BIO120Fall2024_Lecture3_1slideperpage (2).pdf

Beyond BIO events start this week! What is Beyond BIO? A series of optional events offered to BIO120 students throughout the course. They are meant to be fun and informative for any students who are interested. For more information and the complete schedule for this term, see Quercus unde...

Beyond BIO events start this week! What is Beyond BIO? A series of optional events offered to BIO120 students throughout the course. They are meant to be fun and informative for any students who are interested. For more information and the complete schedule for this term, see Quercus under Modules  Beyond BIO. Upcoming Events: BIO120 Social Thursday September 12th at 5:00 pm Room 010 on ground floor of Ramsay Wright (25 Harbord) Start the term with a fun evening of snacks and trivia! Meet your classmates and enjoy refreshments. Everyone welcome! Birds & Wildlife of Toronto Thursday September 19th from 11:10 am – 12:00 pm Room 432 on fourth floor of Ramsay Wright (25 Harbord) Learn about local wildlife, where to see wildlife in Toronto, and how to get out into nature and identify what you see. Snacks provided! 0 © BIO120 Fall 2024  The Evidence for Evolution Relevant reading in Charlesworth & Charlesworth – Chapters 3&4 This lecture will be recorded and posted on Quercus. 1 © BIO120 Fall 2024 Outline Sources of Evidence for Evolution: Geology Homology Biogeography Domestication 2 © BIO120 Fall 2024 Charles Darwin’s Voyage on H.M.S. Beagle (1831‐1836) Age 22, ship’s naturalist Most time spent in South America Observations of fossils, flora and fauna of oceanic islands, geographical distribution of plants and animals Age 31 (1840) 3 © BIO120 Fall 2024 H.M.S. Beagle Sails to Brazil 4 © BIO120 Fall 2024 Evidence from Geology Darwin Finds Fossils of Extinct Mammals in Brazil Tolypeutes matacus Hedwig Storch/Wikimedia Commons © Naturhistorisches Museum, Vienna Extant armadillo Glyptodon giant armadillo (fossil) 5 © BIO120 Fall 2024 Evidence from Geology Discoveries of Transitional Fossils Continue Today Tiktaalik roseae, discovered 2006 Age: 375 million years Origin: Ellesmere Island, Nunavut Number of individuals found: 10 Nickname: “fishapod” 6 © BIO120 Fall 2024 Evidence from Geology Transitional Fossils Provide Understanding of Evolutionary History 7 © BIO120 Fall 2024 Evidence from Geology Transitional Forms: Evolution of Whales Zimmer & Emlen (Evolution: Making Sense of Life Fig. 1.7) 8 © BIO120 Fall 2024 Evidence from Geology Lessons From Geology Earth is very old – Allows for immense amount of time for biological evolution Intermediate forms – Evidence for transitional fossils linking features of seemingly dissimilar relatives (e.g., ungulates and whales, or tetrapods and fish) Fossils in younger strata increasingly resemble modern species in same region – Older strata show increasing differences 9 © BIO120 Fall 2024 H.M.S. Beagle Sails to Galapagos Islands 10 © BIO120 Fall 2024 Evidence From Homology Homology: Similarity of traits in two or more species that is due to inheritance from a common ancestor 11 © BIO120 Fall 2024 Evidence From Homology Mainland cormorants Vestigial Structures: Features inherited from an ancestor, but reduced in morphology and function Are homologous to functional structures in related species Galapagos flightless cormorant 12 © BIO120 Fall 2024 Evidence From Homology Alex Keene Surface‐dwelling (gray) and cave‐dwelling (pink) morphs of Astynax mexicanus 13 © BIO120 Fall 2024 Evidence From Homology Vestigial Structures in Humans Ear muscles Appendix Tailbone Goosebumps 14 © BIO120 Fall 2024 Evidence From Homology Organismal features are consistent with modifications of pre‐existing structures Not expected if each organism was individually optimally designed 15 © BIO120 Fall 2024 Evidence From Homology Approximately 500 genes are shared across all forms of life Strong, shared constraint for genes involved in basic cellular function, e.g. transcription & translation Protein alignment for homologs of translation elongation factor 1‐alpha (letters are amino acids) 16 © BIO120 Fall 2024 Evidence from Homology Lessons From Homology Vestigial traits provide evidence of the evolutionary past – Have no function (or reduced function) in extant organisms – Can only be explained by the presence of functional traits in ancestors, followed by evolutionary degradation Homologous structures are ubiquitous across organisms – Fundamental structural similarity reflects common ancestry – Homologous structures have evolved to serve very different functions 17 © BIO120 Fall 2024 Evidence From Biogeography 18 © BIO120 Fall 2024 Evidence From Biogeography Galápagos Islands 15 main islands of volcanic origin – Formed 0.7 to 4.2 million years ago Flora and fauna colonized from mainland South America – Species capable of long‐distance dispersal – Distinct forms on different islands provide evidence of early stages of speciation 19 © BIO120 Fall 2024 Evidence From Biogeography: Colonization Cacti are early colonizers on land: how did they get there? 