3.3 Threats to Biodiversity

Significant Ideas

• While global biodiversity is difficult to quantify, it is decreasing rapidly due to human activity. Classification of species conservation status can provide a useful tool in the conservation of biodiversity.

Knowledge and Understanding

1. Estimates of the total number of species on Earth vary considerably. They are based on mathematical models, which are influenced by classification issues and a lack of finance for scientific research, resulting in many habitats and groups being significantly under-recorded.

2. The current rates of species loss are far greater now than in the recent past, due to increased human influence. The human activities that cause species extinctions include habitat destruction, introduction of invasive species, pollution, over-harvesting and hunting. Image by http://www.biologicaldiversity.org

Textbook Reading and/or Activities

• Pages XY-YZ

  • Exercises (p.)

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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

Population Growth Calculations

This activity, modified from an unknown online source, will help you practice calculating cbr, cdr, NIR, population growth and doubling time (KU1 and AS1-AS2).

Constructing Population Pyramids (Numbers) or (Excel)

This activity, modified from mrmasters.net, will help you learn how to produce a population pyramid using your computers.

Interpreting Population Pyramids

This activity will provide you with an opportunity to examine and interpret different types of population pyramids using real-world data.

Supplemental Reading

1. The International Union of Conservation of Nature (IUCN) publishes data in the “Red List of Threatened Species” in several categories. Factors used to determine the conservation status of a species include: population size, degree of specialization, distribution, reproductive potential and behaviour, geographic range and degree of fragmentation, quality of habitat, trophic level, and the probability of extinction.

2. Tropical biomes contain some of the most globally biodiverse areas and their unsustainable exploitation results in massive losses in biodiversity and their ability to perform globally important ecological services.

3. Most tropical biomes occur in less economically developed countries (LEDCs) and therefore there is conflict between exploitation, sustainable development and conservation.

Applications and Skills

1. Discuss the case histories of three different species: one that has become extinct due to human activity, another that is critically endangered, and a third species whose conservation status has been improved by intervention.

2. Describe the threats to biodiversity from human activity in a given natural area of biological significance or conservation area.

3. Evaluate the impact of human activity on the biodiversity of tropical biomes.

4. Discuss the conflict between exploitation, sustainable development and conservation in tropical biomes.

Guidance

1. The total number of classified species is a small fraction of the estimated total of species, and it continues to rise. Estimates of extinction rates as a consequence are also varied, but current extinction rates are thought to be between 100 and 10,000 times greater than background rates.

2. Case studies of three species should be carried out. In each case, the ecological, sociopolitical or economic pressures that are impacting on the species should be explored. The species’ ecological roles and the possible consequences of their disappearance should be considered.

Key Vocabulary

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