Abstract
The historic richness of most taxonomic groups increases substantially over geological time. Explanations for this fall broadly into two categories: bias in the fossil record and elevated net rates of diversification in recent periods. For example, the break up of Pangaea and isolation between continents might have increased net diversification rates. In this study, we investigate the effect on terrestrial diversification rates of the increased isolation between land masses brought about by continental drift. We use ecological neutral theory as a means to study geologically complex scenarios tractably. Our models show the effects of simulated geological events that affect all species equally, without the added complexity of further ecological processes. We find that continental drift leads to an increase in diversity only where isolation between continents leads to additional speciation through vicariance, and where higher taxa with very low global diversity are considered. We conclude that continental drift by itself is not sufficient to account for the increase in terrestrial species richness observed in the fossil record.
Highlights
Numbers of taxa in the fossil record show a dramatic increase through geological time
We find that continental drift leads to an increase in diversity only where isolation between continents leads to additional speciation through vicariance, and where higher taxa with very low global diversity are considered
We have investigated whether continental fragmentation could cause the increase in species richness observed in the fossil record based purely on neutral processes of dispersal, speciation and drift among ecologically equivalent species
Summary
Numbers of taxa in the fossil record show a dramatic increase through geological time. Terrestrial tetrapods are well documented in the fossil record and show a sharp increase in diversity over time (figure 1). Periods of steep increase in diversity coincide with events such as the initial break up of Pangaea at ca 180 million years ago (Ma) [3]. These include, for example, the seed-bearing plants which underwent a massive increase in diversity [6,7,8]. Beetles (Coleoptera) experienced a significant rise in species richness around the early Cretaceous [8], possibly associated with the evolution of the first angiosperms [9]
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