Bio201 Exam 2 Prep: Evolution Concepts & Key Terms

THE EXAM2 IS POSTPONED TO APRIL 18th Dear Students, please use the following materials solely as study aids to help you prepare for Exam reviewing the slides. GOOD LUCK AND HAPPY LEARNING~ All Questions are Q&A, no choices questions. Unit 2: Evolution Term/Concept Agents of Evolut...

THE EXAM2 IS POSTPONED TO APRIL 18th Dear Students, please use the following materials solely as study aids to help you prepare for Exam reviewing the slides. GOOD LUCK AND HAPPY LEARNING~ All Questions are Q&A, no choices questions. Unit 2: Evolution Term/Concept Agents of Evolution Allopatric Speciation Biological Species Concept Biological Systems Hierarchy Cladogram vs. Phylogram Convergent Evolution Convergent vs. Divergent Evolution Cryptic Species Ecological Species Concept Endosymbiotic Theory Primary/Secondary/Tertiary Endosymbiosis Evolution (Two-Step Process) Fixation of Alleles Gene Pool Genetic Drift Gene Flow/Migration Homologous Structures Heritable vs. Acquired Traits Irreducible Complexity Macroevolution Microevolution Molecular Clocks Monophyletic vs. Paraphyletic Natural Selection Types Phylogenetic Fuse Phylogenetic Tree Types Pollinator Shifts Pollination Syndromes Prezygotic Barriers Primary vs. Secondary Endosymbiosis Reproductive Isolation Sources of Genetic Variation Sympatric Speciation Theory of Endosymbiosis Transitional Fossil monophyletic clade Key Processes & Case Studies Term/Concept MEGA Plate Experiment Reconstructing Phylogeny Macroevolutionary Patterns Endosymbiosis in Photosynthetic Lineages Pollination Syndromes Anolis Lizards Cycads Mollusk Eyes Aquilegia (Columbines) Bacterial Resistance Critical Distinctions Term/Concept Hypothesis vs. Theory Homologous vs. Analogous Structures Microevolution vs. Macroevolution Directional vs. Stabilizing vs Disruptive Selecti Prezygote vs Postzygote Reproductive Isolation Parsimony Method vs Maximum Likelihood Method Primary vs Secondary Endosymbiosis Divergent Evolution vs Convergent Evolution Cladogram vs Phylogram vs Chronogram Heritable Traits vs Acquired Traits Genetic Variation vs Phenotypic Variation Allopatric speciation vs Sympatric speciation Be able to explain and distinguish the following four concepts in defining species Biological Species Morphological Species Ecological Species Phylogenetic/Evolutionary Species *Defining species uniformly across all life forms is challenging due to biological complexity, evolu Be able to distinguish the four agents of evolution into Non-Random Adaptive and Random Adaptive agent Be able to explain the impact of genetic drift on allele frequencies in SMALL versus LARGE popula Be able to explain how Divergent Evolution and Convergent Evolution differ in the terms of Genetic Mechan Genetic Mechanism: Divergent evolution occurs when two or more populations of a single species accumulate genetic differences over t Convergent evolution occurs when unrelated species independently evolve similar traits or functions, not due to sha Selective Pressure: Divergent evolution is driven by different selective pressures in DISTINCT ENVIRONMENTS. Convergent evolution is driven by similar selective pressures acting on unrelated lineages. When different species o Figures & Examples Term/Concept Tiktaalik Cycad Phylogeny (Nagalingum et al.) Columbine Pollinator Experiment Structure of Chloroplast Make Sure You UNDERSTAND ALL the Case Studies and Questions that we've gone through in class and la NED TO APRIL 18th ials solely as study aids to help you prepare for Exam 2. Keep in mind that these resources are not a substitu stions. Four major agents: Mutation, migration (gene flow), genetic drift,Explanation natural selection. Example: Antibiotic res and selection. Speciation due to geographic isolation (e.g., river splitting a population). Contrast with sympa barrier, e.g., Species definedpolyploidy in plants).isolation. Limitations: Does not apply to asexual organisms o by reproductive Lankan elephants. Levels of organization: Cladogram: molecules Shows branching → organelles relationships. → cells →Branch Phylogram: tissueslengths → organs → organisms represent → pop evolutionar lengths scaled Independent to time. of similar traits in unrelated lineages (e.g., wings in bats vs. birds). Co evolution structures (shared ancestry, like tetrapod limbs). Convergent: unrelated species develop similar traits. Divergent: related species develop diffe Morphologically identical but genetically distinct (e.g., Astraptes fulgerator butterflies). Ident Defines species Proposes by theirand mitochondria ecological roles originated chloroplasts and niches,from even if morphologically engulfed prokaryotes, similar. supported by ribosomes, and double membranes. Primary: Engulfment of prokaryotes (e.g., chloroplasts from cyanobacteria). Secondary: Engu another eukaryote (e.g., Euglena’s chloroplast). 