McPeek, M. A. The ecological dynamics of clade diversification and community assembly.
In general, the association of rates of clade diversification and molecular substitution clearly require further study.
Here we investigate clade diversification and changes in species' precipitation niches in the African cucurbit genus Coccinia.
We also tested for relationships between clade size and substitution rate within specific groups of mammals, as it has been shown that patterns of substitution rate variation and patterns of diversification can differ between these groups [ 27, 28].
If positive selection or reductions in N e at speciation events were responsible for the link between net diversification and substitution rates, then we would expect to observe a positive relationship between ω and clade size.
By choosing 13 diverse angiosperm genera as independent clades for units of comparison rather than sister groups, I was able to determine if the correlation between diversification and substitution rates is robust and generalizable across a range of plants.
However, if the link between diversification and molecular evolution is confounded by effective population size, we might expect to detect an association between ω and clade size, which we have not seen in this study.
Overall, we show a complex evolutionary scenario in which the HECT system has evolved toward different degrees of diversification in different clades, through family diversification and domain shuffling.
In addition to the estimation of rate parameters, the approach presented here can also be used to distinguish between different modes of diversification, and test explicit hypotheses of rate variation through time and between clades using Bayes factors.
Estimated divergence times between clades and sub-clades are shown to correlate with major geological events of the region, the most important of which is the opening of the Red Sea, while climatic instability in the Miocene is hypothesized to have triggered diversification.
