Populations

​The number of organisms in a population

the number of individuals of the same species that live in a given unit of area.

Population Dispersion

Pattern of distribution of organisms in a population.

Immigration

Moving to live permanently in a foreign country.

Emigration

Leaving one's own country to settle permanently in another.

• May also be a small "wave"

• Follows a period of exponential growth; a J-shaped curve where the population keeps increasing

• The line represents population size, so it decreases in response to a limiting factor

• May be a resource, another species, the environment, etc.

• Example: food is a limiting factor because you can't have more individuals than food to feed them

• Include climate, weather, natural disasters, and pollution

• Affect all populations the same, whether they are large or small

• Includes natural resources (food, water, space), diseases, and predators

• Tend to have a greater effect on large, dense populations because of increased competition and more opportunity to attract predators and disease

A keystone species is an organism that helps define an entire ecosystem. 

Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.

The removal of a keystone species REDUCES the BIODIVERSITY of the ecosystem.

The keystone species in this habitat is the sea otter.

The sea otter eat urchins and therefore keep the population of sea urchins low. Sea otters also build dams which create wetlands for other organisms to live in.

Without sea otters, sea urchins over populate and eat all of the kelp. Wetlands are destroyed and biodiversity decreases.

• Invasive species, or a species that causes harm to a new environment. 

• Invasive species have traits that give them a competitive advantage over native species.

• Invasive species can directly (prey on native species) or indirectly (change food webs) impact native species.

• The zebra mussel  was carried to the Great Lakes in the mid-1980s from Eastern Europe in ships. 

• They have become  invasive species whose growth produces huge populations.

• They upset aquatic food webs, filtering so much plankton from the water that some native fishes and shellfish starve.  

• Cane Toads are native to Central and South America.

• Cane Toads were introduced to Australia and other countries to control insects (beetles) that damaged sugar cane plantations.

• The poisonous toads have caused severe damage to local wildlife wherever they were introduced.

The variety of plants and animals and other living things in a particular area or region.

Also means the number, or abundance of different species living within a particular region

• High biodiversity - Many plants and animals in an area.

• Low biodiversity - Low amount of plants and animals in an area​

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​Some text here about the topic of discussion.

Biodiversity

​High - Many variations in DNA between members of the same species

Low - Few variations in DNA between members of the same species​

Genetic Diversity

​High - Many type of different species in the same area

Low - Few types of different species in the same area ​

Species Diversity

High - Many types of habitats for organisms to live

Low - Few types of habitats for organisms to live​

Ecosystem Diversity

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What can genetic diversity protect against?

Genetic Diversity

The more variation in DNA between members in a species, the more protections they have from changes to their environment. ​

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​In this picture, the brown fish and the green fish has the highest genetic diversity. If water oxygen changes, they have the best chance at surviving.

​Different DNA means some organisms have the ability to fight disease better.

Disease

​As environments change, some organisms will be able to adapt to their new environment easier

Climate Change​

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​Different DNA means some organisms will be able to survive their predators better.

Predator Survivability

Before the industrial revolution, most moths were white and speckled black. Only some were black

1848

This white and black speckles gave them camoflauge on trees

​​1848

As the Britshed burned coal, their buildings and trees turned black and so did the moths.

​​1900

Why did the white ones start to disappear?

​​1900

• Biodiversity is essential to supporting and enhancing life on Earth. 

• Humans depend on resources and other benefits provided by diversity. 

• There are economic reasons for preserving biodiversity.

• A healthy biosphere provides many services to humans and other organisms. 

• For example plants provide oxygen and remove carbon dioxide. 

• Healthy ecosystems can also provide protection from floods and drought and regulate local climates.

Indirect Economic Value

Humans depend on plants and animals to provide food, clothing, energy, medicine, and shelter.

Direct Economic Value

• Habitat Loss and Change

• Invasive Species

• Pollution

• Overharvesting

• Climate Change