Female-biased population sex ratios caused by genetic rather than ecological mechanisms in dwarf willow (Salix herbacea L.)

Biased sex ratios among reproductive individuals are common in plants, but the underlying mechanisms, as well as the evolutionary consequences, are not well understood. The classical theory of Düsing and Fisher predicts an equal primary sex ratio at seed production, based on the selective advantage of the rare sex. Biased sex ratios among reproductive plants can arise from sexual dimorphism in survival and flowering. Sex ratio biases can also be present from the seed stage; in these cases, assumptions of Düsing’s and Fisher’s theory, for example, random mating or demographic equilibrium, are thought to be violated.
We investigated mechanisms leading to female-biased sex ratios in the arctic-alpine dwarf willow Salix herbacea L. We studied sex ratios in three natural populations over three years as well as in 29 crosses (full-sib families) under controlled conditions over four growth periods. We tested whether sex ratio was associated with habitat parameters (elevation and snowmelt time)..., We investigated sex ratios in three natural populations over three years as well as in 29 crosses (full-sib families) under controlled conditions over four growth periods. We tested whether sex ratio was associated with habitat parameters (elevation and snowmelt time), or with germination, survival or flowering, and whether females and males differed in size or flowering that may cause observation bias.
We re-analysed published data from three natural S. herbacea populations near Davos Switzerland, Jakobshorn (J), Schwarzhorn (S) and Wannengrat (W), at elevations from 2000 to 2800 m above sea level (Wheeler et al., 2016), supplemented by 116 unpublished records from the same study. In the controlled experiment, we generated 29 hand-pollinated crosses in a natural alpine population of S. herbacea near Jakobshorn, Switzerland (46.7720N, 9.8554E, 2535 m above sea level) between June and August 2020, and collected mature fruits 4-6 weeks after pollination.  A total of 1521 seeds from 29 fam..., , # Data from: Female-biased population sex ratios caused by genetic rather than ecological mechanisms in dwarf willow (*Salix herbacea* L.)

[https://doi.org/10.5061/dryad.cnp5hqcd8](https://doi.org/10.5061/dryad.cnp5hqcd8)

Authors: Xiaomeng Mao, Andres J. Cortés, Christian Rixen, Sophie Karrenberg

This dataset contains all the data collected and analysed in the study. It includes two files: 1) data from the controlled experiments collected in this study (JEcol-2023-1073_controlled_measurements.csv), and 2) data of natural populations from a published dataset and unpublished records in Wheeler et al., 2016 (JEcol-2023-1073_natural_measurements.xlsx).

#### JEcol-2023-1073\_controlled\_measurements.csv:

Reproductive flowering, traits and growth data of *Salix herbacea* under controlled conditions.

* *Tray* & *Position*: location identity 
* *Family*, *ID* & *family_id*: individual identity
* *Final_Sex*: sex identified by reproductive flower after four growth periods ...