Conclusion
Taken together, our results emphasize the role of macroevolutionary
diversity in determining community structure. Over ecological time,
communities at different compositional start points will converge to
similar functional members, even if species identity varies (Fukamiet al. 2005). We suggest a similar process of community filling
over evolutionary timeāso long as evolutionary opportunity is
available, speciation can fill local communities, allowing them to
follow similar ecological trajectories. Evolutionary opportunity allows
for regional environmental specialists to form, increasing
beta-diversity and supplementing alpha-diversity at biological suture
zones. Where speciation is comparatively limited, widespread species
fill rare environments as best they are able, but sub-regional faunas
are unable to form, and local diversity in the rare environments and
their suture zones remains impoverished. Accounting for such dynamics
may help reconcile contradictory results in elevation diversity profiles
across systems, and shed new light on how local or regional factors
control community structure and diversity.