2.1 Species & Populations

Significant Ideas

• A species interacts with its abiotic and biotic environments; its niche is described by these interactions.

• Populations change and respond to interactions with the environment.

• A system has a carrying capacity for a given species.

Knowledge and Understanding

1. A species is a group of organisms that share common characteristics and that interbreed to produce fertile offspring.

2. A habitat is the environment in which a species normally lives.

3. A niche describes the particular set of abiotic and biotic conditions and resources to which an organism or population responds.

4. The fundamental niche describes the full range of conditions and resources in which a species could survive and reproduce. The realized niche describes the actual conditions and resources in which a species exists due to biotic interactions.

5. The non-living, physical factors that influence the organisms and ecosystem - such as temperature, sunlight, pH, salinity and precipitation - are termed abiotic factors.

6. The interactions between the organisms - such as predation, herbivory, parasitism, mutualism, disease and competition - are termed biotic factors.

7. Interactions should understood in terms of the influences each species has on the population dynamics of others and upon the carrying capacity of the others' environment.

8. A population is a group of organisms of the same species living in the same area at the same time and which are capable of interbreeding.

9. S and J population curves describe a generalized response of populations to a particular set of conditions (abiotic and biotic factors).

10. Limiting factors will slow population growth as it approaches the carrying capacity of the system.

Applications and Skills

1. Interpret graphical representation or models of factors that affect an organism's niche. Examples include predatory-prey relationship, competition and organism abundance over time.

2. Explain population growth curves in terms of numbers and rates.

Guidance

1. Students should address valid named species, for example, use "Atlantic salmon" rather than "fish", "Kentucky bluegrass" rather than "grass" and "silver birch" rather than "tree".

2. It is useful to be aware that for some organisms, habitats can change over time as a result of migration.

Key Vocabulary

• Species

• Habitat

• Niche

  • Fundamental

  • Realized

• Biotic

  • Predation

  • Herbivory

  • Parasitism

  • Mutualism

  • Disease

  • Competition

• Abiotic

  • Temperature

  • Sunlight

  • pH

  • Salinity

  • Precipitation

• Population

• Growth curve

  • S

  • J

• Carrying capacity

  • Limiting factor

• Migration

Textbook Reading and/or Activities

• Pages 56-63

  • To think about (p.58)

  • To do (p.62)

Notes

i-Biology Notes (Not available)

A detailed set of notes, created by Stephen Taylor, examining U1 - U8 and A1 - A4.

i-Biology Study Questions (Not available)

A series of questions, created by Stephen Taylor, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Bioknowledgy Notes (Not available)

A detailed set of notes, created by Chris Paine, examining all of the IB learning expectations.

Bioknowledgy Study Questions (Not available)

A series of questions, created by Chris Paine, to help check your understanding of the IB learning expectations. This is VERY GOOD practice.

Learning Activities

Case Study: Reintroduction of Wolves to Yellowstone

Watch THIS VIDEO, by Sustainable Human (4:33), to acquire some background knowledge and then complete THIS ACTIVITY, prepared by the National Center for Case Study Teaching in Science.

Population Biology - Virtual Lab

This activity, prepared by McGraw-Hill, will help you better understand how populations grow based on competition and limiting factors (K&U9-10 and A&S2).

Interpreting Graphs - Population Interactions and Changes

This activity will challenge you to consider the connections between populations and their environment, while improving your skills for interpreting data in graphical form (A&S1).

Supplemental Reading