Community Structure, Population Control, and Competition

Hairston, Nelson G.; Smith, Frederick E.; Slobodkin, Lawrence B.

doi:10.1086/282146

Cited by 3,015 publications

(1,985 citation statements)

References 13 publications

Supporting

Mentioning

1,886

Contrasting

Unclassified

Order By: Relevance

“…Since the landmark paper by Hairston et al (1960), ecologists have been debating whether herbivores are limited by plant defences or by predators (Murdoch 1966;Oksanen et al 1981;Strong 1992). The matter is trivially simple in principle, but in practice, the challenge of experimentally creating predator-free environments in which herbivores can increase without constraint has proven almost insurmountable (Marquis & Whelan 1994;Schmitz et al 2000;Sinclair et al 2000).…”

Section: Resultsmentioning

confidence: 99%

Vegetation dynamics of predator‐free land‐bridge islands

et al. 2006

View full text Add to dashboard Cite

Summary 1We tested the 'green world' hypothesis of Hairston, Smith and Slobodkin by monitoring vegetation change on recently created predator-free land-bridge islands in a huge hydroelectric impoundment, Lago Guri, in the State of Bolivar, Venezuela. 2 Our results affirm the green world hypothesis and expose the operation of a strong top-down trophic cascade that negatively impacted nearly every plant species present, implying that community stability is maintained through the action of predators. 3 To test the hypothesis, we monitored vegetation on nine predator-free islands and compared demographic parameters to those observed at control sites supporting complete or nearly complete suites of predators. 4 Herbivore abundance was high on 'small' ( ≥ 0.5, < 2 ha) islands, moderate on 'medium' islands (> 3, < 15 ha) and low on the 'large' landmasses that served for reference. 5 Small sapling densities on small islands were only 37% of controls in 1997 (after 11 years of isolation), and when recensused in 2002, had fallen to 25% of controls. High mortality and, especially, low recruitment contributed to the decline in sapling cohorts. 6 Sapling decline occurred earlier on small islands, although recruitment failure had become equally pronounced on medium islands by the end of the monitoring period. 7 Several mechanisms could potentially account for suppressed sapling recruitment, but the weight of evidence points to herbivory on seedlings and small saplings by leaf-cutter ants ( Atta spp. and Acromyrmex sp.). Exposure to prevailing trade winds (windward vs. leeward slopes of islands) had no detectable effect on the density or diversity of seedlings or saplings.

show abstract

Section: Resultsmentioning

confidence: 99%

Vegetation dynamics of predator‐free land‐bridge islands

et al. 2006

View full text Add to dashboard Cite

show abstract

“…Evidence that solar energy directly influences endotherm abundance, by adjusting the thermoregulatory load, is lacking (Lennon, Greenwood & Turner, 2000) or circumstantial (Hawkins et al, 2003). Productive energy probably limits an assemblage's biomass (Hairston et al, 1960;Gaston & Blackburn, 2000, p. 83), but the number of individuals comprising this biomass will depend upon the form of the interspecific body size-abundance relationship. A given increase in energy availability will increase total abundance more dramatically in assemblages with a small, compared to a large, mean body mass.…”

Section: ( C) Evaluationmentioning

confidence: 99%

Species–energy relationships at the macroecological scale: a review of the mechanisms

2005

View full text Add to dashboard Cite

Correlations between the amount of energy received by an assemblage and the number of species that it contains are very general, and at the macro-scale such species-energy relationships typically follow a monotonically increasing curve. Whilst the ecological literature contains frequent reports of such relationships, debate on their causal mechanisms is limited and typically focuses on the role of energy availability in controlling the number of individuals in an assemblage. Assemblages from high-energy areas may contain more individuals enabling species to maintain larger, more viable populations, whose lower extinction risk elevates species richness. Other mechanisms have, however, also been suggested. Here we identify and clarify nine principal mechanisms that may generate positive species-energy relationships at the macro-scale. We critically assess their assumptions and applicability over a range of spatial scales, derive predictions for each and assess the evidence that supports or refutes them. Our synthesis demonstrates that all mechanisms share at least one of their predictions with an alternative mechanism. Some previous studies of species-energy relationships appear not to have recognised the extent of shared predictions, and this may detract from their contribution to the debate on causal mechanisms. The combination of predictions and assumptions made by each mechanism is, however, unique, suggesting that, in principle, conclusive tests are possible. Sufficient testing of all mechanisms has yet to be conducted, and no single mechanism currently has unequivocal support. Each may contribute to species-energy relationships in some circumstances, but some mechanisms are unlikely to act simultaneously. Moreover, a limited number appear particularly likely to contribute frequently to species-energy relationships at the macro-scale. The increased population size, niche position and diversification rate mechanisms are particularly noteworthy in this context.

show abstract

“…[564][565] to settle yet another well-known 'paradox' -the paradox of enrichment ( [11,18]). He called such predators 'squabbling'.…”

mentioning

confidence: 99%