(Western Sahara), but Boa Vista (Cape Verde) is
570 km from the nearest mainland at Dakar,
Senegal, and Porto Santo in Madeira is 630 km from
the nearest mainland at Cape Sim (Morocco). Sao
Miguel in the Azores is some 1370 km from main-
land landfall at Lisbon, in south-west Europe.
Furthermore, the islands of Corvo and Flores (in the
Azores), although occurring within the North
American plate, are virtually equidistant from Cape
Race (Newfoundland) and Lisbon.
Macaronesia has been considered a distinct phyto-
geographical region within the Holarctic Kingdom
for more than a century. Floristically, although there
are shared elements, it is now recognized that there
is a transition from strong Eurosiberian–Atlantic
affinities for the Azores, to a Mediterranean flavour
for Madeira and the Canaries and, finally, to a
Saharan–Sudanian character for the Cape Verde
islands (Sunding 1979; Nicoláset al. 1989; Kunkel
1993), leading some to question the validity of the
Macaronesian region (Lobin 1982; Lüpnitz 1995).
Kunkel’s (1993) solution is a hierarchical frame-
work recognizing Central Macaronesia (including
the Canaries and Madeira), Lauri Macaronesia
(including Central Macaronesia, Azores, and the
south-western part of the Iberian peninsula) and
finally Great Macaronesia (including Lauri
Macaronesia, the Cape Verde islands, and a strip of
the African coast). Lobin (1982) prefers dropping
the term Macaronesia altogether, placing the
Azores in the Atlantic region of the Holarctic
Kingdom, Madeira and the Canaries in the
Mediterranean Region (cf. Blondel and Aronson
1999), and finally the Cape Verde islands in the
Saharan region of the Palaeotropic Kingdom.
Lüpnitz (1995) goes still further, advocating the
inclusion of the Canaries in the Palaeotropics. In
addition, although the nucleus of the Canaries and
Madeira are recognized to have zoogeographical
affinities, on the whole Macaronesia is a phytogeo-
graphical rather than a zoogeographical concept
(Pedro Oromí, personal communication).
What becomes clear from the above is that these
widely spaced archipelagos have connections of
varying strength to different mainland regions.
Recent developments in our understanding of the
environmental history of the islands (Chapter 2)
and the phylogeography of Macaronesian lineages
shed considerable light on these phytogeographical
arguments and provide fascinating scenarios of the
colonization history of the region. The general pic-
ture is as follows. The islands emerged more
recently than traditionally thought, at a point when
the continents (Africa, Europe, and North America)
were clearly well separated. So, the islands have
been colonized by long-distance dispersal across
open ocean, in a structured fashion, resulting in
varying island–mainland affinities across
Macaronesia: a scenario some historical biogeogra-
phers dismiss as improbable.
Successful, structured long-distance dispersal
becomes easier to understand and accept as reason-
able when we consider the following factors
(Nicoláset al. 1989):
●First, as a result of continuing volcanic activity,
new territory has been provided for colonization
throughout the history of the various archipelagos.
●Secondly, because of the existence in this part of
the North Atlantic Ocean of well-consolidated
wind and marine current systems since the closure
of the Panama strait (c.3.5–5 Ma), the north-easterly
trade winds and the cool Canarian marine current,
respectively, have favoured the constant arrival of
propagules from the adjacent continents.
●Thirdly, during the repeated and lengthy low
sea-level stands in the Pleistocene, a number of sub-
marine banks have emerged as islands, serving as
stepping stones at intervals of 200 km or less, facil-
itating the flow of colonists to and among these
archipelagos (Fig. 2.10, 2.11; Carine et al. 2004).
These stepping stones may have been particu-
larly important for birds, which in turn have been
responsible for introducing many plant species to
the islands. The banks existing to the north of
Madeira (Seine, Ampere, Gettysburg, Ormonde)
provided stepping-stone connections between
Madeira and the Iberian peninsula, and the Dacia
and Concepción banks similarly linked Madeira
with Africa (Fig. 2.11). Dispersal opportunities
between the Canaries and Madeira were also
enhanced by these banks (Dacia and Concepción)
and by the Salvage Islands. These connections
may play some role in explaining the greater bioticDISHARMONY, FILTERS, AND REGIONAL BIOGEOGRAPHY 61