Download The history of biogeography

The history of biogeography
Prehistory
Humans have always used biogeographic knowledge
First ideas
Aristotle (384 BC - 322 BC)
• First one who asked the central
biogeographic question (and left a
written record):
– How are organisms distributed around
the world?
• Also had a view of a dynamic and
changing Earth
Age of European Exploration
World exploration in 18th and 19th centuries
• Specimens were collected, cataloged and compared
Until mid 18th century, religion drove naturalists
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God created all species
Earth, climate, species changed little over time, or not at all
Single species origination event
How could currently isolated animals and plants adapted to
different climates coexist on Noah’s Ark?
Age of European Exploration
Carl Linnaeus (1707- 1778)
• Species classification system
(hierarchical, binomial)
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Kingdom
Phyla
Class
Order
Family
Genera
Species
• Species are immutable
• Hypothesis to explain biodiversity
distribution: Paradisical Mountain
Age of European Exploration
Linnaeus’ Paradisical Mountain Hypothesis
• All species housed on slopes of
equatorial mountain-island ~6000
years ago
• Flood receded, continents
expanded, terrestrial species
expanded to new sites
• In accordance with biblical events
(Noah’s Ark, biblical timeline) and
biblical beliefs (species do not
change; later abandoned this idea)
Age of European Exploration
Georges-Louis Buffon (1707-1788)
• Studied live and fossilized mammals
• Believed in a single species creation event
• Recognized climatic shifts & their
importance to understanding species
spread
• Critique of Linnaeus:
– Different regions (even with same
environment) often had different species
– If species were incapable of adaptation, they
could not have traveled through hostile
environmental barriers from a single
Age of European Exploration
Buffon’s Hypothesis of Species Dispersal
• Species originated around the north pole
during a warm period
• As globe cooled, species migrated south
– Species changed and adapted to new
environments (“improved” or
“degenerated”)
– Species survived that were “improved”,
and “degenerated” species died out
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Importance of hypothesis:
– Dynamic climate
– Adaptation of species
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Buffon’s Law – environmentally similar
but isolated regions have distinct
assemblages of mammals and birds
(becomes principle of biogeography)
Age of European Exploration
Johann Reinhold Forster (Cook’s 2nd voyage;
1729-1798)
• Affirmed Buffon’s law for plants, mammals, birds
• Recognized plant assemblages and relationship
with specific climatic conditions
• Insights into patterns of species diversity
– Habitat (island) size
– Latitude on species diversity
Captain James Cook’s
Voyages
First - 1768-1771 (red)
Second - 1772-1775 (green)
Third – 1776-1779 (blue)
Age of Enlightenment
• Lots of data regarding species diversity and global
distribution had been gathered
• Sought rational explanations for & conceptual
understanding of observed patterns of biodiversity
Age of Enlightenment
Alexander von Humboldt (1769-1859)
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Father of phytogeography
Covariation of vegetation and climate
Invented isobar and isotherm
Expanded latitudinal biodiversity gradients
into elevational gradients
Age of Enlightenment
Agustin de Candolle (1778-1841)
• Species competition for resources as a key
factor for species persistence
• Factors other than island area influence
biodiversity: isolation, climate, geological
history, age
The
th
19
century
Charles Lyell (1797-1875)
• Studied geology & fossils
• Uniformitarianism – physical
processes now operating are
timeless
• Earth’s climate changes & so do
species’ distributions
• Species go extinct!
• Multiple creation events & sites
• Earth must be older than 6,000 yrs
Charles Darwin (1809-1882)
• 1831 – 5 year voyage on HMS
Beagle to South America
• Collected samples of rocks, plants,
animals, fossils
• Developed the theory of evolution
by natural selection; The Origin of
Species (1859)
• Emphasized importance of longdistance dispersal in biogeographic
distribution of species
Darwin in 1840
Darwin’s voyage
Galapagos –
fascinating
wildlife
Argentina – discovered
large mammalian fossils
Argentinian Fossils
Giant ground sloths
Giant armadillo-like creatures
Galapagos
Galapagos Giant Tortoise
Galapagos Finches
• Finches and tortoises - different
islands, different appearance
• Darwin could not connect biblical views
with natural evidence
• Darwin concluded – species change
over time!! One finch and tortoise
diversified to many species
• Remembered fossils – concluded they
were ancestors of current armadillo
and sloth
Did embryonic stages of animals have
characteristics of ancestors?
Ontogeny recapitulates phylogeny
– Whales had teeth (descended from sea creatures
with teeth?)
– Snakes had rudimentary legs (descended from
lizards?)
– Human have structures similar to gill (descended
from fish?)
Species were related in “tree of life”
Alfred Russel Wallace (1823-1913)
• Self-trained English naturalist
• Developed the theory of evolution
(independently from Darwin)
– Species evolved due to pressure from
competition, predation, and environmental
factors that favor one variety over another
• Father of zoogeography
• Developed numerous biogeographic
principles (box 2.1, p. 33)
Wallace Line
• Species are not immutable, but dynamic
responding to biotic/abiotic factors
• But what explains the geographic
distribution of species?
-cosmopolitan vs. disjunct species
• Debate: Dispersalists vs. Extensionists
– Dispersalists - Long-distance dispersal
events (Darwin)
– Extensionists - Landbridges connecting
continents (lack of evidence; Lyell)
• Further study of dispersal ecology and
greater understanding of geological
processes (e.g. continental drift) would
help settle dispute
First half of the
th
20
century
Alfred Wegener (1880-1930)
• Theory of continental drift - 1912
(first introduced by Antonio SniderPelligrini in 1858)
• Not widely accepted until the 1960s
• Revolutionized biogeography –
rethink reasons for species
distributional patterns
Wegener’s Theory of Continental Drift
• Theory:
– Continents formerly joined
– Slowly drifting on Earth’s surface
• Evidence:
– Landmasses fit together like a
jigsaw
– Geological similarity between
matching sides of continents
– Fossil similarities between
matching sides of continents
• Did not know mechanism
Ernst Mayr (1893-1969)
• Biological species concept
(group of individuals that can
reproduce among themselves
and not with other groups)
• Insights into mechanisms of
allopatric speciation
G. E. Hutchinson (1903-1991)
• Multidimensional niche concept
• Mechanisms of species
coexistence
• Father of Limnology
Late
th
20
century
Theory of Island Biogeography
- Mechanistic explanation of species richness
- large islands close to mainlands have greater biodiversity than small,
isolated islands
Robert H. MacArthur (1930-1972)
• Mathmatician & theoretical ecologist
• Strong emphasis on hypothesis testing
Edward O. Wilson (1929 –
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Naturalist & evolutionary biologist
Global biodiversity and conservation
Evolution of ideas
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Age of European Exploration (early 18th century)
– Catalogue/classify species
– Strongly influenced by religion
– Single origination of immutable species
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Age of Enlightenment (late 18th century)
– Distribution & patterns of biodivsersity
– Climate variability important
– Species compete
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19th century
– Earth is old
– Species are dynamic and respond (i.e. adapt) to biotic/abiotic factors
– Species evolve by natural selection, go extinct
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Early 20th century
– Geographic distribution of species due to geological (e.g. continental drift) as well as biological
(species coexistence) factors
– Mechanisms of speciation & coexistence
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Late 20th century
– Island biogeography: conceptual mechanism explaining species richness
Contemporary Biogeography
• Increasing diversification in Biogeography –
paleontology, geology, meteorology, botany, zoology
• Technological advances allowed complex analyses
– Personal computers, multivariate statistical techniques
– GIS, remote sensing