Chasing the Dragon: The Resilience of a Species to Climate Change in the Wet Tropics, Australia

Abstract

Throughout history, climatic changes have caused environmental systems to shift and have influenced biotic assemblages. Most of these changes have occurred slowly, over millions of years, enabling species to either adapt to new conditions, endure the changes, or shift distributions to maintain their habitat requirements. Due to the fast rate at which climate change is currently occurring, it is unknown if species will be able to use these mechanisms to successfully respond to this rapidly changing environment. Areas that have small geographical extents, elevated uplands and high numbers of endemic species, such as the Wet Tropics in north-eastern Queensland, are expected to be particularly vulnerable to climate change. The endemic species in this at-risk area are also expected to be more susceptible to climate change. The endemic Boyd’s forest dragon (Hypsilurus boydii, Macleay) is a highly camouflaged, large lizard that inhabits lowland and upland forests from the northern to the southern boundary of the Wet Tropics. Determining how H. boydii has responded to previous climate change may give insight into how the species may respond to future climatic changes. The main aims of this study were to understand how geographical features and climate have influenced the genetic makeup, morphology and distribution of H. boydii, and to use this information to determine how climate change may influence future populations. This study used genetic analyses to identify evolutionary and geographical relationships across the Wet Tropics (north vs. south of the Black Mountain corridor [BMC] and upland vs. lowland) and within each of these regions; explore morphological variation across the regions and examine conformity to three eco-geographical rules (Bergmann’s rule, Allen’s rule, and the isolation rule); and attempt to predict species distribution patterns of the species throughout the Wet Tropics during past, present and future climatic scenarios. Seventy-seven dragons were collected from nine sites across the Wet Tropics, with a blood sample (for genetic analyses) taken from each individual, 47 of these individuals, from eight of the sites, were sampled for morphological measurements. Due to the cryptic and ambush nature of the species, sample sizes were low and uneven.