Geography Reference
In-Depth Information
common to both hierarchies. There are interactive processes between the
members of a hierarchy. Additionally, each member of a hierarchy interacts
with the members of the other hierarchy. For this reason, the collapse of a
biota in the ecological hierarchy may cause the extinction of a clade or a
specific gene in the genealogical hierarchy.
Figure 2.2
Entities of the genealogical and ecological hierarchies, with their con-
nections.
Biogeography is a complex discipline because it addresses geographic
patterns exhibited by entities belonging to both hierarchies (Lieberman
2003b). Patterns of the genealogical hierarchy, studied by evolutionary
biogeography, involve historical entities ruled by evolutionary processes.
Patterns from the ecological hierarchy, studied by ecological biogeography,
involve entities that transfer matter and energy. At the upper level of both
hierarchies, the entities contrast markedly, so their study usually entails dif-
ferent data and methodological tools, whereas the distinction between entit-
ies at lower levels may not always be clear. Some biogeographic analyses
may imply both hierarchies simultaneously. When we correlate the richness
of a taxon with the latitude along a continent, we are studying genealogic-
al entities (clades), but it is a basic problem of ecological biogeography.
When we compare the distributional patterns of different clades inhabiting
the same areas, even when biotas are present, we are analyzing clades,
