Fig 1.
Example of a colony of Platycerium bifurcatum.
Each individual produces two types of fronds: sterile nest fronds that senesce almost immediately after maturation but do not abscise after death, and reproductive strap fronds which are typically long, narrow, and lobed, and remain photosynthetic at maturity. Different individuals tend to produce morphologically variable nest and strap fronds dependening on the position along the vertical grandient of the colony.
Fig 2.
Examples of colonial and solitary Platycerium species.
The genus currently comprises 18 species distributed across subtropical and tropical regions, from Peru to Madagascar to Indochina and Australia. All species are within-individual frond dimorphic, and produce sterile “nest” fronds and reproductive “strap” fronds. A) P. bifurcatum; B) P. coronarium © ayuwat; C) P. ridleyi © ayuwat; D) P. alcicorne © Jean-Philippe; E) P. madagascariense © Vincent Porcher; F) P. superbum © Trina. All photos, except for P. bifurcatum were taken from iNaturalist.
Fig 3.
Results of ancestral state reconstruction, showing the evolutionary history of within-individual frond dimorphism across the Platycerium phylogeny.
The ancestor of all extant Platycerium species was likely frond dimorphism, and frond dimorphism was never lost across the phylogeny.
Fig 4.
Results of ancestral state reconstruction, showing the evolutionary history of coloniality across the Platycerium phylogeny.
The ancestor of all extant Platycerium species was likely colonial, with monomorphic colony members. The presence of morphologically variable colony members is a derived condition and evolved twice, once in the ancestor of P. bifurcatum, P. willincki, P. veitchii and P. hillii, and once in the ancestor of P. quadridichotomum, P. madagascariense, P. alcicorne, P. ellisii, P. angolense, P. stemaria and P. andinum. Coloniality was also lost twice, once in P. ridleyi and once in the ancestor of P. wallichii, P. superbum, P. wandae, P. grande and P. holttumii. Finally, coloniality with morphologically differentiated individuals was likely also lost twice, once in P. madagascariense and once in P. andinum.
Table 1.
Results of MCMCglmm models, always using coloniality as the dependent variable. Coloniality negatively correlates with nest frond length and width, and positively correlates with the simultaneous development of sterile and fertile segments of strap fronds. Coloniality is also unrelated to strap frond length, the colour of nest fronds at maturity and the presence of water storage.