Meeting Abstract
Squamellaria are myrmecophytic epiphytes endemic to the islands of Fiji. A clade of six species of Squamellaria form an obligate farming symbiosis with a single ant species (Philidris nagasau), while three further basal Squamellaria species form non-farming facultative symbioses with generalist ants. Here we present the results of an experimental investigation comparing the thermal regulation properties of the ant-farmed and the non-farmed species of Squamellaria. Through continuous monitoring of the internal temperatures of the ant-plants, we observed that the ant-farmed Squamellaria (S. imberbis) can efficiently harness external wind for cooling its internal domatia, while their non-farmed relatives (S. wilkinsonii) do not harness wind. This observation is consistent with the differences between the two types of Squamellaria in internal connectivity and entrance holes distribution. Specifically, the ant-farmed Squamellaria have interconnected domatia and have entrance holes all around their external surfaces, while the non-farmed species have domatia with distinct cavities and have entrance holes almost exclusively at their base. Ant-farmed Squamellaria have lower thermal mass than non-farmed Squamellaria of similar sizes, thus their ability to utilize wind for convective cooling may be of crucial importance to their survival.
