Australia: The Land Where Time Began

A biography of the Australian continent 

Cambrian Explosion - The Ediacaran-Cambrian Metazoan Diversification - Ecological Drivers

Many modern ecosystems are structured to a significant degree by organismal modifications of their physical and chemical environment, and according to the authors¹ it is suggested by experimental evidence that diversity can be increased by such modifications. Such activities perform an  important function in connecting ecology and evolution, though less is known of the impact such influences have on macroevolution, especially in connection with their role at times such as when major evolutionary transitions are taking place. The appearance and early diversification of virtually all major marine animal clades and the establishment of ecosystems dominated by metazoans was encompassed by the metazoan diversification that occurred during the Ediacaran-Cambrian transition. In this paper the authors¹ assess the role played by positive ecological feedbacks by using a new compilation of the first appearance of all metazoan phyla, classes; orders and equivalent stem taxa, as well as from a compendium on fossils from the Early to middle Cambrian of China that was published previously. It is revealed by the results obtained by the authors¹ that during the Ediacaran the feedback was relatively weak, though during the Cambrian the increase was substantial, especially through bioturbation and the first appearance of a number of "structural engineers", among which were the sponges. Filtering and bioturbation appear to have had the largest impact as a result of their role in the chemical modification of the environment. According to the authors¹ taxic diversity data is a poor proxy for abundance, or for the actual impact these activities have on the environment. The authors¹ suggest standardised assessments on the abundance of taxa with different roles in the ecology of the environment will be required for future assessments the ecological feedbacks have on this event.

Sources & Further reading

1. Erwin, Douglas, H, and Sarah Tweedt. "Ecological Drivers of the Ediacaran-Cambrian Diversification of Metazoa." [In English]. Evolutionary Ecology 26, no. 2 (2012/03/01 2012): 417-33.