BIOL 102 Chp 22 Descent with Modification: A Darwinian View of Life

Chapter 22Descent withModification: A Darwinian View of Life BIOL 102:General Biology II Rob SwatskiAssociate Professor of Biology HACC- HACC-York

1859: Charles Darwin publishedThe Origin of Species 3

Main Ideasof Evolution Descendants Current species are descendants of ancestral species “Descent with modification” Natural selection Ancestor 4

Evolution accountsfor the unity &diversity of life 5

Theodosius Dobzhansky “Nothing in biology makes sense except in the light of evolution.” 6

1809 Lamarck publishes his hypothesis of evolution. 1798 Malthus publishes“Essay on the Principle of Population.” 1812 Cuvier publishes his extensive 1858 1795 studies of vertebrate fossils. While studying species inHutton proposes the Malay Archipelago, his principle of 1830 Wallace (shown in 1848) gradualism. Lyell publishes sends Darwin his hypothesis Principles of Geology. of natural selection. 1790 1870 1809 183136 1859 Charles Darwin Darwin travels around On the Origin of is born. the world on HMS Species is published. Beagle. 1844 Darwin writes his essay on descent with modification. The Galápagos Islands 8

Ancient ViewsAristotle Old Testament Species were Species are fixed & individually designed arranged on a scala by God and, therefore, naturae perfect 9

Scala God inNaturae Heaven Angels Humans Animals Plants Rocks Devil in Hell 10

Taxonomy Branch of biology that classifies organisms into taxa 1700’s: Carl Linne, the “father of modern taxonomy” Viewed adaptations as evidence that the Creator had designed each species for a specific purpose 11

Carl Linne“You can call me Carolus Linnaeus” 13

Ursus Species Genus Family Order Class Phylum Kingdom Domainamericanus(American Ursusblack bear) Ursidae Carnivora Mammalia Chordata Animalia EukaryaTaxonomy 15

FossilsRemains or tracesof organisms from the past Usually found insedimentary rock layers (strata) Established the groundwork for Darwin’s ideas 16

Layers of deposited sedimentYounger stratumwith more recentfossilsOlder stratumwith older fossils 17

Suedberg Fossil Pit22 Devonian 375 MYA

Geological ViewsCatastrophism Uniformitarianism 25

Catastrophism 26

Charles LyellPrinciples of Geology 27

Uniformitarianism “The mechanisms of change are constant over time” 28

“The state of the natural world is the resultof a long succession of events.”- Charles Lyell 29

Jean- Jean-BaptisteLamarck Species evolvethrough the use& disuse of body parts Characteristics acquired duringlife are inheritedUnsupported by evidence 30

Lamarck’s Hypothesis 31

Aren’t you gladLamarck was wrong? 33

Darwin’sResearch Darwin always had a deepinterest in science & natureWas a student of medicine & theology at Cambridge5-year voyage onthe Beagle after graduation 34

Don’t Listen to Your Parents “You care for nothing but shooting, dogs, and rat-catching. You will be a disgrace to yourself and your family.”35 - DR. ROBERT DARWIN

Voyage ofthe Beagle Collected specimens of South American plants & animals Observed adaptations to many diverse environments Became interested in the geographic distribution of species after a stop at the Galápagos Islands 36

Darwin in 1840, HMS Beagle in portafter his returnfrom thevoyage Great Britain EUROPE NORTH AMERICA ATLANTIC OCEANThe AFRICAGalápagos PACIFIC Pinta OCEANIslands Genovesa Equator Marchena SOUTH Malay Archipelago Equator AMERICA PACIFIC Santiago Daphne OCEAN Brazil Andes Mtns. Islands Chile Pinzón AUSTRALIAFernandina PACIFIC Isabela Santa Santa OCEAN Cape of Cruz Fe San Argentina Good Hope Cristobal0 20 40 Tasmania Florenza Española Kilometers Cape Horn New Zealand 37

TheGalápagos PACIFICIslands Pinta OCEAN Genovesa Marchena Equator Santiago Daphne IslandsFernandina Pinzón Isabela Santa Santa Cruz Fe San Cristobal0 20 40 Florenza EspañolaKilometers 38

Darwin’s Focus onAdaptation Adaptation to the environment & speciation are closely related Strongly supported by modern biology Galápagos finches 40

Cactus-Cactus-eater 41

Insect- Insect-eater42

Seed-Seed-eater 43

Adaptive Radiation of Galápagos Finches 44

If you had an idea that was going to outrage society… would you keep45 it to yourself?

Darwin’s Two Main Ideas on Evolution Descent with Natural modification Selection Explains the Results in unity & adaptive diversity of life radiation 48

Descent withModification Darwin never used the word “evolution” in the 1st edition of Origin of Species “Descent with modification” summarized his view of the unity of life All organisms are related through descent from an ancestor that lived in the distant past 49

The “Tree of Life” Branches represent life’s diversity Darwin’s theory meshed well with Linnaeus’s hierarchy Ex: elephants 51

Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) †Moeritherium †Barytherium †Deinotherium †Mammut †Platybelodon †Stegodon †Mammuthus Elephas maximus (Asia) Loxodonta africana (Africa) Loxodonta cyclotis (Africa)60 34 24 5.5 2 104 0 Millions of years ago Years ago 52

ArtificialSelection Darwin notedthat humans have modified other species Select & breed individuals with desired traits Selective breeding =artificial selection 54

Cabbage Selection for apical (tip) bud Brussels sprouts Selection for Selection Broccoli axillary (side) for flowers buds and stems Selection for stems Selection for leavesKale Wild mustard Kohlrabi 57

