Phylogenetics, models and evolution

I want to highlight two interesting papers coming out last week in the field of phylogenetics and evolution.

Cycas rumphii. Picture by Raul654, wikimedia commons

The first is a paper by Nagalingum et al. who use fossil-calibrated molecular phylogenies to examine the diversification of cycads, and ancient lineage of woody plants. The cycad record dates back at least to the early Permian (280 mya), and cycads were therefore often named as an example of “living fosils”. The phylogenetic tree by Nagalingum et al., however, shows that despite the age of the lineage as such, most of the current cycads are not much older than ~12 million years and originate from a global, near synchronized radiation event in the late Miocene. The paper is adding to a lot of recent evidence that evolution may be much more dynamic than traditionally thought.

The second paper is a study by Shultz et al., who examine the evolution of sociality in primates by evaluating the fit of alternative evolutionary models of sociality. The approach is based on the assumption that close relatives display similar behavior and traits (phylogenetic inertia), which we sometimes refer to as niche conservatism in ecology. The authors confirm that there is indeed sufficient phylogenetic inertia in the beginning of the paper. An interesting point was for me the subsequent use of Bayesian model selection (Bayes factors) to evaluate the evidence for a number of alternative models, not that this is particularly new, but a very interesting application of that method. Interesting stuff, reminded me of a previous post on the evolution of culture.

References

Nagalingum, N. S.; Marshall, C. R.; Quental, T. B.; Rai, H. S.; Little, D. P. & Mathews, S. (2011) Recent Synchronous Radiation of a Living Fossil. Science, 334, 796-799.

Shultz, S.; Opie, C. & Atkinson, Q. D. (2011) Stepwise evolution of stable sociality in primates. Nature, 479, 219-222.

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