Data from: Island Biogeography, the effects of taxonomic effort and the importance of island niche diversity to single island endemic species

Island biogeography theory is fundamentally reliant on measuring the
number of species per island and hence has taxonomy at its foundation. Yet
as a metric used in tests of the theory, island species richness (S) has
varied with time according to the level of taxonomic effort (a function of
the rate of finding and describing species). Studies using a derivative of
S, single-island endemic species richness (SIE S), may be prone to change
in taxonomic effort. Decreases or increases in species numbers resulting
from taxonomic revision or increased sampling are likely to have a large
effect on values of SIE S, as they tend to be smaller than total S for the
same island. Using simple biogeography models, we analysed estimates of
SIE S in plants, land snails, beetles, and fungi from comprehensive data
sets for eight island groups, produced species accumulation curves and
applied Bayesian regression over five time periods. Explanatory power
differed across taxa, but area and island age were not always the best
explanatory variables, and niche diversity appeared to be important.
Changing levels of SIE S over time had different effects on models with
different taxa and between island archipelagos. The results indicated that
the taxonomic effort that determines SIE S is important. However, as this
cannot often be quantified, we suggest Bayesian approaches should be more
useful than frequentist methods in evaluating SIE S in island biogeography
theory. Fundamentally, the article highlights the importance of taxonomy
to theoretical biogeography.