Honors Biology Chapter 2.1 – 2.7 Population Ecology
Individual One organism Ex: Canis lupus, 1 Wolf
Population A group of one species living in an area Ex: 1000 foxes in Kendall Co.
Population Density The number of individuals per unit area Ex: 6 wolves/km 2
What is the density of house sparrows? 1 square km
What is the density of white-tailed deer? 1 square km
The pattern of spacing among individuals Clumped, Uniform, Random Population Dispersion
Population Growth Positive Population Change Natality: birth rate Immigration: entering Negative Population Change Mortality: death rate Emigration: leaving
Exponential Growth Under ideal conditions with unlimited resources, the larger a population gets, the faster it grows.
Logistic Growth Eventually populations run out of space and resources
Carrying Capacity The maximum number of individuals the environment can support
Population Size Limitations Density Dependent Factors Limitations of a population due to the size of the population Density Independent Factors Limitations of a population with no relationship to the size of the population
Density Dependent Factors Competition Food, water, shelter, space Predation Disease Parasites, illness
Density Independent Factors Natural Disasters Tornado, Hurricane, Volcanism, etc. Temperature Human Activities
Honors Biology Chapter Human Population Problem
7000 BCE world population: ~7 million people
4000 BCE world population: ~20 million people
1000 BCE world population: ~50 million
1800 CE world population: ~ 900 million
Human Population History
If exponential growth continues… In 573 years… 1 person/m 2 on Earth In 1546 years… mass of humanity = mass of the earth No exponential growth can continue indefinitely
Planet Earth’s carrying capacity ~10 billion people This might be reached by 2050
Estimated Human Pop. Growth
Limiting Factors of Human Pop. Food, Water, Shelter All come from the environment
Easter Island Mystery Remote, 163km 2 island ~2,000mi off coast of Chile A group of people arrived by boats around 1100CE By 1600’s, population rose to ~15,000 people
Easter Island Mystery In 1722, Spanish arrived and only 2,000 people remained 21 species of trees & 30 species of birds extinct Fell to only 111 people in 1877 Diseases from Europeans