Evolution, Natural Selection & Antibiotic Resistance Study Guide PDF

Study Guide: Evolution, Natural Selection, and Antibiotic Resistance MRSA and Antibiotic Resistance ​ MRSA (Methicillin-Resistant Staphylococcus aureus) is hard to kill and spreads in hospitals, gyms, and dorms. Do not give someone methicillin because it does not work and makes them sic...

Study Guide: Evolution, Natural Selection, and Antibiotic Resistance MRSA and Antibiotic Resistance ​ MRSA (Methicillin-Resistant Staphylococcus aureus) is hard to kill and spreads in hospitals, gyms, and dorms. Do not give someone methicillin because it does not work and makes them sick. Use vancomycin. ​ Red halo is sign of inflammatory response, it is screening what is self and not self ​ If you carry any strain of staph, but are not infected, you are colonized ​ Antibiotics kill or slow bacterial growth, but bacteria can develop resistance through mutations or gene transfer. Antibiotics interfere with the function of essential bacterial cell structures ​ Misusing antibiotics (e.g., stopping early) leads to antibiotic resistance. The first couple of doses increases the concentration of antibiotic molecule enough to fight off easy bacteria, but does not kill the hard ones ​ Beta-lactam antibiotics target bacterial cell walls, but some bacteria produce beta-lactamases (enzymes) to break them down ​ The rate of human evolution is much slower than bacterial evolution Principles of Natural Selection ​ Natural Selection: Favorable traits increase reproductive success. Most favorable characteristics have more offspring ​ Works on populations, not individuals, and works on the variability that is already there, it is not intentional because you cannot generate new characteristics on purpose ​ Population: group of like individuals that live in the same geographic area at the same time ​ Three types of selection: ○​ Stabilizing Selection – Favors the average trait, more reproductive success in the middle ○​ Directional Selection – Favors one extreme, pushes the population towards one side ○​ Disruptive Selection – Favors both extremes, possibly leading to speciation, bimodal ​ Survival of the Fittest: The offspring that just happen to have the inheritable characteristics that allow them to survive are favored ​ Biological Fitness: refers to an individual’s or group’s ability to survive and reproduce under particular environmental conditions Genetic Diversity & Evolution  ​ Where genetic diversity originates?: Every time a cell divides, a few mutations will result…DNA polymerase makes errors at a predictable rate. Every generation produces more and more genetic diversity within that population ○​ It is not true that daughter cells are identical to each other, sometimes typographical errors occur. Offspring almost never have an exact copy of the parent cells ​ Genetic diversity is due to the accumulation of mutations and reorganization of genetic material ​ Mutations occur naturally and increase diversity. ​ Sexual reproduction increases genetic variation. ​ Microevolution: Small genetic changes in a population. Eye color, skin, hair ​ Macroevolution: Large changes leading to new species. ​ Gene pool: the total collection of genes in a population at any one time ​ Biogeography: the study of species distributions across the planet Speciation & Reproductive Barriers ​ Species: A group that can interbreed and produce fertile offspring. Often described based on anatomical or genetic differences ​ Biological species context: a group of populations whose members have potential to interbreed in nature and produce fertile offspring ​ Reproductive barriers prevent interbreeding: ○​ Temporal Isolation – Different breeding times. ○​ Behavioral Isolation – Different mating behaviors. Hardy-Weinberg & Genetic Drift ​ Hardy-Weinberg Principle: Used to study population genetics. The amount of genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors ​ The founder effect: a type of genetic drift in which a small number of individuals leave one population and establish a new population; by chance, the newly established population may have lower genetic diversity than the original population ​ Bottleneck effect: type of genetic drift that occurs when a population is suddenly reduced to a small number of individuals and alleles are lost from the population as a result. Population suddenly shrinks due to a disaster, less genetic variation. Fossils & Evolutionary Evidence ​ Fossils document macroevolution. ​ Homology: Similar structures from a common ancestor. ​ Convergent evolution: when different organisms develop similar traits even though they are not closely related. Happens because they live in similar environments or face the same challenges.  ​ Analogous Traits: Similar traits due to convergent evolution. Analogous=ALIKE IN STRUCTURE ​ Homologous structures: Features that have different functions, but are structurally similar because of common ancestry: HOMO=same, same ancestry ​ Radiometric Dating: Uses isotope decay (e.g., Carbon-14, Potassium-Argon) to determine fossil age. Typically done on igneous rocks ​ Uranium lead method: a way to date rocks by looking at how uranium slowly turns into lead over time. ​ Tiktaalik: A transitional fossil showing the shift from fish to land-dwelling vertebrates. Mass Extinctions & Adaptive Radiation ​ Mass extinctions lead to rapid diversification. Two big ones were at the end of the Permian and Cretaceuous periods. ​ The Cambrien explosion: a sudden increase in the diversity of animal life as complex organisms evolved ​ Adaptive radiation: Organisms evolve to fill ecological niches. Species turns into multiple different species ○​ May occur in new or newly vacated habitats like after mass extinction Miller-Urey Experiment ​ Demonstrated that organic molecules could form from inorganic compounds. ​ Inputs were water, ammonia, methane. ​ Output were amino acids and biomolecules Taxonomy & Evolutionary Relationships ​ Phylogeny: actual evolutionary history of organisms ​ Phylogenetic Trees show evolutionary relationships. ○​ Branch: natural selection leads to new species or groups of them ○​ Root: common ancestor of all organisms on the tree ○​ Node: last common ancestor of the organisms above this point in the tree ​ Three Domains of Life: Bacteria, Archaea, Eukarya. ​ Five Kingdoms: Animal, plant, fungi, protist, monera Darwin and others ​ Darwin is the most famous person associated with evolution, but did not invent it ​ Went on the HMS beagle and wrote book ​ Descent of modification: one species over time giving rise to new species; It draws two things: all living things are related and that the different species we see today emerged over time as a result of natural selection operating over millions of years. ​ This idea of natural selection was Darwin's original contribution to the theory of evolution.  ​ Thomas Malthus (population growth) and Charles Lyell (geological changes over time) influenced Darwin’s thinking. ​ Alfred Wallace went to the Amazon River. Wrote “On the Origin of Species on the Means of Natural Selection,” and called it Darwinism. Wallace is responsible for our modern day definition of species. Random Textbook Stuff ​ Plate Tectonics: the theory that continents are part of large sections that sit atop earth’s mantle and move around and collide due to heat convection currents in the underlying mantle ​ Domain, supergroup, kingdom, phylum, class, order, family, genus, species ​ Vertebrates: animals with a rigid backbone ​ Mammals: mammary glands and a body covered with hair ​ Continental Drift: the movement of continents relative to one another over time ​ Sedimentary rocks: formed by sand and dust ​ Igneous rocks: formed by volcanic eruptions ​ Most popular theory of how the solar system was formed is that planets are a result of the swirling solar nebula, out of cosmic dust from the cloud ​ Vestigial structures: structure inherited from an ancestor that no longer serves a clear function in the organism that possesses it STUDY QUESTIONS – EXAM 1- BIOLOGY 102, SPRING 2025 1. Do populations evolve on purpose? Is evolution goal-oriented? Explain… No, populations do not evolve on purpose. Evolution is not a straight line process and evolutionary trends reflect forces of selection. 2. Who was Charles Darwin, and why is he in every Biology textbook? (What was his contribution to the field of Biology?) He contributed by developing the theory of evolution by natural selection 3. What was Darwin’s phrase for evolution? What does it mean? Descent of modification: one species over time giving rise to new species 4. What is the difference between natural selection and artificial selection? Can you think of any examples (maybe some that aren’t in the book)? Artificial selection is selective breeding of plants and animals by humans, like breeding dogs or crops. Natural selection is where things with the best traits survive and reproduce more successfully, like giraffes getting longer necks to reach food or moths changing color to camo 5. How do fossils and the fossil record provide evidence that supports evolution? Fossils can show transitional animals, changes over time, extinct species, homologous structures, and dating 6. Do you understand the following terms and concepts? Biogeography, comparative anatomy, homologous structures, molecular biology. Biogeography is the study of species distributions across the world. Comparative anatomy is the comparison of body structures in different species. Homologous structures are features that have different functions, but are structurally similar because of common ancestry. Molecular biology is the study of how life works focusing on DNA and shows how traits are inherited and how species are related. 7. Can natural selection be observed? Would antibiotic resistance in bacteria and pesticide resistance in insects be examples? Why or why not? Other Examples? Yes it can be observed and yes antibiotic resistance is a great example because their lifespan is so short and you can see their changes over time in response to their environment 8. Why can’t an individual evolve? What is a population? A population is a group of like individuals that live in the same geographic area at the same time. Individuals cannot evolve because evolution happens through genetic change and it takes time and natural selection works on populations because the best traits become more common in the future generations 9. How do genetic drift (changes within a population) and gene flow (changes between populations) contribute to evolution? What is the bottleneck effect? What is the Founder effect? Genetic drift is changes within a population, random changes in allele frequencies due to CHANCE events, like random deaths or natural disasters. It can reduce genetic diversity. Gene flow is movement of alleles between populations due to migration, like organisms migrating and reproducing in new populations and it increases diversity. The bottleneck effect is a sudden reduction in a population due to a disaster leaving a few individuals to repopulate. It is a type of genetic drift that reduces diversity. The founder effect is when a few individuals leave a larger population and make their own, which leads to limited genetic diversity. 