Figures and data
The presence and absence of ocelli in queens and workers across ants.
(A) Ocelli develop in the winged reproductive castes across species of formicinae ants exemplified by Camponotus floridanus, Cataglyphis bicolor, Polyrachis bihamata and Dinomyrmex gigas (white dashed circles). Ocelli in the worker caste of formicine ants (white dashed circles) are evolutionarily labile, showing no ocelli (Camponotus floridanus), all 3 ocelli in all individuals of the worker caste (Cataglyphis bicolor) or only 1 ocellus in only the soldiers (Polyrachis bihamata and Dinomyrmex gigas). (B) Schematic representation of the ocelli GRN in Drosophila melanogaster adapted from Jean-Guillaume & Kumar (2022)(Jean-Guillaume and Kumar 2022). The genes investigated in this study are highlighted in orange. Arrowheads indicate activation, and bars indicate repression. Queens are scaled to 1mm, and workers and soldiers are scaled according to the queen of each species. Asterisks indicate that C. floridanus was used for gene expression studies. Photos from Antweb (AntWeb 2024)
Ancestral state reconstruction of ocelli reveals three well-supported reversions of ocelli in the worker caste in the tribe Camponotini.
Maximum clade credibility tree of formicine ants from Blaimer et al.(Blaimer et al. 2015). Ancestral state reconstruction for the presence (blue-colored circles) and absence (red-colored circles) of ocelli based on stochastic character mapping. Each pie chart for the nodes represents the posterior probabilities, scaled by the weight of evidence for each model. Species used to analyze ocelli GRN expression are highlighted in gray, and the species that re-evolved one ocellus is indicated as partial re-evolution. Three tribes within the Formicinae are marked (Melophorini, Plagiolepidini, Lasiini, Myrmelachistini and Camponotini) by arrows.
Characterizing development of the eye-antenna imaginal disc in worker castes of C. floridanus using orthodenticle-1 (otd-1), distal-less (dll) and eyeless (ey) gene expression to mark the developing head capsule and ocelli, antenna, and eyes.
Fluorescent images in panels A, F, K, P, U represent the development of the entire eye-antenna imaginal disc marked with the nuclear stain DAPI across all four larval stages, where the head capsule region is labelled as ‘Hc’, the antennal region is labelled as ‘An,’ and the eye region is labelled as ‘Eye.’ Panels B, G, L, Q, V represent the development of the head capsule (Hc) marked by the genes orthodenticle-1 (otd-1 in magenta); Panels (C,H,M,R,W) represent the antennal region marked by distal-less (dll) in green color; and Panels (D,I,N,S,X) represent the eyes (Eye) is eyeless (ey) (yellow); Panels. (A-E) First instar. Note: the green or yellow staining outside of the structures highlighted by the white arrows in panels C, D and E is background noise. (F-J) second instar, (K-O) third instar, (P-T) fourth instar worker-destined larvae and, (U-Y). Fourth instar soldier-destined larvae. All images are to scale.
Latent expression of otd-1 and hh genes in the ocelli GRN in workers and soldiers of C. floridanus during the 4th larval instar.
Expression of orthodenticle-1(otd-1) is yellow, and hedgehog (hh) is magenta. Early 4th instar; (A, B) males (C, D) soldiers and (E, F) workers. Late 4th instar: (A,’ B’) males (C’, D’) soldiers and (E’, F’) workers.
Latent Expression of toy, eya, and so within the ocelli GRN in the developing worker and soldiers of C. floridanus
Expression of toy (green), eya (yellow), and so (magenta). Early 4th instar;(A to C) males, (D to F) soldiers and (G to I) workers. Late 4th larvae stage;(A’ to C’) males, (D’ to F’), soldiers and (G’ to I’).
Latent expression of the ocelli GRN in the eye-antennal disc in worker larvae of Polyrachis rastellata at 4th larvae stage.
Expression of selected genes otd-1 (yellow), eya (yellow), and so (magenta) at early 4th instar larvae.
Development of rudimentary ocelli in worker and soldier pupae of C. floridanus.
(A) SEM showing ocelli development in males at mid-stages of pupal development. SEM showing development of rudimentary ocelli on (B to E) soldiers and (F to I) minor workers during early (day 6-7), mid (day 16-17), and late (19-20) pupal development. These ocelli rudiments disappear prior to adult stage (E and I).
Simplified Gene tree based on maximum likelihood showing relationships between orthodenticle (otd) orthologs in Drosophila melanogaster, Apis mellifera, Nasonia vitripennis, Tribolium castaneum, Acythosiphon pisum and Camponotus floridanus.
Branch values are bootstrap support (%). Colors: otd-2 (red), otd-1 (blue)
Model selection under maximum likelihood estimation implemented in phytools (Revell 2012).
The results are ordered by decreasing Akaike Weights (w).
