Correlated Evolution of Acrobatic Display and Both Neural and Somatic Phenotypic Traits in Manakins (Pipridae)

Abstract

Brightly colored manakin (Aves: Pipridae) males are known for performing acrobatic displays punctuated by non-vocal sounds (sonations) in order to attract dull colored females. The complexity of the display sequence and assortment of display elements involved (e.g., sonations, acrobatic maneuvers, and cooperative performances) varies considerably across manakin species. Species-specific display elements coevolve with display-distinct specializations of the neuroanatomical, muscular, endocrine, cardiovascular, and skeletal systems in the handful of species studied. Conducting a broader comparative study, we previously found positive associations between display complexity and both brain mass and body mass across 8 manakin genera, indicating selection for neural and somatic expansion to accommodate display elaboration. Whether this gross morphological variation is due to overall brain and body mass expansion (concerted evolution) versus size increases in only functionally relevant brain regions and growth of particular body (“somatic”) features (mosaic evolution) remains to be explored. Here we test the hypothesis that cross-species variation in male brain mass and body mass is driven by mosaic evolution. We predicted positive associations between display complexity and variation in the volume of the cerebellum and sensorimotor arcopallium, brain regions which have roles in sensorimotor processes, and learning and performance of precisely timed and sequenced thoughts and movements, respectively. In contrast, we predicted no associations between the volume of a limbic arcopallial nucleus or a visual thalamic nucleus and display complexity as these regions have no-specific functional relationship to display behavior. For somatic features, we predicted that the relationship between body mass and complexity would not include contributions of tarsus length based on a recent study suggesting selection on tarsus length is less labile than body mass. We tested our hypotheses in males from 12 manakin species and a closely related flycatcher. Our analyses support mosaic evolution of neural and somatic features functionally relevant to display and indicate sexual selection for acrobatic complexity may increase the capacity for procedural learning via cerebellar enlargement and maneuverability via a reduction in tarsus length in species with lower overall complexity scores.

Ongoing introgression of a secondary sexual plumage trait in a stable avian hybrid zone

“…One such system is a hybrid zone between golden-collared manakins ( Manacus vitellinus ) and white-collared manakins ( Manacus candei ) in western Panama. Both are lek breeding species, in which males compete for mating opportunities by performing elaborate displays (Day et al, 2021; Kirwan & Green, 2011), leading to strong sexual selection on male traits (Snow, 2004). This hybrid zone was first characterized nearly 30 years ago by studying clinal variation in morphological and genetic traits that differ between the parental forms along ∼100 km region of a 570 km transect (Brumfield, Jernigan, McDonald, & Braun, 2001; Parsons, Olson, & Braun, 1993).…”

A novel exome probe set captures phototransduction genes across birds (Aves) enabling efficient analysis of vision evolution

“…Secondly, can we detect a pattern of positive selection in the vision exome unique to manakins, and specifically to their capacity for high‐speed vision? Manakins are a diverse family (Pipridae) of colorful, lek‐breeding Neotropical passerine birds that have courtship displays characterized by extremely high‐speed movements (see Bostwick & Prum, 2003; Day et al, 2021; Fusani et al, 2007; Fuxjager et al, 2016; Lindsay et al, 2016). They appear to respond to extremely rapid displays that can only be captured using high‐speed cameras, and thus manakins must have the flicker fusion threshold to detect those displays.…”