The distribution of diversity: challenges and applications
75
were delimited as OGUs or groups of OGUs possessing
at least two endemic species.
These cells or groups of cells were then mapped to
delineate the boundaries of each area of endemism.
Their analysis identifi ed four areas of endemism (two
subsequently combined into a single area) of respectively nine, two, one and one cells. Their analysis has
the benefi t of using a pre - selected method to determine
the areas objectively, but for reasons of data limitations
it was based on only 24 grid cells. Also, although they
report that their results are congruent with distributional patterns in other groups of organisms, it is
notable for present purposes that their three areas of
endemism differ from those previously identifi ed in
three earlier studies of areas of endemism for birds for
this region (including one generated by BirdLife
International), both in terms of the number of areas
of endemism identifi ed and in details of the boundaries
of those in common.
These results suggest that the data and methods
selected for identifying and mapping areas of endemism can have important effects on the resulting
outputs, and thus on the biogeographical science being
fed into strategic conservation planning for the region.
Nevertheless, their three fi nal areas are remarkably
congruent to those identifi ed for tree frogs using a combined BEM and phylogeographical approach (Carnaval
et al ., 2009 ).
4.4.4 Biogeographical r egions
Patterns of endemism have long been used in one
of the most fundamental approaches to summarizing
biogeographical patterns across the Earth. The observation that different regions of the globe were characterized by distinct assemblages of animal and plant
species was recognized long before Darwin ’ s famous
theory of evolution.
The foundations for a theory of biogeographical
regions were laid by Comte de Buffon ’ s observation in
1761 that Old World and New World tropical regions
contained different kinds of large mammals. By 1838,
Augustin de Candolle had delineated 40 different biogeographical regions based on plant distributions. By
1858, Philip L. Sclater had delineated six terrestrial
zoogeographical regions based on the global bird
fauna, and in 1876 Wallace had expanded Sclater ’ s
canonical scheme to incorporate mammals and other
animals. Interestingly, at the same time, Wallace also
turtle ( Chelonia agassizii ) maintained its status and level
of protection as a full species despite being indistinguishable from the green turtle ( C. mydas ) at a genetic
level.
While the CI hotspots scheme applies an extremely
course scale and rather crude approach to analysing
endemism, most other schemes focus on identifying
target areas involving species of restricted range –
sometimes termed local endemics. If working on
oceanic islands, it may be fairly straightforward to
apply the criterion of endemism to individual islands,
archipelagos or groups of archipelagos (as Table 4.5 ),
but for comparative analyses across large land masses,
the choice of areas is not so straightforward.
The range size used to delimit range - restricted
species is an essentially subjective choice but, following
Terborgh & Winter (1983) , many studies, especially for
birds, have adopted a range of 50,000 km
2 (Box 4.1 ;
and see brief discussion in Whittaker et al ., 2005 ). The
identifi cation of areas with notable levels of endemism
then becomes a question of identifying areas in which
a given number of range - restricted species are wholly
confi ned. BirdLife International ’ s Endemic Bird Areas
scheme is an example of such an approach, in which
EBAs are delimited based on the possession of as few
as two range - restricted species (Chapter 5 ).
The concept of endemism as employed by conservation groups such as CI needs to be differentiated from
the formal identifi cation of areas of endemism in historical biogeography, which are units of analysis used
in a range of phylogenetically - based approaches to
reconstructing the historical association of Earth
history and biotic diversifi cation.
Like any other area of biogeography, there are
various approaches to the identifi cation and delineation of areas of endemism (see Box 12.1 in Lomolino
et al ., 2010 ). An example is provided by da Silva et al . ’ s
(2004) analysis of endemism in passerine birds in the
Atlantic forests of Brazil, a well - defi ned biogeographical unit of considerable conservation concern due to
its high endemism and extreme levels of habitat loss.
Their analysis was based on subdividing the region into
one - degree latitude/longitude grid cells, to form the
operational geographical units (OGUs) of the study.
They then used parsimony analysis of endemism (a
much - debated method in historical biogeography, but
less contentious when its use is restricted to delineating
potential areas of endemism; see Riddle and Hafner
(2006) for another example) to produce a ‘ consensus
tree ’ classifi cation, from which areas of endemism
75
were delimited as OGUs or groups of OGUs possessing
at least two endemic species.
