3.8 Criteria Flashcards
Define exploitation:
and give two examples of exploited resources.
The harvesting of a natural resource e.g. trees for timber or fish.
Define overexploitation:
Harvesting a resource at a greater rate than it can be replaced.
Overexploitated populations may what after being reduced to a low level.
Recover
Some species have a naturally low genetic diversity in their population but remain what?
Viable
Define a population bottleneck:
When a population reduces sharply in number to leave a small population with low genetic diversity.
After a bottleneck a population may not have sufficient genetic variation to enable what?
Evolutionary responses to environmental change.
A population bottleneck can result in what?
Inbreeding and poor reproductive rates.
Define habitat fragmentation: and give examples of what can cause this.
The habitat being divided into unconnected fragments due to road building, agriculture or urbanisation.
Degradation of the edges of habitat fragments results in what?
Increased competition between species as the fragments become smaller
Habitat fragmentation may result in a what?
An increase in in those species adapted to habitat edges, and a decrease in those adapted to the habitat interior
Habitat fragmentation results in a decrease in what?
Biodiversity
Smaller habitat fragments show what?
Low biodiversity
Habitat fragments can be linked with what?
Habitat corridors
Habitat corridors allow movement of animals between fragments increasing what?
Their access to food and choice of a mate.
Habitat corridors may lead to what?
Recolonization of small fragments after local extinctions
Define introduced (non-native) species:
Those that humans have moved either intentionally or accidentally to new geographic locations.
Introduced species that have become established within wild communities are described as what?
Naturalised
Naturalised species that spread rapidly and eliminate native species diversity are described as what?
Invasive
Invasive species may be successful and show few limits on their populations due to: (4)
- lack of predators
- lack of parasites
- lack of pathogens
- lack of competitors
Invasive species may prey on native species. Give an example.
Hedgehogs being intentionally released in the Western Isles preying on eggs of wading birds.
Invasive species may out-compete native species for resources. Give an example.
Grey squirrels eating red squirrels food
Invasive species may hybridise with native species. Give an example.
Domestic cats and Scottish wildcats
