Bell Ringer – 1/11/2007 What can happen to a population when the environment changes?

The Theory of Evolution History and evidence for…

Evolution Gradual change in species through adaptations over time What are adaptations?

Charles Darwin ( ) English Naturalist Was NOT the first to propose that species evolve Was the first to propose how they evolve Natural Selection

Darwin’s Voyage

Facts that Darwin observed… 1. Without limiting factors, populations grow exponentially 2. Populations tend to fluctuate above and below carrying capacity 3. Resources are limited. Individuals struggle to survive

Facts that Darwin observed… 4. Individuals are unique; variation exists within a population 5. Those individuals that are able to survive and reproduce keep their variations in the population

Darwin Also Observed Artificial Selection Dogs being bred for certain traits Horses being bred for speed Cotton and wheat being bred for size Darwin theorized that there was a force in nature that worked just like artificial selection (natural selection)

Muy Importante! Natural Selection acts on variations that exist in a population

Quick Review

Speciation – formation of new species Geographic Isolation

Speciation Geographic isolation leads to reproductive isolation Populations become so different that they can no longer interbreed The presence of multiple niches speeds speciation

Evidence for Evolution Structural Adaptations – favorable adaptations are selected for Camouflage Mimicry Etc.

Evidence for Evolution Physiological Adaptations – changes to an organisms metabolic process

Evidence for Evolution Anatomy – homologous structures

Evidence for Evolution Anatomy – analogous structures

Evidence for Evolution Anatomy – vestigial structures

Evidence for Evolution Embryology – comparing embryos

Evidence for Evolution Biochemistry – DNA, ATP, Enzymes

Evidence for Evolution Fossils – show change over time

Fossils

Horse Evolution