3.8 Threats to Biodiversity

• What is overexploitation?

  Where a population is used and numbers reduce quicker than the reproduction rate
• what is the bottleneck effect?

  the dramatic reduction in population numbers which can lead to a decrease in gene diversity
• what can a loss in genetic diversity lead to?

  the population being unable to adapt to environmental changes - cause an inbreeding depression
• what is habitat fragmentation?

  The breaking up of a large habitat into smaller sections
• what is the cause of habitat fragmentation?

  the clearing of habitats for human use.
• what effect does degradation have on the edges of the edges of habitat fragments?

  Increased competition between species as the fragment becomes smaller resulting in a decrease in biodiversity
• what can be seen in isolated fragments and smaller fragments?

  a lower species diversity
• what do habitat corridors allow?

  movement of animals between fragments, increasing the access to food and choice of mate
• what are introduced (non-native) species?

  species that humans have moved intentionally or accidentally to new geographic locations
• what are naturalised species?

  non-native species that become established within wild communities
• what are invasive species?

  naturalised species that spread rapidly and eliminate native species, therefore reducing species diversity
• What is the reason for rapid spread of invasive species?

  Lack of Natural Predators
• what is the effect of invasive species on native species?

  they out-compete them for resources or hybridise with them