been previously removed by a total herbicide and additionally by hoeing. The objective of the experiment was to monitor growth dynamics and the effect of intra- and inter-specific interaction of the species Plantago major and Poa annua in conditions of different sowing densities and proportions. The effects of intra- and inter-specific interference and the density-dependent responses were assessed on the basis of several parameters (natality, mortality, age structure, and measures of ontogenetic changes). Based on the study results, it can be concluded that the responses of the species in the experiment were different, which is explained by different adaptive mechanisms, i.e., strategies, in the specific environmental conditions. An effect of the density dependent response was present in both species in the replacement series experiment. The response was amplified by water deficit caused by intensive evapora?tion of the bare soil. No effect of inter-specific interference was observed at the given densities of the study species on the sample plots. An effect of intra-specific interference of the species Plantago major and Poa annua was observed in the guise of a density-negative response of the rate of ontogenetic changes and fecundity.

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