Yellow bars correspond to the 95% highest posterior density for divergence times of each species. The Quaternary (2.6 Myr ago–present) and the Neogene (23–2.6 Myr ago) periods are shaded in grey and light blue, respectively. Mean stem ages for 25 of the lineages occurred within the Neogene and for two lineages within the Quaternary.Researching how the history and ecology has affected speciation among the 27 lineages of birds has lead to the discovery that the longer length of time a species can inhabit an area, the more likely it will disperse and diverge. Also, the less mobility a species has, the more likely it will diverge as well.
For example, birds restricted to the forest floor showed significantly higher species diversity than birds that inhabited the forest's open canopy. These findings have conservation ramifications. If a species cannot inhabit the same area for an extended time, it will not have the opportunity to evolve and continue.
"Our results suggest that human alterations of the landscape can effectively kill the speciation process," Brumfield said.