Biol 1M03 W25: Biodiversity, Evolution, and Humanity PDF

Biol 1M03 W25: Biodiversity, Evolution, and Humanity Evolution: a framework for understanding life Week 1: Chapter 1 Sections 1.1, 1.3, 1.4 “How Life Works” Jan 7th 2024  Week 1: roadmap What does it...

Biol 1M03 W25: Biodiversity, Evolution, and Humanity Evolution: a framework for understanding life Week 1: Chapter 1 Sections 1.1, 1.3, 1.4 “How Life Works” Jan 7th 2024  Week 1: roadmap What does it Three of the greatest The process mean to say unifying ideas in of doing that something Biology Biology is alive? 1. Life is cellular 3. Life evolves Lecture 1 2. Life processes Lecture 2 information Lecture 3  Learning objectives You should be able to: 1. Name three fundamental characteristics of life 2. Describe the two components of the cell theory 3. Explain the chromosome theory of inheritance 4. Briefly explain the theory of natural selection and clarify the two conditions that are necessary and sufficient for natural selection to bring about evolutionary change in a population. 5. Describe what biologists do, that is, how they approach problems and why they do experiments.  What Does It Mean to Say that Something Is Alive? All living organisms share several fundamental characteristics Can you name them?  What Does It Mean to Say that Something Is Alive? All living organisms share these fundamental characteristics: 1. Cellular All organisms are made up of membrane-bound cells. 2. Process information All organisms process hereditary information encoded in genes as well as information from the environment 3. Evolve Populations of organisms are continually evolving. Textbook Chapter 1.3: The Cell  6 Is it alive? A virus Cellular Processes information Evolves This Photo by Unknown Author is licensed under CC BY-ND  7 Is it alive? A mule Cellular Processes information Evolves  8 Is it alive? A droid Cellular Processes information Evolves This Photo by Unknown Author is licensed under CC BY-SA  What Does It Mean to Say that Something Is Alive? Three theories form the framework for modern biological science: What is a theory, scientifically speaking? An explanation for a broad class of phenomena or observations. Supported by a wide body of evidence (as opposed to a conspiracy theory). Differs from everyday usage of the word “theory” which often carries meanings such as “speculation” or “guess.” Textbook Chapter 1.1: Scientific inquiry  What Does It Mean to Say that Something Is Alive? Three theories form the framework for modern biological science: 1. The cell theory What are organisms made of? 2. The chromosome theory of inheritance How is hereditary information transmitted from one generation to the next? 3. The theory of evolution by natural selection Where do organisms come from?  What Does It Mean to Say that Something Is Alive? Three theories form the framework for modern biological science: 1. The cell theory What are organisms made of? 2. The chromosome theory of inheritance How is hereditary information transmitted from one generation to the next? 3. The theory of evolution by natural selection Where do organisms come from? Textbook Chapter 1.3: The Cell  Life Is Cellular In the late 1660s, Robert Hooke and Anton van Leeuwenhoek were the first to observe cells. A cell is a highly organized compartment – Bounded by a plasma membrane – Containing concentrated chemicals in an aqueous solution. Textbook Chapter 1.3: The Cell  Van Leeuwenhoek’s Microscope Made Cells Visible Animalcules: “concerning little animals…” ‘twas wonderful to see: and I judged that some of these little creatures were above a thousand times smaller than the smallest ones I have ever yet seen upon the rind of cheese’ Letter from Leeuwenhoek to Oldenburg, 7 September 1674, translated in Dobell C. 1958Antony van Leeuwenhoek and his little animals, pp. 109–110. New York, NY: Russell and Russell. Seeing the Invisible - video on A2L Image taken from Wikipedia: https://en.wikipedia.org/wiki/Animalcule  Cells – the building blocks of life Smallest Largest ~200 nm ~2,384 acres Do you know what the smallest and largest individual organisms are?  