Nematode grazing promotes bacterial community dynamics in soil at the aggregate level

The ISME Journal, Journal Year: 2017, Volume and Issue: 11(12), P. 2705 - 2717

Published: July 25, 2017

Abstract Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of effects remains largely rudimentary, particularly natural environment settings. Here, we investigated complex microbial–microfaunal interactions rhizosphere maize grown red soils, which were derived from four long-term fertilization regimes. Root-free soil samples separated into three aggregate fractions whereby abundance examined for nematode total communities. A functional group alkaline phosphomonoesterase (ALP) producing bacteria was included to test hypothesis that grazing may significantly affect specific bacteria-mediated ecological functions, is, organic phosphate cycling soil. Results correlation analysis, structural equation modeling interaction networks combined with laboratory microcosm experiments consistently indicated bacterivorous nematodes enhanced diversity, bacterivores positively correlated biomass, including ALP-producing abundance. Significantly, such more pronounced large macroaggregates than microaggregates. There a positive between most dominant Protorhabditis keystone ‘species’ Mesorhizobium. Taken together, these findings implicate stimulating dynamics spatially dependent manner.

Language: Английский

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Apparent Competition

Annual Review of Ecology Evolution and Systematics, Journal Year: 2017, Volume and Issue: 48(1), P. 447 - 471

Published: Nov. 2, 2017

Most species have one or more natural enemies, e.g., predators, parasites, pathogens, and herbivores, among others. These in turn typically attack multiple victim species. This leads to the possibility of indirect interactions those victims, both positive negative. The term apparent competition commonly denotes negative between that arise because they share a enemy. interaction, which principle can be reflected many facets distribution abundance individual broadly govern structure ecological communities time space, pervades ecosystems. It also is central theme applied problems, including control agricultural pests, harvesting, conservation endangered species, dynamics emerging diseases. At end scale life, characterizes intriguing aspects within organisms—for example, immune system akin ways predator induce different pathogens. intermediate scales biological organization, existence strength depend upon contingent details behavior life history, as well community spatial context play out. broadest macroecology macroevolution, may major, if poorly understood, role evolution species’ geographical ranges adaptive radiations.

Language: Английский

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Fear of the dark or dinner by moonlight? Reduced temporal partitioning among Africa's large carnivores

Ecology, Journal Year: 2012, Volume and Issue: 93(12), P. 2590 - 2599

Published: June 7, 2012

Africa is home to the last intact guild of large carnivores and thus provides only opportunity investigate mechanisms coexistence among predator species. Strong asymmetric dominance hierarchies typically characterize guilds carnivores; but despite this asymmetry, subdominant species may persist alongside their stronger counterparts through temporal partitioning habitat resources. In African guild, wild dogs cheetahs are routinely described as diurnal crepuscular. These activity patterns have been interpreted result from need avoid encounters with stronger, nocturnal spotted hyenas lions. However, idea that diel carnivore strongly shaped by competition predation has recently challenged new observations. a three-year study in Okavango Delta, we investigated daily for dogs, cheetahs, lions fitting radio collars continuously recorded bursts, total 25 individuals. Analysis throughout 24-h cycle revealed an unexpectedly high degree overlap four This was mainly due extensive previously undescribed cheetahs. Their fluctuated lunar cycle, represented up 40% budget primarily constrained moonlight availability. contrast, were unaffected remained constant over cycle. Our results suggest other ecological factors such optimal hunting conditions subdominant, predators. We they "starvation driven" must exploit every obtain meal. The benefits on moonlit nights therefore offset risks encountering night-active predators competitors.

Language: Английский

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Toward a trophic theory of species diversity

Proceedings of the National Academy of Sciences, Journal Year: 2015, Volume and Issue: 112(37), P. 11415 - 11422

Published: Sept. 15, 2015

Efforts to understand the ecological regulation of species diversity via bottom-up approaches have failed yield a consensus theory. Theories based on alternative top-down fared better. Paine’s discovery keystone predation demonstrated that forcing could be simple, strong, and direct, yet ecologists persistently perceive generality in result. Removing top predators destabilizes many systems drives transitions radically distinct states. These typically involve community reorganization loss diversity, implying is crucial maintenance. Contrary expectations theories, terrestrial herbivores mesopredators are capable sustained order-of-magnitude population increases following release from predation, negating assumption populations primary consumers resource limited at or near carrying capacity. Predation sensu lato (to include Janzen–Connell mortality agents) has been shown promote wide range ecosystems, including rocky intertidal shelves, coral reefs, nearshore ocean, streams, lakes, temperate tropical forests, arctic tundra. The compelling variety these ecosystems suggests plays universal role regulating diversity. This conclusion further supported by studies showing reduction absence leads and, more dramatic cases, catastrophic regime change. Here, I expand thesis maintained interaction between competition, such strong reduces allowing coexistence.

Language: Английский

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Quantifying effects of biodiversity on ecosystem functioning across times and places

Ecology Letters, Journal Year: 2018, Volume and Issue: 21(6), P. 763 - 778

Published: Feb. 28, 2018

Abstract Biodiversity loss decreases ecosystem functioning at the local scales which species interact, but it remains unclear how biodiversity affects larger of space and time that are most relevant to conservation policy. Theory predicts additional insurance effects on could emerge across if respond asynchronously environmental variation become increasingly dominant when where they productive. Even only a few maintain within particular place, may be enhanced by many different times places (β‐diversity). Here, we develop apply new approach estimate these previously unquantified arise due turnover places. In long‐term (18‐year) grassland plant diversity experiment, find total positive in sign substantial magnitude, amounting 19% net effect, mostly temporal effects. Species can therefore reduce both locally eliminating would otherwise enhance temporally fluctuating spatially heterogeneous environments.

Language: Английский

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