key concept 58.2 Most Biodiversity Loss Is Caused by Habitat Loss and Degradation

Global Biodiversity Outlook 4, a report published by the United Nations in 2014, identified four principal pressures on biodiversity: (1) habitat loss and degradation, (2) overharvesting of biological resources, (3) species invasions and emerging diseases, and (4) climate change. Here we consider each of these pressures separately while keeping in mind that the threats to biodiversity are often not mutually exclusive.

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  • Human-caused habitat loss and degradation are the major causes of biodiversity loss.

  • Overharvesting of single species for resources has been and still is an important cause of extinction or species decline.

  • Introduction of non-native species has increased exponentially in the last 200 years, and some introduced species become invasive, usually with negative consequences.

  • Climate change is affecting species through changes in distribution, timing of life history events, and decreased growth and reproduction.