Tue, Aug 16, 2022: 8:30 AM-8:45 AM
514A
Background/Question/MethodsWorm and Paine (TREE 2016) proposed that humans are hyperkeystone species - agents that commonly impact other keystone species and thus ecological communities. Here, we test one major element of the hyperkeystone hypothesis: that humans impose community changes via their influence on keystone species not only via direct consumptive effects but also via non-consumptive processes like widespread and significant changes to atmospheric, terrestrial, and aquatic systems. To comprehensively address this hypothesis, we first conducted a systematic literature search to create an evidence-informed list of keystone species. We then quantified various community responses (e.g. changes in geochemical cycling rates, biodiversity, and landscape cover, etc) to human-caused declines or removals of keystone species using a log risk ratio to standardize the magnitude of diverse community responses.
Results/ConclusionsWe found evidence for 128 keystones, which occurred on every continent except Antarctica and in every major biome. Although ranging from 2 to 190,000 kilograms, median body mass was modest (3,278 g). Many keystone species (n = 22; 16%) are rodents, most of which (n = 21; 95%) act as key bioturbators in their communities. Fewer known keystones (n = 13, 10%) are carnivores – an Order commonly associated with keystone processes. We also found that keystone reductions or extirpations resulting from non-consumptive effects (which were common, occurring in 40 of 128 contexts) produced a similar magnitude of community response (x = 0.74, n = 40, 95% CI [0.43, 1.05]) as consumptive effects (x = 1.19, n = 28, 95% CI [0.71, 1.67]). Collectively, these patterns showing the prominence of small-bodied and lower-trophic level taxa suggest a reconsideration of what species and processes are involved in keystone interactions, as well as highlight the myriad ways in which humans impact ecological communities via their influence on keystone species.
Results/ConclusionsWe found evidence for 128 keystones, which occurred on every continent except Antarctica and in every major biome. Although ranging from 2 to 190,000 kilograms, median body mass was modest (3,278 g). Many keystone species (n = 22; 16%) are rodents, most of which (n = 21; 95%) act as key bioturbators in their communities. Fewer known keystones (n = 13, 10%) are carnivores – an Order commonly associated with keystone processes. We also found that keystone reductions or extirpations resulting from non-consumptive effects (which were common, occurring in 40 of 128 contexts) produced a similar magnitude of community response (x = 0.74, n = 40, 95% CI [0.43, 1.05]) as consumptive effects (x = 1.19, n = 28, 95% CI [0.71, 1.67]). Collectively, these patterns showing the prominence of small-bodied and lower-trophic level taxa suggest a reconsideration of what species and processes are involved in keystone interactions, as well as highlight the myriad ways in which humans impact ecological communities via their influence on keystone species.