FourObservations of Nature Made by Darwin 58

1. Members of a population often vary59 greatly in their traits

2. Traits are inherited from61 parents to offspring

3. All species arecapable of producingmore offspring thanthe environment cansupport 62

4. Many offspring don’t survive63 due to lack of food or predation

Two InferencesMade by Darwin 64

1. Individuals whoseinherited traits give them a higher probability of surviving & reproducing in an environment tend to leave more offspring than others 65

2. This unequal ability of individuals to survive & reproduce will lead to the accumulation of favorable traits in the66 population over generations

ThomasMalthus Another major influence on DarwinMalthus wrote about the potential forhuman population to increase faster than food supplies & other resources 67

Value ofBeneficial Traits Traits that provide advantages will accumulate in the population This increases the frequency of individuals having these adaptations Explains the match between organisms & their environment 69

NaturalSelection Individuals with certain traits survive & reproduce at a higher rate than others This increases the adaptation of organisms to their environment over time 70

Limits of NaturalSelection Can only increase or decrease heritable traits in a population Individuals do not evolve… Populations evolve 73

Evolution is supported byan overwhelming amountof scientific evidence 74

Tiktaalik75 the fishapod!

Direct Observations of Evolutionary ChangeNatural selection The evolution of in response to drug-resistantintroduced plant bacteria species 77

Can a change in apopulation’s food FIELD STUDYsource result inevolution bynatural selection? Soapberry bug with beak inserted in balloon vine fruit 78

RESULTS Beak 10 On native species, 8 southern Florida 6 4 Number of individuals 2 0 Museum-specimen average 10 8 On introduced species, central Florida 6 4 2 0 6 7 8 9 10 11 Beak length (mm) 79

MRSA 2,750,000 1 250,000 base pairs 2,500,000 Chromosome map of S. aureus clone USA300 500,000 2,250,000 Key to adaptations Methicillin resistance Ability to colonize hosts 750,000 Increased disease severity 2,000,000 Increased gene exchange (within species) and toxin production 1,000,000 1,750,000 1,250,000 1,500,000 80

Mosquito Resistance to DDT 81

Summary of Natural Selection It does not create new traits It edits or selects for traits already present in a population The local environment determines which traits will be selected for or against in a population 82

Fossils asEvidence Species extinction Origin of new taxonomic groups Changes within groups over time 83

0 2 4 Depth (meters) 4 6 4 Bristolia insolens 8 3 Bristolia bristolensis 10 3 Latham Shale dig site,84 San Bernardino County, CA

Depth (meters) 12 2 Bristolia harringtoni 14 16 18 1 Bristolia mohavensis 21 85

Transitional Forms 86

87 Archaeopteryx

The Transitionto Life in the Sea (a) Pakicetus (terrestrial) (b) Rhodocetus (mostly aquatic) aquatic) 88

Dorudon (fully aquatic) 89

(c) Dorudon (fully aquatic) Pelvis and hind limb Pelvis and hind limb(d) Balaena (recent whale ancestor) 90

Homology Similarity resulting from common ancestry Homologous structures Similarities that represent variations on a structural theme found in a common ancestor 91

HumerusRadiusUlnaCarpalsMetacarpalsPhalanges Human Cat Whale Bat 92

Comparative Embryology Pharyngeal pouches Post-anal tail 95

VestigialStructures Remnants of anatomical features Once served important functions in an organism’s ancestors Ex: spurs of pythons 96

MolecularHomologies Genes inherited from a common ancestor that are shared among organisms Ex: Hemoglobin 98

Homologies and “Tree Thinking” Evolutionary trees are used to explain homologies Hypotheses about relationships among different groups Constructed using anatomical & DNA sequence data 99

Branch point Lungfishes 1 Amphibians Tetrapods Mammals AmniotesDigit- 2bearinglimbs Lizards 3 Amnion and snakes 4 Crocodiles Homologous characteristic 5 Ostriches Birds 6 Feathers Hawks and other birds 101

Melbourne, AustraliaConvergent Evolution 102

Convergent Evolution Similar features (analogous traits) can evolve in distantly related groups Arise when groups independently adapt to similar environments in similar ways Convergent evolution does not provide information about ancestry 103

NORTHSugar AMERICAglider AUSTRALIA Flying squirrel 104

Diacodexis,Diacodexis, an early even-toed ungulate even- 105

Most mammals Cetaceans and even-toed ungulates(a) Canis (dog) (b) Pakicetus (c) Sus (pig) (d) Odocoileus (deer) 106

Other even-toed ungulates Hippopotamuses †Pakicetus †RodhocetusCommonancestor †Dorudonof cetaceans Living cetaceans70 60 50 40 30 20 10 0 Key Pelvis Tibia Millions of years ago Femur Foot 107

Biogeography The geographic distribution of species Major influence on Darwin’s theory Islands have many endemic species closely related to species on the nearest island or mainland 108

Mangrove island research, FL Keys109 E.O. Wilson

Continental Drift Earth’s continents were once united in a super-continent called Pangaea Have since separated by continental drift Understanding impact on species distribution helps predict when & where different groups evolved 110

What is a Theory? Generates SupportedBroad and new by lots of general testable evidence hypotheses 111

Darwin’s Theoryof Evolution by Natural Selection Integrates diverse areas of biological study Ongoing research has only advanced & strengthened our understanding of evolution Stimulates many new research questions 112

Credits by Rob Swatski, 2013 Visit my website for more Biology study resources! http://robswatskibiology.wetpaint.com http://www.flickr.com/photos/rswatskiPlease send your comments and feedback to: rjswatsk@hacc.eduImages used in this work bear a This work bears an Creative Commons license and Attribution-Noncommercial are attributed to their original Share Alike Creative authors. Commons license. 114

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BIOL 102 Chp 22 Descent with Modification: A Darwinian View of Life

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