REVEALING THE FACTORS THAT PROMOTE SPECIATION

What biological attributes of organisms promote speciation, and ultima tely, species diversity? This question has a long history of interest, with proposed diversity promoters including attributes such as sexual selection, ecological specialism and dispersability. However, such id eas are difficult to test because the time-scale of processes involved is too great for direct human observation and experimentation. An inc reasingly powerful solution is to investigate diversity patterns among extant groups to infer the nature of processes operating during the e volution of those groups. This approach relies on the use of robust, p hylogenetically based null models to overcome some of the problems inh erent in observational inference. We illustrate this area by (i) discu ssing recent advances in identifying correlates of diversity among hig her taxa, and (ii) proposing new methods for analysing patterns in spe cies-level phylogenies, drawing examples from a wide range of organism s.