Cells – the building blocks of life Smallest Largest ~200 nm ~2,384 acres Mycoplasma gallisepticum Armillaria ostoyae Bacterium, causes disease in chickens The “humongous fungus”, causes root and many other bird species. disease in many conifer species Image taken from Wikipedia: https://en.wikipedia.org/wiki/Mycopla Image taken from the Scientific American: sma_gallisepticum https://www.scientificamerican.com/article/st range-but-true-largest-organism-is-fungus/ 5000 could fit side-by-side About 9.5 x larger than McMaster’s within one mm entire campus (~300 acres) Casselman (2004) - article on A2L  Where Do Cells Come From? Two competing hypotheses What is a Hypothesis? Textbook Chapter 1.1: Scientific inquiry  Where Do Cells Come From? Two competing hypotheses What is a Hypothesis? A hypothesis is a testable statement that explains something observed An experiment allows researchers to test the effect of a factor on a particular phenomenon A prediction is a measurable or observable result that must be correct if a hypothesis is valid. Textbook Chapter 1.1: Scientific inquiry  Where Do Cells Come From? Two competing hypotheses What is a Hypothesis? Important distinction: Hypothesis Prediction X (explanatory/independent variable) X (explanatory/independent variable) affects/impacts increases/decreases Y (response/dependent variable) Y (response/dependent variable) Does not imply direction Implies direction Textbook Chapter 1.1: Scientific inquiry  Where Do Cells Come From? Two competing hypotheses Spontaneous generation (prevailing paradigm until mid 1800’s) – organisms could arise spontaneously under certain conditions – bacteria and fungi that spoil foods such as milk and wine springing to life from nonliving materials Cell theory (challenger) – All organisms are made of cells and all cells come from preexisting cells. Textbook Chapter 1.3: The Cell  An Experiment to Settle the Question Louis Pasteur’s hypothesis: – Cells arise from cells – Cells do not arise by spontaneous generation How can you rephrase this into the following statement: X is required for Y? Textbook Chapter 1.3: The Cell  An Experiment to Settle the Question Louis Pasteur’s hypothesis: – Cells arise from cells – Cells do not arise by spontaneous generation How can you rephrase this into the following statement: X is required for Y? X = presence of preexisting cells Textbook Chapter 1.3: Y = cell growth The Cell  An Experiment to Settle the Question Hypothesis: – The presence of preexisting cells is required for cell growth Null hypothesis – The presence of preexisting cells is not required for cell growth Predictions – Cell growth will only be observed if preexisting cells already existed – Cell growth will be observed regardless of whether preexisting cells already existed Can Microscopic Life Arise From Nonliving Matter? Louis Pasteur’s Experiment - video on A2L Louis Pasteur Experimentation Based on the results from this experiment, would the Null hypothesis be rejected? Why or why not?  Review – what is life? What does it mean to say that something is alive? There is no single, well-accepted definition of life. Instead, we can identify common characteristics that organisms share. Three of the most influential unifying ideas in biology are the cell theory, the chromosome theory of inheritance, and the theory of evolution. Life emerges from cells The cell theory identified the fundamental structural unit common to all life.  What Does It Mean to Say that Something Is Alive? Three theories form the framework for modern biological science: 1. The cell theory What are organisms made of? 2. The chromosome theory of inheritance How is hereditary information transmitted from one generation to the next? 3. The theory of evolution by natural selection Where do organisms come from? Textbook Chapter 1.3: The Cell  Life Processes Information Chromosomal theory of inheritance proposed in 1902 by Walter Sutton and Theodor Boveri – Hereditary or genetic information is encoded in genes – Genes are units located on chromosomes 1950s: chromosomes are molecules of deoxyribonucleic acid, or DNA – DNA is the hereditary material – Genes are segments of DNA that code for cell products Textbook Chapter 1.3: The Cell Structure of DNA: double helix Each strand of the double helix is made up of four building blocks: A, T, C, and G Sequence of this code is like letters in a word DNA carries, or encodes, information needed for an organism’s growth and reproduction Textbook Chapter 1.3: The Cell Structure of DNA: double helix The two strands of the double helix are held together by connections between the building blocks – A pairs with T – C pairs with G This pairing allows DNA to be copied Preserves the information encoded in the DNA James Watson and Francis Crick, along with Rosalyn Franklin, proposed that DNA is a double- stranded helix The Double Helix – link on A2L Textbook Chapter 1.3: The Cell  The Central Dogma The flow of information in cells: Genes in DNA code the information necessary to produce a functional product, often a protein. DNA is transcribed into an RNA message. The RNA message can then be translated into a protein.  The Central Dogma DNA is copied to pass genetic information from cell to cell or from one organism to its offspring Copying DNA is highly accurate What happens when a mistake is made? – DNA sequence changes may lead to changes in proteins – Outward appearance is a product of proteins produced – DNA sequence changes may cause changes in outward appearance How does the Central Dogma help us to understand how mutations in DNA can result in disease?  