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Evolution BIO Cheat Sheet Chapter 15 by


- evolution: process where modern organisms have descended from ancient organisms
- theory: well supported testable explan­ation of phenomena that have occurred in the natural world

Voyage of the Beagle

- darwin joined the crew of the H.M.S. Beagle
- during his voyage, darwil made a hypothesis about the way life changes over time
- his samples of animal & plants specimen led him to a scientific explan­ation for the diversity of life

Darwin's Observ­ations

- darwin was curious about how organisms were so perfectly suited to their enviro­nment and what role fossils played
- fossils: preserved remains of ancient organisms
- he noticed different shapes in bird beaks and turtle shells among different islands
- he wondered if these organisms had once been a part of the same species

Ancient, Changing Earth

- hutton & lyell discovered that the earth is many millions of years old & the processes that changed the earth in the past are the same processes that operate in the present
- hutton: layers of rock are evidence of how old earth is
- lyell: geological phenomena like volcanoes evidence of how processes shaped earth millions of years ago and still do

Lamarck's Evolution Hypothesis

- lamrack: selective use or disuse of organs -> organisms acquired or lost traits over time -> traits passed to offspring -> change in species
- discovered that enviro­nments also affect organisms

Population Growth

- malthus: if population grows & left unchecked -> fewer resources (livong space & food)

Inherited Variation & Artificial Selection

- artifical selection: nature provides variation & human selected those variations that they found useful

Evolution by Natural Selection

- struggle for existence: compet­ition among species for resources to survive
- fitness: organism's ability to survive and reproduce in an enviro­nment
- adaption: any inherited charac­ter­istic that increases an organism's chance of survival
- survival of the fittest: indivi­duals who survive and reproduce most succes­sfully
- descent w/ modifi­cation: each species has descended with changes from other species over time (all organisms are related to one another)
- common descent: we could find the common ancestors of all living things

Evidence of Evolution

- darwin proposed liing things have been evolving on earth for millions of years; evidence: fossil record, geological distri­bution of living species, homologous structures of living organisms, & simila­rities in embryology
- homologous struct­ures: structure that mature differ­ently ut develop from the same embryonic tissues
- vestigal organs: anatomical structures that are retained in a species despite having lost their primary ancestral function


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