Conservation - extinction and biodiversity

define extinction

When a species dies out

how do humans contribute to climate change

burning fossil fuels releases high levels of CO₂ into the atmosphere causing global warming

how can climate change reduce biodiversity

• global warming is melting polar ice caps - leads to extinction of species living in polar regions, changes migration patterns of Arctic animals

• Rising sea levels flood low lying land - reduces terrestrial habitats, salt water could reduce fresh water habitats in rivers

• High temperatures and less rainfall - reduction in plant species, Xerophytes becoming more dominant, impact on food chains

• Insect life cycles changed - key pollinators of many plants, could lead to the extinction of some plants, greater spread of tropical diseases

when does competition arise

• when resources are not present in adequate amounts

• To satisfy needs of all individuals who depend on them eg due to habitat destruction or introduction of invasive species

Describe what happens to birth and death rates as competition increases

• Rate of reproduction decreases - fewer organisms have enough resources to reproduce

• Death rate increases - fewer organisms have enough resources to survive

What are the possible effects of interspecific competition

• different species seek to occupy similar niche

• Reduction in resources available to competing populations

• If species are equally adapted, reproduction rate decreases in all species and population sizes decrease.

• If one species is better adapted, less well adapted species outcompeted, numbers decline, potentially to extinction levels

How can agriculture reduce biodiversity

• removal of hedgerows destroys habitats and reduces prey for birds

• Monocultures reduce species diversity and habitats

• Pesticides and herbicides reduces species diversity

How can excessive use of inorganic fertilisers cause a reduction in biodiversity

• promotes growth of few plant species so other plant species outcompeted

• Disruption of food chains

• Reduction in soil quality over time so plants cannot grow

Why does a reduction in biodiversity present problems for agriculture in the future

• loss of genetic diversity in wild population

• Environmental requirements may change in the future

• Lost alleles may have been useful to withstand change

Define keystone species

Species that are essential for maintaining diversity. Has disproportionally large effect on their environment relative to their abundance.

Explain why keystone species are often predators

Predators keep populations of prey at a consistent level and allows for balanced coexistence of other species.

Why is it important to maintain biodiversity

• maintains complex, stable food chains

• Maintains variety of habitats for other organisms

• Ensures keystone species are not removed - avoids drastically changing habitat

• Humans have duty to care for other species

• Aesthetic reasons (eg natural beauty provides inspiration and relaxation)

• Economic reasons (eg tourism, preventing reduction in soil depletion)

• Provides natural resources

• Maintains genetic resource for cross-breeding and production of new crops

What is an invasive species

Species that has moved into an ecosystem where it was previously unknown with potential to cause harm to economy, environment or human health

• Eg lion fish in Caribbean, cane toads in Australia

How can invasive species be introduced to an ecosystem

• naturally by species migration or due to own habitat destruction

• Knowingly introduced as biological control for pests

• Unknowingly introduced via transport methods (eg on ships)

Why do invasive species alien species need to be controlled

• they have no natural predators or competitors so numbers increase rapidly and they’re able to outcompete native species in similar niches.

• Can be successful predators causing rapid decline in prey species

• Introduce new disease to an ecosystem

• Reduce biodiversity