[OANNES Foro] Global diversity of marine macroalgae: environmental conditions explain less variation in the tropics

[Mario Cabrejos]

Global Ecology and Biogeography

Volume
<http://onlinelibrary.wiley.com/doi/10.1111/geb.2014.23.issue-5/issuetoc>
23, Issue 5, pages 517-529, May 2014

Article first published online: 4 NOV 2013

DOI: 10.1111/geb.12132

 

Global diversity of marine macroalgae: environmental conditions explain less
variation in the tropics

Sally A. Keith1,*, Ailsa P. Kerswell1,2 and Sean R. Connolly1,2

1 Australian Research Council Centre of Excellence for Coral Reef Studies,
James Cook University, Townsville, QLD, Australia2 School of Marine and
Tropical Biology, James Cook University, Townsville, QLD, Australia *
Correspondence: E-mail:  <mailto:sally.a.keith en gmail.com>
sally.a.keith en gmail.com

 

Abstract

Aim

Marine macroalgae provide an excellent opportunity to test hypotheses about
latitudinal diversity gradients because macroalgal richness decreases
towards the tropics, contrary to classic patterns, and because three
evolutionarily distinct macroalgal clades (Rhodophyta, Chlorophyta,
Phaeophyceae) have converged ecologically. Specifically, we determine the
extent to which environmental conditions can predict genus richness in
macroalgae. We also evaluate whether the magnitude or direction of the
effect of environmental factors, or their ability to explain variation in
macroalgal diversity, varies geographically.

Location

Global oceans.

Methods

We formulated and fitted global spatial regression models and geographically
weighted regression (GWR) models to determine the extent to which
environmental conditions could predict genus richness in macroalgae. GWR
allowed us to determine how the role of environmental conditions varied
amongst geographical regions.

Results

The global regression model showed that sea surface temperature and
nutrients were important predictors of macroalgal genus richness at a global
scale. However, GWR revealed that environmental factors explained less
variability in richness in the tropics than elsewhere.

Main conclusions

Our results show that whilst environmental conditions influence marine
macroalgal diversity, the strength of this influence shows considerable
geographical variation. In particular, environmental conditions explain more
of the observed variation in diversity at high latitudes than at low
latitudes. This finding is consistent with the hypothesis that environmental
tolerances influence species distributions more strongly at high latitudes,
whereas other factors, such as biotic interactions, play a more prominent
role in the tropics.

 

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