Predator Diversity and Ecosystem Functioning: Density Modifies the Effect of Resource Partitioning

Griffin, John N.; Haye, Kate L. de la; Hawkins, Stephen J.; Thompson, Richard C.; Jenkins, Stuart R.

doi:10.1890/07-1220.1

Cited by 139 publications

(125 citation statements)

References 55 publications

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“…Here, we provide contrary evidence that diverse protists mixtures substantially reduced bacterial cell numbers ( Supplementary Figure 2). This is further supported by theory (Thebault andLoreau, 2003, 2006), suggesting that increasing generalist predator richness may have a greater effect on prey abundance than increasing specialist predator richness, as well as by field and laboratory studies (Gamfeldt et al, 2005;Byrnes et al, 2006;Griffin et al, 2008) showing that higher consumer or predator biomass because of increasing richness concomitantly resulted in reduced prey biomass.…”

Section: Discussionsupporting

confidence: 56%

Diversity of protists and bacteria determines predation performance and stability

et al. 2013

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Predation influences prey diversity and productivity while it effectuates the flux and reallocation of organic nutrients into biomass at higher trophic levels. However, it is unknown how bacterivorous protists are influenced by the diversity of their bacterial prey. Using 456 microcosms, in which different bacterial mixtures with equal initial cell numbers were exposed to single or multiple predators (Tetrahymena sp., Poterioochromonas sp. and Acanthamoeba sp.), we showed that increasing prey richness enhanced production of single predators. The extent of the response depended, however, on predator identity. Bacterial prey richness had a stabilizing effect on predator performance in that it reduced variability in predator production. Further, prey richness tended to enhance predator evenness in the predation experiment including all three protists predators (multiple predation experiment). However, we also observed a negative relationship between prey richness and predator production in multiple predation experiments. Mathematical analysis of potential ecological mechanisms of positive predator diversity-functioning relationships revealed predator complementarity as a factor responsible for both enhanced predator production and prey reduction. We suggest that the diversity at both trophic levels interactively determines protistan performance and might have implications in microbial ecosystem processes and services.

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Section: Discussionsupporting

confidence: 56%

Diversity of protists and bacteria determines predation performance and stability

et al. 2013

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“…Predator diversity not only stabilized predation, but also elevated its mean strength to a level that could not be matched by either species alone at equal density, implying that extinction of either of these predators would weaken top-down control of Littoraria. Enhancement of predation with predator diversity can result from a range of mechanisms [2], but several lines of evidence suggest that in the present study it resulted from weaker interspecific compared with intraspecific competition-the hallmark of species complementarity [11,12]. First, the strong densitydependent suppression of predation rate that occurred within single-species treatments was not apparent when species were combined (figure 2c).…”

Section: Discussionmentioning

confidence: 58%

Predator diversity stabilizes and strengthens trophic control of a keystone grazer

Griffin

Silliman

2010

Biol. Lett.

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Despite the global vulnerability of predators to extinction, and the critical functional role they play in many ecosystems, there have been few realistic tests of the consequences of predator species deletion (conversely, predator diversity) in natural ecosystems. We performed a four-month field experiment in a southeastern United States salt marsh to test the role of predatory crab diversity in regulating populations of a keystone grazer that can decimate marsh vegetation at high densities. Our results revealed that a combination of this system's two resident predator species, in comparison to individual species, both stabilize and strengthen predation rates on the potent grazer. Monthly monitoring of predation rates from intense, hot summer months into the cooler autumn indicate this diversity benefit arises from predators responding differentially to changing environmental conditions across seasons. This study provides some of the first experimental field support for the insurance hypothesis from marine ecosystems, suggests that predator temporal complementarity may be more common than currently perceived, and argues for conservation of predator diversity to ensure reliable and effective control of potentially habitat-destroying grazers.

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“…Moreover, the relation of consumer diversity and resource exploitation applies to specialized consumers (Finke and Snyder 2008) and high consumer densities (Griffin et al. 2008). In temperate climates, postdispersal seed predation by invertebrates is less dependent on specialized consumers and generally driven by a diverse consumer community (Lundgren et al.…”

Section: Discussionmentioning

confidence: 99%

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

Dudenhöffer

Pufal

Roscher

et al. 2016

Ecology and Evolution

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Janzen–Connell effects are negative effects on the survival of a plant's progeny at high conspecific densities or close to its conspecifics. Although the role of Janzen–Connell effects on the maintenance of plant diversity was frequently studied, only few studies targeted Janzen–Connell effects via postdispersal seed predation in temperate grassland systems. We examined effects of conspecific density (abundance of conspecific adult plants) on postdispersal seed predation by invertebrates of three grassland species (Centaurea jacea, Geranium pratense, and Knautia arvensis) in experimental plant communities. Additionally, we examined the impact of plant species richness and different seed predator communities on total and relative seed predation (= seed predation of one plant species relative to others). We offered seeds in an exclusion experiment, where treatments allowed access for (1) arthropods and slugs, (2) arthropods only, (3) small arthropods only, and (4) slugs only. Treatments were placed in plots covering a gradient of abundance of conspecific adults at different levels of plant species richness (1, 2, 3, 4, 8 species). Two of the plant species (C. jacea and K. arvensis) experienced higher rates of seed predation and relative predation with increasing abundance of conspecific adults. For C. jacea, this effect was mitigated with increasing plant species richness. Differences in seed predator communities shifted seed predation between the plant species and changed the magnitude of seed predation of one plant species relative to the others. We exemplify density‐dependent increase in seed predation via invertebrates in grassland communities shaping both the total magnitude of species‐specific seed predation and seed predation of one species relative to others. Further differences in seed predator groups shift the magnitude of seed predation between different plant species. This highlights the importance of invertebrate seed predation to structure grasslands via density‐dependent effects and differing preferences of consumer groups.

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Predator Diversity and Ecosystem Functioning: Density Modifies the Effect of Resource Partitioning

Cited by 139 publications

References 55 publications

Diversity of protists and bacteria determines predation performance and stability

Diversity of protists and bacteria determines predation performance and stability

Predator diversity stabilizes and strengthens trophic control of a keystone grazer

Plant density can increase invertebrate postdispersal seed predation in an experimental grassland community

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