THE PALEOCLIMATIC RANGE OF SOUTHERN HEMISPHERE RELICT CONIFER GENERA

Studying the Miocene is critical for understanding modern and future climate analogs. The Middle Miocene Climatic Optimum (MMCO) has been proposed as a good analog for future climate conditions as well as a reference for testing models upon. The Middle Miocene is defined by two distinct periods: MMCO, and the Middle Miocene Glaciation (MMG). When the continents of the Southern Hemisphere separated, the organisms were forced to adapt to their new conditions; those that did not adapt would not survive. Here we test the climate niche adaptation of four distinct endemic conifers that were very abundant in the Miocene. The hypothesis is that following the Middle Miocene Climate Transition (MMCT), these four conifers climatic extent niche decreased in size, and favored both wetter and cooler climates. All four of the genera: Halocarpus, Wollemia, Microcachrys and Lagarostrobos, have survived from at least the Middle Miocene to the modern day. These genera now have a very restricted climatic and geographic range within Australasia. This study aims to analyze how the climatic extent changed as a result of the MMCT, and the transition between the Middle Miocene and modern day. The results suggest that there is no statistically significant difference between the MMG and MMCO precipitation and temperature values of all species. The results also suggest that Halocarpus, Microcachrys and Lagarostrobos all have elevated average surface temperatures, and precipitation values in the modern day compared to the Middle Miocene. The low sample size of Wollemia warrants further study to form significant conclusion.