03 Evolution and Population Ecology AP Environmental Science

What effect has hawaii’s geographic isolation and human influence had on native bird species

Half of native bird species have gone extinct since the 1700s

Species definition

Classification of an organism whose members are able to interbreed with the ability to produce fertile offspring

Population

group of individuals that live in the same geographic area

Natural selection is based off of

-Organisms face a constant struggle to survive and reproduce

-Organisms tend to produce more offspring than can survive to maturity

-Individuals of a species vary in their attributes

True or False: Evolution will usually not occur in small populations

True

How does knowledge of evolution impact vaccines?

• Bacteria reproduce at a high rate

• At a faster rate than most organisms, stronger bacteria that survives passes on traits until population evolves to become immune

• Pharmacists have to predict which strain will be present in the upcoming season

• Vaccines to protect from this strain are created

Key takeaway: bacteria evolves and reproduces at a high rate

Conditions for variation

• have to have many species (high biodiversity) in one area, allows for a variety of traits

Ecological niche

how an organism uses its habitat

What type of niche do specialists have

a narrow niche

What type of niche do generalists have

A broad niche

Specialist examples

Koalas, Polar Bears, Giraffes

Generalist examples

Tigers, deer, lions

True or False: Generalists are more likely to be endangered than Specialists

False; Specialists are more likely to be endangered because they rely on a specific source of food and location. If this food supply is threatened or survival is challenged in locations where that food is found, specialists are more likely to be endangered. For example, Panda Bears are endangered because their primary habitat is the Yangtze Basin in China, but due to infrastructure development, Panda Bears face habitat loss. However, animals like raccoons which are generalists eat whatever is available and therefore can adapt to environments altered by humans.

Random Distribution

An organism is randomly distributed throughout an area. Occurs when resources are randomly distributed. Organisms such as trees and other plants are usually randomly distributed because their seed dispersal depends on factors like wind and animals.

Uniform distribution

Organisms are spaced out in an even way across an area. This usually occurs with territorial species or when there is high competition for resources and therefore an organisms has their own space that they inhabit. For example, lions are very territorial and hunt for the resources available in their space. Some plants may have uniform distribution because their roots excrete poison in order to compete for land.

Clumped distribution

Found when species live better in proximity or when certain resources are found in certain areas. For example, desert plants may have clumped distribution around sources of water. Another example, wolves hunt in packs. For organisms that need mates to reproduce having clumped distribution makes it easier to find mates. Humans, for example, have social cohesion which is a reason for clumped distribution.

Density Dependent Factors

Factors that are affected by the density of a population

They include:

• Competition (for food, water, and mates)

• Size of habitat

• Food and resources

• Outbreaks (this is why meat like chickens are given antibiotics—they are closely packed)

• Predation (more density, better predation outcomes, for example lions wait to see large groups of animals to prey instead of attacking individual organisms for better success)

Density independent factors

Factors that affect organisms regardless of population

They include

• weather events (droughts, earthquakes, volcanoes, tornadoes, hurricanes)

• pollution (climate change, water pollution [oil spills, fertilizer runoff, hazardous waste] any factor that causes an unwanted health effect)

Population growth formula

(birth rate-death rate)+(immigration rate-emigration rate)