3.8 - Threats to Biodiversity Flashcards
Exploitation
To take a natural resource and make the best use of it
Overexploitation
The removal and using of resources at a rate that exceeds the species’ maximum rate of reproduction.
Effect of Exploitation
Some species should ony be exploited to a point where the population is able to recover and remain genetically diverse. With overexploitation, populations can be reduced to a low level but might still recover.
Bottleneck Effect
Natural disasters e.g earthquake or fire
A large population is reduced after a bottleneck event. The small population may lose the genetic variation necessary to enable evolutionary responses to changes in their environment.
Reduciing genetic diversity results in a population that is so genetically similar that reproduction among members is equal to inbreeding.
Effect of the Bottleneck Effect
(nbreeding)
Reducing genetic diversity results in a population that is so genetically similar that reproduction among members is equal to inbreeding.
Inbredding results in poorer reproduction rates which means that populations could either become extinct or slowly recover.
Some species have a naturally low level of genetic diversity among members but are still genetically viable e.g. northern elephant seal
Habitat Fragmentation
Formation of several habitat fragment with a smaller surface area than the original habitat.
Degradation of the edges of fragments leads to further reduction in habitat size.
Issues with Habitat Fragmentation
- Lower genetic diversity (species more likely to go extinct)
- Less resources (e.g food)
- Lower species richness
Edge Degradation
Degradation of habitat fragments forms an interior habitat that is similar to the original habitat and an edge habitat that is less diverse and lower in resources.
Species adapted to the fragment edge (edge species) thrive in the edge habitat.
However, if edge species invade the interior habitat there is a loss of biodiversity as species that are adapted to the interior habitat are outcompeted.
Habitat Corridors
Habitat corridors (areas of natural habitat) link habitats together which allows species to feed, reproduce and colonise new fragments after local extinctions.
Introduced (non-native) Species
Species that humans have moved intentionally or accidently to new locations
Naturalised Species
Intrdouced species that establish themselves within wild communities.
Invasive Species
Naturalised species that spread rapidly and eliminate native species.
Invasive species may prey on or outcompete with native species for resources (e.g. nutrients) or hybridise with native species.
Why are Invasive Species Successful?
Invasive species are successful because they are free from their natural predators, parasites, pathogens, and competitors that would limit their population in their natural habitat.
