Evolution, 4th Edition

THE GEoGRAPHy of EvoluTion 481

Futuyma Kirkpatrick Evolution, 4e

Sinauer Associates

Troutt Visual Services

Evolution4e_18.13.ai Date 12-13-2016

Symphonia verrucosa

Madagascar

species

Symphonia nectarifera

Symphonia

globulifera

S. globulifera

Cameroon, West Africa

Dominica, West Indies

South America, east of Andes

West and north

of Andes

Panama

Coastal Ecuador

Belize

Costa Rica

Panama

FIGURE 18.13 Relationships among popu-

lations of the widespread tree Symphonia

globulifera, a member of an Old World genus

with species in Madagascar. S. globulifera

spread from West Africa to the West Indies

and eastern South America, and from there to

the trans-Andean region, including coastal Ec-

uador and Central America. (After [9], courtesy

of C. W. Dick.)

Futuyma Kirkpatrick Evolution, 4e

Sinauer Associates

Troutt Visual Services

Evolution4e_18.14.ai Date 12-12-2016

Gulf of Mexico Gulf of Mexico Gulf of Mexico

Lepomis

punctatus

(A) (B)

Amia calva

(C)

Dicerandra

spp.

FIGURE 18.14 Patterns of genetic divergence among populations may show that

many species have a similar history of subdivision (vicariance). Gene trees of these spe-

cies show sharp division between eastern and western populations of both freshwater

and terrestrial species in the coastal plain of the southeastern United States. These pop-

ulations are thought to have been isolated and to have diverged in two refugia during

the Pleistocene. (A) Spotted sunfish (Lepomis punctatus). (B) Bowfin (Amia calva).

(C) Sister species of mints in the genus Dicerandra. (After [41].)

Geographic Range limits: Ecology and Evolution

The geographic distribution of a species results not only from the history of its

ancestors, but also from current factors, a major subject of ecological biogeogra-

phy. Several difficulties can retard or prevent a species from expanding its range.

It must disperse to the new region. Individuals in sexually reproducing species

must find mates, which may be difficult if there are few individuals and the initial

population density is very low. They must be able to survive physical conditions,

find suitable resources (food, habitat), and contend with other species, such as

competitors, predators, and parasites.

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