Review – what is life? Life processes information The chromosome theory of inheritance states that genes are located on chromosomes. A chromosome consists of a molecule of DNA – the hereditary material. Genes, located on chromosomes, consist of specific segments of DNA that code for products in the cell. The flow of information from DNA to RNA to protein is called the central dogma. Imperfect replication (i.e., mutation) provides the source of heritable variation in traits – fueling evolution  What Does It Mean to Say that Something Is Alive? Three theories form the framework for modern biological science: 1. The cell theory What are organisms made of? 2. The chromosome theory of inheritance How is hereditary information transmitted from one generation to the next? 3. The theory of evolution by natural selection Where do organisms come from? Textbook Chapter 1.4: Evolution  What Is Evolution? If a non-biology major friend asked you "What is evolution?", what would your initial response be?  Before Darwin (mid 1800’s and earlier) Prevailing paradigm Special Creation (aka natural theology): 1. all species were created separately, and thus, are unrelated to one another; 2. each species is unchanging, and there is little variation within each. Species = a distinct, identifiable type of organism  Challenges to Special Creation Early paleontologists (such as Mary Anning, 1799-1847) discovered fossils for life forms that no longer existed. – The claim that species could go extinct was met with lots of resistance (why would the divine Image taken from” https://www.tchevalier.com/10- creator “wipe out” its creation?) rc/100-remarkable-creatures Chevalier’s Remarkable Creatures – link on A2L  Challenges to Special Creation In 1858, Charles Darwin and Alfred Russel Wallace made two claims regarding the natural world: 1. All species are related by common ancestry 2. Characteristics of species can be modified from generation to generation (descent with modification) Species changing over time = microevolution Species splitting and diverging = macroevolution Textbook Chapter 1.4: Evolution  What Is Evolution? Evolution – is a change in the characteristics of a population over time. – It means that species are related to one another and can change through time. A population is – A group of individuals of the same species – Living in the same area – At the same time Textbook Chapter 1.4: Evolution  How does evolution occur? Adaptive (aka Selection) - – Chapter 20.4 Nonadaptive (genetic drift, gene flow, mutation, non-random mating) - – Chapter 20.5  How does evolution occur? Adaptive (aka Selection) - – Chapter 20.4 Nonadaptive (genetic drift, gene flow, mutation, non-random mating) - – Chapter 20.5  Natural selection Darwin wasn’t the first to challenge the idea that species were unchanging, but he was the first to amass a cornucopia of evidence to back it up. Darwin, together with Wallace, proposed the most famous mode of evolution: Natural selection Textbook Chapter 1.4: Evolution Two Conditions of Natural Selection Two conditions must be met for natural selection to occur in a population: 1. Individuals must vary in traits that are heritable—can be passed on 2. In a particular environment, certain versions of these heritable traits help individuals reproduce more than other versions Textbook Chapter 1.4: Evolution Two Conditions of Natural Selection If certain heritable traits lead to increased success in producing offspring – These traits become more common in the population over time In this way, the population’s characteristics change (evolution) as a result of natural selection acting on individuals – Natural selection acts on individuals – Evolutionary change occurs in populations Speciation occurs when populations diverge to form new species  Fitness and Adaptation Fitness is – The ability of an individual to produce offspring. – Individuals with high fitness produce many surviving offspring. Adaptation is – A heritable trait that increases the fitness of an individual in a particular environment. Textbook Chapter 1.4: Evolution  Fitness and Adaptation Example of natural selection: Finches on a Galápagos island – Variation in finch beak size and shape – When rainfall became consistent, small soft seeds became more abundant – Observed a shift in the Image taken from Wikipedia: proportion of finches with https://commons.wikimedia.org/w/inde x.php?curid=3918303 small, pointed beaks Are smaller, pointed beaks an adaptation to prolonged rainfall? How could you test this?  