Geology Reference
In-Depth Information
The idea is that a concentraion of endemics in a
single area is indicaive of a prolonged period of
isolaion. It is only a descripive term and should
not be confused with area of origin, which is an
explanaion of a patten ound (of course, the two
may coincide).
There are so few butterfly species above the
timber-line that they will be dealt with in a single
paragraph. For the other butterflies we shall pro-
ceed along the following lines.
The same holds for monophyletic groups
consising of endemic species, but as said
before, this kind of inormaion is very
scarce.
6. For the delimitaion of the areas of
endemism, only taxa that are endemic to
EAT have been taken. Other taxa are of
interest in showing relaions to other
areas, but they cannot be used to delimit a
possible area of endemism within the
boundaries of EAT.
7. The predicions given above are tested
against the actual distribuions. Where
possible phylogeneic data will be used.
8. New hypotheses will be framed if needed
to explain actual distribuion pattens. In
these cases the kind of evidence needed
for tesing will be indicated.
9. Area relaionship as conceived here is a
descripive term and not explanatory as in
cladistic biogeography; two areas are
considered related if a taxon (be it an
extant taxon or an ancestor) occurs in and
is restricted to both; how the relaionship
originated is a matter of eplanaion
(process), not of deiniion (patten).
10. Even though phylogeneic evidence may
be lacking, genera are taken to be
monophyleic groups.
11. If one species of a genus occurs in area A
and all other species in area B, and if
there is no evidence of the single species
being the sister species of the rest of the
genus, the species n area A, or rather its
ancestor, is supposed to have originated
from area B.
12. Being restricted to a montane habitat is
considered a specialisaion, i.e. an
apomorphy if the sister species is not
restricted to this kind of habitat.
1. Three kinds of habitats are disinguished:
(a) Afroalpine (above the imber-line), (b)
montane grassland, (c) montane forest.
Each will be dealt with separately since
they may have different histories of
epansion and fragmentaion.
2. A descripion is given of possible scenarios
and disribuion pattens are predicted
based on these scenarios.
3. The present distribuion of montane
habitats is well known. On this basis a
number of potenial (not necessary all)
areas of endemism are disinguished.
4. Authors may differ as to the taxonomic
rank of isolates, i.e. whether a populaion
is a subspecies of a more widely
disributed species or if it consitutes a
species of its own. We have generally
followed Carcasson (1981), unless
otherwise stated.
5. The distribuion of all species and
subspecies resricted to montane habitats
in EAT is listed and actual areas of
endemism are idenified. These areas may
consist of one or more of the potenial
areas of endemism. Areas of endemism
are grouped into larger areas of endemism
in such a way that the new area has more
endemics than the sum of the endemics of
the consituent areas. Subspecies have
been included since they can break up
otherwise uninformaive wide
disribuions. If in a grouping of areas all
subspecies of a species are included, that
species is another endemic of the
combined area and must be added to the
further endemics of the combined area.
Above he imber-line
The upper limit of the montane forest belt in
EAT is between 2800 and 3300 m a.s.l. It is
usually followed by a belt dominated by Ericaceae
or moorland up to 35004100 m (Afroalpine
moorland: Moreau, 1966; etage afro-subalpin:
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