Geology Reference
In-Depth Information
butterflies have no connecions with areas outside
Africa at the species level. This is not surprising
since as far as we know there has never been a
orest connecion between the Oriental and
Afroropical regions (unless we go back to Gond-
wana imes). At the genus level, however, there
are several connecions involving 17 of the 46
genera. None of these genera is resricted to forest
(i.e. some of the species live in woodland or
sill more open habitats) and it seems likely that
the contact came about through species with pref-
erence for more open habitats. It implies either
that the African forest species of these genera
originated from species with another habitat pref-
erence, or that the habitat preference was orig-
inally for forests and the Oriental contact could
come into being only when a species arose with a
changed habitat preference. Anyway, the import-
ance of the Oriental connecion or the butterflies
of the EAT montane forests of EAT seems to be
negligible.
An excepion to the above may be the genus
Celaenorrhinus. The species are generally forest
species. It is the only genus of the Hesperiidae
with a pantropical disribuion. The possibility
that this distribuion is very old must be
considered.
Southn comzeaion
Among the montane forest species of EAT there
are only three that are also represented in South
Africa. One of these, Antanartia dimorphica, is
moreover also found in Cameroon and is thus a
rather widespread species. Another species of this
genus in East Africa, A. schaeneia, is also found in
South Africa, where still another species occurs
A. hippomene) . Even if we knew the exact rela-
ionships in this genus, the large distribuional
overlaps would hamper a geographic analysis of
the speciaion events. The third species also
found in South Africa is Pap ilio eclzerioides. . This
species belongs to the ynorta group (Hancock,
1984) the seven species of which are found from
West to East Africa and south to Angola and
Malawi, only echerioides going further south and
reaching Transvaal and Natal. We can hardly
avoid the conclusion that this species is a northen
intruder in South Africa.
Ecological relationships
In cases where phylogeneic data are available we
can test whether the sister species (or sister
group) of a montane forest species has the same
habitat preference. As stated above such informa-
tion is scarce, but the data available are interesing
enough to menion here.
All five Ch ondro/pis species listed form a
monophyleic group (de Jong, 1986). Thus, the
speciaion events leading to these species did not
involve habitat change. The sister group of the
five species has a slightly wider habitat prefer-
ence, also occurring at much lower elevaions,
down to 800 m (and, not surprisingly, a wider
disribuion reaching Cameroon). Although there
is alitudinal overlap the srictly montane forest
species must have originated from a species
generally living at lower elevaions. The anckel-
mani species group of the genus Biyclus is sup-
posed to be monophyleic (Condamin, 1973). It
consists of six montane forest species in EAT (all
listed in Appendix 8.2). The evoluion of the
group did not need to involve a habitat change.
The sister group of the anckelmani group, the
similis group (with a single species), is also restric-
ted to montane forest. The sister group of the
Wes tn conneaion
West of the Westen Border Range there are
several mountain areas high enough to cary high-
land forest, in south Zaire/north Zambia, Angola
and Cameroon. We are concened only with the
third area here: the montane fauna of Angola is
badly known, and the mountains of south
Zaire/north Zambia are relaively close. There
are 17 species (10%) of the montane forest fauna
in East Africa that are represented in Cameroon
(by a separate subspecies). The shared species are
not evenly distributed in EAT, the largest number
being found in the Westen Border Range (see
Table 8.5). In Cameroun the lowland forest fauna
ascends to unusual heights in the mountains
because of the high humidiy; the strictly montane
forest fauna is poor in species (Carcasson, 1964),
and these species are apparently he ones that are
shared with EAT.
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