Data from: Dissecting biodiversity in a global hotspot: uneven dynamics of immigration and diversification within the Cape Floristic Region of South Africa

Aim: Fragmented distributions should show immigration and diversification
dynamics consistent with the predictions of island biogeography theory. We
test whether this applies to the fragmented Cape fynbos vegetation.
Location: Southern Africa, Cape Floristic Region (CFR) Taxon: Angiosperms,
Restionaceae (restios) Methods: We used a large occurrence dataset and
environmental layers to characterize an existing regionalization and the
intervals between the regions ecologically and spatially. We extended the
available phylogeny for restios and inferred their historical biogeography
using models implemented in BioGeoBEARS. We then measured the relative
contribution of immigration and in situ speciation to the species richness
of each region within the CFR. We used standard statistical methods to
test the predictions of the island biogeography theory. Results: The area
and environmental heterogeneity of the seven regions of the CFR are
positively correlated with in situ speciation rate. Furthermore, more
isolated areas, and areas colonized more recently, have proportionally
higher immigration rates, and more central and older areas proportionally
higher in situ speciation rates. Main Conclusions: The variation in
immigration and diversification dynamics among the regions within the CFR
is extensive and consistent with the archipelago model of island biography
theory. This dynamic may contribute significantly to the diversity of the
Cape flora. Such a model could be generally useful for understanding the
generation and maintenance of diversity in biodiversity hotspots, and may
even scale up to explain continental biodiversity.