10. Why are genetic bottlenecks of particular relevance to endangered species? Because genetic bottlenecks reduce a population’s genetic diversity which is key for long term survival and health 11. Where does the physical variation in population arise? What generates physical variation? How are various physical variations passed along to successive generations? They arise from differences in genes and environmental factors. They are passed down by inheritance and can be influenced by natural selection 12. What is evolutionary fitness? Refers to an individual’s or group’s ability to survive and reproduce under particular environmental conditions. The more offspring an organism has that survive and reproduce then the higher the fitness 13. How can natural selection alter variation in a population? (Stabilizing, directional, and disruptive selection) Can you recognize examples of each? Stabilizing favors the average trait, not extremes, like birth weights bc if you are too small or too big you will die. Directional favors one side of the spectrum, a birds beak size decreasing over time. Disruptive favors both extremes leaving nothing in the middle leading to possible speciation, like peppered moths because darker moths survive and light ones survive 14. While it would seem that organisms are perfectly adapted for their environment, does natural selection produce perfect organisms? Explain...No natural selection does not produce perfect organisms because changes are random. Sometimes NS favors traits that work well enough even if they are not the best. Some changes may have costs too, like peacock feathers are attractive to mates but are bad to hide from predators. Also environmental pressures can change 15. What is a species? : A group that can interbreed and produce fertile offspring. Often described based on anatomical or genetic differences 16. Can you discuss different ways to describe the concept of species? (Biological, morphological, etc...) Biological is a group of populations whose members have potential to interbreed in nature and produce fertile offspring. Morphological is where you use physical characteristics to define species. 17. Why is the fossil of Tiktaalik so important? It showed an intermediate animal between land and water and helped support the theory of evolution 18. What is the difference between microevolution and macroevolution? Microevolution is small changes like hair and eye color. Macroevolution is large changes that could make new species. 19. Why are analogous structures said to result from convergent evolution? Analogous structures have no common ancestry but same function. Convergent evolution is when different organisms develop similar traits even though they are not closely related. Happens because they live in similar environments or face the same challenges. Divergent evolution is when a species has a common ancestor but they evolve different traits 20. Why can sexual selection act as such a strong selective force in shaping the makeup of a population? It affects the organism's ability to reproduce and pass on its genes. It depends on mating success Evolutionary History: 1. Does the rate of evolution change over time? Could it be the rate or occurrence of selective events? Distinguish the gradualism model from punctuated equilibrium. The rate of evolution can change over time, it can speed up or slow down depending on a bunch of factors like environmental changes, mutations, natural selection, genetic drift. It is influenced by the frequency and intensity of selective pressures. The gradualism model suggests that evolution happens slowly and steadily over long periods and that small genetic changes accumulate gradually. The punctuated equilibrium model suggests that species remain relatively unchanged for long periods and that evolution occurs in short, rapid bursts. 2. What is continental drift? Plate Tectonics? Has the movement of continents over time affected the distribution of plant and animal species? How? Continental drift is the movement of continents relative to each other over time. Plate tectonics is a theory that continents sit atop of the earth and shift due to heat. 3. What is a mass extinction? Can you think of any examples? Why might species experience an explosion of diversification following an extinction event? Might mass extinctions contribute to adaptive radiation? How? Mass extinction leads to rapid diversification. Examples are the Permian and Cretaceous periods. Species experience an explosion of diversification after an extinction cause there is reduced competition, new ecological niches, rapid evolutionary change, and environmental changes. Mammals used to be small and stuff but they rapidly diversified into a lot more forms after the dinosaur extinction. Mass extinctions removed dominant species, clearing the way for surviving species to diversify and evolve rapidly, this adaptive radiation leads to the rise of new species.