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University of Toronto St. George
Doug Thomson

WHY EVOLUTION IS TRUE? Chapter 1 notes: evolution erodes our sense of self, and our morality two ideas that completely rejected god: natural selection and evolution parts of the evolutionary theory: 1. evolution- organisms undergo genetic change overtime depending on pressures 2. gradualism- it takes many generations to produce a substancial change 3. speciation(or splitting)- species split from a common ancestor. The common ancestor b/w descendant groups is called the “missing link” - the groups that split can no longer interbreed (unattractive mates, or sterile offspring etc) - speciation does not happen very often, but when it does, the number of opportunities for future speciation are doubled! 4. Common ancestory- flip side of speciation, means we have a common ancestor - mammals and reptiles are joined by having an “amniotic egg” – nested hieracy -plants and animals fell under “natural classification” -if speciation is true, then common ancestry is true 5. Natural Selection- survival of the fittest - wooly mammoth got coolderthose with think hair genes survived, passed on genes. - mutations sometimes lead to the perfect design (rhinos with antlers) - however brand new features are not made. And so compromises must be made. - Male testes would be better if outside he body, but they are not, they have evolved form fish-like testes. Why would intelligent design make us go through this pain? 6. Processes other than natural selection can cause evolutionary change- such as random changes in genes. (genetic drift) theory of evolution is not just that it happened, but how and why it happens. Also, it is testable and can make verifable predictions. Another theory: continental drift caused by plate tecto niound fossils! Theory of evolution can be supported by evolutionary predictions: fossil record as evidence for evolutionary change “descent with modification” speciation should be found in fossil record – splitting of species species that link, “missing links”, together major groups should be found show genetic variation be able to find imperfect designs! See natural selection happening in the wild Retrodictions (things that only make sense in the light of evolution): patterns of species distribution, vestigial features, how organisms develop. Chapter 2: -we only have a fossil record for 0.1-1 percent of all life in all of history - principle of super position- ordering rocks by age, tells relative age, not - radio isotopes used too, uranium-235 for older rocks and carbon-14 for younger - rocks that bear fossils are sedimentary and harder to date (can be aged by using adjacent igneous using radioisotopes) - earth is 4.6 billion years old, corals used to find days and months length - evolution is not always consistent, sometimes it is irregular like the psecdus vema - transitional forms: fossils that fill gaps b/w different kinds of organisms, from bird to humans. - Creationists believe in microevolution (minor changes) but not macroevolution (one animals completely changes into another!) - transitional and ancestral species are not the same. Transitional could be cousins to the descendants, and they have to appear before and after one of the species not just b/w the two species, as do ancestral species. - link b/w fish and amphibians: tetrapods (titaalik) Like fish + amphibian, could breather with lungs and gills. [transitional] - how did animals begin to fly? First by gliding flying squirrel & lemur are examples -archaeopteryx – dinsosaur had feathers, change from reptiles to birds! Called a “mosaic”. Then in Chain, another feathered dinosaur was discovered “S. milleni”, then the 4-winged dinosaur called “M. gui” - these bird-like dinsosaurs (theropods- even behaved like birds (sleeping) - wings came from the genes that make scales in reptiles - wings could have developed b/c of two reasons: ground up theory – leaping to catch prey, or b/c of the trees down theory- living in trees for food, escaping predation - transitional form b/w aquatic and terrestrial: the hippo! spend most time in water (birth) but can come on land. Release a red oil sunscreen to - whales have vestigial features, like hind legs, which suggest it came from a species that lived on land, the closet relative of the whale is the hippo! - a cousin (not ancestor)of whales- indohyous (partially in water)- similar to whales b/c it took in oxygen and b/c it had bones denser than land animals (to swim) - ambulocetus- “walking whale” then dorudon (closet to whales right now) - evolution of whales was fast. But why did only some animals go to water, and not all? B/c when reptile competitors went extinct, the sea was ripe for invasion (resources) - “transitional ant” wasplike and antlike - Fossils teach us three things: 1. evolution happens! 