1. Variation arises in a population. 2. Proportions of variants change across generations, requ When All an allele alleles present becomes the only variant in a population. Criticalin fora genetic population, oftenand diversity dueevolution. to geneticExample: drift or selectio Chan bacterial populations on the MEGA plate under antibiotic pressure. Random changes in allele frequencies, impactful in small populations (e.g., bottlenecks, foun Movement of alleles between populations, introducing genetic diversity or homogenizing pop AnatomicalPassed Heritable: similarities duegenes through to shared (e.g.,ancestry (e.g.,inlimb flower color bones in mammals). hydrangeas). Acquired: Develop during docked tails Argument in dogs, against which do evolution not eye (e.g., affect offspring). Counterexample: Mollusc eye diversity (fr complexity). patches to complex camera eyes). Large-scale evolutionary changes (e.g., origin of tetrapods, cycad radiation). Changes in allele frequencies within populations (e.g., antibiotic resistance in bacteria). Genetic data used to estimate divergence times between species, calibrated with fossils. Monophyletic: Ancestor + all descendants. Paraphyletic: Ancestor + some descendants (e.g., Directional Clade (favors origin one extreme), precedes Stabilizing (favors rapid diversification. intermediates), Example: Disruptivecycad Nagalingum’s (favorsstudy extremes) selection showing Cen origins. Cladogram (shows branching patterns), Phylogram (branch lengths reflect evolutionary chan represent Changes intime). floral traits (e.g., spur length in Aquilegia) leading to reproductive isolation. Exam bee-pollinated columbines. Floral traits Prevent (e.g., color, shape) mating/fertilization: adapted Habitat to attract isolation specific (different pollinators, driving environments), temporalreproductive iso isolation (diff mechanical Primary: isolation origin Chloroplast (incompatible structures). from engulfed cyanobacterium (e.g., green algae). Secondary: Eu eukaryote (e.g., diatoms, dinoflagellates). Prezygotic (prevents mating/fertilization) and postzygotic (prevents hybrid viability/fertility) b Mutation (introduces new alleles) and recombination (shuffles alleles during meiosis). Speciation without geographic Mitochondria/chloroplasts isolation originated from (e.g., polyploidy engulfed in plantsEvidence: prokaryotes. or pollinator shiftsDNA, Circular driving bacr membranes. Fossils showing intermediate traits between ancestral and derived groups (e.g., Tiktaalik brid Supports macroevolutionary patterns.  A monophyletic clade (or simply clade) is a group of organisms that includes a single commo Explanation Demonstrates bacterial evolution under increasing antibiotic gradients. Shows allele fixation Use molecular (DNA or Protein sequences) or morphological data. Software like Mesquite applies parsimo Large-scale trends (e.g., Cambrian explosion, mass extinctions). Fossils calibrate phylogenies Primary: Archaeplastida (red/green algae). Secondary: Stramenopiles (diatoms) engulfed red Floral traits (color, shape, nectar) attract specific pollinators. Example: Red tubular flowers (h Adaptive radiation driven by ecological niches. Decline linked to angiosperm competition and dinosaur extinction. Gradual evolution from light-sensitive patches to complex structures. Pollinator shifts driving sympatric speciation. Demonstrated via MEGA-plate experiments. Explanation Hypothesis: Testable prediction (e.g., "Mutation rates increase under UV"). Theory: Well-supp Homologous: Shared ancestry (e.g., tetrapod limbs). Analogous: Similar function, independen Microevolution refers to small-scale changes in gene frequencies within a population over short periods, w scale evolutionary changes that occur over long timespans, resulting in the formation of new species or hi patterns of life’s history Directional: Favors reproductive oneoccurs isolation extreme phenotype. after Stabilizing: fertilization and resultsFavors intermediates. in hybrid Disruptive: offspring that Fav are either i (unable to reproduce) Maximum parsimony eukaryote that alreadyconstructs a phylogenetic contains organelles fromtree by finding primary the topology endosymbiosis, that requires resulting the in addition acquired organelle. Divergent evolution occurs when closely related