H Biology - Unit 3 - KA8 - Threats to Biodiversity

What does overexploitation of a species reduce?

Overexploitation of a species reduces genetic diversity

What can some species do when their genetic diversity is reduced?

Some species can recover from reduced genetic diversity

What do species that recover from reduced genetic diversity have?

Species that recover from reduced genetic diversity have naturally low genetic diversity but are still viable

What does the bottleneck effect do?

The bottleneck effect;

• Creates a small population

• Decreases genetic diversity

• Can cause inbreeding, leading to poor reproductive rates

What is an example of a species that went through a bottleneck effect?

An example of a species that went through a bottleneck effect is the Black Robin (Petroica traversi). All individuals alive today are descended from one pair, Old Blue and Old Yellow.

What is habitat fragmentation?

Habitat fragmentation is when habitats are broken into smaller parts, separating populations

What happens as fragments become smaller?

As fragments become smaller, the competition between species increases. This can decrease biodiversity.

What is lower in smaller and more isolated fragments?

The smaller and more isolated a fragment is, the lower it’s species diversity

What can habitat corridors be used to do?

Habitat corridors can be used to link isolated fragments

What do habitat corridors do?

Habitat corridors;

• Mean animals can move between fragments to access food and mates

• Allow species to recolonise a fragment after local extinction. This means they repopulate an area where there weren’t any of the species

What are introduced species?

Introduced species are non-native species that humans have moved intentionally or unintentionally to a new geographical location.

What is a naturalised species?

A naturalised species is a species which has been established in the wild

What is an invasive species?

An invasive species is a naturalised species that has spread rapidly and is eliminating native species, reducing species diversity.

Invasive species succeed in a new habitat free from what?

Invasive species succeed in a new habitat free from;

• Predators (do not say for plants)

• Parasites

• Pathogens

• Competitors

How do invasive species reduce species diversity?

Invasive species reduce species diversity by;

• Outcompeting native species

• Hybridising with native species