Cladistics 17, 313�353 (2001)
doi:10.1006/clad.2001.0168, available online at http://www.idealibrary.com on
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All rightsiation of the Spider Genus Dysd
deridae) in the Canary Islands:
ssment Based on Multiple Data
l A. Arnedo,
1
Pedro Orom�,* and Carles Ribera
ment de Biologia Animal, Universitat de Barcelona, Avenida Diagonal 6
partamento de Biologia Animal, Universidad de La Laguna, S/C de Ten
d May 20, 2001
lcanic archipelago of the Canary Islands, 100 km co
stunorthwestern coast of Africa, harbors 43 endemic
of the mostly circum-Mediterranean spider genus tio
fora (Araneae, Dysderidae). This amounts to approx-
one-fourth of all known Dysdera species in an in
peat represents 0.1% of the range of the genus. In
o address the origin of this extraordinary number premic species, the phylogenetic relationships
all the endemic taxa and a sample of 27 continen-
cies were reconstructed. A simultaneous cladistic
s was performed on 66 morphological characters,
of the cytochrome oxidase I and 424 bp of the
INTR
NA mitochondrial genes. The preferred most par-
ous tree supports a single origin for most of the
ic species (84%), although this tree is ambiguous
Geolo
ng the total number of overseas colonizations
Oce
ng a minimum of two and a maximum of four
quired
ation events). Our data suggest that the Canary
in the
have been the source of the colonizers of some
coinci
remaining Macaronesian archipelagoes (certainly
si�cat
Selvagem Islands and the Cape Verdes and possi-
condu
Madeira); the Azores have been independently
effect
cycle h
winia
nt address: Division of Insect Biology, ESPM, University of
ia at Berkeley, 201 Wellman Hall, Berkeley, CA 94720-3112. hypot
01 $35.00
313
q 2001 by The Willi Hennig Society
of reproduction in any form reservedzed by dysderids from the continent. The present
provides a phylogenetic framework for an excep-
case of insular species radiation, an essential tool
raveling the factors that have promoted this amaz-
versification. Species radiations in oceanic archi-
es are excellent models for the study of speciation
ses. q 2001 The Willi Hennig Societya (Araneae,
ladistic
ets
E-08028 Barcelona, Spain;
, SpainODUCTION
gical and Geographical Settings
anic islands offer the experimental conditions re-
to study the patterns and processes involved
genesis of biodiversity (Mayr, 1967). It is not a
dence that hypotheses concerning species diver-
ion have been developed largely from research
cted in large part on islands, e.g., the founder
theory (Carson and Templeton, 1984), the taxon
ypothesis (Wilson, 1959, 1961), or even the Dar-
n paradigm itself. Unfortunately, most of these
heses were proposed at a time when sciences

314 Arnedo, Orom�, and Ribera
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All righ as ecology, ethology, and population genetics re-
exclusively on explanations based on observable
ent-day processes (Wanntorp et al., 1990). How-
r, more recent treatments of the comparative
hod (Brooks and McLennan, 1990; Brooks et al.,
5; Coddington, 1988; Desutter-Grandcolas and
ndcolas, 1996; Harvey and Pagel, 1991; Miller and
zel, 1995; Wanntorp et al., 1990) have motivated
logenetically based tests of species diversi�cation
slands (Gillespie, 1997; Hollocher, 1998; Kamby-
is and Craddock, 1997; Kim et al., 1996; Liebherr
Hajek, 1990; Losos, 1990, 1992; Petren and Case,
7; Radtkey et al., 1997; Thorpe et al., 1995; Wagner
Funk, 1995). Cladistic tests of a process statement
ire, �rst, the explicit de�nition of a phylogenetic
ario resulting from such a process and, second, the
struction of a cladogram for representative exem-
taxa (Liebherr and Hajek, 1990).
he Canary Islands are a volcanic archipelago lo-
d in the Atlantic Ocean, 100 km off the northwest-
coast of Africa. The origins of the archipelago are
troversial, although most recent treatments favor
hypothesis that the islands are the result of hot-
t volcanism (Carracedo et al., 1998a, b). Geological
malies exhibited by the Canaries when compared
rototypical hot-spot archipelagoes such as the Ha-
ian Islands have motivated previous alternative ex-
ations [e.g., a propagating fracture originated dur-
the Atlas formation (Anguita and Herna�n, 1975)].
se anomalies are currently thought to result from
location of the hot spot close to a passive continen-
margin. The seven main islands are roughly ar-
ged in a straight line, representing a gradient of
e of origin and proximity to the mainland (Fig. 1).
eastern islands are the summits of a continuous
anic ridge parallel to the African coast (Coello et
992) and include the oldest islands, Fuerteventura
5�17.0 Mya) and Lanzarote (15.5�10.2 Mya), as well
everal islets (Ancochea et al., 1996; Coello et al.,
2). In the center of the archipelago, Gran Canaria
single volcanic edi�ce formed about 16.12�13.9
a (Abdel-Monem et al., 1971; McDougall and
mincke, 1976; Schmincke, 1981). Tenerife arose from
oceanic �oor as three independent islands (Anaga,
�6.5 Mya; Teno, 6.7�7.1 Mya; Roque Conde, 11.6
a) that became united after a new volcanic pulse 2
a (Abdel-Monem et al., 1972; Ancochea et al., 1990).
single-edi�ce island of La Gomera (subaerial stageight q 2001 by The Willi Hennig Society
hts of reproduction in any form reservedAzores
Cape Verde
Canaries
Selvagens
Madeira
(A)Fuerteventura
Tenerife
El Hierro
La Gomera
La Palma
Gran Canaria
La Graciosa
Lanzarote
(B)
. 1. (A) The Macaronesian region; (B) the Canary Islands.
Mya) is located west of Tenerife (Ancochea et al.,
0; Cantagrel et al., 1984). However, it has recently
n proposed that the island of La Gomera is older
n Tenerife, which would represent an exception to
general spreading trend (Carracedo et al., 1998a,
The islands of La Palma (2 Mya) and El Hierro (0.8
a) (Ancochea et al., 1994; Fuster et al., 1993) are the
sternmost and youngest of the Canaries.
umidity is one of the main factors shaping the
tribution of the Canary Island ecosystems. A near-
manent cloud belt on the northeastern slopes of
st islands is formed by the interaction of humid,
rm NE trade winds, dry, cool NW trade winds, and
h elevations (.1450 m). However, the elevation of
eastern islands rarely reaches 800 m (as a result of
remarkable erosion they have undergone due to
ir older age), which prevents the formation of a