20 © BIO120 Fall 2024 Evidence From Biogeography: Colonization Cacti have fleshy bird‐dispersed fruits 21 © BIO120 Fall 2024 Evidence From Biogeography: Patterns of Variation Tortoises on Different Islands Have Different Shell Shapes "animals on separate islands ought to become different if kept long enough apart with slightly differing circumstances” ‐ Darwin notebook entry 22 © BIO120 Fall 2024 Evidence From Biogeography: Patterns of Variation Galapagos Finches: An Evolutionary Icon 23 © BIO120 Fall 2024 Evidence From Biogeography: Patterns of Variation Beak Diversity Among Galapagos Finch Species Sketches by John Gould 24 © BIO120 Fall 2024 Evidence From Biogeography: Patterns of Variation Daphne Major: location of 50‐yr study of natural selection in Galapagos Finches by Drs. Peter & Rosemary Grant (Princeton) 25 © BIO120 Fall 2024 H.M.S. Beagle Sails to Australia 26 © BIO120 Fall 2024 Evidence From Biogeography: Similarities & Differences Australia Although a continent, Australia also is an island Distinct flora and fauna with high endemism and many unique adaptations – Biological uniqueness is a result of its long history of isolation from other land masses Australia has endemic radiations of species that are ecologically convergent with those of other continents 27 © BIO120 Fall 2024 Evidence From Biogeography: Similarities & Differences Endemic Australian Biota © Justin Cally Mammal‐pollinated Banksia 28 © BIO120 Fall 2024 Evidence From Biogeography: Similarities & Differences Endemic Australian Biota Platypus 29 © BIO120 Fall 2024 Evidence From Biogeography: Similarities & Differences Geographically close organisms resemble each other Different groups of organisms adapt to similar environments in different parts of the world Geographically isolated regions have unusual organisms 30 © BIO120 Fall 2024 Evidence from Biogeography Lessons From Biogeography Remote island biotas – Have continental affinities – Are dominated by good colonists – Have locally‐differentiated species Biogeographically isolated regions – Have species adapted to niches unusual for their group – Harbor endemic radiations of species that are convergent with radiations elsewhere 31 © BIO120 Fall 2024 H.M.S. Beagle Sails Back to England 32 © BIO120 Fall 2024 Darwin Returns to England Darwin gets married and settles down at Down House Begins to assemble evidence for his theory of evolution by natural selection 33 © BIO120 Fall 2024 Evidence From Domestication Darwin’s Gardens Darwin’s Gardens 34 © BIO120 Fall 2024 Evidence From Domestication Teosinte and Maize 35 © BIO120 Fall 2024 Evidence From Domestication Wolves Domestic Dogs 36 © BIO120 Fall 2024 Evidence From Domestication Domesticated Pigeon Diversity Feral Pigeon "some domestic races of the rock‐pigeon differ fully as much from each other in external characters as do the most distinct natural genera" ‐ Darwin 1868 37 © BIO120 Fall 2024 Evidence From Domestication Vast amounts of heritable variation found within species This variation can be selected on, leading to dramatic changes over generations Artificial selection as the human imposed analog to natural selection in the wild 38 © BIO120 Fall 2024 A Compendium of Evidence for Evolution Geology Homology Biogeography Domestication 39 © BIO120 Fall 2024 Evidence for Evolution: 165 Years On Abundant evidence for evolution in action – e.g. antibiotic resistance, herbicide resistance, adaptation to pollution, experimental evolution Strength of natural selection measured in the wild – Evolutionary responses can be faster than Darwin realized Genomic DNA evidence for vestigial traits, homology, descent with modification – Molecular evolution Fossil discoveries have dramatically filled out knowledge of past life, including transitional forms 40 © BIO120 Fall 2024 Recap Recall: – Different types of evidence Simple Application: – Similarities & differences between evidence available to Darwin and current evidence Easy Synthesis: – How many different lines of evidence can we make sense of only by invoking evolution? – What does the number of types of evidence do to the strength of our inference? Harder Synthesis: – New evidence not available to Darwin. How does it fit? Anything inconsistent? 41 © BIO120 Fall 2024 Next lecture: Evolutionary Significance of Genetic Variation 42 © BIO120 Fall 2024