DOI: 10.5061/dryad.gtht76hm0
title: Data from: Ancestral ecological regime shapes reaction to food limitation in the Least Killifish, Heterandria formosa

description: Populations with different densities often show genetically-based
 differences in life histories. The divergent life histories could be
 driven by several agents of selection, one of which is variation in
 per-capita food levels. Its relationship with population density is
 complex, as it depends on overall food availability, individual metabolic
 demand, and food-independent factors potentially affecting density, such
 as predation intensity. Here we present a case study of two populations of
 a small live-bearing freshwater fish, one characterised by high density,
 low predation risk, low overall food availability, and presumably low
 per-capita food levels, and the other by low density, high predation risk,
 high overall food availability, and presumably high per-capita food
 levels. Using a laboratory experiment we examined whether fish from these
 populations respond differently to food limitation, and whether size at
 birth, a key trait with respect to density variation in this species, is
 associated with any such differential responses. While at the lower food
 level growth was slower, body size smaller, maturation delayed and
 survival reduced in both populations, these fitness costs were smaller in
 fish from the high-density population. At low food, only 15% of
 high-density fish died, compared to 75% of low-density fish. This
 difference was much smaller at high food (0% vs. 15% mortality). The
 increased survival of high-density fish may, at least partly, be due to
 their larger size at birth. Moreover, being larger at birth enabled fish
 to mature relatively early even at the lower food level. We demonstrate
 that sensitivities to food limitation differ between study populations,
 consistent with selection for a greater ability to tolerate low per-capita
 food availability in the high-density population. While we cannot preclude
 other agents of selection from operating in these populations
 simultaneously, our results suggest that variation in per-capita food
 levels is one of those agents.
description: Please find this information in the manuscript and supporting
 information.
description: General note: Please also read the ReadMe files that accompany
 each dataset; they explain the column headers.
 <b>Fish data</b> This file
 contains the experimental treatment, ancestral population, measured
 life-history traits, maternal identity and maternal size of 80
 second-generation laboratory-reared individuals. Note that the body sizes
 and age at maturity of one individual (H7) may contain measurement errors.
 We thus excluded this individual from all analyses except that of survival
 to maturity, where the individual was retained but its size at birth was
 not used as a covariate in the analysis. The data in this file were used
 to produce Figs. 3-7. <b>Water
 data</b> This file contains measurements of water
 quality from both study locations across three years. Note that
 concentrations of nitrate were below the detection limit in Trout Pond,
 and that concentrations of nitrite and total phosphorus were undetectable
 in both water bodies. The data in this file were used to produce Fig.
 2. <b>Measuring trial</b>
 This file provides the results of a smaller laboratory experiment
 aimed at estimating the correlation between standard length and dry mass
 in newborn fry. The fish used for this experiment were separate from those
 used in the main study. The results and further details of the experiment
 can be found in the Methods section.