Biology - Chapter 17: Theories of Evolution

Charles Darwin

developed a theory of biological ecolution that offered a scientific explanation for the unity and diversity by proposing how how modern organisms evolved through common ancestors.

Species vary Globally

Darwin noticed that different, yet ecologically similar, animal species inhabited separated, but ecologically similar, habitats around the globe.

Species vary Locally

Darwin noticed that different yet related species often occupied different habitats within a local area

Species vary over time

fossils; extinct animals were similar to living species

Alfred Wallace

Came up with the idea of natural selection to explain evolution, joint published with Darwin

James Hutton

suggested that Earth is much more than a a few 1000 yrs old, geoelogical processes are the same processes that shaped Earth over millions of years

Uniformitarianism

one of Lyell's principles of geology: laws of nature are constant over time so processes are the same throughout time

Lyells other principle of geology (basis of evolution)

Geology + Biology = if it has taken Earth millions of years to change, life has probably changed as a result

Lamarck's Hypothesis #1

tendency towards perfection

Lamarck's Hypothesis #2

use and disuse

Lamarck's Hypothesis #3

inheritance of acquired traits

Artificial Selection

nature provides the inherited variations & humans select those variants

Natural Selection

Darwin's proposed mechanism for evolution: struggle for existence, variation and adaptation, survival of the fittest

Inherited Variation

members of each species have many different traits that they can pass on

Fitness

ability to survive and reproduce

Adaptation

inherited trait that increases chance of survival (makes better suited for environment)

Biogeography

patterns in the distribution of species and combined with information from geology tell us how modern organisms evolved

Fossil Record

evidence that living things have been evolving for millions of years

Homologous structures

structures that are shared by related species and have been inherited from a common ancestor

Vestigial structures

inherited strucures from ancestors but have lost much of their original size and function

Analogous structures

Body parts that serve similar functions, but do not share structure and development

Embryological development

evidence of common ancestor

At the molecular level...

similarities in the genetic code along with homologous genes and molecules provide evidence of common descent

Life's common genetic code

Molecular homology