Synergies among extinction drivers under global change

Brook, B. W., Sodhi, N. S., & Bradshaw, C. J. (2008). Synergies among extinction drivers under global change. Trends in ecology & evolution, 23(8), 453-460. PDF.

Summary

Modern extinction rates greatly surpass those of the past. As such, in recent decades, substantial research effort has been dedicated to understanding the patterns and processes responsible for widespread mass extinctions. In spite of these efforts, generalizations of extinctions remain largely unknown. Brook et al. (2008) fills this gap in knowledge by conducting a systematic review of all observational, experimental, meta-analytical work conducted on extinctions from 1988 to 2008. They note that the literature has shifted from single-factor causes of extinction (e.g., habitat destruction, fragmentation, overexploitation, climate change and invasives) to synergies amongst these factors that accelerate extinction. With respect to climate change and invasive species, the authors anticipate increased extinction rates due to the creation of unoccupied niches (via novel environments or species losses), which may be easily exploited by (typically generalist) invasive species. Habitat degradation may also compound extinction rates by creating more edge habitat thereby increasing invasibility further. To minimize species losses in the future, management and policy decisions should incorporate measures that address these synergies causing accelerated extinction. 

Take home points

  • A systematic review of the literature (1998-2008) of extinction patterns and processes indicates that research has shifted from single-factor causes (e.g., climate change, invasive species, fragmentation) to synergies between these factors that accelerate extinction.

  • Climate change is anticipated to increase empty niches (by creating novel environments or via species losses) and fragmentation will increase edge habitat. Together, these factors will increase invasibility of affected ecosystems. 

  • Management plans and policies that acknowledge synergies between these factors will reduce future extinctions.

Management implications

  • Long-term monitoring (e.g., species inventories) will allow managers to detect species losses which may increase invasibility via the creation of empty niches. Additionally, long-term monitoring will facilitate the early detection and rapid response of invasive species.

  • Identify habitats prone to disturbance (natural or human-caused). Disturbed areas are more prone to establishment by (typically generalist) invasive species.

Keywords

Impact Study; Meta-analysis