Adaptive phenotypic evolution of Skeletonema costatum to ocean acidification and warming with trade-offs from a multi-year outdoor experiment

Human-induced climate change is increasing variability in marine environments, significantly affecting marine organisms and ecosystems. While marine diatoms can adapt to ocean acidification and warming in stable laboratory settings, their responses to long-term environmental changes under natural variability remain unclear. To investigate this, we cultivated Skeletonema costatum in outdoor semi-continuous cultures for over three years, exposing them to fluctuating natural light and temperature that tracked the in situ sea surface temperatures. We simulated current and future ocean conditions through four treatments: ambient CO2 and temperature (LTLC), elevated CO2 (LTHC), elevated temperature (+ 4°C, HTLC), and combined increases (HTHC). After 1,396 days, we assessed populations in two assay environments (20°C, 400 ppm CO2 and 24°C, 1,000 ppm CO2) for adaptations in growth rate, pigment composition, and photosynthesis. The HTLC-selected group showed highest growth rates in the HTHC assa..., , , # Adaptive phenotypic evolution of Skeletonema costatum to ocean acidification and warming with trade-offs from a multi-year outdoor experiment

Dataset DOI: [10.5061/dryad.v6wwpzh6m](10.5061/dryad.v6wwpzh6m)

## Description of the data and file structure

The uploaded data files provide the original empirical results from both the long-term selection experiment and the short-term assay experiment described in the manuscript. The dataset includes:

* **.csv files** containing raw and processed data such as recorded environmental variables (e.g., temperature and light intensity), growth rates, and other physiological and experimental parameters.
* **.R files** with annotated scripts used for data cleaning, statistical analyses, and figure generation, enabling full reproducibility of the results presented in the paper.

### Files and variables

#### File: all.csv

**Description:** All parameters used for the figures of the long-term experiment and the assay experiment.

##### Variables

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