Long-term decrease in colouration: A consequence of climate change?

Climate change has been shown to affect fitness-related traits in a wide range of taxa; for instance, warming leads to phenological advancements in many plant and animal species. The influence of climate change on social and secondary sexual traits, that are associated with fitness due to their role as quality signals, is however unknown. Here, we use more than 5800 observations collected on two Mediterranean blue tit subspecies (Cyanistes caeruleus caeruleus and C. c. ogliastrae) to explore whether blue crown and yellow breast patch colourations have changed over the past 15 years. Our data suggests that colouration has become duller and less chromatic in both sexes. In addition, in the Corsican C.c.ogliastrae, but not in the mainland C.c.caeruleus, the decrease is associated with an increase in temperature at moult. Quantitative genetic analyses do not reveal any microevolutionary change in the colour traits along the study period, strongly suggesting that the observed change over tim..., This dataset includes 15-years of information about the blue tit colouration , , # Long-term decrease in colouration: A consequence of climate change?

[https://doi.org/10.5061/dryad.w6m905qr9](https://doi.org/10.5061/dryad.w6m905qr9)

## Description of the data and file structure

Files:

1. code_manuscript: contains the R code used to run the analysis and plots present in the
paper, the code also includes a sample code on how to obtain the colour variables from the
spectra using pavo. The description of the colour variables can be found in SM-1.
2. data_base_colour.csv: data set containing the information required for running the analyses in
sections one, three and four. It contains the following information:
a. cod -> identity of the individuals.
b. yr/yrcont -> year, one is meant to be coded as a factor and the other one as
continuous in the analyses (see code).
c. isla -> described whether the observations were obtained from Corsica (isla=2) or
Rouviere (isla=1).
d. bb -> blue crown brightness (colour variable)....