Summary from the last lectures We have a reliable method for determining the age of rocks and fossils. As a result we know: The Earth and the solar system are 4.6 billion years old. The oldest fossil organisms on Earth (bacteria) are 3.5 billion years old. There is plenty of time for evolution And the data do not support the hypothesis of Devine Creation of a 6,000 year old universe.

I believe this is the way the world is

Not this

Biogeography= the study of the distribution of organisms

From Wallace’s 1876 book The Geographical Distribution of Animals

How do we explain these distribution patterns? Proteaceae family

Flying squirrel distribution

Cichlid fish distribution

Wolverine distribution

How do organisms get to where they are found? Created (evolved) there. Active Immigration: under their own power (walking, swimming, flying). Passive immigration carried by water, air, or land movement. a. floating rafts of debris. b. birds carrying seeds c. insects carried by air currents d. tectonic plates e. humans carrying domestic animals & plants invasive species

Test: Look at distribution patterns of organisms Deduction (Prediction) If the Hypothesis of Creationism is correct then there was a single Center of Creation . And places with similar environments should have similar organisms Test: Look at distribution patterns of organisms

Creationist argument: Biblical Flood led to recolonization of the world when organisms disembarked from Noah’s Ark

The conventional explanation that species had been created with adaptations to their particular climate made no sense to Wallace because he knew similar climatic regions had very different animals in them. Instead, he found that closely related species were found together even though they might be in different habitats.

If the Hypothesis of Creationism is correct then places with similar environments should have similar organisms. Linnaeus (1701—1778) Father of Taxonomy Different species live in different areas Buffon (1707—1788) French Naturalist Mammals of Africa & South America are different. Humboldt (1769—1859) Plants of Africa & South America are different.

No species are alike in Africa & South America Lattreille (1762—1833) French zoologist Insects are different in Africa & South America Cuvier (1769—1832) French Paleontologist Reptiles are different in Africa & South America No species are alike in Africa & South America even though their climates are similar. They are in distinct Biogeographic Zones

Biogeographic Zones

There is no single center for Creation Evaluation: Data do not support the hypothesis of Devine Creation. There is no single center for Creation

Test: Look at distribution patterns of organisms Deduction (Prediction) If the Hypothesis of Evolution is correct then related species should live near one another Or distribution patterns should be explained by the geological record—barriers and diffusion Test: Look at distribution patterns of organisms

Distance between related species Data: Darwin in South America found species living close together are more similar than those living farther apart. X X Similarity Index X X X X X X X X X X Distance between related species

Real Data for Gastropods (Snails Etc.)

Patterns of Distribution Cosmopolitan Distribution (found almost everywhere in the world) Brown rat

Patterns of Distribution Continuous Distribution (found spread over a large range. E.g. starlings over Europe and N. America

Patterns of Distribution Continuous zonal distribution (found throughout certain climatic zones. E.g. moose spread throughout the Northern latitudes

Patterns of Distribution Endemic Distribution (highly restricted to one area) e.g. lemurs are restricted to Madagascar

Patterns of Distribution Discontinuous (= Disjunct) Distribution (found in a few separated areas) e.g. bog turtle

The challenge is to explain how a once continuous population became discontinuous. Two answers: Dispersal—population spreads out to distant places—flying, swimming, carried by wind or water or animals. Vicariance—population gets split up by continental drift, glaciers, mountain building, rivers, and the intervening populations become extinct.

Patterns of Distribution Scattered Distribution (small local populations) e.g. Bighorn sheep

History matters How can we explain these distributions? The creation model doesn’t help us. But the evolution model plus the geological record should help us. History matters

Abiotic Factors What are the factors that determine distribution? 1. Physical factors (e.g temperature, light, soil, fire, currents) Abiotic Factors 2. Chemical factors (e.g. water, oxygen, salinity, pH, soil nutrients) 3. Biological factors (e.g. predators, parasites, disease, competition, food.) 4. Geographical & geological barriers to dispersal (e.g. rivers, mountains, glaciers, oceans)

Patterns of interchange between biotic provinces. Corridors = large areas where free migration can occur. e.g. the animals of Western Europe , North China and North America are similar.

Land Bridges—Bering Strait Asia North America

Patterns of interchange between biotic provinces. Filter bridge = an area of exchange between two areas that is restricted. e.g. The Isthmus of Panama restricts movement between North and South America. 30—120 miles across Formed 3 mya when South American continent collided with North America

Filter Land Bridges—Isthmus of Panama

Filter Land Bridges—Isthmus of Panama

Patterns of interchange between biotic provinces. Sweepstakes Route = a route of exchange that is rare Volcanic Islands are populated like this. e.g. Galapagos Islands. ~600 miles from Ecuador Animals and plants are like the mainland species

Island biogeography: Effect of distance from mainland Bird species in the Lesser Antilles (D. Lack's data)

Species number and Island Area Reptiles and Amphibians in the Caribbean Islands

So we can explain island biogeography on the basis of immigration into islands and extinction. Immigration depends upon the distance from colonizing source (e.g. mainland). The more isolated the islands, the fewer species. Extinction depends on the area available for speciation and niche specialization (The greater the island area, the more species can specialize and survive.)

Fragmentation of the environment producing islands A big take a way message of this island study is that the smaller the island is, the fewer the species will survive. As humans alter their environment with more houses, agricultural fields, parking lots and towns, they break up the environment into smaller and smaller parcels of land. They fragment the environment into islands. And fewer and fewer species can exist.

How do we explain this? Mysterious case of Mesosaurus Freshwater reptile living in lakes and steams. One meter long.

Mysterious case of Mesosaurus . Biogeography is forever seeking explanations of distributions using the principles of evolution, ecology, and geology.

Explained by continental drift ! Mysterious case of Mesosaurus Explained by continental drift !

Continental Drift

Continental Drift

Plate Tectonics explains this

Flying squirrel distribution Convergent evolution explains this Flying squirrel distribution

How do we explain this?

Wallace Line A line separating the Asian and Australian biogeographic zones

The evidence from biogeography Conclusion There is no single center of distribution as you would expect with the Biblical Story of Creation. The model of evolution can explain the patterns of distribution of organisms with the help of geology, ecology, evolution, and radiometric dating. The evidence from biogeography supports the model of evoltuion

Next Time Evidence from Anatomy & Embryology