Local-scale species-energy relationships in fish assemblages of some forested streams of the Bolivian Amazon.
Productivity (trophic energy) is one of the most important factors promoting variation in species richness. A variety of species-energy relationships have been reported, including monotonically positive, monotonically negative, or unimodal (i.e. hump-shaped). The exact form of the relationship seems to depend, among other things, on the spatial scale involved. However, the mechanisms behind these patterns are still largely unresolved, although many hypotheses have been suggested. Here we report a case of local-scale positive species-energy relationship. Using 14 local fish assemblages in tropical forested headwater streams (Bolivia), and after controlling for major local abiotic factors usually acting on assemblage richness and structure, we show that rising energy availability through leaf litter decomposition rates allows trophically specialized species to maintain viable populations and thereby to increase assemblage species richness. By deriving predictions from three popular mechanistic explanations, i.e. the 'increased population size', the 'consumer pressure', and the 'specialization' hypotheses, our data provide only equivocal support for the latter.
Tedesco
Pablo A
PA
Institut d'Ecologia Aquàtica, Universitat de Girona, Campus de Montilivi, 17071 Girona, Spain. pablo.tedesco@udg.es
Ibañez
Carla
C
Moya
Nabor
N
Bigorne
Rémy
R
Camacho
Jimena
J
Goitia
Edgar
E
Hugueny
Bernard
B
Maldonado
Mabel
M
Rivero
Mirtha
M
Tomanová
Sylvie
S
Zubieta
José P
JP
Oberdorff
Thierry
T
D000818:Animals; D001838:Bolivia; D017753:Ecosystem; D005399:Fishes / Q000145:classification / Q000235:genetics / Q000502:physiology*; D005618:Fresh Water; D014644:Genetic Variation; D018515:Plant Leaves / Q000502:physiology; D011156:Population Density; D011235:Predatory Behavior; D012621:Seasons