Threats to Biodiversity : Key Area 8

    Cards (13)

    • Exploitation and recovery of populations
      The impact on their genetic diversity
    • With overexploitation, populations can be reduced to a low level but may still recover
    • Some species have a naturally low genetic diversity in their population and yet remain viable
    • Bottleneck effect
      • Small populations may lose the genetic variation necessary to enable evolutionary responses to environmental change
      • In small populations, this loss of genetic diversity can be critical for many species, as inbreeding can result in poor reproductive rates
    • Habitat loss and habitat fragments
      Impact on species richness
    • The clearing of habitats has led to habitat fragmentation
    • Degradation of the edges of habitat fragments results in increased competition between species as the fragment becomes smaller, which may result in a decrease in biodiversity
    • To remedy widespread habitat fragmentation
      1. Isolated fragments can be linked with habitat corridors
      2. The corridors allow movement of animals between fragments, increasing access to food and choice of mate
      3. This may lead to recolonisation of small fragments after local extinctions
    • More isolated fragments and smaller fragments exhibit a lower species diversity
    • Introduced, naturalised and invasive species

      Impact on native populations
    • Introduced (non-native) species

      • Humans have moved them either intentionally or accidentally to new geographic locations
    • Naturalised species

      • Introduced species that become established within wild communities
    • Invasive species
      • Naturalised species that spread rapidly and eliminate native species, therefore reducing species diversity
      • They may be free of the predators, parasites, pathogens and competitors that limit their population in their native habitat
      • They may prey on native species, out-compete them for resources or hybridise with them
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