These cells or groups of cells were then mapped to
delineate the boundaries of each area of endemism.
Their analysis identifi ed four areas of endemism (two
subsequently combined into a single area) of respectively nine, two, one and one cells. Their analysis has
the benefi t of using a pre - selected method to determine
the areas objectively, but for reasons of data limitations
it was based on only 24 grid cells. Also, although they
report that their results are congruent with distributional patterns in other groups of organisms, it is
notable for present purposes that their three areas of
endemism differ from those previously identifi ed in
three earlier studies of areas of endemism for birds for
this region (including one generated by BirdLife
International), both in terms of the number of areas
of endemism identifi ed and in details of the boundaries
of those in common.
These results suggest that the data and methods
selected for identifying and mapping areas of endemism can have important effects on the resulting
outputs, and thus on the biogeographical science being
fed into strategic conservation planning for the region.
Nevertheless, their three fi nal areas are remarkably
congruent to those identifi ed for tree frogs using a combined BEM and phylogeographical approach (Carnaval
et al ., 2009 ).
4.4.4 Biogeographical r egions
Patterns of endemism have long been used in one
of the most fundamental approaches to summarizing
biogeographical patterns across the Earth. The observation that different regions of the globe were characterized by distinct assemblages of animal and plant
species was recognized long before Darwin ’ s famous
theory of evolution.
The foundations for a theory of biogeographical
regions were laid by Comte de Buffon ’ s observation in
1761 that Old World and New World tropical regions
contained different kinds of large mammals. By 1838,
Augustin de Candolle had delineated 40 different biogeographical regions based on plant distributions. By
1858, Philip L. Sclater had delineated six terrestrial
zoogeographical regions based on the global bird
fauna, and in 1876 Wallace had expanded Sclater ’ s
canonical scheme to incorporate mammals and other
animals. Interestingly, at the same time, Wallace also
turtle ( Chelonia agassizii ) maintained its status and level
of protection as a full species despite being indistinguishable from the green turtle ( C. mydas ) at a genetic
level.
While the CI hotspots scheme applies an extremely
course scale and rather crude approach to analysing
endemism, most other schemes focus on identifying
target areas involving species of restricted range –
sometimes termed local endemics. If working on
oceanic islands, it may be fairly straightforward to
apply the criterion of endemism to individual islands,
archipelagos or groups of archipelagos (as Table 4.5 ),
but for comparative analyses across large land masses,
the choice of areas is not so straightforward.
The range size used to delimit range - restricted
species is an essentially subjective choice but, following
Terborgh & Winter (1983) , many studies, especially for
birds, have adopted a range of 50,000 km
2 (Box 4.1 ;
and see brief discussion in Whittaker et al ., 2005 ). The
identifi cation of areas with notable levels of endemism
then becomes a question of identifying areas in which
a given number of range - restricted species are wholly
confi ned. BirdLife International ’ s Endemic Bird Areas
scheme is an example of such an approach, in which
EBAs are delimited based on the possession of as few
as two range - restricted species (Chapter 5 ).
The concept of endemism as employed by conservation groups such as CI needs to be differentiated from
the formal identifi cation of areas of endemism in historical biogeography, which are units of analysis used
in a range of phylogenetically - based approaches to
reconstructing the historical association of Earth
history and biotic diversifi cation.
Like any other area of biogeography, there are
various approaches to the identifi cation and delineation of areas of endemism (see Box 12.1 in Lomolino
et al ., 2010 ). An example is provided by da Silva et al . ’ s
(2004) analysis of endemism in passerine birds in the
Atlantic forests of Brazil, a well - defi ned biogeographical unit of considerable conservation concern due to
its high endemism and extreme levels of habitat loss.
Their analysis was based on subdividing the region into
one - degree latitude/longitude grid cells, to form the
operational geographical units (OGUs) of the study.
They then used parsimony analysis of endemism (a
much - debated method in historical biogeography, but
less contentious when its use is restricted to delineating
potential areas of endemism; see Riddle and Hafner
(2006) for another example) to produce a ‘ consensus
tree ’ classifi cation, from which areas of endemism