Uncovering Morphological and Cellular Patterns of Gliding Membrane Formation in the Gecko, Hemidactylus platyurus

Abstract

Passive flight has evolved multiple times across different species through the use of gliding membranes called patagia, but there is little known about the development of these structures. Although there is existing research on mammal patagium development that provides insight into its tissue structure and cellular activity patterns, there is no similar data for other gliding organisms. This research aims to uncover the developmental mechanisms underlying patagium formation in reptiles. Specifically, I compare the development of the patagium of a gliding gecko, Hemidactylus platyurus, to the lateral trunk skin of its non-gliding relative, Hemidactylus turcicus. Using histological and fluorescent assays, I characterize the tissue composition, growth patterns, and cell density of developing gecko trunks across embryonic stages. These results reveal that H. platyurus patagium development is marked by the early formation of a dermal condensate of cells early in development, which persists and expands as the patagium grows and is absent in non-gliding trunk tissue. This pattern of increased cell density mirrors the development of the patagium primordium seen in marsupial sugar gliders, suggesting that there exist shared developmental features underlying patagium formation across distant lineages. Although attempts to detect patterns of cell proliferation and apoptosis in H. platyurus tissue were inconclusive, this work highlights potential early developmental constraints in the evolution of gliding membranes and offers new insights into how convergent structures repeatedly arise across vertebrates.