Fossils have been found of organisms that no longer live on Earth. Ch.14 – History of Life 14.1 – Fossil Evidence of Change Fossils have been found of organisms that no longer live on Earth. Traces (fossils) of modern organisms can only be dated back to a certain point in the Earth’s 4.6 billion year history. Therefore, Life on Earth has changed (EVOLVED) over the course of the Earth’s history and continue to do so. What do we know about fossils and their age? How/Why do living things change over time?

Any evidence of an organism Ch.14 – History of Life 14.1 – Fossil Evidence of Change Fossils Any evidence of an organism Replacement Mold & Cast Trace Petrified Preserved

Nearly all fossils form in sedimentary rock Ch.14 – History of Life 14.1 – Fossil Evidence of Change Nearly all fossils form in sedimentary rock because it prevents rapid decomposition (99% of all living things left no fossils behind)

Fossil Dating Relative Dating Absolute Dating Radiometric Dating Ch.14 – History of Life 14.1 – Fossil Evidence of Change Fossil Dating Relative Dating Absolute Dating Based on the law of superposition: newer layers of rock form on top of older layers Radiometric Dating Uses the half life of radioactive isotopes in order to determine specific age. -Cannot give exact age -Earth’s geology is constantly shifting changing the position of artifacts

Fossil Dating Relative Dating Absolute Dating Radiometric Dating Ch.14 – History of Life 14.1 – Fossil Evidence of Change Fossil Dating Relative Dating Absolute Dating Based on the law of superposition: newer layers of rock form on top of older layers Radiometric Dating Uses the half life of radioactive isotopes in order to determine specific age. -Cannot give exact age -Earth’s geology is constantly shifting changing the position of artifacts

Half-life – 4.5 billion years Ch.14 – History of Life 14.1 – Fossil Evidence of Change Absolute Dating U238 decays to Pb206 Half-life – 4.5 billion years C14 decays to N14 Half-life – 5730 years Age=(halflife/.693)(Ln(1 / %remaining))

Geologic Time Scale Precambrian Ch.14 – History of Life 14.1 – Fossil Evidence of Change Geologic Time Scale Precambrian 4600mya – 542mya Earth formed about 4.6 billion years ago It took about 500 million years for the crust to form and for water to start collecting on the surface Prokaryotic & eukaryotic unicellular organisms emerge Autotrophic prokaryotes begin to enrich the atmosphere with O2. Multicellular organisms emerge (1st animals)

Life moves out of the oceans Insects, amphibians, reptiles scatter Ch.14 – History of Life 14.1 – Fossil Evidence of Change Paleozoic 488mya – 251mya Animals diversify 1st plants 1st vertebrates Life moves out of the oceans Insects, amphibians, reptiles scatter Ferns & Evergreens cover the Earth

Gymnosperms (seed-bearing plants) diversify Flowering plants appear Ch.14 – History of Life 14.1 – Fossil Evidence of Change Mesozoic 199mya – 65mya 1st mammals Dinosaurs Birds Gymnosperms (seed-bearing plants) diversify Flowering plants appear Mass extinction wiped out all dinosaurs, except for the birds, at the end of the era.

Mammals diversify and scatter Flowering plants scatter Primates appear Ch.14 – History of Life 14.1 – Fossil Evidence of Change Cenozoic 55mya – present Mammals diversify and scatter Flowering plants scatter Primates appear Humans create civilizations and pollution

Spontaneous Generation Ch.14 – History of Life 14.2 – Origin of Life Origin of Life Early Ideas Spontaneous Generation Life arises from non-life Francisco Reddi 1668 Louis Pasteur mid 1800’s Biogenesis Life arises from existing life

Origin of Life Ch.14 – History of Life 14.2 – Origin of Life Origin Movie

Darwin made two main points in his book: Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection A new era of biology began on November 24, 1859, the day Charles Darwin published On the Origin of Species by Means of Natural Selection Darwin made two main points in his book: 1. Many current species are descendants of ancestral species 2. Natural selection is the mechanism for this evolutionary process

Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection Darwin’s Influences: Geologists Hutton and Lyell (late 1700’s) perceived that changes in Earth’s surface can result from slow continuous actions still operating today (gradualism) Thomas Robert Malthus (late 1700’s) hypothesized that in nature plants and animals produce far more offspring than can survive, and that Man too is capable of overproducing if left unchecked

Darwin’s Observations: Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection Darwin’s Observations: He observed plant and animal adaptations from many diverse environments After graduating college Darwin was accepted on board the HMS Beagle, which circled the world from 1831-1836

Many of the islands had unique climate & vegetation Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection Darwin’s most famous observations were of finches found on the Galapagos Islands off the coast of Ecuador Many of the islands had unique climate & vegetation Similar looking finches found on the different islands had different adaptations from each other and were different from finches found on the mainland

Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection Upon return to England Darwin began reflecting on his observations and started hypothesizing about how populations change over time. He did not agree with French scientist Jean-Baptiste Lamarck that living things changed due to use and disuse of certain characteristics