species develop distinct traits over time due pressures, often leading to speciation. Convergent evolution involves unrelated species indep as adaptations to comparable ecological challenges. Cladogram: Represents hypothesized relationships based on shared derived traits; Phylogram: Illustrates both relat divergence blood between type, whilelineages; acquiredChronogram: Branchduring traits develop lengths:an Proportional to time individual's (e.g., millions lifetime due toofenvironmental years), often calib experiences, Genetic like muscle variation refers tostrength frominexercise differences or learned DNA sequences skills,individuals among and are notwithin transmitted to a populati or mutations,evolution, independent while phenotypic variationspeciation while sympatric encompasses observable involves differences the emergence in physical, of new species phwi which arise from both genetic factors and environmental due to ecological, behavioral, or genetic barriers. influences. ur concepts in defining species  A species is a group of interbreeding natural populations reproductively isolated from other s Species are distinguished by physical traits (morphology), such as body shape, size, or struct A species is a set of organisms adapted to a specific ecological niche, exploiting distinct reso The smallest irreducible group with a unique genetic lineage and shared ancestry ms is challenging due to biological complexity, evolutionary processes, and practical limitations into Non-Random Adaptive and Random Adaptive agents n allele frequencies in SMALL versus LARGE populations onvergent Evolution differ in the terms of Genetic Mechanisns and Selective Pressures. ons of a single species accumulate genetic differences over time, often after becoming reproductively isolated ndependently evolve similar traits or functions, not due to shared ancestry but as a result of adapting to similar environmental c ssures in DISTINCT ENVIRONMENTS. ssures acting on unrelated lineages. When different species occupy similar ecological niches or face comparable environmenta Explanation Transitional fossil with fish-like fins and tetrapod-like wrists. Fills "gap" between aquatic and Molecular clock analysis shows extant cycad diversity arose recently (Miocene), contradicting Spur length and color affect pollinator preference: long spurs attract hawkmoths, shorter spu Does the structure of a chloroplast fit in the endosymbiosis theory? If so, why? Do you have a better hypothesis? es and Questions that we've gone through in class and lab sessions. descendants. nd spatial expansion of resistant strains. ample: Cycad phylogeny revealing recent Miocene radiations. gellates with chloroplasts from secondary endosymbiosis. fragrant flowers (moths). Promotes prezygotic isolation. evolution supported by fossils, genetics, biogeography). k size in finches). anges, while maximum likelihood builds the tree that has the highest probability of producing the obse trates behavioral isolation. f producing the observed genetic data under a specified statistical model of evolution Exam Preparation Q&A: Unit 2 (Evolution): Covering Key Concepts from Slides & Le Q: Define heritable variation and explain why it is essential for evolution. A: Heritable variation refers to genetic differences in a population that can be passed to offsp Q: Differentiate between acquired traits and heritable traits. Provide examples. A: Acquired traits (e.g., scars, docked tails) develop during an organism’s lifetime and are no Q: Describe the two-step process of evolution. A: Variation arises via mutation/recombination. Proportions of variants change across generations due to selection, drift, migration, or mutat Q: What are homologous structures vs. analogous structures? Give examples. Homologous: Shared ancestry, different functions (e.g., human arm vs. whale flipper). Analogous: Similar functions, independent origins (e.g., bird wings vs. insect wings). Q: Explain how Tiktaalik serves as a transitional fossil. A: Tiktaalik has fish-like features (scales, gills) and tetrapod-like traits (robust ribs, limb-like fi Q: List three lines of evidence supporting the endosymbiotic theory. A: Chloroplasts/mitochondria have circular DNA (like bacteria). Reproduce via binary fission. Double membranes and ribosomes resemble prokaryotes. Q: How do cladograms, phylograms, and chronograms differ? Cladogram: Shows branching relationships. Phylogram: Branch lengths = evolutionary change. Chronogram: Branch lengths = time. Q: What is the purpose of an outgroup in phylogenetics? A: Outgroups help determine ancestral