Evolution Diversity of Life 1 Definition Evolution is

Evolution Diversity of Life 1

Definition • Evolution is the slow , gradual change in a population of organisms over time 2

History of Evolutionary Thought 3

Early Ideas On Earth’s Organisms Aristotle believed species were fixed creations arranged by their complexity n Idea lasted 2000 years n 4

Early Ideas On Earth’s Organisms n n n Linnaeus – 1 st to group similar organisms and assign them Latin names Two word name (Genus species) Known as Binomial nomenclature 5

: • • • Contributor’s to Darwin’s thinking included: Charles Lyell –uniformintarianism (geologic processes still changing Earth) Georges Cuvier – species extinction (Catastrophism) Thomas Malthus – struggle for existence (resources) 6

: • • • Contributor’s to Darwin’s thinking included: James Hutton - Gradualism John Baptiste Lamarck – Inheritance of acquired Characteristics and Law of Use and Disuse Alfred Russel Wallace – organisms evolved from common ancestors 7

Catastrophism n Idea proposed by George Cuvier n Studied fossils in sedimentary rock strata of Paris n Found some species completely disappeared in more recent layers 8

Catastrophism n Stated that species disappear due to a catastrophic event of the earth’s crust (volcano, earthquake…) 9

Hutton’s Theory of Geological Change n. James Hutton, 1795, Scottish geologist n. Studied invertebrate fossils in Paris Museum n. Described the geological forces that have changed life on earth over millions of years (erosion, earthquakes, volcanoes…) 10

Hutton’s Theory of Geological Change n Changes in Earth’s crust due to slow continuous processes n Idea Known as Gradualism 11

Charles Lyell Proposed theory of Uniformintarianism n Geological processes at uniform rates, building & wearing down Earth’s crust n Proposed that the Earth was millions of years old instead of a few thousand years old n 12

Principles of Geology Published by Lyell & read by Darwin n Explained geological processes that shaped the earth n Helped Darwin understand sea shells in the andes mountains at 12, 000+ Feet – Expanded Earth’s age n 13

Lamarck’s Theory of Evolution n n Jean-Baptiste Lamarck, 1809 One of the first scientists to understand that change occurs over time. Stated that changes are adaptation to the environment acquired in an organism’s lifetime Said acquired changes were passed to offspring 14

Lamarck’s Theory of Evolution Idea called Law of Use and Disuse n If a body part were used, it got stronger n If body part NOT used, it deteriorated n 15

Lamarck’s Theory of Evolution n Inheritance of Acquired Characteristics Proposed that by selective use or disuse of organs, organisms could acquire or lose certain traits during their lifetime. n These traits could then be passed on to their offspring. n n Over time, this led to new species! 16

Lamarck’s Theory of Evolution n Use & Disuse – Organisms could change the size or shape of organs by using them or not using them – Blacksmiths & Their Sons (muscular arms) – Giraffe’s Necks Longer from stretching 17

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Lamarck’s Theory of Evolution n Inheritance Of Acquired Traits – Traits Acquired During Ones Lifetime Would Be Passed To Offspring 19 Clipped ears of dogs could be passed to offspring!

Lamarck’s Theory of Evolution n Tendency toward perfection – Organisms are continually changing and acquiring features that help them live more successfully in their environment – Example: bird ancestors desired to fly so they tried until wings developed 20

Lamarck’s Mistakes n Lamarck Did NOT know how traits were inherited (Traits are passed through genes) n Genes are NOT changed by activities in life n Change through mutation occurs before an organism is born. 21

Population Growth n Thomas Malthus, 1798 n Economist n Observed babies were being born faster than people were dying. n Population size limited by resources, such as the food supply 22

The Struggle for Existence n Malthus’ Influence: – High birth rates & limited resources would force life and death competition n Each Species Struggles For: – Food – Living Space – Mates 23

Population Growth n n Malthus reasoned that if the human population continued to grow unchecked, sooner or later there would be insufficient living space & food for everyone Death rate will increase to balance population size & food supply 24

Charles Darwin the Naturalist 25

Voyage of the Beagle Charles Darwin n n n Born Feb. 12, 1809 Joined Crew of HMS Beagle, 1831 Naturalist 5 Year Voyage around world Avid collector of flora & fauna Astounded by variety of life 26

Darwin’s Voyage of Discovery A reconstruction of the HMS Beagle sailing off Patagonia. 27

Darwin Left England in 1831 Darwin returned 5 years later in 1836 28

The Galapagos Islands n Small Group of Islands 1000 km West of South America n Very Different Climates n Animals on islands are extremely unique » Tortoises » Iguanas » Finches 29

The Galapagos Islands n n Volcanic islands off the coast of South America Island species varied from mainland species & from island-toisland species – Each island had long or short neck tortoises 30

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The Galapagos Islands Finches on the islands resembled a mainland finch with a few differences. n More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) n Finches had different types of beaks adapted to their type of food gathering n 32

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Darwin’s Observations & Conclusions The Struggle for Existence 34

Darwin’s Observations n n n Patterns of Diversity were shown Unique Adaptations in organisms Species Not Evenly Distributed » Australia, Kangaroos, but No Rabbits » S. America, Llamas 35

