(i) Preamble:

A brief section on the history of Zoogeography is intended to give you an appreciation of:

1. the historical roots of the discipline

2. some the major players in early zoogeographical thought

3. how the discipline has evolved from largely a descriptive endeavor of naturalists to a "true" science that erects hypotheses, develops predictions based on these hypotheses, and uses a wide array of analytical techniques to test these hypotheses.

Because zoogeography is more of the most synthetic of fields within biology (one often has to be well versed in ecology, geography, climatology, genetics) there is no single "central event" that gave rise to zoogeography.

Historical developments can be viewed as occurring over three time periods:

1. Pre-1900’s

2. 1900-1960

3. 1960-present

(ii) pre-1900’s

Since the creation of the first prehistoric cave paintings to the musings of the ancients such as Aristotle, humans have had a practical and intellectual interest in the distribution of animals.

Cave paintings (circa 15000 BC) in the Lascaux Cave in southwestern France.

The central themes of zoogeography, however, had their origins during the "age of exploration" (late 1600’s) when ships traversed the globe for economic/political gains. Many such ships had naturalists on board who made extensive collections. As these collections built up in national institutions, people began noticing trends in species distributions and abundance and hypothesized about the origins of such patterns.

Major trends developed by such workers involved:

(1) Classification of geographic regions based on their biotas

(2) Reconstruction of biotas,i.e. historical reconstruction of their development (origin, spread, diversity

(3) Examining what controls species diversity in different regions

(4) Examining what controls geographic variation in attributes of species (morphology, demography, behaviour)

Some highlights:

Carl von Linneaus (Swedish botanist, 1707-1778). Of course the father of classical binomial nomencalture/taxonomy, but he also suggested that the world's biodiversity originated by dispersal from Mount Ararat in eastern Turkey where Noah’s Ark was thought to have landed after the biblical flood. This was perhaps the first incidence of the idea that taxa have "centres of origin".

When one considers that 250 years ago, fewer than 1% of today's known species (~1.8 million) were described, the "Age of Discovery" and Linneaus really started something!

Carl von Linneaus outfitted for a collecting trip to Lapland (northern Fennoscandia)

Georges-Louis Leclerc, Comte de Buffon (French naturalist,1707-1788).

Wrote "Histoire Naturelle" in which he suggested that the earth must be much older than the biblical claim of 6,000 yr, taxa "changed" through time as did the earth, i.e. there must be a connection between the geological and biological histories of earth.Very radical ideas at the time and over 100 years before Lyell’s and Darwin’s ideas (see below).

Made observations cited as the first "law of biogeography", i.e. Buffon's Law that climatologically similar, but geographically separate regions of the world has distinct biotic assemblages. Suggested "centre of origin" for earth’s biota was in the far north when climates were more benign, biotas changed and diversified as they colonised southward into present day North America and Eurasia.

Alexander von Humboldt (German, 1769-1859). Extended Buffon's Law to many plants and terrestrial animals. Coined the term "floristic belts" and promoted the idea that plant distribution determined by local climate. First one to note the "complementarity" of the South American and west African coastlines and that they may have been joined at one time (heavily ridiculed for such "fantasy" by peers).

Johan Forster (German, 1729-1798). Naturalist for James Cook’s 2nd voyage. Defined distinct regions by distinct plant assemblages. Noted that plant and animal communities may be interdependent.

Noted the unique features of islands for biogeographic study (species numbers increased as island size increased), latitudinal trends in plant species diversity. First hints of "ecological biogeography". Similar ideas and the idea that physical elements may determine species distributions particularly plants were species may compete for these resources (water, nutrients, light) were presented by Augustine de Candolle (Swiss botanist,1778-1841).

Charles Lyell (British, 1797-1875). Several "breakthrough" ideas summarized in his Principles of Geology (1830). Among these were the study of stratigraphic layers and fossils to propose that the earth and its biota changed through time and that these changes were gradual and ongoing, i.e. the earth and its biota were dynamic through time, and that understanding the present geological processes was a key element of understanding the past. In addition, such "uniformitarianism" encompassed the idea that basic natural laws and processes have and continue to act on the earth (and indeed throughout the universe) - a set of ideas popularized in Lyell's book. It went a long way to displace the prevailing idea that all changes in earth and its biota were the result of large scale catastrophic ("catastrophism") geological events that occurred "suddenly". He also observed changes in species composition in the fossil record and inferred that such changes coupled with the gradual nature of geological changes implied that the earth must be must be much older than just a few thousand years. Key effect was how his thoughts showed how the earth and its biota (through the fossil record) were historically inseparable and hence stimulated change in the way people (led by Darwin and Wallace) thought about the dynamics of natural populations (i.e. maybe they changed through time as well).

Five major contributors to zoogeographic thought in the 1800's (clockwise from top right: C. Darwin, J.D. Hooker, C. Lyell, P. Hooker, and A.R. Wallace).

Charles Darwin: (British, 1809-1882). Not primarily a biogeographer, but made key observations on geographic variation within and between species during the voyage of The Beagle (1831-1836).

He was greatly influenced by Lyell’s work and made the connection between changes in the earth’s and changes in its biota that might be the result of geographic isolation and natural selection.

Culminated in writing The Origin of Species (1859) which proposed natural selection as a key factor in the origin of species and hence differences in species diversity and composition amongst different geographic areas. Also, considered long distance dispersal as important in resulting in geographic isolation and evolutionary divergence. Much opposed by so-called "extentionists" (including Lyell) who believed long distance dispersal was unimportant and that long-extinct land bridges could explain the occurrence of widespread taxa and disjunctions (shades of the "dispersalist" versus "vicariance" debate).

Examples of land bridges proposed by "extensionists" who opposed Darwin's (an others) ideas on the importance of long distance dispersal.

Phillip Sclater: (British, 1829-1913, contemporary of Darwin). Developed first major classification scheme for the earth’s biota based on the distribution and composition of birds (of which he described over 1,000 species), principally passerines. Made the connection between dispersal ability and the ability to reconstruct origin of a region's biota from current composition (that’s why he picked passerines as he figured that had greater site fidelity and might better represent ancestral states of species composition and diversity). He erected six regions in 1858: Nearctica (North America and parts of Mexico) Palearctica (Eurasia), Neotropica (tropical central America and South America), Aethiopica (Africa), Indica (Indian subcontinent), and Australiana (Australia) and proposed each as a distinct "centre of origin" for their respective regional faunas. These basic divisions are still recognized (and used) today.