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A cohort life table tracks organisms through the stages of life, while a static life table shows the distribution of life stages among the population at a single point in time. [3] Following is an example of a cohort life table based on field data from Vargas and Nishida (1980). [4]
Life table" primarily refers to period life tables, as cohort life tables can only be constructed using data up to the current point, and distant projections for future mortality. Life tables can be constructed using projections of future mortality rates, but more often they are a snapshot of age-specific mortality rates in the recent past, and ...
Survivorship curves can be constructed for a given cohort (a group of individuals of roughly the same age) based on a life table. There are three generalized types of survivorship curves: [ 1 ] Type I or convex curves are characterized by high age-specific survival probability in early and middle life, followed by a rapid decline in survival in ...
The logistic population model, the Lotka–Volterra model of community ecology, life table matrix modeling, the equilibrium model of island biogeography and variations thereof are the basis for ecological population modeling today. [6]
An important concept in population ecology is the r/K selection theory. For example, if an animal has the choice of producing one or a few offspring, or to put a lot of effort or little effort in offspring—these are all examples of trade-offs.
Natality in population ecology is the scientific term for birth rate. Along with mortality rate, natality rate is used to calculate the dynamics of a population. They are the key factors in determining whether a population is increasing, decreasing or staying the same in size. Natality is the greatest influence on a population's increase.
In this equation, b is the crude birth rate while e o is the life expectancy at birth. Q is the total number of births per initial birth. = This equation is used to derive Q (total births per initial birth), r is the growth rate and μ is the unchanging population mean age at childbearing.
For example, if the abundance of large piscivorous fish is increased in a lake, the abundance of their prey, zooplanktivorous fish, should decrease, large zooplankton abundance should increase, and phytoplankton biomass should decrease. This theory has stimulated new research in many areas of ecology. Trophic cascades may also be important for ...