Populations et communautés Analyses multivariées des ... - Ecobio

Populations et communautés Analyses multivariées des ... - Ecobio Populations et communautés Analyses multivariées des ... - Ecobio

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Populations et communautés : Analyses multivariées de données spatialisées Combinaison des variables environnementales et spatiales Etude des communautés de poissons des coraux Mer des Caraïbes Data: Fish community composition observed along underwater transects off 7 islands of the Caribbean arch. Sampling design: 248 underwater transects surveyed by a diver (visual census of 231 species). Questions • Is there a significant spatial pattern of community variation among the islands? • Is that pattern explained (in part) by environmental variables? Note: underwater visual censuses have high sampling variance.

Populations et communautés : Analyses multivariées de données spatialisées Combinaison des variables environnementales et spatiales Etude des communautés de poissons des coraux Mer des Caraïbes Variation in fish presence-absence = Habitat classes = 15.2% 10.8% Residuals = 77.6% 2.1% 1.7% 1.1% Depth = 3.9% Geographic gradients (Caribbean arch and latitude) = 8.4% 5.9% 0.6% 0.1%

<strong>Populations</strong> <strong>et</strong> <strong>communautés</strong> : <strong>Analyses</strong> <strong>multivariées</strong> de données spatialisées<br />

Combinaison <strong>des</strong> variables environnementales <strong>et</strong> spatiales<br />

Etude <strong>des</strong> <strong>communautés</strong> de poissons <strong>des</strong> coraux<br />

Mer <strong>des</strong> Caraïbes<br />

Data: Fish community composition observed along underwater<br />

transects off 7 islands of the Caribbean arch.<br />

Sampling <strong>des</strong>ign: 248 underwater transects surveyed by a diver<br />

(visual census of 231 species).<br />

Questions<br />

• Is there a significant spatial pattern of community variation among<br />

the islands?<br />

• Is that pattern explained (in part) by environmental variables?<br />

Note: underwater visual censuses have high sampling variance.

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