Population growth rate
We contend that the primary factor bridging the many aspects of population ecology is population growth rate.
The key role that the population growth rate plays in predicting future population trends contributes to its significance. In fact, if the density dependence’s form were constant and well-known, future population dynamics might be somewhat predictable.
We contend that population growth rate is likewise crucial to our comprehension of environmental stress, and that environmental stressors need to be classified as elements that, when first introduced to a population, slow population increase.
Population growth rate determinants
An organism’s ecological niche, which should be understood as the set of environmental conditions where population growth rate is greater than zero (where population growth rate = r = loge(Nt+1/Nt)), is determined by the combined influence of such stressors. Environmental stressors have a detrimental impact on population growth rate, but they also have a detrimental impact on population density, a situation in which negative linear effects are present and are consistent with the well-known logistic equation. We acknowledge population regulation to occur when population growth rate is negatively density dependent, as Sinclair did. Only 25 studies were found in the literature that have plotted population growth rate versus population density, which is surprising given its critical role in population ecology.
Twelve of these showed linear effects of density; in all but two of the remaining cases, the connection seemed concave from above.
The many methods for determining the factors affecting the population growth rate are examined, with a focus on the demographic and mechanistic methods.
Population growth rate an overview
According to a “numerical response,” the evidence for which is briefly reviewed, the impacts of population density on population growth rate may work through their effects on food supply and related effects on somatic growth, fertility, and survival.
As an alternative, there can be impacts on population density in addition to those that result from the division of food among competitors; this is known as “interference competition”.
An exact replication of a lab experiment employing a marine copepod serves as an example of the distinction Battaglia, Tisbe.
We briefly discuss the use of these methods in ecotoxicology, human demography, and conservation biology.
We come to the conclusion that population growth rate is the best way to identify and analyse factors including population management, density dependency, resource and interference competition, the effects of environmental stress and the shape of the ecological niche.