Figure 23.10: Worldwide human population growth from 10,000 BCE through today ( 9 )Lesson Summary
- A population is comprised of organisms belonging to the same species, all living in the
same area and interacting with each other - One measure of a population’s health is the dispersion of individuals within a popula-
tion - Information about birth rate, death rate, and survivorship curves also show how pop-
ulations grow and change - The population growth rate shows how the population size changes per population
member per unit of time and depends on birth and death rates and migration - There are different types of migrations that affect population density
- Under ideal conditions, populations show exponential growth; under more realistic
conditions, limiting factors (density-dependent and density-independent factors) cause
logistic growth - There are two major schools of thought about human population growth; the Neo-
Malthusians and the cornucopians
Review Questions
- Name two ways in which ecologists can get an idea of the health of a population.
- For a secretive or highly mobile species, how might you determine population size?
- What might cause a clumped or clustered dispersion?
- In an altricial reproductive strategy used by robins and hummingbirds, the birds hatch
helplessandnaked. Parentsinvestlittleenergyinjustafew, smalleggs. Itisimportant
these offspring survive, because there are so few. What strategies might parents use
to ensure that their young survive? - How does a limiting factor such as food supply limit population size?
- Inhumanhistory, majoradvancesintechnologycausedanincreaseincarryingcapacity.