Synergies among extinction drivers

24 08 2008

Hopefully one for the Potential list:

© J. Hance

Brook, BW, NS Sodhi, CJA Bradshaw. (2008) Synergies among extinction drivers under global change. Trends in Ecology and Evolution 23, 453-460

A review my colleagues, Barry Brook and Navjot Sodhi, and I have just published in Trends in Ecology and Evolution demonstrates how separate drivers of extinction (e.g., habitat loss, over-exploitation [hunting, fishing, etc.], climate change, invasive species, etc.) tend to work together to heighten the extinction probability of the species they affect more than the simple sum of the individual effects alone.

In what we termed ‘synergies’, the review compiles evidence from observational, experimental and meta-analytic research demonstrating the positive and self-reinforcing actions of multiple drivers of population decline and eventual extinction. Examples include experimental evidence that wild radishes experiencing inbreeding depression have lower fitness than expected from simple population reduction (Elam et al. 2007), inter-tidal polychaetes succumb to pollution effects much more so at low densities than when populations are abundant (Hollows et al. 2007), and habitat fragmentation, harvest and simulated climate warming increase rotifer extinction risk up to 50 times more than expected from the additive effects of the threatening processes (Mora et al. 2007).

We argued that conservation actions only targeting single drivers will more than likely be inadequate because of the cascading effects caused by unmanaged synergies. Climate change will also interact with and accelerate ongoing threats to biodiversity, so the importance of accounting for these interactions cannot be understated.

CJA Bradshaw

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14 responses

1 08 2015
All (fisheries) models are wrong, but some are useful (to indigenous people) |

[…] probably exacerbates the effects of fisheries, which highlights that you still have to examine the combination of these effects. And that is exactly what an excellent team of modellers […]

24 07 2015
Ice Age? No. Abrupt warmings and hunting together polished off Holarctic megafauna |

[…] subsequent warming would be bad for wildlife, but now we have definitive, empirical proof that the synergy of human over-hunting and global warming can lead to catastrophic extinction events. We told you […]

26 06 2015
The extinction vortex |

[…] First coined by Gilpin & Soulé in 1986, the extinction vortex is the term used to describe the process that declining populations undergo when”a mutual reinforcement occurs among biotic and abiotic processes that drives population size downward to extinction” (Brook, Sodhi & Bradshaw 2008). […]

13 09 2013
Conservation: So easy a child could do it |

[…] Of course, she didn’t use that nomenclature, but the concepts came through loud and clear nonetheless. As a contextual prologue, she has been fascinated with extinction for the last six months. She wants to know about every animal or plant that went extinct since the Ediacaran, what caused them to go extinct, and how important they were in the grand ecosystem scheme of things. Yes, this is obviously of prime interest to me, hence the subject at hand, but I’m amazed at how obsessed she is with the topic. When it comes to everything from the Late Pleistocene onward, the cause almost always comes down to humans, whether directly by exploitation, or indirectly through habitat loss or invasive species (or all of the above). […]

11 12 2012
The biggest go first «

[…] of the forest, we’ll lose countless other species. This is just another sad chapter in the synergistic loss of life on […]

5 07 2012
Ghost extinctions «

[…] loss/fragmentation, overkill, introduced species and extinction chains [with climate change and extinction synergies (2), the updated expression would be ‘evil sextet”]. However, one third of ‘extinct’ mammal […]

9 05 2012
No more ecology «

[…] the complexities of ecosystem services. And let’s not forget our infancy in understanding the synergies of extinctions in the past and projections into the future. Multiply this uncertainty by several orders of […]

5 04 2012
Tentacles of destruction «

[…] exactly. With our work on extinction synergies, I eventually came to realise that roads are some of the first portals to the devastation to come. […]

11 01 2012
When did it go extinct? «

[…] of the historical record general supports the conclusion that most extinctions arise from a perverse synergy of drivers which increase kill rates beyond the mere sum of their individual effect…. Thus, why human overkill and a series of large climate shifts could not have ‘worked’ […]

18 05 2011
The evil sextet «

[…] it’s time though to add a sixth rider – extinction synergies (Brook et al. 2008). For example, exacerbating the problems associated with recent climate change […]

19 08 2010
Climate change basics III – environmental impacts and tipping points « BraveNewClimate

[…] Compounding the issue of the rate of recent climate change, is that plant and animal species trying to move to keep pace with the warming must now contend with landscapes dominated by farms, roads, towns and cities. Species will gradually lose suitable living space, as rising temperatures force them to retreat towards the away from the relative safety of existing reserves, national parks and remnant habitat, in search of suitable climatic conditions. The new conditions may also facilitate invasions by non-indigenous or alien species, who will act to further stress resident species, as novel competitors or predators. Naturally mobile species, such as flying insects, plants with wind-dispersed seeds, or wide-ranging birds, may be able to continue to adjust their geographical ranges, and so flee to distant refugia. Many others will not. […]

4 01 2010
The biodiversity extinction numbers game «

[…] that it’s all probably worse than we currently predict because of extinction synergies (see previous post about this concept) and the mounting impact of rapid global climate change. If anything, the “100 […]

4 12 2009
Scoping the future threats and solutions to biodiversity conservation «

[…] the ‘evil quintet’ that includes climate change, and I would even go so far as to add extinction synergies as a the sixth member of the ‘evil […]

9 01 2009
Measuring the amphibian meltdown «

[…] in the short term, such interventions cannot substitute for habitat protection and restoration. The synergies between ecological/life history traits and environmental conditions demonstrate how management must address each of the major drivers of decline together for any […]

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