untitled

Convergence occurs when organisms of different ancestry (i.e. from different phyletic

groups) adapt to similar environments and thus develop similar characteristics. One

of the classic examples is the placental mammals and the marsupials that have evolved

similar morphology and behavior even though they are quite unrelated (Fig. 3.2).

The rock ringtail possum (Pseudocheirus dahli), a marsupial of northern Australia,

lives in the crevices of large rock piles. Bruce’s hyrax (Heterohyrax brucei), from the

very different placental order Hyracoidea confined to Africa and Arabia, has precisely

ANIMALS AS INDIVIDUALS 21

Ciridops anna

Himatione sanguinea

(insect/nectar)

Vestiaria coccinea

(nectar)

Hemignathus virens

(insect / nectar)

Hemignathus lucidus

(bark feeder)

Drepanis funerea

(nectar)

Hemignathus obscurus

(bark crevasse)

Psittirostra psittacea

(fruit eater)

Loxiodes bailleui

(seed eater)

Chloridops kona

(seed eater)

Fig. 3.1Adaptive
radiation of the
Hawaiian honeycreepers
(Drepanididae). Only a
few of the species are
illustrated here. There
are four main functional
groups: insect feeders in
foliage, nectar feeders,
bark feeders, and seed
eaters. (After Futuyma
1986 with nomenclature
from Pratt et al. 1987.)

3.4 Examples of adaptation

3.4.1Convergence