Last Week's Discussion

I am doing poorly at remembering to update this blog.

Last week we discussed the Smith et al, (2010) paper in Science on the evolution of maximum mammalian body size. The paper discussed the increase in maximum mammalian body size following the end Cretaceous extinction of the dinosaurs. The hypothesis is that the removal of the dinosaurs and thus openning of niches allowed the mammals to proliferate as well as to increase in body size. This is a traditional view of mammalian evolution (and by traditional I don't mean defunct, it is pretty clear that at least some (probably a lot) mammalian speciation occurred after the extinction of the dinosaurs. But if you want a different view consult Bininda-Edmonds et al, (2007)
 http://www.nature.com/nature/journal/v446/n7135/abs/nature05634.html).
 We found the Smith et al (2010) paper interesting and informative. The pattern of increasing maximum body size was apparent on all continents and was correlated with continental area (bigger animals need bigger home ranges) and temperature (18O; warmer means more primary productivity among other things). They implement the Gompertz model in their testing of the above parameters based on a less the 1.0 difference in AIC scores. In our opinion, this is not a big enough difference (< 2.0) to reject the use of the power law and would have liked to see delta AIC for each continent. We also found it interesting that the largest animals were generally hindgut fermenters and would like to see a discussion of the influences of other such factors on the observed patterns (of course we recognize the length limit on Science papers).