A Competitive Hierarchy Model Integrating Roles of Physiological Competence and Competitive Ability Does Not Provide a Mechanistic Explanation for the Zonation of Three Intertidal Fucus Species in Europe

Karez, Rolf; Chapman, A. R. O.

doi:10.2307/3546769

Cited by 23 publications

(16 citation statements)

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“…In a small number of cases, a few plants escaped during the maintenance procedure of the cultures. So, in the end, there were still about 1300 genets in the high density beakers, and determination of individual weight [as in Karez and Chapman (1998)] was not feasible.…”

Section: Methodsmentioning

confidence: 99%

“…The same monocultures of F. vesiculosus were used for replacement series with F. serratus and with F. spiralis. Densities were chosen to be comparable with those used in Karez and Chapman (1998), i.e. 10,000 (low), 50,000 (medium) or 100,000 (high) shoots m -2 , corresponding to 130, 650 or 1300 shoots per cultivation beaker of 13 cm diameter.…”

Section: Methodsmentioning

confidence: 99%

“…Germlings of all three Fucus species were cultivated in the laboratory from zygotes that were sown on ceramic tiles [for details see Karez and Chapman (1998)]. When they had grown to an average 1 cm length, they were detached gently from the tiles and distributed individually into the various mixtures and monocultures of the replacement series.…”

Section: Methodsmentioning

confidence: 99%

“…Assuming that the lower intertidal is the benign end of the shore gradient, this should (according to Keddy's model) also be the order of their competitive dominances. However, replacement series competition experiments by Karez and Chapman (1998) revealed a competitive hierarchy of F. vesiculosus > F. serratus > F. spiralis. It is the aim of the present paper to evaluate if competitive ranks obtained in controlled laboratory experiments are consistent with the findings of the former field study.…”

Section: Introductionmentioning

confidence: 99%

“…This was done in field experiments by Karez and Chapman (1998) with the three zone-forming species of Fucus that occur in the intertidal of the island of Helgoland (North Sea) in the landward order F. serratus, F. vesiculosus, F. spiralis. Assuming that the lower intertidal is the benign end of the shore gradient, this should (according to Keddy's model) also be the order of their competitive dominances.…”

Section: Introductionmentioning

confidence: 99%

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Competitive ranks of three Fucus spp. (Phaeophyta) in laboratory experiments?testing of Keddy's competitive hierarchy model

Karez

2003

Helgoland Marine Research

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Keddy's competitive hierarchy model describes species distribution patterns along gradients under equilibrium conditions and can potentially serve as an explanation for zonation patterns of intertidal seaweeds on rocky shores. One of the assumptions of the model is a competitive hierarchy with the top competitor occupying the benign end of the gradient. Another assumption is the consistency of competitive ranks of species in all environmental conditions included in the shared parts of species' fundamental niches. In laboratory replacement series experiments, the competitive ranks of pairs of Fucus species that occupy adjacent zones in the field were analysed and compared to ranks found in previous field experiments. Unattached thalli of Fucus serratus versus F. vesiculosus or F. vesiculosus versus F. spiralis, respectively, were held in aerated beakers to establish the competitive ranking of the three congeners. Each replacement series was conducted at three total densities. F. vesiculosus was clearly competitively dominant over F. serratus. In competition with F. spiralis, F. vesiculosus was only dominant at its lowest absolute input frequencies, but at higher frequencies dominance was reversed. At high densities, the total ranking was F. spiralis > F. vesiculosus > F. serratus, which is the opposite order to that which would be expected from Keddy's model. Although all three species thrived well under the laboratory conditions, the results did not reflect in situ competitive dominances, which may be an effect of nutrient competition in the laboratory. Keddy's assumption that competitive ranks are consistent over the whole range of fundamental niches cannot be supported for Fucus spp.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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