scholarly journals On carrying-capacity construction, metapopulations and density-dependent mortality

2017 ◽  
Vol 22 (3) ◽  
pp. 1099-1110
Author(s):  
J. X. Velasco-Hernández ◽  
◽  
M. Núñez-López ◽  
G. Ramírez-Santiago ◽  
M. Hernández-Rosales ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Analysis of an estuarine striped bass (Morone saxatilis) population: influence of density-dependent mortality between metamorphosis and recruitment

2000 ◽  
Vol 57 (2) ◽  
pp. 478-486 ◽  
Author(s):  
W J Kimmerer ◽  
J H Cowan, Jr. ◽  
L W Miller ◽  
K A Rose
Keyword(s):  
San Francisco ◽  
Striped Bass ◽  
Carrying Capacity ◽  
Food Limitation ◽  
Morone Saxatilis ◽  
Fish Stock ◽  
Compensatory Mechanism ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Dependent Mortality

Compensation due to density-dependent mechanisms is essential for the maintenance of an exploited fish stock. Understanding compensation is important for understanding population regulation and responses to added mortality. We examined possible density-dependent effects on striped bass (Morone saxatilis) in the San Francisco Estuary. Three sets of data from sampling programs for young striped bass showed density-dependent mortality between 1 month of age and 8-12 months. The relationships between two indices of young striped bass abundance and recruitment at age 3 fit a Beverton-Holt function, also indicating density dependence. The carrying capacity, as determined by the asymptote of the Beverton-Holt curves, has declined over the last two to three decades. These results are consistent with a compensatory mechanism based on food limitation occurring after metamorphosis and with the decline in food resources observed in the estuary over the same period. The decline in striped bass over the last two to three decades may be partly due to this declining carrying capacity.

An Experiment On Spacing-Out as a Defence Against Predation

Behaviour ◽  
1967 ◽  
Vol 28 (3-4) ◽  
pp. 307-320 ◽  
Author(s):  
D. Franck ◽  
M. Impekoven ◽  
N. Tinbergen
Keyword(s):  
Selection Pressure ◽  
Standard Sample ◽  
Direct Detection ◽  
Natural Populations ◽  
The Other ◽  
Detection Distance ◽  
Density Dependent ◽  
Density Dependent Mortality ◽  
Scattered Population ◽  
Dependent Mortality

AbstractThe paper is concerned with the tracing of a selection pressure which would account for the fact (believed to be sufficiently well established) that individuals of many well-camouflaged species live further away from other individuals of their species than the distance from which even bird predators are able to detect them. Artificially camouflaged hens' eggs were laid out in plots of different densities. Wild Carrion Crows were attracted to each plot by a standard "sample egg" which, while painted in the same way as the other eggs on the uppermost half, was laid out in a more conspicuous way. In spite of the fact that the Crows spent more time searching in the "scattered" than in the "crowded" plots, the crowded eggs suffered a much higher mortality. It is concluded that even for individuals of a well-camouflaged species it must be of advantage to live further away from others than the Direct Detection Distance of their predators. However, the experiments do not show that a crowded population as a whole suffers higher predation than a scattered population; experiments to test this and other aspects of the problem are in progress. It is argued that the absolute values of the density dependent mortality scores of the experiments cannot be applied to natural populations, because their density will in most cases be determined by other ultimate factors as well.

POPULATION DYNAMICS OF THE CEREAL LEAF BEETLE, OULEMA MELANOPUS (COLEOPTERA: CHRYSOMELIDAE): A MODEL FOR AGE SPECIFIC MORTALITY

1972 ◽  
Vol 104 (6) ◽  
pp. 797-814 ◽  
Author(s):  
Robert G. Helgesen ◽  
Dean L. Haynes
Keyword(s):  
Pupal Stage ◽  
Leaf Beetle ◽  
Fourth Instar ◽  
Egg Survival ◽  
Density Dependent ◽  
Cereal Leaf Beetle ◽  
Density Dependent Mortality ◽  
Oulema Melanopus ◽  
First Instar ◽  
Dependent Mortality

AbstractThe cereal leaf beetle, Oulema melanopus (L.), has rapidly increased its numbers and range since it was discovered in Michigan in 1962. We have shown in this report that intraspecific density-dependent mortality is the major constraint on survivorship. We have attempted to quantify survival within a generation from the egg stage to the adult.Larval mortality varies among populations. Density-dependent mortality, caused by intraspecific competition, accounts for most of the variation of within-generation survival of the cereal leaf beetle in wheat and oats. Mortality in the first instar on oats and the fourth instar on wheat and oats is a linear function of the logarithm of total egg density. Establishment of the first instar on oats appears to become more difficult as density increases because leaf surface disturbance and interference with larger larva increases. Competition for food accounts for the increase in mortality of the fourth instar in both wheat and oats as density increases. Egg survival, survival of the first instar on wheat and in the second, third, and pupal stage in both crops are constants with respect to density. These constants can be expected to change with respect to other environmental parameters however, e.g. host variety, planting date, rainfall, etc.

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