48
Basic biogeography: estimating biodiversity and mapping nature
4.1.2 Why d o w e m ap?
I soon found that the Amazon, the Rio Negro and
the Madeira formed the limits beyond which certain
species never passed. Thus there are four districts,
the Guiana, the Ecuador, the Peru and the Brazil
districts, whose boundaries on one side are determined by the rivers I have mentioned.
(Alfred Russel Wallace, 1852 , p. 110)
As a young naturalist and scientifi c collector in the
tropical forests of the Amazon, Alfred Russel Wallace
had already developed a remarkable understanding of
the importance of accurate distributional mapping as
a basis for whatever could subsequently be learned
about biogeographical patterns and processes. For
example, carefully recording the geographical distributions of species of monkeys, birds and insects gave him
the insight which led him to speculate on the relationship between geographical features and attributes
of species affi nities and distributions to a degree not
realized amongst his contemporaries. Indeed, as the
above quote indicates, 24 years before reinforcing
and expanding upon Sclater ’ s (1858) scheme of six
great terrestrial zoogeographical regions of the Earth
(Wallace, 1876 ), he was already dividing Amazonia
into geographic units according to species ’ distributions and features of the Earth associated with limits
to their distributions.
Of course, Wallace and Sclater also had predecessors
who had begun to understand and summarize
the non - random nature of species ’ distributions on
grand scales (Ebach & Goujet, 2006 ; Lomolino et al .,
2010 ). Commencing largely in the 18th century, and
more fully developed by Wallace and his contemporaries, these studies form the foundations for efforts
to map the distribution of biodiversity across the
Earth.
Several persistent themes in biogeography developed
in conjunction with distributional mapping at taxonomic scales, ranging from intraspecifi c to higher
taxa, using aggregations from single taxa to entire
biotas, and at geographical scales ranging from local
to global (Lomolino et al ., 2010 , their Chapter 2). In
illustration, we have picked out three deep - rooted
themes foundational to modern conservation biogeography which provide the framework for predicting
effects of climate change, invasive species, habitat
fragmentation and loss, and other anthropogenically -
mediated infl uences on populations, species and
biotas.
essentially cultural in origin or maintenance (in the
UK, chalk grassland, lowland heaths and hay meadows
come to mind) or of conserving valuable ecosystem
function (e.g. estuarine habitat for wintering wildfowl
or habitat connectivity for migratory terrestrial species)
(see Chapters 2 and 3 ).
Many of the most fundamental questions in conservation biogeography require knowledge of the
geographical distributions (and ecological niche
requirements) of individual species. Such knowledge
is, of course, essential before we can assess the threats
to the viability of their populations in a rapidly changing world (see Chapter 7 ). Unfortunately, we all too
often lack this knowledge – a defi cit that has, for
reasons outlined below, been called the Wallacean
shortfall (Lomolino, 2004 ). Also, before we can even
begin to understand the distributions of organisms, we
need to know that they actually exist, and unfortunately our knowledge gap between formally described
and yet - to - be - discovered species, referred to as the
Linnean shortfall (Raven & Wilson, 1992 ), is vast.
These two knowledge defi cits contribute signifi -
cantly to a third key knowledge shortfall, which is that
our grasp of the magnitude of anthropogenic extinctions (past, present and especially future) is also marked
by a high degree of uncertainty. There is a strong consensus that the rate of loss is already signifi cantly
above background levels of extinction derived from the
fossil record, but no one can be quite sure by how
much. We therefore begin the present chapter with
consideration of these three themes, before moving on
to describe other forms and levels of biological organization used in conservation biogeography.
In terms of functionalist approaches to mapping
nature, we focus particularly on two types: biomes and
ecoregions. In essence, these are closely related concepts concerned with delineating and mapping Major
Ecosystem Types (METs). These METs, in turn, represent a key way in which humans perceive nature in the
terrestrial realm based largely on physiognomic features of the vegetation (e.g. temperate grasslands or
temperate deciduous woodland). Species are also constrained to varying degrees in their distribution to particular METs, so there is a broad, albeit imperfect,
correspondence between functionalist and compositionalist approaches. Both are foundational to the
efforts of those involved in conservation planning, as
will be discussed further in Chapters 5 , 6 and 7 , and in
practice many fully developed multi - scalar approaches
to the problem of mapping nature involve a mixture of
the two.
