Carrying Capacity of Spatially Distributed Metapopulations

Highlights

• The logistic equation, with carrying capacity, K, and growth rate, r, has traditionally been used to describe dynamics of ecological populations.

• Experiments confirmed the prediction that dispersal could increase metapopulation abundance in heterogeneous environments, whereas they rejected the prediction that heterogeneous environments support a larger metapopulation abundance than homogeneous environments with the same sum over K values.

• Consumer-resource models, which explicitly consider the resource inputs and time scales of feedbacks between organisms and their resource, agree consistently with experimental results, suggesting they are more appropriate for describing populations in space.

• The theoretical results have important management implications on wildlife, such as the important role of dispersal, or habitat connectivity, in influencing population abundance in patchy environments.

Carrying capacity is a key concept in ecology. A body of theory, based on the logistic equation, has extended predictions of carrying capacity to spatially distributed, dispersing populations. However, this theory has only recently been tested empirically. The experimental results disagree with some theoretical predictions of when they are extended to a population dispersing randomly in a two-patch system. However, they are consistent with a mechanistic model of consumption on an exploitable resource (consumer–resource model). We argue that carrying capacity, defined as the total equilibrium population, is not a fundamental property of ecological systems, at least in the context of spatial heterogeneity. Instead, it is an emergent property that depends on the population’s intrinsic growth and dispersal rates.