Low functional β-diversity despite high taxonomic β-diversity among tropical estuarine fish communities.
The concept of β-diversity, defined as dissimilarity among communities, has been widely used to investigate biodiversity patterns and community assembly rules. However, in ecosystems with high taxonomic β-diversity, due to marked environmental gradients, the level of functional β-diversity among communities is largely overlooked while it may reveal processes shaping community structure. Here, decomposing biodiversity indices into α (local) and γ (regional) components, we estimated taxonomic and functional β-diversity among tropical estuarine fish communities, through space and time. We found extremely low functional β-diversity values among fish communities (<1.5%) despite high dissimilarity in species composition and species dominance. Additionally, in contrast to the high α and γ taxonomic diversities, α and γ functional diversities were very close to the minimal value. These patterns were caused by two dominant functional groups which maintained a similar functional structure over space and time, despite the strong dissimilarity in taxonomic structure along environmental gradients. Our findings suggest that taxonomic and functional β-diversity deserve to be quantified simultaneously since these two facets can show contrasting patterns and the differences can in turn shed light on community assembly rules.
Laboratoire Évolution et Diversité Biologique, Université Paul Sabatier, Toulouse, France. sebastien.villeger@univ-tlse3.fr
Sébastien
S
Villéger
Julia
J
Ramos Miranda
Domingo
D
Flores Hernandez
David
D
Mouillot
D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D005399:Fishes / Q000145:classification*; D060851:Gulf of America; D015233:Models, Statistical; D011157:Population Dynamics; D014329:Tropical Climate