Testing Darwin’s hypothesis on the evolution of ornamental eyespots in peafowl and their relatives Rebecca T. Kimball, Keping Sun, Kelly Meicklejohn, Edward Braun, Brant Faircloth, Travis Glenn Darwin • “As no ornaments are more beautiful than the ocelli on the feather of various birds…they deserve to be especially noticed.” (The Descent of Man: And Selection in Relation to Sex) Hypothesis • Darwin suggested a gradual evolution from the simple spots and ocelli of some species, to the magnificent ocelli of peafowl Ocelli in other taxa • Noted similarities between peafowl (Pavo), argus pheasant (Argusianus), and peacock pheasants (Polyplectron) Relationships • Based on the shared ocelli, some classifications have united the peafowl, peacock pheasants and argus pheasants into a clade • However, molecular phylogenies have not been able to resolve relationships of these taxa with confidence What we do know • Based on molecular phylogenies: – The peafowl are most closely related to the Congo peafowl (which lacks ocelli) – The argus pheasant is most closely related to the crested argus (which lacks ocelli) • So the simplest interpretation of Darwin’s ideas, that the ocellated taxa would be each other’s closest relatives, is not supported Ocelli can be lost • Within the peacock pheasants, one species lacks complex ocelli – This appears to be a derived species – So loss of ocelli does occur • A modification of Darwin’s hypothesis might be that ocelli evolved once, but have been lost in Congo peacock, crested argus, and one species of peacock pheasant To understand pathway • Need to obtain a well-resolved phylogeny of the genera with ocelli, and all possible related taxa • To determine appropriate taxon sampling: – Went through the literature – Analyzed available mitochondrial data from GenBank (sampled over 90% of species in family) Mitochondrial data • Many basal nodes were poorly supported – As expected, gives no support for placement of three clades with ocellated species Peacock pheasants • Mitochondrial data did suggest that peacock pheasants might be related to two non- ocellated taxa With these candidate species • To test relationships among candidate species • We collected data from nearly 2000 ultra- conserved elements – Sampled three genera with ocelli – Sampled non-ocellated relatives – Other putative sister taxa based on the literature – Multiple outgroups What about evolution of ocelli? • Reconstruction of ancestral state using maximum likelihood Ancestral state equivocal One gain P. chalcurum P. bicalcaratum P. inopinatum P. katsumatae 5 losses P. germaini P. malacense (6 total P. schleiermacheri P. napoleonis evolutionary G. spadiceus steps) G. lunulata H. sanguiniceps P. muticus P. cristatus A. congensis R. ocellata A. argus Two gains P. chalcurum P. bicalcaratum P. inopinatum P. katsumatae 3 losses P. germaini P. malacense (5 total P. schleiermacheri evolutionary P. napoleonis G. spadiceus steps) G. lunulata H. sanguiniceps P. muticus P. cristatus A. congensis R. ocellata A. argus Three gains P. chalcurum P. bicalcaratum P. inopinatum P. katsumatae 1 loss P. germaini P. malacense (4 total P. schleiermacheri P. napoleonis evolutionary G. spadiceus steps) G. lunulata H. sanguiniceps P. muticus P. cristatus A. congensis R. ocellata A. argus Gain(s) of ocelli Gains Differences among ocelli • There are differences among ocelli in species – Ocelli not only vary in appearance (which does not refute homology) – Ocelli are located on different types of feathers Pre-existing sensory bias • Independent evolutionary origins of a presumably sexually selected trait could be do to a pre-existing bias for that trait • In pheasants, many displays accentuate eyes Conclusions • Although the phylogeny now appears to be resolved with confidence – Evolutionary pathway of ocelli is still not clear – Other types of information, such as development of ocelli on feathers, might shed light on whether ocelli have had one, two or three origins in these taxa Acknowledgements Kimball-Braun Lab • Tissues: LSUNMS, San Diego Zoo, Ron Sumner, Susan Lattimer • HiPerGator (UF Research Computing) Keping Sun supported by China Scholarship Council and Northesast Normal DEB 1118823 Univeristy to RTK and ELB .