Lecture 24/25

Individual

A single organism, such as one deer.

Population

A group of the same species living in one area, such as a herd of deer.

Community

All species in one area interacting, for example, deer, wolves, and trees in a forest.

Ecosystem

A community plus its non-living environment, such as a forest with soil, water, and animals.

Population characteristics

Size, density, distribution, and growth rate can be studied about a population.

r-selected species

Species with high reproduction rates, short lifespans, and rapid growth, like insects.

k-selected species

Species with low reproduction rates, long lifespans, and stable populations, such as elephants.

Population growth equation

ΔN/Δt = rN, where ΔN is the population change, r is the growth rate, and N is the population size.

Carrying capacity (K)

The maximum population that the environment can support, determined by available resources.

Density-dependent environmental resistance

Factors that worsen with population size, such as food shortages and disease.

Density-independent environmental resistance

Factors that affect populations regardless of size, like natural disasters and weather.

Exponential growth model

A growth model characterized by rapid growth, represented by a J-shaped curve.

Logistic growth model

A growth model where growth slows as it approaches carrying capacity, represented by an S-shaped curve.

Mutualism

A type of interspecific interaction where both species benefit, e.g., bees and flowers.

Competition (interspecific)

An interaction where both species are harmed, such as two species competing for food.

Predation

An interaction involving one species benefiting and another being harmed, e.g., a lion and zebra.

Parasitism

An interaction where one species benefits at the expense of another, e.g., a tick on a dog.

Commensalism

An interaction where one species benefits and the other is unaffected, e.g., a bird nesting in a tree.

Competitive exclusion

When one species outcompetes another, driving it out of the area.

Resource partitioning

When species divide resources to reduce competition among them.

Coevolution

A process where species evolve in response to each other, such as flowers evolving for specific pollinators.

Biogeochemical cycle

The movement of elements like water, carbon, and nitrogen through living and non-living parts of ecosystems.

Impact of human industry on the carbon cycle

Human activities add CO2 through burning fossil fuels, increasing atmospheric carbon.

Rising atmospheric carbon levels impacts

Results in climate change, ocean acidification, and habitat loss.

Reducing carbon emissions

Can be achieved by planting trees, reducing fossil fuel use, and using renewable energy.

Nitrogen absorption by plants

Plants absorb nitrogen from soil as nitrates.

How animals get nitrogen

Animals obtain nitrogen by eating plants or other animals.

Nitrogen-fixing organisms

Bacteria that convert atmospheric nitrogen into usable forms, found in soil or plant roots.