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Forget the old tree of life. Here’s a new, improved tree for mammals, incorporating bursts

Denyse O'Leary
September 23, 2011
Evolution, News
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File:Darwins tree of life 1859.gif

From “Evolutionary Tree of Life for Mammals Greatly Improved” (ScienceDaily, September 23, 2011), we learn:

Springer explained that the research team looked for spikes in the diversification history of mammals and used an algorithm to determine whether the rate of diversification was constant over time or whether there were distinct pulses of rate increases or decreases. The researchers found an increase in the diversification rate 80-82 million years ago, which corresponds to the time — specifically, the end of the Cretaceous Terrestrial Revolution — when a lot of different orders were splitting from each other.

“This is when flowering plants diversified, which provided opportunities for the diversification of small mammals,” Springer said.

Springer and colleagues also detected a second spike in the diversification history of mammals at the end of the Cretaceous — 65.5 million years ago, when dinosaurs, other large terrestrial vertebrates, and many marine organisms went extinct, opening up a vast ecological space.

Hmmm. Almost as if it were spring-loaded.

Comments
HMMM this quote is interesting,
Relaxed clock analyses support the long-fuse model of diversification and highlight the importance of including multiple fossil calibrations that are spread across the tree.
Yes indeed, as well throw out all sequences that completely contradict your preconceived conclusions no matter what you do then WA LAA just like our evolutionary imagination says it should look! :) Darwin would be so happy! bornagain77
The interesting thing about the reptile->mammal transition is that there isn't a line between them. All of the "transitions" are all different mosaics between reptilian and mammal parts. If you want to call it evolution, it sure is rather Lamarckian, since they all seemed to be "aiming" at modern mammals, but going via different routes. johnnyb
Impacts of the Cretaceous Terrestrial Revolution and KPg Extinction on Mammal Diversification Robert W. Meredith et al. Abstract Previous analyses of relations, divergence times, and diversification patterns among extant mammalian families have relied on supertree methods and local molecular clocks. We constructed a molecular supermatrix for mammalian families and analyzed these data with likelihood-based methods and relaxed molecular clocks. Phylogenetic analyses resulted in a robust phylogeny with better resolution than phylogenies from supertree methods. Relaxed clock analyses support the long-fuse model of diversification and highlight the importance of including multiple fossil calibrations that are spread across the tree. Molecular timetrees and diversification analyses suggest important roles for the Cretaceous Terrestrial Revolution and Cretaceous-Paleogene mass extinction in opening up ecospace that promoted interordinal and intraordinal diversification, respectively. By contrast, diversification analyses provide no support for the Eocene delayed rise of present-day mammals hypothesis. Science http://www.sciencemag.org/content/early/2011/09/21/science.1211028 Enezio E. De Almeida Filho

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