2. find transitional forms where we should in fossil records 3. evolutionary changes models old into new (not creates new from scratch!) CHAPTER 3: ostriches have vestigial wings, that were useful to its ancestor but not anymore. Still help bird mate, threaten enemies and maintain balance also other flightless birds: kakpos “parachte” gently to floor of forest. Kiwis have small wings, hidden behind feathers, have no use. In penguins, wings=flippers. Vestigial means it is useless for the function for which it evolved. Wings are not needed when food is found on ground, when you don’t need to fly (being on an island), and when wings are injured b/c they come in our way (large) So, natural selection got rid of wings b/c they are metabolically expensive Eyes are vestigial too, for burrowers, that don’t neeemre.duced vision Why don’t eyes go away completely? Regulate animals bodily rhythym! Humans have vestigial append ix actually more harmful. But helps immune system. Our ancestors needing it b/c appendixes break down leaves, we no longer eat leaves. But, it does not go away, b/c a smaller appendix is more dangerous. (roadblock) We also have a vestigial tail: coccyx (some useful muscles attach to it) Another vestigial feature is goosebumps and wiggling ears! Atavisms- expressed remnants of ancestral features. For example: a horse being born with an extra toe (come from ancestors with 5 toes, or whales being born with legs, splint bones in horses are examples of vestigial features) Atavisms can be made in the lbhen’s teeth. Using mouse tissue. Chickens have the genes to make teeth, but they are silences. A gene that doesn’t function (atavism or vestigial) is called a pseudogene. Most famous human pseudogene is GLO (makes Vitamin C). primates carry gene to make vitamin c but they don’t. A mutation has caused this. We also have dead genes from viruses called “endogeneous retroviruses” All animals have OR genes (to detect different smells). But in animals like dolphins, a lot of these genes are dead b/c dolphins don’t rely much on odour. Mammals produce a yolk sac like reptiles, but is yolkless and detaches from fetus. Platypus lacks a stomach diet of insects require no processing. All vertebrates begin with the same fish-lie developengtrow to have different systems. Arches become gills in fish, and ear bones for humans. Descendants inherit the developmental program of its ancestor “biogentic law” When in womb, we become completely covered with a coat of hair called lanugo, not for warmth b/c womb is warm alrea dyancestral remnant. Another example “grasping reflex” like monkeys = atvastic behaviour Examples of imperfect design: flat-fsheyes on one side, swim on one side, asyymterical. But can camofluage and hide from predators Another example: laryngeal nerve , which runs down larynx forms loop, instead of taking straight rout. more prone to injury [fish-like pattern of nerves] Another example: male’s urethra passes right through prostate g lnadin in urine causing infection... bad design! Also, women give birth through pelvis, but infants head is huge= a lot of pain!! Better design= exit through abdomen=less pain! Also, our reptile and fish ancestors shed their eggs directly from the ovary to the outside of bodies. Humans too have this, but this is fatal to us, as a gap b/w ovary and fallopian tube causes abdominal pregnancy=fatal! SO, these designs only makes sense as they evolved form features of earlier ancestors! CHAPTER 4: 3 islands of juan fernandes have endemic species- found nowhere else (fur seal, rust-brown humming bird…). However, not a single native species! How do species that are so similar live on diff continents: 1. Continental Drift- 2. Molecular Taxonomy- convergent evolution placentals and marsupials look alike even though placentals are in S. and N America, and marsupials in Australia marsupials also found in Antartica b/c of large continent before drift! Glacier movement (scratches) also supports the one large-continent theory Two types of islands 1. continenetal islands- those islands once connected to lconitenet, but then disconnected 2. Oceanic islands- islands that arise from sea floor (volcano). These islands are missing native species that live on continenetal islands. (Galapagos islands). Yet the species found on oceanic comprise of many similar species (radiation) - Life on oceanic islands is UNBALANCED! Only contains animals that can travel there (birds) - Trees are also rare on oceanic islands (large seeds) with exception of coconut tree. Though oceanic islands have no terrestrial mammals, they do have aerial mammals and aquatic mammals. - Oceanic animals resemble nearest mainland animals. (animals on the Galapagos resemble animals from south American west coast!) - Oceanic islands demonstrate all tenents of evolutionary history - the distribution of earth is by chance and lawfulness. CHAPTER 5: only native bees can “roast” hornet b/c they have
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