vs. derived traits (polarity). Example: Jawless fish as o Q: How do fossils help calibrate phylogenies? A: Fossils provide minimum age estimates for nodes (e.g., Tiktaalik dates tetrapod origins to Q: What is a phylogenetic fuse? Use cycads as an example. A: A delay between clade origin and diversification. Cycads originated in the Mesozoic but rad Q: Compare allopatric and sympatric speciation. Provide examples. Allopatric: Geographic isolation (e.g., river splitting a population). Sympatric: No geographic barrier (e.g., polyploidy in plants). Q: What are prezygotic barriers? Name three types. A: Barriers preventing fertilization: Habitat isolation (different environments). Temporal isolation (different mating times). Mechanical isolation (incompatible structures). Q: How do pollinator shifts promote speciation in columbines (Aquilegia)? A: Changes in floral traits (e.g., spur length) attract specific pollinators (bees vs. hawkmoths) Q: Why does the biological species concept fail for asexual organisms? A: It relies on reproductive isolation, which is irrelevant for asexual reproduction (e.g., bacter Q: Explain how the MEGA plate experiment demonstrates natural selection. A: Bacteria with antibiotic resistance mutations survive and spread radially in high-concentration zones, sh Q: What is irreducible complexity? How does mollusc eye diversity refute it? A: Argument that complex structures (e.g., eyes) cannot evolve gradually. Counterexample: Q: How does convergent evolution explain similar traits in unrelated species? A: Similar selective pressures lead to analogous structures (e.g., wings in bats and birds). Q: Why are cycads considered "living fossils," and what did Nagalingum’s study re A: Cycads have ancient origins but low morphological change. Nagalingum’s molecular data Q: If allele frequencies in a population remain stable over time, does evolution occ A: No—evolution requires changes in allele frequencies. Stability suggests equilibrium (e.g., H Q: Design an experiment to test how flower color affects pollinator behavior. A: Expose pollinators to flowers of different colors (e.g., red vs. white) and measure visitation Q: Why might two phylogenies (nuclear vs. chloroplast genes) conflict for photosyn A: Chloroplasts have separate evolutionary histories due to endosymbiosis (e.g., secondary e Q: How would you distinguish directional vs. stabilizing selection using trait distribution graphs? ( Directional: Peak shifts toward one extreme. Stabilizing: Peak narrows around the mean. Q: What is a gene pool? A: The complete set of alleles present in all individuals of a species. Q: Name the two sources of genetic variation. A: Mutation and recombination. Q: How do heritable traits differ from acquired traits? A: Heritable traits are passed through DNA (e.g., flower color); acquired traits arise from envi Q: What is the key difference between genetic drift and natural selection? A: Genetic drift is random allele frequency changes, while natural selection is non-random, fa Q: Explain the founder effect. A: A small group establishes a new population, leading to reduced genetic diversity compare Q: Define allopatric speciation and provide an example. A: Speciation due to geographic isolation (e.g., river splitting a lizard population). Q: What is a synapomorphy in phylogenetics? A: A shared derived trait defining a clade (e.g., feathers in birds). Q: Why are transitional fossils like Tiktaalik significant? A: They bridge gaps between major groups (e.g., fish to tetrapods). Q: What evidence supports the endosymbiotic theory? A: Chloroplasts/mitochondria have circular DNA, bacterial-like ribosomes, and double membr Q: How do pollination syndromes drive reproductive isolation in plants? A: Floral traits (e.g., color, shape) attract specific pollinators, reducing cross-species mating. Q: What is convergent evolution? Give an example. A: Unrelated species evolve similar traits (e.g., wings in bats and birds). Q: What does the MEGA-plate experiment demonstrate about evolution? A: Bacteria evolve resistance to antibiotics in a gradient, showing adaptive evolution in real-t Q: How did Anolis lizards in the Caribbean undergo adaptive radiation? A: They diversified into distinct ecological niches (e.g., tree trunks vs. twigs) on different islan Q: Why are cycads considered "living fossils"? A: They show long-term morphological stasis but recent molecular diversification. Q: If a population undergoes a severe bottleneck, how might genetic drift impact i A: Reduced genetic diversity increases fixation of random alleles, limiting adaptive