UNIT 3 — Populations

What factors cause changes in population size?

Births, deaths, immigration, and emigration.

What is carrying capacity (K)?

The maximum population that an environment can support.

What is exponential growth?

A type of growth represented by a J-curve that occurs in the presence of unlimited resources.

What is logistic growth?

A type of growth represented by an S-curve that occurs when resources are limited and the population reaches carrying capacity.

What are r-selected species?

Species that produce many offspring, provide little parental care, have short lifespans, and include examples like insects and mice.

What are K-selected species?

Species that have few offspring, provide high parental care, have long lifespans, and include examples like humans and elephants.

What does Type I survivorship curve represent?

Species that have high survival rates in early and middle life, such as humans.

What does Type II survivorship curve represent?

Species that have a constant death rate throughout their life, such as birds.

What does Type III survivorship curve represent?

Species that have high mortality rates early in life, such as fish and insects.

What characterizes Stage 1 of the Demographic Transition Model?

High birth rates and high death rates.

What characterizes Stage 2 of the Demographic Transition Model?

High birth rates and falling death rates, leading to rapid population growth.

What characterizes Stage 3 of the Demographic Transition Model?

Falling birth rates and low death rates.

What characterizes Stage 4 of the Demographic Transition Model?

Low birth rates and low death rates resulting in a stable population.

What characterizes Stage 5 of the Demographic Transition Model?

A declining population in some countries.

What is the Rule of 70 used for?

To estimate the doubling time of a population based on its growth rate.

How do you calculate doubling time using the Rule of 70?

By dividing 70 by the growth rate percentage.