Animals use mating traits to compete for, attract, and choose mates. Because mating traits influence mate choice, the divergence of mating traits between populations can result in reproductive isolation. This can occur without associated morphological divergence, producing reproductively isolated cryptic species that are visually indistinguishable. Thus, identifying the mating traits in morphologically conservative groups is key to resolving diversity and speciation processes. Lizards contain many such groups, with phylogeographic studies often revealing highly divergent but morphologically cryptic lineages within species. Considering that cryptic lizard species can be sympatric but morphologically indistinguishable, we hypothesize that candidate species will exhibit divergent pheromones and that pheromones will have typically diverged more than morphology. To test this, we used gas chromatography to characterize pheromones (epidermal pore secretions) from 10 genetically divergent lineages of the Bynoe's gecko (Heteronotia binoei) species complex in northern Australia. Multivariate analyses of pheromone blends and morphology indicate that pheromones are lineage specific and have diverged relatively more than morphology. Such specificity suggests that pheromones influence behavioral isolation in this morphologically conservative lizard radiation. These results suggest that pheromone data may unlock the tremendous cryptic diversity currently being uncovered in many lizard groups.

There is increasing concern about the ecological effects of light pollution, as artificial lighting spreads with urban expansion. While artificial lighting can negatively affect some species, others use it in novel ways. In tropical and subtropical regions, artificial lighting has created a novel niche: the 'night light' niche. Geckos living as human commensals (house geckos) are apparently well adapted to occupy this niche. In an urban area in north-eastern Australia, we found that the invasive Asian house gecko Hemidactylus frenatus (Gekkonidae) occupies a broader range of light environments in the field than does the native gecko Gehyra dubia (Gekkonidae). Experimental removal of the invasive species from a building indicated that it did not behaviourally influence the light environments chosen by the native species in the short term; they continued to use darker areas even after the invasive species was removed. In Y-maze experiments, neither species showed a significant preference for light or dark areas; however, preliminary data suggest the invasive species was more willing to explore the Y-maze than the native species. The willingness of H. frenatus to forage closer to lights, where insect abundance is typically higher, might account for its success as a global invader of human environments, even in areas where other gecko species are established.

Signalling systems serve important functions in animals that influence survival and reproduction: finding and choosing mates; orientation; warning, detecting and assessing competitors; recognizing kin and familiars; deceiving rivals, prey and predators; and alerting others of-and being alerted to-danger (Bradbury & Vehrencamp, 2011). These functions influence the fitness of both signallers and receivers; an individual that cannot attract a mate or that does not heed a warning call in the presence of a predator will have fewer offspring. To function effectively, a signal must be transmitted through and perceived against its background environment (Endler, 1992). For example, blue colouration is an ineffective signal for fish inhabiting murky water where blue wavelength light is scarce

Selection for effective locomotion can lead to specialized morphological structures. Adhesive toepads, which have arisen independently in different lizard clades, facilitate the use of vertical and inverted substrates. Their evolution is poorly understood because functionally intermediate morphological configurations between padless and pad-bearing forms are rare. To shed light on toepad evolution, we assessed the subdigital morphology of phylogenetically distinct lineages of the Bynoe’s gecko species complex (Heteronotia binoei). Most populations of H. binoei are terrestrial, but two relatively distantly related saxicoline (rock-dwelling) lineages have enlarged terminal subdigital scales resembling toepads. We reconstructed the ancestral terminal subdigital scale size of nine lineages of H. binoei in eastern Australia, including these two saxicoline lineages. Additionally, we compared the subdigital microstructures of four lineages: the two saxicoline lineages and their respective terrestrial sister-lineages. Surprisingly, all four lineages had fully developed setae, but the setae of the two saxicoline lineages were significantly longer, branched more often and were more widely spaced than the terrestrial sister-lineages. We conclude that the saxicoline lineages represent examples of parallel evolution of enlarged adhesive structures in response to vertical substrate use, and their morphology represents a useful model as an intermediate state in toepad evolution.