Evolution and Biology Notes

Week 3 Notes: Intro to Organisms **Objectives for Module 5 and 6:** Define the mechanisms that drive evolution and speciation events and explain their roles in evolutionary change within populations. Describe the different types of variation in a population. Explain why only natural selection can a...

Week 3 Notes: Intro to Organisms **Objectives for Module 5 and 6:** Define the mechanisms that drive evolution and speciation events and explain their roles in evolutionary change within populations. Describe the different types of variation in a population. Explain why only natural selection can act upon heritable variation. Describe genetic drift and the bottleneck effect, explain how each evolutionary force can influence a population's allele frequencies. Notes from Textbook: Chapter 18 I. ***[Chapter 18.1 Understanding Evolution]*** a. Evolution by natural selection describes a mechanism for how species change over time. b. Pre-Darwin Evolutionary Ideas: i. Ancient Greeks had mixed views on species change. Plato saw species as static. ii. Buffon (18^th^ century): Suggested species evolved, and that geography influenced species differences. iii. Hutton (18^th^ century): Proposed gradual geological changes over long periods (contrasted with catastrophic events theory). iv. Lyell (19^th^ century): Expanded on Hutton's ideas; influenced Darwin by suggesting Earth was much older. v. Lamarck (early 19^th^ century): Suggested evolution via inheritance of acquired traits (later disproven but still influential). c. Darwin and Wallace- Natural Selection (Mid-19^th^ century) vi. Both independently discovered natural selection. vii. Darwin's Voyage (1831-1836, H.M.S. Beagle) 1. Observed species worldwide, especially in the Galapagos Islands. 2. Noted finches had different beak shapes suited to their food sources. 3. Concluded species adapt over time based on environmental pressures. viii. Wallace's Expeditions 4. Came to similar conclusions about species adaptation. ix. Natural Selection 5. Species with beneficial traits survive and reproduce more successfully. "Survival of the fittest." 6. Over time, this leads to evolutionary changes in a population. 7. Three principles of Natural Selection: a. Inheritance: traits are passed from parents to offspring. b. Overproduction and Competition: more offspring are produced than resources can support, leading to competition. c. Variation and Differential Survival: Offspring vary; those with beneficial traits survive and reproduce more. 8. Natural selection is the only known mechanism for adaptive evolution. d. Processes and Patterns of Evolution: x. Variation is required for natural selection: 9. Differences must have a genetic basis to be passed to the next generation. 10. Environmental factors do not lead to evolutionary change. xi. Mutation: changes in DNA create new genetic variations (alleles). xii. Adaptations: heritable traits that help an organism survive and reproduce. Platypus having webbed feet to swim, snow leopard thick fur for cold survival, etc. xiii. Traits that are beneficial can change depending on the environment. xiv. Divergent Evolution: Two species evolve in different directions from a common ancestor. xv. Convergent Evolution: similar traits evolve independently in species that do not share a recent common ancestor. e. Evidence of Evolution: xvi. Fossil Record: shows gradual changes over time. xvii. Anatomy & Embryology 11. Homologous Structures: same basic structure, different function (shared ancestor). 12. Vestigial Structures: no apparent function, leftover from ancestors. 13. Analogous Structures: similar function, different evolutionary origin. 14. Embryology: shows relatedness between organisms by examining development. xviii. Convergent evolution in form: similar environments lead to similar traits due to selection pressures. f. Biogeography & Evolutionary Patterns: xix. Geographic distribution of organisms aligns with evolutionary history and tectonic plate movement. g. Molecular Biology & Genetic Evidence xx. DNA is universal in all life forms, proving a common ancestor for all organisms. xxi. Similarities in DNA sequences reflect evolutionary relationships. xxii. Gene duplication allows for evolution of new protein functions by modifying one gene copy while the other remains functional. II. Chapter 18.2 and 18.3 Notes: h. Species: a group of individual organisms that interbreed and produce fertile, viable offspring. xxiii. Members of the same species share both external and internal characteristics, which develop from their DNA. xxiv. Hybrid: a cross between two species. i. Speciation: the formation of two species from one original species. j. Allopatric speciation: involves geographic separation of populations from a parent species and subsequent evolution. "allo"="other and "-patric" means "homeland". k. Sympatric Speciation: involves speciation occurring within a parent species remaining in one location. "sym-" means "same" and "-patric" means "homeland". New species form in the same habitat without physical separation. l. Biologists think of speciation events as the splitting of one ancestral species into two descendant species. m. Disperal: when a few members of a species move to a new geographical area. n. Vicariance: when a natural situation arises to physically divide organisms. o. Adaptive Radiation: single species to multiple new species due to adaptation to different environments. Example: Darwin's finches. p. Polyploidy xxv. Polyploidy (extra chromosome sets) is a key mechanism in plants. xxvi. Types of Polyploidies: 15. Autopolyploid: extra chromosome sets from the same species. 