The end-Permian mass extinction event was the big daddy of all the known mass extinction events. Life on the planet Earth was almost entirely wiped out. A new paper explores the post-extinction recovery of ecological systems.
Post extinction dynamics can be understood in relation to several dimensions: Taxonomy (the range and structure of different taxonomic groups); ecology (the interrelationship between the new species and the niches available, as well as the structure and distribution of those niches); and morphology (the overall morphospace filled by the new taxa). The present study focuses on taxonomic diversity in the context of ecological diversity.
There are several meanings for the term ‘recovery’ after mass extinctions. Past studies have revealed that faunal revival after a devastating ecological event may follow a pattern similar to ecological succession … and recovery may be considered as the point at which the model is complete and the new ecosystem is stable. … On both the scale of modern ecological recovery and recovery from mass extinction, disaster (‘weedy’ or generalist) taxa are known to insinuate themselves into empty guilds, pushing the boundaries of their geographical range and ecospace. Early Triassic terrestrial ecosystems are clearly dominated by a small number of genera, most notably the dicynodont Lystrosaurus, which accounted for approximately 90% of terrestrial vertebrates (Benton 1983). Disaster taxa then experienced rapid turnover in the time immediately following the event, later giving way to more specialized organisms…
The present paper focuses on carefully chosen, well represented and preserved fossil communities, in order to reduce the effects of vagaries of preservation and sampling. Data from 69 tetrapod communities spanning the relevant period were assembled, checked for quality, and then subsampled. The study is global, however, geographically.
Three distinct extinction pulses were responsible for the mass extinction of tetrapods in the Permian and Triassic: Olson’s extinction; the end-Guadalupian event; and the
end-Permian event. … The global diversity rose sharply after each extinction pulse, probably the result of disaster taxa filling empty guilds. After the end-Permian event, this rapid refilling resulted in a return to pre-extinction taxonomic diversity by the Olenekian. However, this did not last, as there was a subsequent loss of nine families.
Essentially, this research suggests that while taxonomic recovery … the increase to higher levels in the number of species from the few that survive the extinction … community and ecological level systems take perhaps tens of millions of years to return to something like the pre-extinction state. According to one of the study’s authors, Sarda Sahney, “Our research shows that after a major ecological crisis, recovery takes a very long time. So although we have not yet witnessed anything like the level of the extinction that occurred at the end of the Permian, we should nevertheless bear in mind that ecosystems take a very long time to fully recover.”
Sahney, S., Benton, M.J. (2008). Recovery from the most profound mass extinction of all time. Proceedings of the Royal Society B: Biological Sciences, -1(1), -1–1. DOI: 10.1098/rspb.2007.1370
Bristol University Press Release