THE SCIENCE OF THE SCIENCE OF BIOGEOGRAPHYBIOGEOGRAPHY

What is Biogeography?What is Biogeography?

Biogeography Biogeography - the science of documenting - the science of documenting and understanding spatial patterns of and understanding spatial patterns of biodiversity. Includes the the study of the biodiversity. Includes the the study of the distributions of organisms (both past and distributions of organisms (both past and present) and of related patterns of variation over present) and of related patterns of variation over the earth in the numbers and kinds of living the earth in the numbers and kinds of living things.things.

QUESTIONSQUESTIONS

Types of questions asked:Types of questions asked: 1. Why is a species or higher taxonomic group 1. Why is a species or higher taxonomic group

(genus, family, order, etc.) confined to its (genus, family, order, etc.) confined to its present range?present range?

QUESTIONSQUESTIONS

2. What enables a species to live where it does? 2. What enables a species to live where it does? What prevents its dispersal?What prevents its dispersal?

QUESTIONSQUESTIONS 3. What roles do climate, topography, and 3. What roles do climate, topography, and

interactions with other organisms play in limiting interactions with other organisms play in limiting the distribution of a species?the distribution of a species?

QUESTIONSQUESTIONS 4. Why are the animals and 4. Why are the animals and

plants of large, isolated plants of large, isolated regions, such as Australia, regions, such as Australia, New Caledonia, and New Caledonia, and Madagascar, so distinctive?Madagascar, so distinctive?

QUESTIONSQUESTIONS

5. Why are some groups of closely related 5. Why are some groups of closely related species confined to the same region, and others species confined to the same region, and others found on opposite sides of the world?found on opposite sides of the world?

QUESTIONSQUESTIONS 6. Why are there so many more species in the 6. Why are there so many more species in the

tropics than at temperate or arctic latitudes? tropics than at temperate or arctic latitudes? How are isolated oceanic islands colonized, and How are isolated oceanic islands colonized, and why are there nearly always fewer species on why are there nearly always fewer species on islands than in the same kinds of habitats on islands than in the same kinds of habitats on continents?continents?

SPECIALIZATIONSPECIALIZATION

Biogeography is a large field and specialization is Biogeography is a large field and specialization is common:common:

Phytogeographer Phytogeographer - study plants- study plants

ZoogeographersZoogeographers - study animals - study animals

SPECIALIZATIONSPECIALIZATION

Historical biogeographers Historical biogeographers - reconstruct the origin, - reconstruct the origin, dispersal and extinction of taxa and biotas.dispersal and extinction of taxa and biotas.

Ecological biogeographersEcological biogeographers - account for present - account for present distributions in terms of interactions between distributions in terms of interactions between organisms and their physical and biotic environments.organisms and their physical and biotic environments.

Paleoecology Paleoecology - bridges the gap between historical and - bridges the gap between historical and ecological biogeographers, investigates the relationship ecological biogeographers, investigates the relationship between organisms and past environments.between organisms and past environments.

SPECIALIZATIONSPECIALIZATION

Relationship to other sciences:Relationship to other sciences:

Basic knowledge of Geography is important.Basic knowledge of Geography is important.

GondwanalandGondwanaland

Example 1: We see related species on distinct Example 1: We see related species on distinct land masses such as South America, Africa and land masses such as South America, Africa and Australia (Living fishes, insects, birds, Australia (Living fishes, insects, birds, earthworms and extinct reptiles). Until 135 earthworms and extinct reptiles). Until 135 million years ago, South America, Africa and million years ago, South America, Africa and Australia were part of a single giant land mass Australia were part of a single giant land mass existed called Gondwanaland.existed called Gondwanaland.

LANDMASS FORMATIONLANDMASS FORMATION

Example 2: As North America shifted away Example 2: As North America shifted away from Europe forming the North Atlantic, North from Europe forming the North Atlantic, North America moved closer to South America and the America moved closer to South America and the Isthmus of Panama formed about 3.5 million Isthmus of Panama formed about 3.5 million years ago. years ago.

=> Resulted in a terrestrial connection between => Resulted in a terrestrial connection between NA and SA.NA and SA.

=> Also resulted in the separation of the => Also resulted in the separation of the tropical Atlantic and Pacific oceans.tropical Atlantic and Pacific oceans.

