The Bottom Line: It’s the ecology, stupid.

Rabbits and Bears and Humans, Oh My…

Summary: In nature, organisms (and ecosystems) expand to fill niches that have untapped resources. When an ecological niche is nearly empty of organisms and full of resources, individuals typically live full lives with plenty of surviving offspring, who in turn live to reproduce. During this phase, populations rise exponentially. Over time, though growth continues, the population becomes so large that the change in growth per period diminishes as competition for dwindling resources ensues. Eventually, as the population reaches the maximum size an ecosystem can support, the population stabilizes and bounces around carrying capacity (more on this in the next section). This population is now in equilibrium ( steady state ) with its environmental conditions. If shown as a graph (below), exponential growth , deceleration , and steady state comprise an S shaped curve – and together comprise what’s termed the “logistic growth curve,” which generally operates according to the mathematical logistic function . Don’t worry about the math, just understand that there’s a simple equation which relates the rate of change of a population N to the current population size and expresses the effect of two parameters, with r representing the rate while K represents carrying capacity.

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