title: ECOLOGICAL DIFFERENTIATION BETWEEN SYMPATRIC PSEUDOCRYPTIC SPECIES IN THE ESTUARINE BENTHIC DIATOM NAVICULA PHYLLEPTA (BACILLARIOPHYCEAE)(1).
abstract: The occurrence of cryptic and pseudocryptic species, often living in sympatry, is widespread among microalgae. This phenomenon raises important questions about niche partitioning between these closely related species. To date, however, few studies have addressed the ecological mechanisms underlying sympatry in cryptic and pseudocryptic species. As a result, we have only a limited understanding of the factors that govern their distribution along environmental gradients. Here, we used the ribosomal internal transcribed spacer (ITS), 18S rRNA gene, and the RUBISCO LSU (rbcL) chloroplast gene sequence data together with cell wall morphology to show that estuarine populations of the widespread and common benthic diatom Navicula phyllepta Kütz. consist of pseudocryptic species. Growth rate measurements in function of salinity showed that N. phyllepta strains assigned to the different species differed in their tolerance to low salinities (<5 practical salinity units, psu), which was reflected by their different (but widely overlapping) distribution in the Westerschelde estuary (the Netherlands). Multiple regression analyses of the factors determining the abundance of the different species in field samples revealed that, in addition to salinity, sediment type and ammonium concentrations were probably equally important. Our results show that N. phyllepta sensu lato comprises different species with specialized ecophysiological characteristics rather than generalists with a broad adaptability to different environmental conditions.
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Bart
authors.initials: B
authors.lastname: Vanelslander
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Véronique
authors.initials: V
authors.lastname: Créach
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Vanormelingen
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Anneliese
authors.initials: A
authors.lastname: Ernst
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Chepurnov
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Emel
authors.initials: E
authors.lastname: Sahan
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Gerard
authors.initials: G
authors.lastname: Muyzer
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Lucas J
authors.initials: LJ
authors.lastname: Stal
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Wim
authors.initials: W
authors.lastname: Vyverman
authors.affiliation: Laboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, BelgiumDepartment of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, the NetherlandsNetherlands Institute of Ecology, (NIOO-KNAW), PO Box 140, 4400 AC, Yerseke, the NetherlandsLaboratory of Protistology & Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281-S8, 9000 Ghent, Belgium.
authors.forename: Koen
authors.initials: K
authors.lastname: Sabbe
keywords: 18S rRNA gene; Navicula phyllepta; RUBISCO large subunit (rbcL); diatom; niche differentiation; pseudocryptic diversity; ribosomal internal transcribed spacer; salinity; valve morphology