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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 ...
An example of an epidemiological question that can be answered using a cohort study is whether exposure to X (say, smoking) associates with outcome Y (say, lung cancer). For example, in 1951, the British Doctors Study was started. Using a cohort which included both smokers (the exposed group) and non-smokers (the unexposed group).
The source–sink model of population dynamics has made contributions to many areas in ecology. For example, a species' niche was originally described as the environmental factors required by a species to carry out its life history, and a species was expected to be found only in areas that met these niche requirements. [ 18 ]
Population viability analysis (PVA) is a species-specific method of risk assessment frequently used in conservation biology.It is traditionally defined as the process that determines the probability that a population will go extinct within a given number of years.
As a consequence, it is an interdisciplinary concept, but maintains biological roots. The hierarchical organizations that are inherent to both biology (cell, organ, individual) and demography (individual cohort, population) form a chain in which the individual serves as the link between the lower mechanistic levels, and the higher functional ...
The Leslie matrix is a discrete, age-structured model of population growth that is very popular in population ecology named after Patrick H. Leslie. [1] [2] The Leslie matrix (also called the Leslie model) is one of the most well-known ways to describe the growth of populations (and their projected age distribution), in which a population is closed to migration, growing in an unlimited ...