Evolution Change through Time copyright cmassengale 1 What

Evolution Change through Time copyright cmassengale 1

What You Should Know How To Explain at End of Unit… copyright cmassengale 2

Evolution and Biodiversity Central Concepts: 1. Evolution is the result of genetic changes that occur in constantly changing environments. Over many generations, changes in the genetic make-up of populations may affect biodiversity through speciation and extinction. (CHANGE IN POPULATION THROUGH TIME) copyright cmassengale 3

2. Explain how evolution is demonstrated by evidence from the fossil record, comparative anatomy (embryos), genetics, molecular biology, and examples of natural selection. copyright cmassengale 4

3. Describe species as reproductively distinct groups of organisms. Recognize that species are further classified into a hierarchical taxonomic system (kingdom, phylum, class, order, family, genus, species) based on morphological, behavioral, and molecular similarities. Describe the role that geographic isolation can play in speciation. copyright cmassengale 5

4. Explain how evolution through natural selection can result in changes in biodiversity through the increase or decrease of genetic diversity within a population. copyright cmassengale 6

History of Evolutionary Thought 7

Early Ideas On Earth’s Organisms • Aristotle believed species were fixed creations arranged by their complexity 8

Early Ideas On Earth’s Organisms • Linnaeus – 1 st to group similar organisms and assign them Latin names • Two word name (Genus species) • Known as Binomial nomenclature copyright cmassengale 9

Taxonomy King Phillip Came Over For Good Spaghetti 10

• • USA MA Taunton Bristol-Plymouth Room # Jennifer Bisch Kingdom Phylum Class Order Family Genus Species copyright cmassengale 11

Lamarck’s Theory of Evolution • Jean-Baptiste Lamarck, 1809 • One Of First Scientists To Understand That Change Occurs Over Time • Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime • Said acquired changes were passed to offspring (NOT TRUE) copyright cmassengale 12

Lamarck’s Theory of Evolution • Idea called Law of Use and Disuse • If a body part were used, it got stronger • If body part NOT used, it deteriorated 13

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Charles Darwin 15

Voyage of the Beagle Charles Darwin • Born Feb. 12, 1809 • Joined Crew of HMS Beagle, 1831 16

Darwin Left England in 1831 Darwin returned 5 cmassengale years later in 1836 copyright 17

The Galapagos Islands • Volcanic islands off the coast of South America • Island species varied from mainland species & from island-to-island species • Each island had long or short neck tortoises copyright cmassengale 18

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The Galapagos Islands - Finches • Finches on the islands resembled a mainland finch • More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) • Finches had different types of beaks adapted to their type of food gathering (speciation) 20

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Darwin’s Observations & Conclusions The Struggle for Existence copyright cmassengale 22

Definition • Evolution is the slow , gradual change in a population of organisms over time copyright cmassengale 23

Darwin’s Conclusion • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest through Natural Selection 24

DAY 2 copyright cmassengale 25

Evidence Supports… • Either: – EVOLUTION – change over time – DESCENT WITH MODIFICTION • (We came from a common ancestor, but, have changed through time based on our environment. ) copyright cmassengale 26

Common Descent with Modification • Darwin proposed that organisms descended from common ancestors • Idea that organisms change with time, diverging from a common form • Caused evolution of new species (speciation) 27

Descent With Modification copyright cmassengale 28

Evolution By Natural Selection Concepts • The Struggle for Existence (compete for food, mates, space, water, etc. ) EVOLUTION • Survival of the Fittest (strongest able to survive and reproduce) Natural Selection • Descent with Modification (new species arise from common ancestor replacing less fit species) copyright cmassengale 29

Natural Selection • Cannot Be Seen Directly • It Can Only Be Observed As Changes In A Population Over Many Successive Generations – Radiation – Fossil Record 30

Speciation • The formation of new species Results from: • Genetic Drift (HAPPENS BY ACCIDENT) • Gene Flow • Temporal isolation • Geographic Isolation (MOVEMENT IN OR OUT) (TIMING OFF) (SEPARATED) 31

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Theory of Evolution Today Evidence copyright cmassengale 33

Fossil Record • Earth is Billions of Years Old • Fossils In Different Layers of Rock (sedimentary Rock Strata) Showed Evidence Of Gradual Change Over Time 34

Similarities in DNA Sequence (molecular evidence) best one! 35

Analogous & Homologous Body Structures They have separate evolutionary origins, but are superficially similar because they have both experienced natural selection that shaped them to play a key role in flight (lived in similar environment). Analogies are the result of convergent evolution They have traits that are similar because they were inherited from a common ancestor Divergent Evolution

Convergent Evolution • Process whereby organisms not closely related independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. Divergent Evolution • Process whereby organisms closely related independently evolve different traits as a result of having to adapt to different environments or ecological niches. copyright cmassengale 37

Homologous Structures 38

Vestigial Organs – Vestigial Organs • Appendix In Man • Hip bone in whale 39

Embryonic Evidence • Embryonic Structures Of Different Species Show Significant Similarities • Embryo – early stages of vertebrate development copyright cmassengale 40

Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development copyright cmassengale 41

Modes of Selection • Stabilizing Selection – average trait is advantageous • Disruptive Selection – both extremes are advantageous • Directional Selection – one extreme is advantageous copyright cmassengale 42