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Morphology and allometry suggest multiple origins of rostral appendages in S ri Lankan agamid lizards
Author(s) -
Johnston G. R.,
Lee M. S. Y.,
Surasinghe T. D.
Publication year - 2013
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.2012.00962.x
Subject(s) - appendage , biology , sexual selection , sexual dimorphism , sauria , zoology , allometry , phylogenetic tree , clade , morphology (biology) , evolutionary biology , anatomy , lizard , ecology , biochemistry , gene
Rostral appendages occur in a very small number of species spread across the entire clade of iguanian lizards. The five species of S ri L ankan agamid lizards of the poorly known endemic genus C eratophora show remarkable variation in the morphology and development of rostral appendages, which are absent in two species and present in the other three. Parsimony and B ayesian comparative methods do not robustly resolve whether the appendage evolved once (with two losses), twice (with one loss) or thrice independently. The appendage in C . tennentii is leaf‐shaped, present in juveniles and monomorphic in adults. It is quite dissimilar to the appendages in C . aspera and C . stoddartii which are horn‐shaped, absent in juveniles and dimorphic in adults. C eratophora stoddartii is more closely related to C . erdeleni , which lacks the rostral appendage, than it is to C . aspera . The combined morphological, allometric and phylogenetic evidence suggests rostral appendages evolved three times within C eratophora : perhaps once as a result of natural selection for crypsis (in C . tennentii ) and twice as a result of sexual selection (in C . aspera and C . stoddartii ). Our results suggest that these unusual ornaments can evolve by more than one mechanism and more readily than is suggested by their low frequency among iguanian lizards.