Emeritus Professor Mike Crisp ‘Callitris: an Evolutionary Chronicle of Extinction, Survival and Re-diversification '
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Thursday, 21 March 2019 - 12:30pm
Mike, from the ANU, will discuss how the cypress family of conifers has been an important model for studying the way organisms came to be distributed, where they are found today, and how ancient changes in the earth's environment influenced their distribution
Abstract
The cypress family of conifers (Cupressaceae) has been an important model for studying how organisms came to be distributed where they are found today, and how ancient changes in the earth's environment influenced their distribution. An exceptional fossil record and new DNA sequences from living species have allowed us to better assess their extinction and, in some lineages, rediversification after past global upheavals. We have reassessed some key fossils and how they relate to living species. By comparing DNA data with the fossil record, we have teased apart the contributions of continental drift and long-distance dispersal in shaping the distribution of cypresses across the southern hemisphere. In the Australian genus Callitris, we found a signature of extinction, around 30 million years ago, in both the DNA and the fossil record. However, Callitris survived, adapted and expanded into the present-day dry, fire-prone biomes. Serotiny, a key adaptation to fire, evolved in Callitris soon after the biome shift. The fossil record is essential to understanding lineage turnover but taxonomic uncertainty of fossils undermines biogeographic reconstructions.
Biography
Dr Mike Crisp is currently Emeritus Professor, ANU, Research School of Biology. His broad interests are the evolution, biodiversity and biogeography of the Australian and global floras arising from a lifelong study of the systematics and taxonomy of Australian plants. Mike’s research is focused on two overarching questions: (i) How is biodiversity distributed in space and what factors limit distribution? And (ii) how have species and their traits diversified through time and what drives that diversification?