LANDBRIDGESLANDBRIDGES Example 3: Bering landbridge connected Alaska to Example 3: Bering landbridge connected Alaska to

Siberia in NE Asia up to approximately 10,000 years Siberia in NE Asia up to approximately 10,000 years ago.ago.

GEOLOGIC TIME SCALEGEOLOGIC TIME SCALE

Example 4: Great lakes of North America did Example 4: Great lakes of North America did not exist 15,000 yrs ago.not exist 15,000 yrs ago.

Mediterranean ClimatesMediterranean Climates However, history can not explain all patterns - However, history can not explain all patterns - Mediterranean ClimatesMediterranean Climates for for

example!example! - Distinctive vegetation occurs throughout the world in- Distinctive vegetation occurs throughout the world in isolated regions.isolated regions. - Rainfall is low and occurs in mild winter months- Rainfall is low and occurs in mild winter months - Summers dry and hot- Summers dry and hot - Distinctive semiarid plant communities- Distinctive semiarid plant communities - Plants appear superficially similar- Plants appear superficially similar - Plants in each region belong to different genera and even- Plants in each region belong to different genera and even familiesfamilies => Result of convergent evolution in response to similar=> Result of convergent evolution in response to similar environmentsenvironments

Mediterranean ClimatesMediterranean Climates

Philosophy and Basic Principles:Philosophy and Basic Principles:

““Philosophers and historians of science, viewing its progress with 20/20 Philosophers and historians of science, viewing its progress with 20/20 hindsight, often suggest that it is possible to give a recipe for the most hindsight, often suggest that it is possible to give a recipe for the most effective way to conduct an investigation. Unfortunately, as most practicing effective way to conduct an investigation. Unfortunately, as most practicing scientists know, scientific inquiry is much more like working on a puzzle or scientists know, scientific inquiry is much more like working on a puzzle or being lost in the woods than like baking cookies or following a road map. being lost in the woods than like baking cookies or following a road map. There are numerous mistakes and frustrations. Luck, timing, and trial and There are numerous mistakes and frustrations. Luck, timing, and trial and error play crucial roles in even the most important scientific advances. Some error play crucial roles in even the most important scientific advances. Some important discoveries, such as Alfred Wegner’s evidence of continental drift, important discoveries, such as Alfred Wegner’s evidence of continental drift, are long ignored or even totally rejected by other scientists. While the are long ignored or even totally rejected by other scientists. While the progress of science owes much to such admirable human traits as intelligence, progress of science owes much to such admirable human traits as intelligence, creativity, perseverance, and precision, it is also retarded by equally human creativity, perseverance, and precision, it is also retarded by equally human but less admirable characteristics such as prejudice, jealousy, shortsightedness, but less admirable characteristics such as prejudice, jealousy, shortsightedness, and stupidity. ” Brown and Lomolino, 1998. and stupidity. ” Brown and Lomolino, 1998.

PATTERN AND PROCESSPATTERN AND PROCESS

Scientists investigate the relationships between Scientists investigate the relationships between pattern and process:pattern and process:

PatternPattern - is defined as nonrandom, repetitive - is defined as nonrandom, repetitive organization.organization.

ProcessProcess - or processes, lead to the occurrence - or processes, lead to the occurrence of pattern in the natural world.of pattern in the natural world.

UniformitarianismUniformitarianism or or Actualism:Actualism:

In dealing with historical aspects, In dealing with historical aspects, biogeographers make one critical assumption - biogeographers make one critical assumption - UniformitarianismUniformitarianism or or Actualism.Actualism.

- The assumption that basic physical and - The assumption that basic physical and biological processes now operating on the earth biological processes now operating on the earth have remained unchanged throughout time have remained unchanged throughout time because they are manifestations of universal because they are manifestations of universal scientific laws.scientific laws.

UniformitarianismUniformitarianism or or Actualism:Actualism:

- - ActualismActualism is the preferred term because some is the preferred term because some scientists have implied that scientists have implied that Uniformitarianism Uniformitarianism also means that the average intensities of also means that the average intensities of processes have remained approximately constant processes have remained approximately constant over time and that both geological and biological over time and that both geological and biological changes are always gradual. changes are always gradual.