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?

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 20 th century Viral explanation popular in the late 20 th century

Climatic explanation popular in the early 21 st 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