Distribution of iridescent colours in hummingbird communities results from the interplay between selection for camouflage and communication

Hugo Gruson (1) , Marianne Elias (2) , Juan L. Parra (3) , Christine Andraud (4) , Serge Berthier (5, 6) , Claire Doutrelant (1) , Doris Gomez (1)

1 CEFE - Centre d’Ecologie Fonctionnelle et Evolutive
2 ISYEB - Institut de Systématique, Evolution, Biodiversité
3 Grupo de Ecología y Evolución de Vertrebados
4 CRCC - Centre de Recherche pour la Conservation des Collections
5 INSP - Institut des Nanosciences de Paris
6 INSP-E4 - Nanostructures et optique

Identification errors between closely related, co-occurring, species may lead to misdirected social interactions such as costly interbreeding or misdirected aggression. This selects for divergence in traits involved in species identification among co-occurring species, resulting from character displacement. On the other hand, predation may select for crypsis, potentially leading co-occurring species that share the same environment and predators to have a similar appearance. However, few studies have explored how these antagonistic processes influence colour at the community level. Here, we assess colour clustering and overdispersion in 189 hummingbird communities, tallying 112 species, across Ecuador and suggest possible evolutionary mechanisms at stake by controlling for species phylogenetic relatedness. In hummingbirds, most colours are iridescent structural colours, defined as colours that change with the illumination or observation angle. Because small variations in the underlying structures can have dramatic effects on the resulting colours and because iridescent structures can produce virtually any hue and brightness, we expect iridescent colours to respond finely to selective pressures. Moreover, we predict that hue angular dependence - a specific aspect of iridescent colours - may be used as an additional channel for species recognition. In our hummingbird assemblages in Ecuador, we find support for colour overdispersion in ventral and facial patches at the community level even after controlling for the phylogeny, especially on iridescence-related traits, suggesting character displacement among co-occurring species. We also find colour clustering at the community level on dorsal patches, suspected to be involved in camouflage, suggesting that the same cryptic colours are selected among co-occurring species.

Mots clés: Ecuador; Community structure; Angle-dependent colouration; Structural colours; Camouflage; Reproductive Character Displacement; Agonistic Character Displacement

Domaines: Biodiversité et Ecologie; Biophysique [physics.bio-ph]; Optique [physics.optics]; Evolution [q-bio.PE]; Systématique, phylogénie et taxonomie

Hugo Gruson, Marianne Elias, Juan L. Parra, Christine Andraud, Serge Berthier, et al.. Distribution of iridescent colours in hummingbird communities results from the interplay between selection for camouflage and communication. Peer Community Journal, 2021, 1, pp.e64. ⟨10.24072/pcjournal.7⟩. ⟨hal-02372238v3⟩