What conclusions can you make based on your observations of your geological timeline?

Warm Up Warm Up 9/18/089/18/08

Ch 15.1 Notes

Natural Selection & Evidence for

Evolution

Charles DarwinCharles DarwinEnglish Scientist (1809-1892)

Used fossils to shape ideas about evolution

Suspected species change or evolve over time

Darwin on HMS Beagle•Took many years to develop theory of evolution

•Ships naturalist studies and collects specimens

•Becomes curious about relationships

•These studies provide foundation for his theory

Darwin in Galapagos Islands

•Group of small islands near equator

•Species were unique to island but similar to species elsewhere

•These observations led him to believe species change over time

Darwin Continues His Studies

Works for another 20 years to refine his explanation

English Economist Thomas Malthus proposes idea about human population

Species produce large number of Offspring

Creates competition for food space an finding mates

Natural Selection

Mechanism for change in populationsOrganisms with favorable variations survive and reproduceThese variations are passed on to next generation

Interpretation of Evidence

Volumes of data collectedSubject to interpretationProcesses are difficult for humans to observeGenetics has added more data

Part Two

Adaptations: Evidence for Evolution

Structural Adaptations

According to Darwin’s theory species adaptations occur over many generations

Study the Mole–rat: Lives in ground and has many adaptations , is blind, has big claws, large teeth

MIMICRY is a structural adaptation that enables one species to look like another

CAMOUFLAGE adaptations that allow species to blend in environment

MIMICRY

Camouflage

Physiological Adaptations

Most structural adaptations develop over a millions of years

Physiological adaptations evolve quicker

Physiological adaptations are changes in organisms metabolic processes

Example: antibiotics and pesticides

Fossils

Provides record of early life Ancestors of whales where dog like

creatures The fossil record is incomplete Like putting together a jigsaw puzzle

ANATOMY Look at forelimbs of whale, crocodile, and bird Evidence that animals evolved from common

ancestor Homologous Structures: structural features with

common evolutionary origin Analogous Structure: do not have common

evolutionary origin but have similar function Vestigial Structure: body structure in modern day

organism that no longer serves it original purpose

Homologous Structures

Analogous Structures

Vestigial Structures

Embryology

Easy to distinguish between adult organisms but can you distinguish between there organisms?

It is the shared features in the young embryos that suggest evolution from an distant common ancestor

Biochemistry

Provides strong evidence for evolutionNearly all organism share DNA, ATP and many enzymesOrganisms that are biochemically similar have fewer differences in their amino acid squences