10.1 Early Ideas About Evolution

Early scientists proposed ideas about evolution. Evolution is the biological change process by which descendants come to differ from their ancestors. A species is a group of organisms that can reproduce and have fertile offspring.

There were many important naturalists in the 18th century. Linnaeus: classification system from kingdom to species Buffon: species shared ancestors rather than arising separately E. Darwin: more-complex forms developed from less complex forms Lamarck: environmental change leads to use or disuse of a structure

Theories of geologic change set the stage for Darwin’ s theory. There were three theories of geologic change. p300 catastrophism gradualism uniformitarianism

Uniformitarianism is the prevailing theory of geologic change Uniformitarianism is the prevailing theory of geologic change. (key to the past)

10.4 Evidence of Evolution

Evidence for evolution in Darwin’s time came from several sources. Fossils in older layers are more primitive than those in the upper layers.

The study of geography provides evidence of evolution. island species most closely resemble nearest mainland species populations can show variation from one island to another Biogeography – the study of the distribution of organisms around the world

Embryology provides evidence of evolution. p311 identical larvae, different adult body forms similar embryos, diverse organisms Embryology "the unborn, embryo“ is the branch of biology that studies the development of gametes (sex cells), fertilization, and development of embryos and fetuses. 

The study of anatomy provides evidence of evolution. p312 Homologous structures are similar in structure but different in function.

Analogous structures have different structure, similar function. Analogous structures are not evidence of a common ancestor.

Structural patterns are clues to the history of a species. Vestigial structures are remnants of organs or structures that had a function in an early ancestor. Ostrich wings are examples of vestigial structures.

10.5 Evolutionary Biology Today

Fossils provide a record of evolution. Paleontology is the study of fossils or extinct organisms.

Molecular and genetic evidence support fossil and anatomical evidence. DNA Sequence Analysis Two closely-related organisms will have similar DNA sequences.

Pseudogene sequences providing evidence of evolution. no longer function carried along with functional DNA can be clues to a common ancestor

Homeobox genes indicate a very distant common ancestor.

Protein Comparisons Molecular fingerprinting Cells from different species that have the same proteins most likely have common ancestors.

Evolution unites all fields of biology Scientist from any fields contribute to the understanding of evolution. The basic principles of evolution are used in many scientific fields.