BIO220H1 Lecture 17: Lecture 17 Human Population Ecology

• School: UTSG
• Department: Biology
• Course: BIO220H1
• Professor: Doug Thomson

Document Summary

Human projection from allee et. al. predicted logistic model. Extrapolating from logistic poor prediction: statistical, biological, extrapolating beyond range of data always dangerous, logistic not law, just possible hypothesis for density-dependent growth, logistic allows no overshoots, logistic assumes r, k to be constants. Human trajectory can"t be modeled simply: growth (r) depends on fertility rates (bx), mortality (inverse of lx, birth rates high, death rates dropped radically 19-20th century, health care increased r, agriculture increased k. Age structure affects trajectory population momentum: fast growing populations have broad-based age pyramids, excess children, even if r 0, populations keep growing as children reproductive age high momentum, low momentum typical for rapid growing populations. Lester brown: k depends on how people live. Causes of declining fertility: government policy, voluntary parent decisions, motivated by, increased survival children, children expensive, society provides security in old age, worry: overpopulation, contraception/abortion, postpone marriage/family, and made possible by: Smooth demographic transitions in developing countries: maybe no, might stall.