Reproductive Advantage Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection With his knowledge of artificial selection – done by farmers for centuries in order to improve their livestock or crop populations, and the observations made on the HMS Beagle, Darwin put together his theory of Natural Selection Heritable Genetic Variation Over- production Reproductive Advantage + = Original Population New Population Descent with Modification

Survival of the Fittest Ch.15 – Evolution 15.1 – Darwin’s Theory of Natural Selection Survival of the Fittest An adaptation is any characteristic that increases fitness, which is defined as the ability to survive and to produce fertile offspring Living things adapt to their environment Genetic Variation Over- production Reproductive Advantage + = Original Population New Population Descent with Modification

Evidence for Evolution Comparative Embryology Comparative Biochemistry Ch.15 – Evolution 15.2 - Evidence for Evolution Evidence for Evolution The Darwinian view of life predicts that evolutionary transitions should leave signs in the fossil record Paleontologists have discovered fossils of many such transitional forms The Fossil Record Comparative Anatomy Comparative Embryology Comparative Biochemistry

Ch.15 – Evolution 15.2 - Evidence for Evolution The Fossil Record The Darwinian view of life predicts that evolutionary transitions should leave signs in the fossil record Paleontologists have discovered fossils of many such transitional forms

Comparative Anatomy Analogous Structures Ch.15 – Evolution 15.2 - Evidence for Evolution Most animals show similarities in internal structure Comparative Anatomy Homologous Structures Vestigial Structures Similar structure – different use Structures with reduced function (“leftover parts”) Just because structures perform a similar function does not mean they are evidence of common ancestry Analogous Structures Similar use – different structure

Comparative Embryology Ch.15 – Evolution 15.2 - Evidence for Evolution Comparative Embryology Vertebrate embryos exhibit homologous structures during certain phases of development

Insert info about biological resistance…visualizing evolution… Ch.15 – Evolution 15.2 - Evidence for Evolution Insert info about biological resistance…visualizing evolution…

Comparative Biochemistry Ch.15 – Evolution 15.2 - Evidence for Evolution Comparative Biochemistry Many organisms share complex biomolecules. The more closely related the more similar the molecules

Have you been paying attention? 1. How does the concept of “descent with modification” explain both the unity and diversity of life? 4. Increased UV irradiation causes the skin of humans to become more darkly pigmented over a period of days. The notion that the offspring of such tanned individuals should consequently inherit darkened skin from their parents is consistent with the ideas of whom? 2. Explain how over-reproduction and heritable variation relate to evolution by natural selection 3. If you found a fossil of a mammal that lived high in the Andes, would you predict that it would more closely resemble present –day mammals from South American jungles or present –day mammals that live high in Asian mountains? Explain. 5. Most species of whale have 5 phalange (finger bones) supporting their flippers. Why would a whale have fingers? What would you call those phalange?

Population Genetics Macroevolution Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Population Genetics Macroevolution The Gene Pool is all of the alleles found in a population Natural selection works on individuals but only populations evolve Evolution is the change of the allelic frequency in a population BB bb Bb 20 bugs 40 alleles for color (incompletely dominant) bb BB Bb B – 18/40 = .45 b - 22/40 = .55 Over Time B – 12/40 = .30 b - 28/40 = .70

Populations evolve due to three main causes: Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Populations evolve due to three main causes: Natural Selection – Genetic Drift – Gene Flow Natural Selection alters populations in one of three ways Original Population Distribution Stabilizing Selection Disruptive Selection Directional Selection The average is selected for Both extremes are selected for One Extreme is selected for

Usually only occurs in small populations Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Populations evolve due to three main causes: Natural Selection – Genetic Drift – Gene Flow Genetic Drift is random changes in a gene pool usually due to independent assortment Usually only occurs in small populations 2 Examples Founder Effect Bottleneck Effect A population declines to a small # and then rebounds A small sample of the population relocates X X X X X X X X X X X X X X X X X X

Populations evolve due to three main causes: Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Populations evolve due to three main causes: Natural Selection – Genetic Drift – Gene Flow Gene Flow is the exchange of genes between populations from migration

Populations can also evolve due to nonrandom mating and mutations Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Populations can also evolve due to nonrandom mating and mutations Therefore, according to the Hardy-Weinberg Principle A population in genetic equilibrium must meet 5 conditions: No Genetic Drift No Gene Flow No Mutation Random Mating No Natural Selection

Reproductive isolation either occurs Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Speciation New species arise because of reproductive isolation Reproductive isolation either occurs with a physical barrier or without a physical barrier Allopatric Sympatric Speciation Animation

There are two hypothesis as to how different species come to exist Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory There are two hypothesis as to how different species come to exist Punctuated Equilibrium Gradualism Changes occur rapidly between periods of little change Changes occur little by little

Organisms not closely related evolve similar traits Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Patterns of Evolution Divergent Evolution Convergent Evolution or Adaptive Radiation Organisms not closely related evolve similar traits Many species arise from one original species

Patterns of Evolution Coevolution Ch.15 – Evolution 15.3 – Shaping Evolutionary Theory Patterns of Evolution Convergent Evolution Divergent Evolution or Adaptive Radiation Many species arise from one original species Organisms not closely related evolve similar traits Coevolution Many species evolve in close relationship with other species