BIO220H1 Lecture 7: Human Population Ecology
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BIO220H1 Full Course Notes
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If rates are constant and if (birth + immigration) > (death + emigration), growth trajectory is density-independent and exponential: exponential growth if r > 0. Logistic model: simplest model of density-dependent regulation, sigmoid growth, asymptotic approach to carrying capacity (k) Best fit of logistic equation to data suggests leveling off at about 2. 6 million. Data does not match model: human population growth looks much more exponential than logistic, 2015: about 7. 2 billion and climbing, profound effects on the globe. Statistically: extrapolating beyond range of data is dangerous, logistic is not a law, just a simple possible hypothesis for density-dependence. Biologically logistic curve does not allow overshoots; as well, assumes that r and k are constants: humans" use of technology and culture will change carrying capacity. K is changing (instead of population overshooting due to delayed response) Population will grow exponentially, and then will crash or equilibrate. Unsure what the real model for human population is what the equation looks like.
