Space-Time Structure of the Environment and the Survival of Parasite-Host Systems

Pimentel, David; Nagel, W. P.; Madden, J. L.

doi:10.1086/282265

Cited by 183 publications

(90 citation statements)

References 23 publications

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“…The shifting of predation pressure in response to changes in prey populations and its various implications have been considered by MacArthur ( 1955), Tin bergen (1960) , Paine (1963Paine ( , 1969, Holling (1965), Salt (1967), Murdoch (1969), and several others. Similarly, specialized predators and parasites are less likely to fluctuate widely because the refuge provided by a complex environment enables their prey I host species to escape widespread annihilation (e.g., Huffaker 1958, Pimentel, Nagel, andMadden 1963). Finally, diverse habitats offer many important requisites for adult parasitoids and predators, such as nectar and pollen sources, that are not available in a monoculture (van Emden 1963b(van Emden , 1965.…”

Section: Influence Of Diverse Habitatmentioning

confidence: 99%

Organization of a Plant‐Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea)

Root¹

1973

Ecological Monographs

2,633

147

2,046

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Collards were grown at Ithaca, New York, in two experimental habitats: pure stands and single rows that were bounded on each side by diverse, meadow vegetation. The arthropods associated with these plants were sampled on 20 dates over a 3—year period. The status of the herbivore species was measured by their rank in biomass in each sample. The two most prominent species, Phyllotreta cruciferae and Pieris rapae, maintained high status throughout the investigation, but another important species, Brevicoryne brassicae, was absent for an entire season. Pit feeders usually formed the most important herbivore guild. Nevertheless, the guild spectrum, which describes the functional structure of the fauna, varied widely in time and space. The size distributions of species and of individuals were both highly skewed toward the smaller sizes. Herbivore loads, the mean biomass of herbivores per 100 g of consumable foliage, were consistently higher in the pure stands. Moreover, herbivore loads varied significantly with season in each experimental habitat. Both the number of herbivore species and the diversity of the herbivore load were greater in the diverse habitat. Biomass was more heavily concentrated among the prominent herbivores in the pure stands; increased dominance, rather than differences in species richness, appeared to be the major cause for the lower herbivore diversity in this habitat. The diversity of predators and parasitoids was higher in the pure stands. Most of the abundant species found on collards shared a similar narrow range of hosts. As a result the species in this core group of herbivores and parasitoids were regularly associated with each other. Predators and the less abundant herbivores tended to be less specialized and served to link the collard association with the surrounding community. Plant—arthropod associations are representative of component communities, well—integrated systems that form portions of larger compound communities. This distinction facilitates the analysis of community structure. Microclimates and the effectiveness of "enemies" did not appear to differ sufficiently in the two experimental habitats to account for the observed differences in the herbivore load. The results suggest a new proposition, the resource concentration hypothesis, which states that herbivores are more likely to find and remain on hosts that are growing in dense or nearly pure stands; that the most specialized species frequently attain higher relative densities in simple environments; and that, as a result, biomass tends to become concentrated in a few species, causing a decrease in the diversity of herbivores in pure stands.

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Section: Influence Of Diverse Habitatmentioning

confidence: 99%

Organization of a Plant‐Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea)

Root¹

1973

Ecological Monographs

2,633

147

2,046

View full text Add to dashboard Cite

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“…However, for an open system or patchy region the S for each patch does not have to change for the diversity of the region to change. Both laboratory (Huffaker 1958;Pimentel et al 1963) and mathematical (Caswell 1977) modelling of simple systems have demonstrated how the dynamics of an open system present an exceedingly strong force counteracting the expected results of highly deterministic processes (in this case, predator-prey relationships). The question is, therefore, whether specific global diversity patterns can still be explained without relying on any differences in biological organization between regions.…”

Section: Global Patterns In Evolutionary Timementioning

confidence: 99%

Patterns of species diversity: fact or artifact?

Osman¹,

Whitlatch

1978

Paleobiology

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Abstract.-The pattern observed in nature has often served as a compelling motivation for seeking the underlying processes which are assumed to control the pattern. Spatial and temporal patterns of species diversity are the most commonly observed and described from the study of recent and paleocommunities. These patterns include those found within a local or discrete region such as succession and changes along an environmental gradient and interregional or global patterns such as latitudinal diversity gradients and comparisons of the deepsea and the continental shelf faunas. Many hypotheses have been advanced to explain these patterns in terms of differences in the biology of species adapted to different or changing environments. However, a more simple explanation is possible: that these patterns do not result from any specific biologic processes.We examine this possibility and show that succession can result from probabilistic immigration and local extinction of species, diversity gradients can result from probabilistic disturbance in naturally patchy environments, and that latitudinal gradients can be simply a function of the shape of the earth. As long as such diversity patterns can be explained independent of any specific biologic processes, they offer no test of the importance of these processes, either ecologically or evolutionarily.

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“…Carrying capacity.-Do predators take only ''surplus" individuals (Pimentel 1961, Pimentel et al 1963, Pimental and Soans 1971)? Or do they determine the distinction between "surplus" and "capital" individuals and, thus, the apparent carrying capacity of the environment for the prey population?…”

mentioning

confidence: 99%

Distribution Ecology: Variation in Plant Recruitment over a Gradient in Relation to Insect Seed Predation

Louda¹

1982

Ecological Monographs

325

241

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Abstract. Although predispersal seed predation by insects is common, no test exists of its effect on plant recruitment. This study examines seed predation in the population dynamics of a native, temperate shrub, Haplopappus squarrosus H. and A. (Asteraceae), over an elevational gradient in the coastal sage scrub vegetation of San Diego County, California USA. Frequency and abundance of H. squarrosus increase from coast to mountains. Expected abundance, based on flowers initiated, was highest at the coast and lowest in the interior, the opposite of the observed adult plant distribution. Overall flower and seed predation by insects was high (44-73%) and was greatest at the coast. Insect exclusion experiments at sites along the gradient had three main results. (1) Seedling recruitment was proportional to the number of viable seeds after seed predation. The exclusion plots had significantly higher numbers of seedlings established at all sites than did control plots; the greatest increase was at the coast. (2) Seedling survivorship was independent of both seedling and adult densities. (3) Juvenile recruitment was proportional to seedling establishment. Predation by insects prior to release of seeds played a critical role in the population recruitment of H. squarrosus within and among sites along the gradient. Survivorship of established plants, in addition, was as high at the coast as it was in the interior. These results suggest that indigenous insect seed predators can be a major force controlling the dynamics of a native plant species over its natural distributional range.

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Space-Time Structure of the Environment and the Survival of Parasite-Host Systems

Cited by 183 publications

References 23 publications

Organization of a Plant‐Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea)

Organization of a Plant‐Arthropod Association in Simple and Diverse Habitats: The Fauna of Collards (Brassica Oleracea)

Patterns of species diversity: fact or artifact?

Distribution Ecology: Variation in Plant Recruitment over a Gradient in Relation to Insect Seed Predation

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