Kinds of Fitness: survival of--fittest, first, anybody, fastest to propagate, etc.

Les fastes de la cour de France à Blois pendant la Renaissance

by sebastien Nadot

Article de presse généraliste Article de presse généraliste

Recovery from the most profound mass extinction of all time

by Sarda Sahney

Sahney, S. and M.J. Benton 2008. Recovery from the most profound mass extinction of all time. Proceedings of The Royal Society of London. Series B, Biological Sciences 275:759-765.

The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time,... more The end-Permian mass extinction, 251 million years (Myr) ago, was the most devastating ecological event of all time, and it was exacerbated by two earlier events at the beginning and end of the Guadalupian, 270 and 260 Myr ago. Ecosystems were destroyed worldwide, communities were restructured and organisms were left struggling to recover. Disaster taxa, such as Lystrosaurus, insinuated themselves into almost every corner of the sparsely populated landscape in the earliest Triassic, and a quick taxonomic recovery apparently occurred on a global scale. However, close study of ecosystem evolution shows that true ecological recovery was slower. After the end-Guadalupian event, faunas began rebuilding complex trophic structures and refilling guilds, but were hit again by the end-Permian event. Taxonomic diversity at the alpha (community) level did not recover to pre-extinction levels; it reached only a low plateau after each pulse and continued low into the Late Triassic. Our data showed that though there was an initial rise in cosmopolitanism after the extinction pulses, large drops subsequently occurred and, counter-intuitively, a surprisingly low level of cosmopolitanism was sustained through the Early and Middle Triassic.

Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land

by Sarda Sahney

Sahney, S., Benton, M.J. and Paul A. Ferry 2010. Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land. Biology Letters. 6:544-547

Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod... more Tetrapod biodiversity today is great; over the past 400 Myr since vertebrates moved onto land, global tetrapod diversity has risen exponentially, punctuated by losses during major extinctions. There are links between the total global diversity of tetrapods and the diversity of their ecological roles, yet no one fully understands the interplay of these two aspects of biodiversity and a numerical analysis of this relationship has not so far been undertaken. Here we show that the global taxonomic and ecological diversity of tetrapods are closely linked. Throughout geological time, patterns of global diversity of tetrapod families show 97 per cent correlation with ecological modes. Global taxonomic and ecological diversity of this group correlates closely with the dominant classes of tetrapods (amphibians in the Palaeozoic, reptiles in the Mesozoic, birds and mammals in the Cenozoic). These groups have driven ecological diversity by expansion and contraction of occupied ecospace, rather than by direct competition within existing ecospace and each group has used ecospace at a greater rate than their predecessors.