How is 'growth rate' defined in population ecology?

In population ecology, 'growth rate' is defined as the change in size of a population over time. This concept encompasses how populations increase or decrease in number, taking into account factors such as birth rates, death rates, immigration, and emigration. The growth rate provides insight into how quickly a population can expand or contract, which is essential for understanding the dynamics of ecosystems and the viability of species within their habitats.

While other options touch on relevant population concepts, they do not capture the comprehensive nature of growth rate. The ratio of births to deaths focuses solely on one aspect of population change, while total population size over a year does not indicate how that size is changing. The number of offspring produced annually pertains specifically to reproductive output rather than the overall dynamics of population change. Thus, defining growth rate as the change in size of a population over time allows for a broader understanding of population health and changes.