|
A
few macroecological predictions were supported among snakes, but many were not.
My results offer further evidence that Rapoport's rule is not a general phenomenon,
and that the longitudinal boundedness of geographic ranges may be a better predictor
of range size than is latitude. Although I found that body size is positively
correlated with range area, the low mass-specific energy requirements of ectotherms
may negate popular resource-based explanations of the effects of body size on
geographic range area. Alternatively, the reproductive advantages of large body
size in snakes (larger clutch sizes and larger offspring) may allow populations
of large-bodied species to attain relatively higher local population densities,
providing source populations able to colonize new areas; this may result in
large geographic range. Ultimately, however, observed latitudinal patterns of
species richness suggest that trends in geographic range sizes among pitvipers
may have been structured more by historical biogeography (especially multiple
orogenic episodes in Central America) than by macroecological biotic factors. |
