Thermal history mediates the ecological role of body size in a freshwater fish

Intraspecific trait variation among populations may strongly alter community and ecosystem structure and function. Body size is a fundamental trait of all organisms, affecting both organismal physiology and ecological effects, which may differ across populations. For example, body size is predicted to decline with warming. As such, in this study, we aim to determine how population differences in thermal history mediate the ecological role of body size in a freshwater fish. We conducted a mesocosm experiment in which we manipulated fish (Gambusia affinis [Baird and Girard, 1853]) source populations (ambient source vs warm source) and body size while holding their biomass constant. We monitored community and ecosystem response variables including, macroinvertebrate abundance, zooplankton biomass, phytoplankton abundance, and greenhouse gas flux. Changes in fish body size influenced most ecological responses, but these effects often depended on the thermal history of the fish populati..., , # Thermal history mediates the ecological role of body size in a freshwater fish

Dataset DOI: [10.5061/dryad.qv9s4mwsd](10.5061/dryad.qv9s4mwsd)

## Description of the data and file structure

Mescosm (experimental pond) data were collected over 6 time points (The first was before adding fish (T0) and then measurements were taken at 4 (T1), 8 (T2), 16 (T3), 24 (T4), and 32 (T5) days after adding fish. Experimental ponds contained small or large-sized fish from ambient or warm source populations. There are also control tanks. In total, there are 5 experimental treatments (Control, Small-warm, Small-cool, Large-ambient, Large-ambient).

### Files and variables

#### File: Meso_body_size.csv

**Description:** Treatment description and data from the variables measured throughout the mesocosm experiment. Units for variables measured are described below. Where data were not collected for a response variable in a given week or for a treatment, cells are filled with n/a.

##### Variables

* Po...,