Introduction to Biogeography

Tues, Jan 12th

Science

• Science is a way of thinking much more than it is a body of knowledge – Carl Sagan

• There are many hypotheses in science which are wrong. That’s perfectly all right; they’re the apeture to finding out what’s right. Science is a self-correcting process. To be accepted, new ideas must survive the most rigorous standards of evidence and scrutiny – Carl Sagan

• Scientific method

What is Biogeography?

• Biogeography – the study of the past and present geographic distribution of plants, animals, and other organisms

• Biogeographers explain and describe

• Biogeographers are interested in:– How the great diversity of life arose – Where the modern human species came from – How we can alter and preserve the natural

environment

The Ultimate Question

• How have speciation, adaptation, extinction, and other ecological processes interacted with one another and with climate, sea level, continental configurations, and other physical characteristics of the environment (which are themselves ever-changing) to produce distributional patterns in the world’s biota over time?

Biogeography

• A synthetic science because it borrows knowledge from several disciplines:– Ecology– Evolutionary biology– Geology– Paleontology– Physiology– Anatomy– Pedology– Climatology– Limnology – oceanography

Alligator Distribution

Figure 1.1

Biogeography Subdisciplines• Phytogeographers • Zoogeographers

• Ecological biogeography

• Historical biogeography

• Analytical biogeography

• Conservation biogeography

Definition of Species• Phylogenetic species concept

• Biological species concept

• Evolutionary species concept

Biological Species Concept

The western meadowlark (left) and the eastern meadowlark (right) appear to be identical, and their ranges overlap, but their distinct songs prevent interbreeding – appearance isn’t everything!

Gray wolf (Canis lupus)

Coyote (Canis latrans)

Red wolf (Canis rufus)

Is the red wolf a species?

Is the red wolf a species?

• Biological species concept –

• Phylogenetic species concept –

• Evolutionary species concept –

• Is a hybrid a species?

Ecological Hierarchy

• Population – all individuals of a species in a given area

• Metapopulation – • Loose metapopulations –

• Tight metapopulations –

• Community – populations of organisms that live and interact in a given area

• Synecological approach – concentration on communities, not individuals

• Autecological approach – concentration on individuals

Ecological Hierarchy

Humans• The biological and cultural development of

humans is a product of geography, the Earth’s physical environment, and interactions with other organisms

• Example: Human migration into Americas

• How is migration/settlement reconstructed?

Climatic/Environmental Determinism

• At the beginning of the Holocene, everyone was at the same starting point

• So why did some parts of the world end up better off than others?

• Why are Eurasians and Americans better off than the rest of the world?

• Racial explanation popular in early 20th century

• Viral explanation popular in the late 20th century

• Climatic explanation popular in the early 21st century

• Domesticated plants and animals spread more easily east to west

• Climate and ecological zones extent east to west (remember daylength)

• Therefore north-south axis continents (Africa and South America) and those separated by water (Australia and North America) were less innovative

Climatic/Environmental Determinism

• 2/3 of domesticated grasses grow naturally in western Eurasia– 1/10 in east Asia and 1/30 in South America and

Australia

• 9 of the 14 large domesticated animals found in western Eurasia: goat, pig, sheep, cattle– South America has 1: llama

• Importance of frost– Control of parasites, pests, and disease vectors– Frost limits the breakdown of organic matter in soil

and preserves soil moisture

Climatic/Environmental Determinism