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and tongues; thus providing one of the most popu-
lar illustrations of evolutionary radiation (Fig. 9.6;
Carlquist 1974; Williamson 1981). It is now known
that there were actually many more species in the
recent past. Estimates of the number of species
known historically range from 29 to 33, with
another 14 having recently been described from
subfossil remains: most extinctions occurring
between the colonization of the islands by the
Polynesians and European contact (Olson and
James 1982, 1991; James and Olson 1991; Tarr and
Fleischer 1995). As noted, different genera are
generally recognized within this subfamily, includ-
ingPsittirostra(the Hawaiian name of which is ou)
which have short, conical beaks, for seed eating
(essentially they are still finches), and Pseudonestor
(Maui parrotbill), which uses its powerful beak to

tear apart twigs in order to reach wood-boring bee-

tles. The main evolutionary line, however, is quite

different. Its members have longer, narrower bills,

and they feed on insects (in the case of Paroreomyza,

the Molokai creeper) and on nectar (Loxops(Akepa)

andHemignathus(e.g. Akialoa) ).

Tarr and Fleischer (1995) observe that genetic dif-

ferentiation between species of drepanidines is less

than would be expected on the basis of their mor-

phological divergence, indicating that they are the

product of a relatively recent arrival (in the order of

3.5–8 million years), followed by rapid adaptive

radiation. They concluded that evidence for an

allopatric model of speciation was fairly convincing

for some of the honeycreepers, but they were not

able to rule out sympatric speciation (particularly in

the light of recent fossil finds). Himatione sanguinea

ADAPTIVE RADIATION 223

Insects, no nectar

Fruit

and

seeds

Insects and

some nectar

Nectar and some insects

Fruit

6

7 8 9 13

14

11

12

17

?

16

15

1

10

4

5

3

2

Figure 9.6The inferred pattern of evolution of dietary adaptations as represented by 16 of the Hawaiian honeycreepers (family Fringillidae,
Subfamily Drepanidinae). 1, Unknown finch-like colonist from Asia; 2,Psittirostra psittacea;3,Chloridops kona (Psittacirostra kona) (extinct);
4,Loxioides bailleui (Psittacirostra bailleui);5,Telespyza cantans (Psittacirostra cantans);6,Pseudonestor xanthophyrs;7,Hemignathus munroi
(H. wilsoni);8,H. Iucidus;9,H. obscurus (H. procerus); 10,H. parvus (Loxops parva); 11,H. virens (Loxops virens); 12,Loxops coccineus; 13,
Drepanis pacifica(extinct); 14,Vestiaria coccinea; 15,Himatione sanguinea; 16,Palmeria dolei; 17,Ciridops anna(extinct). Source: Cox and Moore
(1993, Fig. 6.11). The taxonomy preferred here follows Pratt et al. (1987), with that given in Cox and Moore (1993) in brackets where different.