0198566123.pdf

●Progressive clades and grades.A clade is an
entire group descended from one common ances-
tor (i.e. it is monophyletic). Grade refers instead to
the level of adaptation, such that two organisms
can be classed as of equivalent grade but not have a
common ancestor (e.g. Old World and New World
fruit bats). Progressive clades and grades are joined
together because both result from radiations that
differ only in which taxon of the group is involved
in the dispersion to another island. This complex
combined pattern presents a common feature in
which species from a particular island are grouped
together (either in a clade or in a grade) and the
overall pattern in the area cladogram is consistent
with the progression rule. Hawaiian examples are

shown by Tetragnathaspiders,Prognathogryillusand

Laupala crickets, as well as Hybiscadelphus

(Malvaceae) and Dubautia (Asteraceae) plant

genera.

●Terminal resolution.Taxa showing this pattern

have either an unresolved base or a base that has

experienced a radiation on an older island, with

subpatterns involving several well-defined clades.

The latter can be either progressions or radiations,

in each case indicating repeated introductions from

an older, now largely or entirely submerged island.

Hawaiian examples can be found in the plant gen-

eraSchiedeaandAlisinidendron(Caryophyllaceae)

andCyanea(Campanulaceae), as well as in Sarona

(Miridae) plant bugs.

236 EMERGENT MODELS OF ISLAND EVOLUTION

Canary Islands

L

F

C

T

G

H

P AFRICA

H GHP T C F L Isl.

?

?

Gallotia

gen.

(*)

(*)Psammodromus

Gallotiinae

Lacertinae

Eurasia-Africa

Africa

(a)

Figure 9.9Phylogenies of (a) Gallotializards (based on mtDNA) and (b) Olea europeaeasubspeciescerasiformis

(based on internal transcribed spacer 1 (ITS-1) sequences, randomly amplified polymorphic DNAs (RAPD), and

intersimple sequence repeats (ISSR) analyses) on the Canary Islands (after Marrero and Francisco-Ortega 2001 figures

15.5 and 15.6; in turn based on papers by Gonzálezet al. 1996, Fu (2000) and Hess et al. (2000)). L = Lanzarote, L.

Isl. = islets close to Lanzarote, F= Fuerteventura, C = Gran Canaria, T = Tenerife, G = La Gomera, H = El Hierro,

P = La Palma.

(b) Canary Islands

L

F

C

T

G

H

P

AFRICA

PGPCFT

subsp.cerasiformis

Olea europaea

GTC CCCCCF

var. sylvestris

West Mediterranean

subsp.europaea

West Mediterranean

Madeira

subsp.laperrinei

Morocco–Hoggar

O. cuspidata

East and South Africa