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MEPS 273:251-267 (2004)
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Abstract
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Strength, slope and variability of marine latitudinal gradients
Helmut Hillebrand1,2,*
1Institute for Marine Research, University of Kiel, Section for Marine Ecology, Düsternbrooker Weg 20, 24105 Kiel, Germany
2Present address: Institute for Botany, University of Cologne, Gyrhofstrasse 15, 50931 Cologne, Germany
*Email: helmut.hillebrand@uni-koeln.de
ABSTRACT: Latitudinal declines of species richness from the tropics to the poles represent a general spatial pattern of diversity on land. For the marine realm, the generality of this pattern has frequently been questioned. Here, I use a database with
nearly 600 published gradients (198 of which were marine) to assess whether there is a marine latitudinal diversity gradient of similar average strength and slope as that for terrestrial organisms. Using meta-analysis techniques, I also tested which
characteristics of organisms or habitats affected gradient strength and slope. The overall strength and slope of the gradient for marine organisms was significantly negative and of similar magnitude compared to gradients for terrestrial organisms. Marine
gradients were on average stronger as well as steeper than freshwater gradients. Latitudinal gradients were clearly a regional phenomenon, with stronger gradients and steeper slopes for diversity assessed on regional than on local scales. The gradient
parameters differed also between oceans and between different habitats, with steeper gradients related to the pelagial rather than the benthos. There were on the other hand no significant differences between hemispheres and between different gradient
ranges, although such differences have often been presumed. The most important organismal characteristic related to gradient structure was body mass, with significant gradients related to large organisms. A significant increase in gradient strength with
increasing trophic level was observed. The meta-analysis also revealed strongest gradients for nekton and mobile epifauna, whereas the gradients were weak for sessile epifauna and for infauna. In conclusion, marine biota reveal a similar overall decline
in diversity with latitude to that observed in terrestrial realms, but the strength and slope of the gradient are clearly subject to regional, habitat and organismal features.
KEY WORDS: Diversity · Latitude · Evolution · Dispersal · Meta-analyses · Macroecology · Habitat type
Full text in pdf format
Published in MEPS Vol.
273
(2004) on June 8
Print ISSN: 0171-8630; Online ISSN: 1616-1599.
Copyright © Inter-Research, Oldendorf/Luhe, 2004
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