Limitations to Population Growth A limiting factor is anything that causes the growth rate of a population to slow or stop. – Competition – Predation – Parasitism – Disease – Climate fluctuations – Humans!

Density-Dependent Factors These limiting factors depend on population size – Competition…Niche resources Food, water, habitat, mates, … – Predation Predator/prey dependency – Parasitism – Disease Ease of transmission

Density-Independent Factors Factors that do not depend on population size – Climate Precipitation/drought Global warming Catastrophes… tornados, hurricanes, floods – Human activities Dams Urban sprawl Clear cutting of forests

Human Population Growth Until the age of industrialization only ~1/2 of children survived until adulthood – Scarce resources – Incurable disease 2015

Demographic Transition Demography… study of populations – Demographic transition As technology increases longevity… birth rates will also fall accordingly – Assumes an educated population with adequate resources – Currently the case in USA, Japan, Europe

Age Structure Diagrams Show total number of males and females in a population by age

Predicting Future Population Growth Limiting factors predict a logistic growth pattern by 2050 as the world eclipses 9 billion people – Limitations Famine Disease Water / drought War