ESHS/HSS Annual Meeting

“The roles of Biological Systematics and Plate Tectonics in 20th century Historical Biogeography”

• In Event: Histories of Biogeography Part 2

English Abstract

By the start of the 20th century the ecological/historical division of biogeography had been established. Historical biogeography focused on past continental-wide distributions of taxa and endemism, while ecological biogeography was concerned with populations and habitats. The development of historical biogeography was central in the mobilist and to an extent the fixist (i.e., land bridges) narratives within the continental drift debate. With the development of phylogenetic systematics and plate tectonics, the fixist/mobilist divide moved into biogeography with dispersalists preferring a fixed Earth compared to those on the vicariance side who preferred continental drift. As this divide disappeared in geology it continued in biogeography with dispersalists accepting plate tectonics but rejecting a wholesale vicariant explanation for continental-wide and global distributions. With the development of new computational methods these ideas were inferred from a combination of graphs (i.e., phylogenetics) and taxic distributions to form areagrams. As the validity of identifying ancestors were brought into question within systematics during the cladistic revolution of 1970s, centres of origin and directions of dispersal were undisputed in biogeography. With the onset of molecular phylogenetics in the 1980s, a new cohort of biologists had entered biogeography effectively revisiting the dispersal/vicariance debates of the previous decades. The lack of a working knowledge of plate tectonics meant that biologists incorrectly formed the notion that taxic distributions were geologically young. Dismissing plate tectonics as relevant had meant dispersalism was the primary interpretation of taxic distribution in historical biogeography, an idea that was challenged by the discovery of very old dates in 21st century studies using molecular clocks.

Author

• Malte Ebach, UNSW, Australian Museum