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SUMMARY:Patterns of tetrapod diversification on land (and possible explana
 tions) - Dr Roger Benson - University of Oxford
DTSTART:20181112T173000Z
DTEND:20181112T183000Z
UID:TALK110965@talks.cam.ac.uk
CONTACT:Ben Johnson
DESCRIPTION:Tetrapods - mammals\, birds and other reptiles - comprise arou
 nd 30\,000 species today and play important roles in terrestrial ecosystem
 s. They evolved from a single ancestor species that lived c.360 million ye
 ars ago. Patterns of both species richness and phenotypic disparity\, and 
 how they have changed through time\, have been subject to debate\, and the
  prevailing hypothesis has been one of near-continual expansion through ti
 me\, driven by frequent innovation. This hypothesis is central to macroevo
 lutionary hypotheses about biotic diversification on Earth. The Mesozoic '
 age of dinosaurs' is though to have witnessed particularly large increases
  in species richness of tetrapods on land\, but this has received surprisi
 ngly little scrutiny.\n\nMy work has focussed on quantitative approaches t
 o characterising patterns of phenotypic diversification and of tetrapod sp
 ecies richness in a spatially-patchy fossil record. Dynamic evolutionary r
 adiations\, involving increases in phenotypic diversity\, and expansion of
  species richness occur frequently on shorter timescales (~ 10 Ma) and loc
 al phylogenetic scales. However\, longer-term\, large-scale patterns are a
 lmost static\, with species diversification rates of approximately zero ov
 er extended intervals. This background of little net change in species ric
 hness is punctuated by abrupt episodes of dramatic radiation\, that substa
 ntially elevated species richness on land beyond previous levels. These ar
 e associated with post-extinction radiations\, and with a small number of 
 truly exceptional evolutionary innovations. Explanations for this pattern 
 may be rooted in macroecology and energetics.
LOCATION: Harker 1\, Department of Earth Sciences\, Downing Street
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