188 PAUL J. MARKWICKFig. 7. The distribution of total amphibian species diversity for North America, Europe, southern Africa and
Australia.
latitudinal distribution of annual precipitation
(Fig. 4f), This complexity is further revealed
when mammalian diversity is divided into its
constituent taxonomic parts, as shown in Figure
10, in which the most speciose orders of
mammals are considered as a proportion of the
total mammalian fauna. The proportion of
bats increases equatorward to dominate the
high-diversity faunas of northern South
America (perhaps following the increases in
insect diversity upon which most feed). Never-
theless, the proportion of both carnivores and
rodents decrease, and it is largely the high
rodent diversity of the western interior USA
that generates the mammal species diversity
pattern seen in the mid-latitudes in Figures 3b
and 9.The physiological and ecological composition
of each fauna is therefore important in under-
standing the relationship between diversity and
Table 5. Spearman rank test rho values for environmental variables and amphibian species diversity by region
n
Absolute latitude
Elevation
MAT
MART
CMM
WMM
Radiation
Cumulative T 0
Cumulative T 5
Annual precipitation
P range
Months T 10 P 40
PET
Mean annual NDVI
NDVI ISO
South
America_ - - - _ - - - - _ - _ - - - -North
America144
-0.791
NS
0,779
-0.425
0.711
0.761
NS
0.793
0.792
0.644
0.339
0.844
0.745
0.864
-0.683Europe204
-0.457
0.467
0.286
NS
NS
0.372
NS
0.295
0.367
NS
NS
0.458
0.325
0.601
-0.407Arabia_
__
_ _ _ _ _ _ _ _ _ _ ___
_
_Southern
Africa12
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NSAustralia40
NS
NS
NS
NS
NS
NS
NS
NS
NS
0.799
NS
0.677
NS
NS
NS(p < 0.0001; NS, not significant, p > 0.0001)