16. Allopolyploid: chromosome sets from two different species. xxvii. Polyploidy leads to reproductive isolation and polyploids can't mate with normal diploids. q. Reproductive Isolation: xxviii. Genetic and phenotypic divergence between populations over time can prevent mating or result in nonviable/sterile offspring. xxix. Prezygotic barriers: prevent mating or fertilization from occurring. 17. Temporal isolation: species reproduce at different times. 18. Habitat Isolation: populations live in different habitats. 19. Behavioral Isolation: Differences in mating behaviors. 20. Gametic Isolation: Incompatibility of gametes. 21. Mechanical Isolation: differences in reproductive structures. xxx. Postzygotic barriers: affect offspring without fertilization. 22. Hybrid Inviability: hybrids don't survive past embryotic stages. 23. Hybrid Sterility: Hybrids are born but cannot reproduce. r. Hybrid Zones: area where two closely related species continue to interact and produce hybrids. III. Chapter 19 Terms: s. Adaptive Evolution: increase of frequency of beneficial alleles and decrease in deleterious alleles due to selection. t. Allele Frequency: (also, gene frequency) rate at which a specific allele appears within a population. u. Assortative Mating: when individuals tend to mate with those who are phenotypically similar to themselves. v. Bottleneck Effect: magnification of genetic drift as a result of natural events or catastrophes. w. Cline: x. Directional Selection: y. Diversifying Selection: z. Evolutionary Fitness: IV. Notes from Lecture: Wednesday 2/12/2025 a. Pangea split into Laurasia and Gondwana, during the Triassic and Jurassic periods of the Mesozoic. b. Big Five Mass Extinctions- Millions of years ago (Mya) xxxi. End Ordovician (444 Mya) 24. 86% species, 57% genera, and 27% families extinct 25. When there was a change in temp and climate, it resulted in mass extinctions. Different gases in the atmosphere. Plates moving. xxxii. Late Devonian (360 Mya) 26. 75% species, 35% genera, and 19% families extinct 27. Rapid growth in diversified plant but it became so cold that they just died off. Acid ocean..... we get it in the Gulf, its called the dead zone. It's when CO2 is poured into the ocean and all of the ocean and marine life can't use that oxygen, because it's hooked to carbon. They die if they can't breath oxygen. xxxiii. End Permian (250 Mya) 28. 96% species, 56% genera, and 57% families extinct 29. Global Warming. Most think of this and end crustaceous. We study fossils from this time. xxxiv. End Triassic 30. 80% species, 47% genera, and 23% families extinct. 31. Here is where dinosaurs come in. Underwater volcanic activity that created tsunamis and the chemistry in the atmosphere is changing. xxxv. End Cretaceous 32. 76% species, 40% genera, and 17% families extinct 33. Dinosaurs were just walking around. Evidence shows that an asteroid came and hit earth. No oxygen left to breath, and it is all just ash and dust. xxxvi. Future near-term extinction rates are driven by human actions today. We are in the 6^th^ mass extinction. xxxvii. Acid Rain 34. Rain that has picked up chemicals. Sulfur and nitric acid. 35. Our rain is more acidic than other parts of the country. Dead zones. xxxviii. Volcanoes in North America 36. Earthquake initiated recently from the Appalachians. We live on a fault that runs along the Appalachian trail. There is no where you can go to be safe from an earthquake. 37. San Andreas Fault in California. c. Aristotle xxxix. 300 BC, father of the scientific method, and created the Scala Naturae: the great chain of being. xl. The Great Chain of Being 38. Ability to grow and reproduce: humans, animals and plants 39. Ability to move: humans and animals 40. Ability to think rationally: humans d. Carl Linnaeus: 1700s- taxonomic classification system e. George Cuvier: 1800's- extinction, based on fossils f. Jean-Baptiste Lamarck: 1800's- evolution, through gradual improvement g. Charles Lyell: 1830- Principles of Geology: theorized about supercontinents: Pangea h. Charles Darwin: 1830s-50s- "decent with modification" or evolution by natural selection (on the origin of species, 1859) i. Alfred Russell Wallace: 1858- evolution by natural selection j. 1918-1942: Modern Synthesis; combined evolution by natural selection & Gregor Mendel's work on genetics k. 1990's-Present: Modular evolution l. Types of evolution: xli. Microevolution: a change in gene frequency within a population can be observed over short periods of time. xlii. Macroevolution: Major evolutionary change over long periods of time m. Hardy-Weinberg Principle: n. Evidence of Evolution: xliii. Fossil Record xliv. Biogeography, Plate Tectonics, and Continental Drift o. Comparative Morphology xlv. Morphological divergence: Change from the body from a common ancestor xlvi. Homologous structures (homologies): body parts that appear different in different lineages but are similar in some aspect. 