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Find
world species by region
click
on a biogeographic region:
Biogeographic
regions of the world (numbered) for bumblebees
(updated from Williams, 1996
[pdf] ).
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Britain
| Europe | USA+Canada
| Introductions
of non-native species
Biogeographic
regions
Equal-area grid map
Bumble bee distribution data
.
Biogeographic
regions
Rather
than using the familiar traditional biogeographic regions
that are based largely on birds (Sclater, 1858;
Wallace, 1876, map below),
the biogeographic regions used here are based directly
on their bumblebee faunas.
Biogeographic
regions of the world from Wallace (1876)
Biogeographic
regions for bumblebees were derived using a TWINSPAN
classification. This divides the equal-area (611,000
km) grid-cells (see below and the map of species richness) into 12 groups by differences in the species
composition of their bumblebee faunas (updated from
Williams, 1996
[pdf] ).
The
resulting
faunal regions for bumblebees are broadly similar to
the traditional biogeographic regions based largely
on birds. Where these regions correspond, the traditional
names are used here. More regions are recognised in
the New World because bumblebee species are fewer there
and the species' distribution patterns are more concordant.
In
contrast, the island bumblebee faunas of Japan and Sumatra
do not agree with the traditional biogeographic regions.
The Japanese and Sumatran Regions are distinguished
from the neighbouring Oriental and Palaearctic Regions
by having a subset of their species, with either a low
proportion of endemics (Japan), or very few species
in total (Sumatra). Similarly, most species recorded
in the Arctic Region are shared with the more southerly
boreal fauna, although species of the subgenus Alpinobombus
are strongly associated with this region.
.
Equal-area
grid map
The
maps used here are based on a cylindrical, equal-area
projection of the world (excluding Antarctica). However,
this does not ensure equal areas of land among grid
cells, or equal areas of habitat suitable for bumblebees.
The
map shown above uses a cylindrical equal-area projection
that is orthomorphic (minimum shape distortion) at 46°
North and South (where bumble bee records are particularly
plentiful). Intervals of 10 longitude (the map is opened
at 30 West) are used to calculate intervals of latitude
(4°59', 9°59', 15°03', 20°14', 25°36',
31°13', 37°12', 43°41', 51°00', 59°41',
71°44' North and South of the equator) that provide
equal-area grid cells of approximately 611,000 km².
A grid map shows the grid coordinates
superimposed with the known extent of the indigenous
distribution of bumblebees.
.
Bumblebee
distribution data
This
checklist was compiled in conjunction with distribution
data for use in biogeographic studies. The maps of world-wide
distribution were designed specifically for the coarse-scale
comparisons of regional bumblebee faunas described above
(Williams, 1996
[pdf], 1998
[pdf] ).
Aside
from any difficulties in identifying species or localities,
comparisons among faunas are complicated by two principal
factors: first, by differences in sampling effort (as
illustrated by 'species-accumulation curves', e.g. Colwell
& Coddington, 1994);
and second, by differences in the extent of sampling
areas ('species-area effects', e.g. MacArthur &
Wilson, 1967). Fortunately
for the first problem, the attractiveness of bumblebees
to collectors has ensured that they have been relatively
intensively sampled, so that most faunas are relatively
well known. But in order to reduce this problem further,
rather than extrapolate local richness and lose information
on individual species, the expected distributions of
some species are interpolated on the basis of knowledge
of their habitat associations. To reduce the second
problem of species-area effects, equal-area
grid cells are used.
Because
the intention is to study biogeographic patterns, maps
are required to show all historical records, including
data from areas where species may now be extinct. On
the other hand, data exclude fossil taxa (reviewed by
Zeuner & Manning, 1976)
and documented introductions.
Maps for every
species are not included with this checklist because
many data are still being collected and analysed. The
sources of the distribution data will be presented in
a later atlas.
For each subgenus a preliminary map of species richness
is included as a general guide. These blue-scale maps
use equal-interval classes, which have the advantage
that each blue-scale class remains consistent in its
range of richness values within each map. Scale keys
are not included with each map because the numbers of
species are shown directly on each grid cell. The maps
were made using WORLDMAP
software.
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