title: Role of food partitioning in structuring the zooplankton community in mountain lakes.
abstract: Trophic-niche differentiation is often cited as a main factor in structuring zooplankton assemblages, although field evidence for this is rarely presented. The study was based on a survey of 29 Pyrenean lakes with altitudes ranging between 1,875 and 2,990 m carried out during July and August 2000. Because of the oligotrophic nature of these lakes, we aimed to confirm that food partitioning is a major factor in shaping zooplankton assemblages. We analysed the amino acid composition of six cladocera and seven copepod species. A discriminant analysis showed that each species could be distinguished according to its amino acid composition. A negative relationship between amino acid differentiation and co-occurrence among the cladocera and cyclopoid copepod was observed. In contrast, calanoids did not show any relationship and were characterised by a high amino acid differentiation between species. As the differences in the amino acid composition among zooplankton species indicate distinct food sources, the relationship found indicates that trophic-niche differentiation plays a key role in determining the assemblage of these zooplankton communities. Therefore exploitative competition, either at present or in the past by driving co-evolutionary histories, has been a significant factor in structuring the cladocera and cyclopoid communities in these oligotrophic lakes.
authors.affiliation: Facultad de Ciencias, Universidad de Vigo, Lagoas-Marcosende, 36200 Vigo, Spain. castor@uvigo.es
authors.forename: C
authors.initials: C
authors.lastname: Guisande
authors.forename: F
authors.initials: F
authors.lastname: Bartumeus
authors.forename: M
authors.initials: M
authors.lastname: Ventura
authors.forename: J
authors.initials: J
authors.lastname: Catalan
mesh_terms: D000531:Altitude; D000596:Amino Acids / Q000032:analysis*; D000818:Animals; D005075:Biological Evolution; D033361:Cladocera / Q000737:chemistry*; D033342:Copepoda / Q000737:chemistry*; D020387:Food Chain; D011157:Population Dynamics; D014881:Water Supply; D015048:Zooplankton
chemical_list: D000596:Amino Acids