Herpetofauna of the eastern African forests - Biogeography and Ecology of the Rain Forests of Eastern Africa - page 193

employed by Stuart (1983) on birds and Strij-
bosch (1980) on anurans may help determine
answers to these quesions.
Kingdon (1971) has emphasised the import-
ance of local environmental condiions and their
efects on local populaions of mammals, especi-
ally with regard to reproducion. Brosset (1968),
for example, found hat in the forests of Gabon,
two populaions of the insecivorous bat Hip -
posideros cae r only 6 m apart had completely
diferent reproducive cycles. Broadley (1979) has
demonstrated diferences in the iming of
reproducion in symparic lizards in dry wood-
land, but I know of no similar studies of forest
species of amphibians or repiles in easten
Africa. The possible adapive signiicance of the
exremes ofpolymorphism seen in reefrogs of the
genus Hyperolius remains unknown (Muze, 1976).
Elsewhere, polymorphism in some anurans has
been shown to be related to predaion (Caldwell,
1982). Dodd (1981) notes that differences in
infrared light reflectance in amphibians and
repiles are of potenial importance in thermo:
regulaion mechanisms and/or crypsis, and
reported differences among five species of
chameleons, but admits his suggesions are
speculaive. Detailed ecophysiological studies
may prove especially valuable in determining the
evoluionary history of forest species. For exam-
ple, Lin & Nelson (1981 ), n a detailed study of
Chamaeleo jacksoni and . hoehnelii, concluded on
the basis of diferences in their reproducive
srategies, desiccaion tolerance, criical thermal
maima and close proimiy of the study site to
two different environmental zones, that .
hoehnelii was originally resricted to the montane
forest belt on Mount Kenya and the Aberdares
where low temperature and high humidiy are
condiions common throughout much of the year.
. jacksoni, on the other hand, is adapted to the
hotter, drier, more seasonal climate found at
lower alitudes.
It is difficult to assess the role of non-forest
species which are able to live along paths, roads,
and in open areas, both man-made and natural n
forests, on forest-dependent faunas. For example,
I have regularly found the toad Buo guturalis, a
non-forest form, on roads along forest on Mount

explain the muliplicity of orest species in boh
South America and Africa. Poynton (1982)
emphasised this with regard to hybridisaion n
southen Africa. Laurent indicates that in West
Africa six regions were isolated: a Guinea block
from Sierra Leone to the Ivory Coast; a Gold
Coast block from the Ivory Coast to Ghana; a
Nigeria block from southen Dahomey to the
Cross River; a Cameroun block from
southeasten Nigeria to the Congo estuay, with
easten limits poorly deined; a northen and
easten Congo block; and a southwesten Congo
block between the left bank of he Congo River
and the gallery forest of the left affluents of the
Kasai and Sankuru rivers. In South America he
notes that similar 'core areas' have been pro-
posed: a Guiana block, a coastal Venezuelan
block, an Andean block, with Colombian Peruvian
and Equadorian subdivisions, and a Mato Grosso
block.
Endler (1982) and Livingstone (1982) have,
however, expressed doubt over the eistence of
postulated Pleistocene forest refuges, and discuss
in detail the problems inherent in defining past
refuges using modem distribuion pattens. The
former author gives speciic suggesions for future
work and notes the need to examine one or two
pairs of postulated refuges in great detail to test
the predicions of various models attemping to
explain species disribuions.
A number of fascinaing biological problems
related to the origin of the herpetofauna of
easten Africa are highlighted by the distribuions
of amphibians and repiles and suggest areas
where more research is needed. For example, it is
not at all clear exactly what fe atures of the habitat
and/or microclimate determine boh the broad
and local distribuion ofspecies. As already noted,
there appear to be differences between the forests
of West and easten Africa which make generalisa-
ions about species' preference difficult. What in
West Africa may be considered a montane spe-
cies, such as Typh/ops ierai, may be found in
much lower forests in easten Africa. Is this
related to characterisics of the forest - or to dif-
ferences of various populaions of species in their
tolerance to different ecological condiions? The
use of habitat ordinaion techniques such as those