Metapopulation dynamics, abundance, and distribution in a microecosystem

Science

Volumn 281, Issue 5385, 1998, Pages 2045-2047

  Gonzalez, A ^a   Lawton, J H ^a   Gilbert, F S ^b   Blackburn, T M ^a   Evans Freke, I ^b  

^a NATURAL ENVIRONMENT RESEARCH COUNCIL   (United Kingdom)

^b UNIVERSITY OF NOTTINGHAM   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

ABUNDANCE; HABITAT FRAGMENTATION; METAPOPULATION; POPULATION DYNAMICS; SPATIAL DISTRIBUTION;

ARTICLE; ECOSYSTEM; GEOGRAPHIC DISTRIBUTION; IMMIGRATION; NONHUMAN; POPULATION DENSITY; POPULATION DYNAMICS; PRIORITY JOURNAL; SPECIES DIFFERENCE;

EID: 0032566576     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.281.5385.2045     Document Type: Article

References (26)

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11. J. H. Lawton, Trends Ecol. Evol. 8, 409 (1993); in Extinction Rates, J. H. Lawton and R. M. May, Eds. (Oxford Univ. Press, Oxford, UK, 1995), pp. 147-163.
12. R. C. Davis, Ecol. Monogr. 5, 125 (1981); E. L. Seyd, Zool. J. Linn. Soc. 106, 115 (1992). Experiments were carried out on large, flat, moss-covered limestone rocks near Wirksworth in the Peak District (Derbyshire, UK; OS map reference SK 264566). The moss species present were predominantly Hypnum cupressiforme, Thuidium tamariscinum, and Tortella tortuosa. Within the mosses exists a species-rich microinvertebrate community of producers, herbivores, and predators, including Acari, Collembola, Nematoda, Protista, Rotifera, Tardigrada, algae, bacteria, and fungi. All the organisms in this system have very short generation times, ranging from a few hours to a few months. Here we focus on the microarthropods, mainly Acari and Collembola, which are highly abundant and, in comparison with the other groups, easy to extract and identify. They include herbivores, feeding primarily on fungal hyphae and dead plant material, and predators, feeding on nematodes and other Acari and Collembola. They are susceptible to desiccation and so are highly dependent on the mesic microclimate of their moss habitat.
13. R. C. Davis, Ecol. Monogr. 5, 125 (1981); E. L. Seyd, Zool. J. Linn. Soc. 106, 115 (1992). Experiments were carried out on large, flat, moss-covered limestone rocks near Wirksworth in the Peak District (Derbyshire, UK; OS map reference SK 264566). The moss species present were predominantly Hypnum cupressiforme, Thuidium tamariscinum, and Tortella tortuosa. Within the mosses exists a species-rich microinvertebrate community of producers, herbivores, and predators, including Acari, Collembola, Nematoda, Protista, Rotifera, Tardigrada, algae, bacteria, and fungi. All the organisms in this system have very short generation times, ranging from a few hours to a few months. Here we focus on the microarthropods, mainly Acari and Collembola, which are highly abundant and, in comparison with the other groups, easy to extract and identify. They include herbivores, feeding primarily on fungal hyphae and dead plant material, and predators, feeding on nematodes and other Acari and Collembola. They are susceptible to desiccation and so are highly dependent on the mesic microclimate of their moss habitat.
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17. 2) (containing populations of 140 to less than 10 individuals) and a larger continuous area of moss acting as a control (at least 50 cm by 50 cm). Every 2 months during the ensuing year, one fragment was randomly chosen and removed from each of the eight replicates. At the same time, an equivalently sized patch was removed from the control area of each replicate. The microarthropod community of all samples was extracted with a Tullgren funnel and sorted into morphotypes. Extraction efficiency was high (14), and the same extraction protocol was applied to all moss samples. About 18,000 individual animals were counted and sorted in total; they were mostly Acari (63%) and Collembola (24%). Species richness was taken as an average of the replicate samples, for both control samples and fragments. The total abundance and distribution of each species across the replicate patches sampled at each time period were also estimated for each treatment. The results here refer to comparisons between control and fragmented communities (30 and 21 species, respectively) made after 12 months in six of the original eight replicates (two others were lost to natural destruction).
18. A. Gonzalez, thesis, University of London (1998).
19. The second experiment was a 6-month repeat of the first, with the addition of two corridor treatments (Fig. 2A). In these two additional treatments, fragment islands were connected to other fragments by an intact corridor, or a corridor was present but was broken by a small strip (∼10 mm) of bare rock. The pseudocorridor treatment accounted for the possible confounding effect of the extra moss area associated with the corridor treatment. The only effect of unbroken corridors, therefore, was to facilitate micro-arthropod dispersal between moss fragments.
20. F. S. Gilbert, A. Gonzalez, I. Evans-Freke, Proc. R. Soc. London B 265, 1 (1998).
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24. E. O. Wilson and E. Willis, in Ecology and Evolution of Communities, M. L. Cody and J. M. Diamond, Eds. (Harvard Univ. Press, Cambridge, MA, 1975), pp. 522-534; P. D. Taylor, K. Fahrig K. Henein, G. Merriam, Oikos 68, 571 (1993); T. H. Keitt, D. L. Urban, B. T. Milne, Conserv. Ecol. [online] 1 (no. 1), 4 (1997). Available at www. consecol.org/Journal/vol1/iss1/art4.
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26. We thank E. Chaneton, M. Bonsall, and J. Birch for helpful comments and discussions on the manuscript; H. Mace for help with a pilot study; J. Murphy for help with mite identification; J. Rieley for identifying the mosses; and M. Wright, O. Petchey, G. Couper, A. Kelley, and B. Morris for help in the field. A.G. was supported by a National Environment Research Council (NERC) studentship. T.M.B. is a Leverhulme Special Research Fellow and was supported in part by NERC grant GST/03/1211.