potential. Q: Why can’t sexual selection alone explain the evolution of complex traits like eye A: Intermediate forms (e.g., light-sensitive patches in mollusks) show gradual functional evol Q: How might a phylogeny and fossil record disagree, and why? A: Incomplete fossils may miss transitional forms, while molecular data might suggest unsee Explain how each of the following evidence below supports the Theory of Evolution 1. Fossil evidence Fossils provide direct, physical records of organisms that lived in the past, allowing scientists to trace the progressio 2. Homologous traits Homologous traits are anatomical or developmental features shared by different species due to inheritance from a c 3. Molecular Evidence Molecular evidence involves comparing DNA, RNA, and protein sequences among different organisms. Closely rela ng Goals It is essential because natural selection acts on this variation, driving evolutionary change. Example: netically inherited. Heritable traits (e.g., flower color in hydrangeas) are encoded in DNA and passed to bridging aquatic and terrestrial vertebrates. oup for tetrapod limb evolution. d in the Miocene due to global cooling. ucing gene flow and leading to reproductive isolation. ome plants). g allele fixation via directional selection. uscs show a range from simple light-sensing patches (limpets) to complex camera eyes (squid). ed recent Miocene radiations, contradicting the "static" fossil label. y-Weinberg conditions). s. Control for scent, shape, and nectar rewards. tic lineages? ymbiosis in diatoms). compare with Disruptive Selection) mental interactions (e.g., docked tails in dogs). ng adaptive traits. the original population. ture evolution? ationships. d transformation of life forms over millions of years. The fossil record reveals transitional forms—organisms that bridge gaps bet on ancestor. These traits may serve different functions in modern organisms but retain underlying structural similarities. pecies have more similar genetic sequences, while more distantly related species show greater differences, reflecting the time s ry change. Example: Variation in antibiotic resistance genes in bacterial populations. n DNA and passed to offspring. eyes (squid). nisms that bridge gaps between major groups. uctural similarities. ences, reflecting the time since they shared a common ancestor. 100 points in total All are Short Q&A Questions, so I expect answers with key words. Understand the principle of t What does each branch repr What does each branching e The principle for the MEGA p Be able to describe which ag  derstand the principle of the MEGA plate hat does each branch represent hat does each branching event represent e principle for the MEGA plate is simple; however, the design is quite clever. Would you have a similar design? able to describe which agent(s) of evolution are represented by each node Be able to explain how the fossil evidences Be able to explain the importance of Tiktaa n how the fossil evidences could be used to supporrt the Theory of Evolution n the importance of Tiktaalik, why it serves as the answer to a missing link to evolution Make sure you understand these two figures. I will include a detailed description soon. Make sure that you understand how to interpret the chronical scale located at the end of the figure Be able to explain why Cycade is not as old as previously thought ption soon. at the end of the figure Fossil as evidence of transitioning species Homologous Structures Convergent evolution Divergent evolution Structures of Chloroplast as the result of endosymbiosis Endosymbiosis Process How to interprete the Land Plants Chloroplast gene resides within the green algae branch Three Domains of Life Two mechanisms of Reproductive Isolation Make sure you understand how allele frequ Be able to explain the agents of evolution c nderstand how allele frequencies would change with distance increases. n the agents of evolution contribution Make sure how the frequency pattern would change Distinguish the three types of selection and their effects Be able to draw the new curve based on selection Sexual Selection Make sure you understand Be able to answer how con Be able to answer how div Be able to tell the differenc Understand the brief distinction of the THREE DOMAINS OF LIFE Remember the Hierarchical Classification ake sure you understand what the MESQUITE result mean. able to answer how convergent evolution has shaped the biodiversity able to answer how divergent evolution has shaped the biodiversity able to tell the difference between Convergent Evolution and Divergent Evolution