Shifts in thermal preference of introduced Asian house geckos (Hemidactylus frenatus) in temperate regions of southeastern Australia.

Despite its tropical origin, the Asian house gecko (Hemidactylus frenatus) is currently invading higher latitudes around the world. In this study, we investigated whether the introduced geckos in the subtropical/temperate region of southeastern Australia have shifted their thermal biology to cope with colder temperatures. In the lab, we measured the body temperatures of geckos from Thailand and Australia in a cost-free thermal gradient. Native H. frenatus from Thailand displayed a diel pattern of thermoregulation. Geckos maintained higher body temperatures during mid-afternoon and at dusk but selected cooler temperatures during the night. Introduced geckos showed a similar pattern of thermoregulation, but selected lower body temperatures in summer (mean = 28.9 °C) and winter (mean = 25.5 °C) than native geckos (mean = 31.5 °C). While the Asian house geckos from Thailand did not alter their body temperatures after feeding, their conspecifics from southeastern Australia selected body temperatures that were 1.6-3.1 °C higher after feeding. In conclusion, our study shows that invasive house geckos in Australia have shifted their preferred body temperatures downwards relative to their native conspecifics in Thailand, presumably as a result of plasticity or natural selection. Our findings suggest that these tropical geckos have adapted to colder regions, and thus, they may spread much further than expected for a tropical ectotherm.

Genome-wide data help identify an avian species-level lineage that is morphologically and vocally cryptic.

Species identification has traditionally relied on morphology. However, morphological conservatism can lead to a high incidence of cryptic species, as characters other than morphological ones can be biologically important. In birds, the combined application of bioacoustic and molecular criteria has led to an avalanche of cryptic species discoveries over the last two decades in which findings of deep vocal differentiation have usually been corroborated by molecular data or vice versa. In this study, we use genome-wide DNA data to uncover an unusual case of cryptic speciation in two species within the South-east Asian Streak-eared Bulbul Pycnonotus blanfordi complex, in which both morphology and vocalizations have remained extremely similar. Despite a considerable pre-Pleistocene divergence of these two bulbul species, bioacoustic analysis failed to uncover differences in their main vocalization, but examination of live birds revealed important differences in eye color that had been overlooked in museum material. Our study demonstrates that genome-wide DNA data can be helpful in the detection of cryptic speciation, especially in species that have evolved limited morphological and behavioral differences.