41. Become modified to a different size, shape, or function in different lineages. 42. Are evidence of a common ancestor. p. Morphological Convergence: Independent evolution of similar body parts in different lineages. q. Analogous Structures (Analogies): Body parts that look alike in different lineages but did not evolve in a common ancestor. r. Comparative Development: xlvii. Similar patterns of embryonic development reflect shared ancestry xlviii. Master genes that control embryonic development patterns have changed very little or not at all over evolutionary time. xlix. Master genes with similar sequence and function in different lineages are strong evidence that those lineages are related. s. Molecular Genetics: Consistencies in genetic codes indicate and have been a major part in the attempt to understand LUCA. Last Universal Common Ancestor. t. Biological Evolution: change in heritable traits in a population over generations. u. Have they come together through convergence, or do they have that common ancestor? l. Look at fossil records, look at embryo development, molecular comparative (looking at genes), homologies, comparative morphology, macro vs micro evolution, micro is gene-frequency changing in a population, macro is species changing over time when looking at all the species. v. Acquired vs. Innate li. Innate you are born with. lii. Acquired you obtain. 43. Example: you are born with innate immune system and then you get an acquired immune system through time, like with viruses and vaccines. You fight off viruses. w. Mendel is known as the father of genetics. He worked with pea plants. liii. Genotype vs Phenotype 44. Phenotype is phonetic term. A characteristic that you can see. Short hair, brown eyes, etc. 45. Genotype is genetic term. What type of genetic material they have. d. Heterozygous vs Homozygous i. Heterozygous 1. Hetero-means different or other ii. Homozygous 2. Homo- means the same iii. Refers to genetic makeup of the DNA. x. DNA liv. ATCG- Bases of what our code is 46. Each is attached to a sugar and a phosphate and its called a nucleotides. 47. The sugar and phosphate don't change. What does change are the bases attached to it chemically. 48. You cant know someone's genotype until you pull their DNA. 49. We read them in 3's (a triple code). 50. A gene is a section of DNA that codes for something. Could code for some type of color of a flower. 51. Allele e. You get 2 alleles. One from mom, one from dad. f. Dominant and Recessive. g. Most of our traits are hybrids. h. If it's a dominating allele, it's capitalized. If its recessive, its lowercase. 52. Mendel called them factors, not alleles. 53. Harvey Weinberg y. Biological Evolution lv. Individuals do not evolve. Populations do. lvi. Common descent: all species are related and gradually change over time/generations. z. Requirements for Evolution: lvii. Genetic Variation/Mutation: 54. Genetic variation increases populations chances of survival from selective forces. 55. Phenotypes change based on gene expression. 56. Mutations. i. Different cultures can have different mutations. lviii. Sexual Reproduction 57. Sexual Reproduction increases genetic variability. 58. Sexual Reproduction of closely related individuals can lead to increased mutations. 59. Genome- mapping out where every gene is in our body. lix. Natural Selection: Adaptive Evolution 60. Variation 61. Competition 62. Adaptations 63. Selection j. Survival of the fittest DOES NOT MEAN STRONGEST OR BEST!! k. We will be going over types of natural selection next class. lx. Gene Flow lxi. Genetic Drift 64. Genetic bottlenecks are stochastic events that limit genetic variation in a population and result in founding populations that can lead to genetic drift. 65. Founder effect refers to a small subset of a population gets separated from the parent population and becomes established in a novel environment. a. Hardy-Weinberg Amoeba Sisters Video lxii. Assumptions of Hardy-Weinberg Equilibrium: All of these 5 assumptions must be kept in order for Hardy-Weinberg Equilibrium to happen. (knowing they won't evolve) 66. No Selection 67. No Mutation 68. No Migration 69. Large Population 70. Random Mating lxiii. P+q=1 (allele frequencies) 71. P is dominant allele frequency. 72. q is recessive allele frequency. 73. p\^2+2pq+q\^2=1 l. p\^2 is homozygous dominant m. 2pq is heterozygous n. q\^2 is homozygous recessive