Fitness and Adaptation Example of natural selection: Finches on a Galápagos island – If finches with small, pointed beaks had higher fitness (produced more offspring) AND – Small beak size was heritable (has a genetic basis) – Then, small, pointed beaks can be considered an adaptation that increased finches’ ability to thrive – Resulting in the frequency of Image taken from Wikipedia: finches with small, pointed beaks https://commons.wikimedia.org/w/inde x.php?curid=3918303 increasing in the population  Daphnia spp. example Fraser (2016) - link on A2L Are spines an adaptation to the presence of predators? Spines Lake A: No predators Lake B: Predators present Image taken from: https://blogs.scientificamerican.com/artful- amoeba/predator-no-problem-water-fleas-grow-weapons/  Review – what is life? Life evolves The theory of evolution states that all organisms are related by common ancestry. Natural selection is a well-tested explanation for why species change through time and why they are so well adapted to their habitats. Textbook Chapter 1.4: Evolution  Doing Biology All scientists ask questions that can be answered by measuring things – by collecting data. Science is about formulating hypotheses and finding evidence that supports or conflicts with those hypotheses. – For example, using carefully designed experiments, biologists test ideas about the way the natural world works by testing the predictions made by alternative hypotheses. Textbook Chapter 1.1: Scientific inquiry  Important Characteristics of Good Experimental Design A well-designed experiment: 1. It includes one or more control groups to check for other factors that might influence the outcome. 2. Experimental conditions were controlled to eliminate other variables. 3. Tests were repeated or replicates were included to reduce the effects of distortion due to small sample size. Textbook Chapter 1.1: Scientific inquiry  The angler fish (activity) Jot down a few traits of the angler fish you notice in the following video:  The angler fish (activity) Added video clip to A2L (Extra Resources)  The angler fish (activity) Form groups (or working individually) to answer the following questions: 1. Pick one trait that you think could be an adaptation 2. Formulate a hypothesis using the X affects Y formula What factor would you test (X) What would you measure (Y) 3. What’s the Null?  The angler fish (activity) 2. How would you go about testing your hypothesis? – Approaches: observational vs manipulative – Treatment vs control groups – Randomization – Replication 3. What are the potential outcomes of your experiment? – See if you can sketch them out  The angler fish (activity) - example X (adaptation): brightness of lure Y (fitness measure): number of approaches by male Hypothesis: the brightness of the lure affects the female’s ability to attract a mate Null: The brightness of the lure does not affect the female’s ability to attract a mate  The angler fish (activity) - example Approach: manipulative Two treatments, one control group: 1) Dull (non-toxic coating that decreases brightness) 2) Bright (non-toxic coating that increases brightness) 3) Control (non-toxic coating that does not impact brightness)  The angler fish (activity) - example Experiment: Place 10 individual females of each treatment group (replication) into an enclosure that mimics the natural environment in every way Allow females to swim around and males to approach freely (randomization) Count the number of approaches males make towards each female over a ten-minute period  The angler fish (activity) - example Predictions if Null was rejected: approaches by male approaches by male Ave. number of Ave. number of Dull Control Bright Dull Control Bright Note: there are more outcomes that we could draw, but these are the two most obvious. You want to include not just the prediction you think is most likely, but also alternative outcome(s)  58 FAQs Q) Do you recommend I read the textbook ahead of lectures, or afterward, to learn the material most effectively? A) For some students, reading chapters ahead of time helps them "prime" their brain, allowing them to apply their knowledge more effectively during lecture. For other students, they take note of challenging concepts introduced in lecture, and lookup this topic in the textbook so they can read more about it. Some do both.  59 FAQs Q) Is all the material covered in the textbook testable? How can I tell what part is testable and what part isn't? A) Use the lecture material as your guide. The textbook covers material from BIOL1A03, which is NOT testable. If the information is in lecture, it's testable, and you can use the textbook to reinforce your understanding. If the information in the textbook is NOT in lecture, it's not testable. You can skip over it.