Darwin’s Observations n Both Living Organisms & Fossils collected n Fossils included: » Trilobites » Giant Ground Sloth of South America This species NO longer existed. What had happened to them? 36

Evidence for Evolution – The Fossil Record 37

Darwin’s Observations Left unchecked, the number of organisms of each species will increase exponentially, generation to generation n In nature, populations tend to remain stable in size n Environmental resources are limited n 38

Darwin’s Conclusions • • • 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 39

Darwin’s Observations • • Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike. Much of this variation between individuals is inheritable. 40

Population Growth n n Darwin realized Malthus’s principles were visible in nature Plants & animals produce far more offspring than can be supported – Most die – If they didn’t, Earth would be overrun. 41

Darwin’s Conclusion • • Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals Called Natural Selection 42

Darwin’s Theory of Evolution Organisms Change Over Time 43

Darwin’s Theory of Evolution • The unequal ability of individuals to survive and reproduce leads to a gradual change in a population, with favorable characteristics accumulating over generations (natural selection) 44 • New species evolve

Common Descent with Modification n Darwin proposed that organisms descended from common ancestors Idea that organisms change with time, diverging from a common form Caused evolution of new species 45

Natural Selection n Driving force for evolution During the struggle for resources, strongest survive & reproduce Idea that at least some of the differences between individuals, which impact their survival and fertility, are inheritable. 46

Natural Variation and Artificial Selection Abandoned the idea that species were perfect and unchanging n Observed significant variation in all species observed n Observed farmers use variation to improve crops & livestock n – Called Selective Breeding 47

Natural Variation and Artificial Selection n Natural Variation – Differences among individuals of a species n Artificial Selection – Selective breeding to enhance desired traits among stock or crops 48

Natural Variation and Artificial Selection Key Concept: In Artificial Selection, nature provided the variation among different organisms, and humans selected those variations that they found useful 49

Origin of Species Concepts and Controversy 50

Evolution By Natural Selection Concepts The Struggle for Existence (compete for food, mates, space, water, etc. ) n Survival of the Fittest (strongest able to survive and reproduce) n Descent with Modification (new species arise from common ancestor replacing less fit species) n 51

Survival of the Fittest n Fitness – Ability of an Individual To Survive & Reproduce n Adaptation – Inherited Characteristic That Increases an Organisms Chance for Survival 52

Survival of the Fittest n Adaptations Can Be: – Physical » Speed, Camouflage, Claws, Quills, etc. – Behavioral » Solitary, Herds, Packs, Activity, etc. 53

Survival of the Fittest n Fitness is central to the process of survival n Individuals with Low Fitness – Die – Produce Few Offspring Survival of the Fittest AKA Natural Selection 54

Survival of the Fittest Key Concept Over time, Natural Selection results in changes in the inherited characteristics of a population. These changes increase a species fitness in its environment. 55

Descent With Modification n Takes place over long periods of time n Natural Selection can be observed as changes in… – Body Structures – Ecological Niches – Habitats 56

Descent With Modification n Species today look different from their ancestors. n Each Living Species Has -Descended –With Changes –From Other Species –Over Time 57

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Descent With Modification n Implies: – All living organisms are related. – Single Tree of Life » DNA, Body Structures, Energy Sources – Common Descent » All species, living & extinct, were derived from common ancestors. 59

Major Problem in Darwin’s Theory No mechanism to explain natural selection • • • . How could favorable variations be transmitted to later generations? With the rediscovery of Mendel’s work in the first half of the 20 th century, the missing link in evolutionary theory was found 60

Opposition to Evolution • • The upheaval surrounding evolution began with Darwin’s publication of On the Origin of Species By Means of Natural Selection The debate continues nearly 150 years later 61

Theory of Evolution Today Supporting Evidence 62

Evolutionary Time Scales Macroevolution: Long time scale events that create and destroy species. 63

Evolutionary Time Scales Microevolution: Short time scale events (generationto-generation) that change the genotypes and phenotypes of populations 64

Evidence for Evolution 1. 2. 3. 4. 5. Fossil Record The Geographical Distribution of Living Species Homologous Structures Similarities in Embryonic Development Similarities in DNA Sequence 65

Fossil Record Earth is billions of years old. n Fossils in different layers of rock (sedimentary Rock Strata) showed evidence of gradual change over time n 66

Geographic Distribution of Living Species n Different animals on different continents but similar adaptations to shared environments 67

Homologous Structures 68

Homologous Body Structures n Scientists noticed animals with backbones (Vertebrates) had similar bone structure n May differ in form and function n Limb bones develop in similar patterns » Arms, Wings, Legs, Flippers 69

Homologous Body Structures that have different mature forms, but develop from the same embryonic tissues. n Strong evidence that all four-limbed animals with backbones descended, with modification, from a common ancestor n Help Scientist Group Animals n 70

Homologous Body Structures 71

Homologous Body Structures n Not All Serve Important Functions – Vestigial Organs » Appendix In Man » Legs On Skinks 72

Evidence for Evolution - Comparative Embryology Similarities In Embryonic Development 73

Similarities In Early Development Embryonic structures of different species show significant similarities n Embryo – early stages of vertebrate development n 74

Human Fetus – 5 weeks 75

Chicken Turtle Rat 76

Similarities in DNA Sequence 77