Conservative whole-organ scaling contrasts with highly labile suborgan scaling differences among compound eyes of closely relatedFormicaants.
Static allometries determine how organ size scales in relation to body mass. The extent to which these allometric relationships are free to evolve, and how they differ among closely related species, has been debated extensively and remains unclear; changes in intercept appear common, but changes in slope are far rarer. Here, we compare the scaling relationships that govern the structure of compound eyes of four closely related ant species from the genusFormica. Comparison among these species revealed changes in intercept but not slope in the allometric scaling relationships governing eye area, facet number, and mean facet diameter. Moreover, the scaling between facet diameter and number was conserved across all four species. In contrast, facet diameters from distinct regions of the compound eye differed in both intercept and slope within a single species and when comparing homologous regions among species. Thus, even when species are conservative in the scaling of whole organs, they can differ substantially in regional scaling within organs. This, at least partly, explains how species can produce organs that adhere to genus wide scaling relationships while still being able to invest differentially in particular regions of organs to produce specific features that match their ecology.
School of Life Sciences Centre for Computational Neuroscience and Robotics University of Sussex Falmer Brighton UK.
Craig D
CD
Perl
School of Life Sciences Centre for Computational Neuroscience and Robotics University of Sussex Falmer Brighton UK; Present address: Department of Physiology, Development and Neuroscience University of Cambridge Downing Site, Downing Street Cambridge CB2 3EG UK.
Sergio
S
Rossoni
School of Life Sciences Centre for Computational Neuroscience and Robotics University of Sussex Falmer Brighton UK.
Jeremy E
JE
Niven
evolutionary allometry; facet; static allometry; wood ant