Geography Reference
In-Depth Information
the tenth edition (1890) he added a footnote stating that he had concluded
that no such connecting land was needed to explain the facts.
Philip Lutley Sclater (1829-1913), a British ornithologist, published
On
the General Geographical Distribution of the Members of the Class Aves
in 1858. He divided the world into six biogeographic regions that would re-
flect “the most natural primary ontological divisions of the Earth's surface”
(1858:130), although he acknowledged that his system was rudimentary
and that much work was left to be done. Sclater's biogeographic regions
were modified by Wallace (1876) and other authors; however, they have
stood the test of time, and many textbook accounts use them (Briggs and
Humphries 2004; Brown and Lomolino 1998). In contrast to other biogeo-
graphers at that time, Sclater believed that organisms did not disperse to
favorable habitats; rather, they changed over time in the same area. When
explaining the presence of some mammal taxa in Madagascar, Sclater con-
cluded,
The anomalies of the mammal-fauna of Madagascar can be best ex-
plained by supposing that, anterior to the existence of Africa in its
present shape, a large continent occupied parts of the Atlantic and
IndianOceansstretchingouttowardsAmericaonthewest,andtoIn-
dia and its islands on the east; that this continent was broken up into
islands, of which some have become amalgamated with the present
continent of Africa, and some possibly with what is now Asia, and
that [in] Madagascar and the Mascarene Islands we have existing
relics of this great continent. (Sclater 1864:219)
This statement makes Sclater a precursor of vicariance biogeography.
Darwin's and Wallace's dispersalist ideas were challenged by several au-
thors. The extensionists, such as Forbes and Hooker, considered long-dis-
tance dispersal an unlikely process to explain disjunct distributions (Brown
and Lomolino 1998). They chose instead to postulate ancient land bridges
and continents now submerged in the oceans, which once linked the surviv-
ing continents (Bowler 1996). Extensionists initially had a profound influen-
ce, but at the end of the nineteenth century their ideas were abandoned.
