Ecological, genetic and geographical divergence explain differences in colouration among sunbird species (Nectariniidae)

Ecology and Evolution, vol. 14, pp. e11427

Abstract

How extravagant ornamental traits evolve is a key question in evolutionary biology. Bird plumages are among the most elaborate ornaments, displaying almost all colours of the rainbow. Why and how birds evolved to be so colourful remains an open question with multiple and sometimes competing hypotheses. Different colours in different patches (i.e. body parts) might have different functions and thus result from different forms of selection (e.g. natural vs. sexual selection). Here we test the influence of three factors on colour diversity in sunbirds: (1) geographical distance, (2) differences in light environment and (3) phylogenetic distances. We show that both natural and sexual selection affect the evolution of sunbird colouration, but that their extent and direction differs between sexes, and varies with the extent of species overlap and across different patches on the body. Even though overlap in light environment partially explains colour differences among species, no colour metric (brightness, hue or chroma) covaries with light environment. Our results suggest that multiple forms of selection influence the colouration of different colour patches in different ways across an organism's body, highlighting the need to investigate colouration as a network of individual but inter-connected colour patches. These results are likely to be generalizable across the multitude of colourful animals.

Authors 6

1. Michaël P. J. Nicolaï corresponding

   Ghent University

   Affiliation as printed

   UGent Gent Belgium

2. Svana Rogalla

   Ghent University · Instituto Biofisika

   Affiliation as printed

   Biofisika Institute Leioa Spain

   UGent Gent Belgium

3. Masoud Yousefi

   Damghan University · Leibniz Institute for the Analysis of Biodiversity Change

   Affiliation as printed

   Damghan University Damghan Iran

   Leibniz Institute for the Analysis of Biodiversity Change (LIB), Museum Koenig Bonn Germany

4. Rauri C. K. Bowie

   Museum of Vertebrate Zoology · University of California, Berkeley

   Affiliation as printed

   Museum of Vertebrate Zoology and Department of Integrative Biology University of California Berkeley California USA

5. Liliana D’Alba Aachen Naturalis Biodiversity Center Leiden The Netherlands

   Naturalis Biodiversity Center · Ghent University

   Affiliation as printed

   Naturalis Biodiversity Center Leiden the Netherlands

   UGent Gent Belgium

6. Matthew D. Shawkey

   Ghent University

   Affiliation as printed

   UGent Gent Belgium