DOI: 10.5061/dryad.kn0v7
title: Data from: Seasonal population and individual niche dynamics in a tetra fish in the Pantanal wetlands

description: In seasonal tropical regions, rainfall and/or temporary floods during the
 wet season generally increase the abundance and diversity of food
 resources to many consumers as compared to the dry season. Therefore,
 seasonality can affect intraspecific competition and ecological
 opportunity, which are two important ecological mechanisms underlying
 population and individual niche variations. Here, we took advantage of the
 strong seasonality in the Pantanal wetlands to investigate how within- and
 between-individual diet variations relate to seasonal population niche
 dynamics of the tetra fish Astyanax lacustris. We quantified dietary niche
 using gut contents and stable isotopes. Tetras had higher gut fullness and
 better body condition in the wet season, suggesting that competition is
 more intense in the dry season. The population niche was broader in the
 wet season due to an increase in diet divergence between individuals, in
 spite of potential stronger competition in the dry season. We posit that
 low ecological opportunity in the dry season limits the diversifying
 effect of intraspecific competition, constraining population niche
 expansion. Our results add new insights on how seasonality affects
 population and individual diets, indicating that intraspecific competition
 and ecological opportunity interact to determine temporal niche variations
 in seasonal environments.
description: Data_Costa-Pereira_Biotropica2017GutFullness_BodyCondition: Residual body mass and gut fullness of the tetra fish Astyanax lacustrus in the wet and dry seasons in the Pantanal wetlands. Presence_preys_diet: Food items and respective trophic categories consumed by the tetra fish Astyanax lacustris in the Pantanal wetlands during the wet and dry seasons. Population_diet_proportions: Proportions of the mass of resources in the diet of the tetra fish Astyanax lacustris in the wet and dry seasons in the Pantanal wetlands. Individual_diet_proportions: Relative proportion of food categories in the diet of individuals of the tetra fish Astyanax lacustris in the wet and dry seasons in the Pantanal wetlands. PSi is the proportional similarity index of each individual, which quantifies the overlap between individual i’s niche and the population niche. Source_contribution_isotope: Confidence intervals (CI 95%) and modes of source contribution distributions to the isotopic composition of the tetra fish Astyanax lacustris in the wet and dry seasons in the Pantanal wetlands. Simulations_V_dry: Simulated V values in the dry season based on the isotope variances (adaptation of the method proposed by Araújo et al. 2007a). Rows represent simulated populations with different degrees of individual specialization and variance in individuals’ isotope values (Varδi). Simulations_V_wet: Simulated V values in the wet season based on the isotope variances (adaptation of the method proposed by Araújo et al. 2007a). Rows represent simulated populations with different degrees of individual specialization and variance in individuals’ isotope values (Varδi).