Evolution of visual signals in the antwrens of the tribe Formicivorini (Aves, Thamnophilidae)

Thamnophilidae is a large family of insectivorous passerine birds which has high phenotypic, ecological, and behavioural diversity. One of the best supported groups in the family by recent molecular studies is the tribe Formicivorini, which contains 39 species, commonly known as antwrens. They are small birds that inhabit a wide diversity ofhabitats and exhibit contrasting patterns of foraging behavior, acoustic and visual signals that are linked to environmental conditions. In addition, they are sexually dimorphic in plumage anddifferences among species are associated to both color and plumagepatterns. Our main objectives were to 1) quantify the variation of visual signals in the Formicivorini, and 2) assess to what extent such variation is associated to foraging behavior and habitat. We collected plumage data using standardized photos of taxidermised museum specimens. Males and females of each species were photographed in such way that the following regions were available for analyses: head, throat, cheek, belly, back, wings, flanks and tail. The calibration and plumage values were made in ImageJ software. Preliminary results indicate that throat, belly and flanks are lighter and more diverse than the wing, head, back and tail. In relation to sexual dimorphism, throat and belly regions are more different between males and females than other body regions. The spotted and streaked patterns of the different body regions vary inside the group, but are not different between sexes. Lastly, we found that variation in coloration seems to be associated with habitat.