Basic biogeography: estimating biodiversity and mapping nature
4.1.2 Why d o w e m ap?
I soon found that the Amazon, the Rio Negro and
the Madeira formed the limits beyond which certain
species never passed. Thus there are four districts,
the Guiana, the Ecuador, the Peru and the Brazil
districts, whose boundaries on one side are determined by the rivers I have mentioned.
(Alfred Russel Wallace, 1852 , p. 110)
As a young naturalist and scientifi c collector in the
tropical forests of the Amazon, Alfred Russel Wallace
had already developed a remarkable understanding of
the importance of accurate distributional mapping as
a basis for whatever could subsequently be learned
about biogeographical patterns and processes. For
example, carefully recording the geographical distributions of species of monkeys, birds and insects gave him
the insight which led him to speculate on the relationship between geographical features and attributes
of species affi nities and distributions to a degree not
realized amongst his contemporaries. Indeed, as the
above quote indicates, 24 years before reinforcing
and expanding upon Sclater ’ s (1858) scheme of six
great terrestrial zoogeographical regions of the Earth
(Wallace, 1876 ), he was already dividing Amazonia
into geographic units according to species ’ distributions and features of the Earth associated with limits
to their distributions.
Of course, Wallace and Sclater also had predecessors
who had begun to understand and summarize
the non - random nature of species ’ distributions on
grand scales (Ebach & Goujet, 2006 ; Lomolino et al .,
2010 ). Commencing largely in the 18th century, and
more fully developed by Wallace and his contemporaries, these studies form the foundations for efforts
to map the distribution of biodiversity across the
Earth.
Several persistent themes in biogeography developed
in conjunction with distributional mapping at taxonomic scales, ranging from intraspecifi c to higher
taxa, using aggregations from single taxa to entire
biotas, and at geographical scales ranging from local
to global (Lomolino et al ., 2010 , their Chapter 2). In
illustration, we have picked out three deep - rooted
themes foundational to modern conservation biogeography which provide the framework for predicting
effects of climate change, invasive species, habitat
fragmentation and loss, and other anthropogenically -
mediated infl uences on populations, species and
biotas.
essentially cultural in origin or maintenance (in the
UK, chalk grassland, lowland heaths and hay meadows
come to mind) or of conserving valuable ecosystem
function (e.g. estuarine habitat for wintering wildfowl
or habitat connectivity for migratory terrestrial species)
(see Chapters 2 and 3 ).
Many of the most fundamental questions in conservation biogeography require knowledge of the
geographical distributions (and ecological niche
requirements) of individual species. Such knowledge
is, of course, essential before we can assess the threats
to the viability of their populations in a rapidly changing world (see Chapter 7 ). Unfortunately, we all too
often lack this knowledge – a defi cit that has, for
reasons outlined below, been called the Wallacean
shortfall (Lomolino, 2004 ). Also, before we can even
begin to understand the distributions of organisms, we
need to know that they actually exist, and unfortunately our knowledge gap between formally described
and yet - to - be - discovered species, referred to as the
Linnean shortfall (Raven & Wilson, 1992 ), is vast.
These two knowledge defi cits contribute signifi -
cantly to a third key knowledge shortfall, which is that
our grasp of the magnitude of anthropogenic extinctions (past, present and especially future) is also marked
by a high degree of uncertainty. There is a strong consensus that the rate of loss is already signifi cantly
above background levels of extinction derived from the
fossil record, but no one can be quite sure by how
much. We therefore begin the present chapter with
consideration of these three themes, before moving on
to describe other forms and levels of biological organization used in conservation biogeography.
In terms of functionalist approaches to mapping
nature, we focus particularly on two types: biomes and
ecoregions. In essence, these are closely related concepts concerned with delineating and mapping Major
Ecosystem Types (METs). These METs, in turn, represent a key way in which humans perceive nature in the
terrestrial realm based largely on physiognomic features of the vegetation (e.g. temperate grasslands or
temperate deciduous woodland). Species are also constrained to varying degrees in their distribution to particular METs, so there is a broad, albeit imperfect,
correspondence between functionalist and compositionalist approaches. Both are foundational to the
efforts of those involved in conservation planning, as
will be discussed further in Chapters 5 , 6 and 7 , and in
practice many fully developed multi - scalar approaches
to the problem of mapping nature involve a mixture of
the two.