Evolution Chapter 15 “A change over time”

The Theory of Evolution Evolution literally means to change over time. A theory is a well supported, testable explanation that observes observations from the natural world

Questions that evolution attempts to answer. How do species adapt to changes in the environment? How do new species develop?

Charles Darwin 1809-1882 Studied to be a doctor and a minister 1831 sailed around the world as a naturalist on the HMS Beagle

HMS Beagle

Darwin’s Voyage

Galapagos Islands

Galapagos Islands

15-2 Darwin’s Influences

James Hutton Geologist Proposed that the earth was millions of years old based on geologic evidence

Sir Charles Lyell Geologist Proposed that geologic changes occur slowly over long periods of time. Darwin read his book, Principles of Geology, on the Beagle

Jean Baptiste Lamarck French Naturalist Published his ideas on evolution in 1809 in Philosophie zoologique

Lamarck’s Hypothesis Organisms Strive for Perfection – all individuals are trying to better themselves

Lamarck’s Hypothesis Use and Disuse – If an individual uses a trait it will be more useful If an individual does not use a trait it will decrease in usefulness

Lamarck’s Hypothesis Inheritance of Acquired characteristics

Analyzing Lamarck’s Hypothesis There is no evidence to suggest that plants and animals are trying to improve themselves

Analyzing Lamarck’s Hypothesis Use and disuse do not change all characteristics Stretching will not make you taller Reading will not make your eyesight better

Analyzing Lamarck’s Hypothesis Acquired characteristics are not inherited A mouse that loses its tail will still produce offspring with tails

Erasmus Darwin Charles Darwin’s Grandfather Physician and Scientist 'All vegetables and animals now living were originally derived from the smallest microscopic ones.'

Thomas Malthus – Economist Starvation War (Competition) Disease Human Population would be limited Starvation War (Competition) Disease

15-3 Darwin Presents His Case

Alfred Wallace Developed his own theory of Natural Selection Contacted Darwin This caused Darwin to finally publish his theory with Wallace

On Origins of Species After publishing with Wallace, Darwin submitted all of his ideas in a book titled On Origin of Species, By Means of Natural Selection in 1858

Artificial Selection Darwin was influenced to believe change was possible because of the humans selecting for traits in plants and animals.

Darwin’s Theory Evolution “Change” is driven by natural selection

Evidence for Evolution Fossil Record Anatomy Development Molecular Evidence

Fossil Record Since most of the “ancestor” species are extinct, fossils are the only evidence that can be examined. Intermediate “missing link” fossils are very informative

Archaeopterix A fossil of a bird like creature Has feathers, teeth and claws in its wings

Whale Ancestors

Anatomy Structures similarities in body structure indicates organisms are related

Homologous Structures Structures that have common function and design (ancestry)

Vestigial Organs Structures that have reduced size and or function

Developmental Evidence Similarities in embryonic development are interpreted to mean closer relationships.

Developmental Evidence Similarities in embryonic development are interpreted to mean closer relationships.

Molecular Evidence Organisms are considered to be more closely related if DNA sequences in genes are more similar Amino acid sequences in proteins is more similar

Molecular Evidence Organisms are considered to be more closely related if DNA sequences in genes are more similar Amino acid sequences in proteins is more similar

Summary of Darwin’s Theory

Variation There are differences within a population Mutation and Sexual Reproduction

Competition for resources Not all offspring will survive Starvation Overcrowding Predation

Fitness Some of the variants will have an advantage over the others, they will survive and produce more offspring

Reproduction and Inheritance These advantages will be passed on to the next generations

Descent with Modification Species alive today are descended with modification from ancestral species

Tree of Life All species are connected on a single tree of life

Modern Theory Mendel’s discoveries in genetics explained a great deal in evolution

Strengths of Darwin’s Theory Many discoveries in Physics, Geology and Biology have supported and expanded Darwin’s ideas

Strengths of Darwin’s Theory Many discoveries in Physics, Geology and Biology have supported and expanded Darwin’s ideas

Weaknesses of Darwin’s Theory Researchers still debate how new species arise and how they become extinct. The origin of life is still very uncertain