Biogeography

Chapter 2

The Age of Exploration

► The Early European explorers and naturalists traveled the Earth collecting specimens and describing the patterns of their distribution.

Carolus Linnaeus (1707-1778)

Developed the system of binomial nomenclature to classify all organisms. He noticed that species where well adapted for the locations where they where found, but he believed that species where immutable and created as they where by God.

He described 6000 species in his

Species Plantarum.

Comte de Buffon (1707-1788)

Buffon suggested that species and climate where mutable and he postulated what later became known as Buffon’s Law. “Environmentally similar but isolated regions have distinct assemblages of mammals and birds.”

Hypotheses for the Origin of All Species Linnaeus thought that all life survived the biblical flood on the slopes of Mount Ararat. At successively higher elevations was a series of environments ranging from desert to tundra. Each region with species perfectly adapted to the environment but immutable. Buffon noted that migration across different environments would not be possible, so suggested the origin of all organisms to be at the North Pole and migrations proceeded from that place.

James Hutton (1726-1797)

Realized that given the gradual nature of geologic processes, the Earth must be much older than a few thousand years old. Only an ancient Earth could account for the formation and erosion of mountains, the submergence of ancient landmasses, and the migrations or replacements of entire biotas that where documented in the fossil record.

Johann Reinhold Forster (1729-1798) He Circumnavigated the globe with Captain Cook and presented one of the first systematic world views of biotic regions. He extended Buffon’s Law to plants. He also provided important early insights into what became Island Biogeography Theory and Species Diversity Theory.

Sir Joseph Banks (1743-1820)

One of the explorer/naturalist who traveled for three years with Captain James Cook on the Endeavor (1768-1771) and collected 3600 plant specimens including 1000 species not known to science.

Alexander von Humboldt (1769-1859) The Father of Phytogeography. He extended Buffon’s Law to plants and most terrestrial animals. He noted that Forster’s floristic zonation also occurred with changes in altitude as well as latitude.

Augustin de Candolle (1778-1841)

Swiss botanist noted that not only are organism distributions controlled by light, heat, and water but they

compete

for these resources. He brought in the concept of the

habitat

of a species. He added to Forster’s ideas on

Island Biogeography

that besides island size, species numbers are controlled by island age, volcanism, climate, and isolation.

Theoretical Advances in the Nineteenth Century

► Better estimate of the age of the Earth.

► Understanding of Plate Tectonics.

► Better understanding of the mechanisms involved in the spread and diversification of species – dispersal, vicariance, extinction, and evolution.

Charles Lyell (1797-1875)

Father of Geology and influenced the development of Biogeography with his book

Principles of Geology

in 1830. Realized from the fossil record that climate is mutable.

Lyell also documented that sea levels had changed and that the Earth’s surface changed with the lifting up of mountains and the erosion of the same. He provided evidence for the process of extinction.

A B D C Four British scientists who, in the mid-nineteenth century, revolutionized our understanding of the history of the Earth and the distribution of its organisms. They were close friends and much can be learned from their personal letters as well as their formal publications. A) Charles Darwin, B) Joseph Dalton Hooker, C) Philip Lutley Scalter, D) Alfred Russel Wallace

Charles Darwin (1809-1882)

In 1831 set sail for a 5-year surveying voyage on the HMS Beagle with Robert Fitzroy. He observed fossils of extinct fossils in Argentina, seashells at high elevations in the Andes, and observed different forms of animals on different islands. These observations lead to his idea that geographic isolation facilitates inherited changes within and between populations.

In 1845 he wrote a manuscript on evolution by natural selection but he withheld it from print for 15 years to gather more evidence. Darwin also proposed that the spread and eventual isolation and disjunction of biotas resulted from long-distance dispersal.

Darwin’s Voyage on the HMS Beagle (1831-1836)

Alfred Russel Wallace

Wallace independently wrote up his ideas on evolution by natural selection. His work prompted Darwin to publish his 15 year old manuscript on the topic and their papers where read together before the Linnaean Society of London in 1858.

Louis Agassiz (1807-1873)

Agassiz was a Swiss-born naturalist who trained most of North America’s leading zoologists and geologists from his professorship at Harvard. His studies into glacial deposits lead him to the postulation of past ice ages. He was an ardent opponent to many of Darwin’s ideas and his students supported the idea of the emergence of land bridges for the dispersal of organisms.

Proposed Land Bridges by the Extensionsists

“Rules” of Biogeography

► ► ► ► ► Allen's Rule state that certain extremities of animals are relatively shorter in the cooler parts of a species' range than in the warmer parts.

Bergmann's Rule asserts that geographic races of a species possessing smaller body size are found in the warmer parts of the range, and races of larger body size in cooler parts.

Gloger's Rule states that dark pigments increase in races of animals living in warm and humid habitats.

The Egg Rule states that the average number of eggs in a set, or clutch, laid by songbirds and several other kinds of birds increases as one moves north in latitude.

Cope’s Rule the evolution of a group shows a trend toward increased body size.

C. Hart Merriam (1855-1942)

Confirmed that elevation changes in vegetation type and plant species composition are generally equivalent to the latitudinal vegetation changes found as one moves toward the poles.

Merriam’s Life Zones

Latitude and Altitude

Ernst Mayer (1893-1969)

Mayer made major contributions to the fields of systematics, evolution, and historical biogeography. He developed the biological species concept which states that a species is definable as a group of populations that is reproductively isolated from all other such groups.

George Gaylord Simpson (1902 – 1984) Simpson, among other paleontologists, described the origin, dispersal, radiation, and decline of land vertebrates. They showed that new groups increase in number of species, radiate to fill new ecological roles, expand their geographic ranges, and become dominant over and contribute to the extinction of older forms.

Alfred L. Wegner (1880-1930)

German meteorologist who revitalized Antonio Snider-Pelligrini’s 1958 idea of continental drift. Wegner’s observations where based on the geological and biological evidence.

Continental Slope Fit

Fossils of Mesosaurus

Wegener’s matching of mountain ranges on different continents

Paleoclimatic evidence for Continental Drift

Development of Plate Tectonics

► In 1963 Fred Vine and D. Matthews tied the discovery of magnetic stripes in the ocean crust near ridges to Hess’s concept of seafloor spreading (1939-present) (1906-1969)

Robert H. MacArthur (1930-1972)

Published with E.O. Wilson Island Biogeography. One of the most influential modern ecologists.

E. O. Wilson (1929 – Present)

Books On Human Nature Pulitzer Prize (1978) won the Biophilia (1984) suggests that human attraction to other living things is innate Consilience (1998) urges wider integration of the sciences The Diversity of Life (1992) The Ants, with Bert Hölldobler (1990; Pulitzer Prize) The Future of Life (2002)

Recent Growth of Biogeography in OCLC – First Search