B1106+FA24 Final Exam Review Notes PDF

12/4/24 The fundamental niche is the possible range of habitats Topics to review for final exam o...

12/4/24 The fundamental niche is the possible range of habitats Topics to review for final exam occupied by a species, while the realized niche is the actual range of habitats ØFundamental vs. realized niche ØTransitionary fossils - Tiktaalik ØMechanisms of Evolution ØMass extinction effects on adaptive radiation Calculate Allele Frequencies in Populations Natural selection/adaptive evolution ØHuman evolution – major transitions Descent with modification and homologous ØProkaryotes vs. Eukaryotes – key differences features (examples) Convergent evolution and analogous ØEvolution of eukaryotic organelles from features (examples) prokaryotes – endosymbiosis Mutation (non-adaptive) ØTransition to life on land from aquatic ancestors: Genetic drift (non-adaptive) Vertebrate animals (features that aided in Bottleneck & Founder Effect this transition) Migration/Gene Flow Land plants (features that aided in this transition) ØTaxonomy/Classification ØModes of Speciation – allopatric vs. sympatric Why might the fundamental ØSpecies concepts – biological species concept vs. evolutionary/phylogenetic species concept and realized niches be different? 1 2 Interactions between species can impact each HOMEWORK 1 CONNECTION species’ ecological niche Distinct species of warblers occupy different niches within a spruce tree habitat. The table below indicates the feeding height (meters) within a spruce tree that is occupied by two warbler species. Warbler Species No Treatment Yellow-Rumpled Bay-Breasted removed removed Yellow-Rumpled 2 m – 7.5 m ------- 2 m – 11 m Bay-Breasted 7.5 m – 11 m 7.5 m – 11 m -------- 1. What ecological species interactions are driving this pattern? 2. Based on the data above, what are the fundamental and realized Harmful Beneficial niches of the Yellow-Rumpled and the Bay-Breasted warbler interactions interactions species? Explain. 3 4 1  12/4/24 Evolution is a change in allele frequency of a particular Mechanisms of Evolution trait over generations within a population Genetic variation – present in all populations and a pre-requisite ØNatural selection/adaptive evolution for evolution - Descent with modification and homologous Natural selection – adaptive evolution = increases fit of a population for its environment; environment selects phenotypes that features (examples) are best/least fit; change in environment à change in fitness - Convergent evolution and analogous features Other evolutionary mechanisms (not adaptive) (examples) Migration/Gene flow – movement of some individuals from one population into a new one; RANDOM à can counteract or support ØMutation (non-adaptive) natural selection Mutation – rare, random, can have positive or negative or neutral ØGenetic drift (non-adaptive) effects; enhances variation in populations! Genetic drift – change in allele frequency due to random Bottleneck & Founder Effect factors, effects greatest in small populations ØMigration/Gene Flow Bottleneck – disaster leaves a few random individuals Founder Effect – a random assortment of a few individuals found a new population 5 6 Differences in the genotype may manifest at the phenotype level Evolution is observed by measuring changes in allele or genotype frequency § Evolution is a change in allele or genotype frequency in a particular population over generations. § To measure genetic variation in a population, one must know the rates of occurrence of the alleles in the population. 7 8 2  12/4/24 Calculating Allele Frequencies Practice with evolution concepts In a population of guppies (Poecilia reticulata) in a freshwater stream, there are two alleles for a coloration gene: allele G (bright coloration, dominant) and allele g (dull coloration, recessive). A study of a local guppy population found the following genotype frequencies in a sample of 100 individuals: GG: 30 individuals Gg: 50 individuals gg: 20 individuals Part A: Calculate the allele frequencies of alleles G and g in this guppy population. 9 10 How may allele frequency change over time in populations? (In Evolution by Natural selection other words, what are the mechanisms by which evolution occurs? facilitates adaptation Variations in the population When there is variation within a population of organisms, and when (alleles are present due to mutations) that variation can be inherited (that is, when it can be passed from one generation to the next), the variants best suited for growth and Adaptive evolution Non-adaptive evolution reproduction in a given environment will contribute disproportionately Some alleles confer better survival or Changes in allele frequency NOT tied to to the next generation. reproductive benefit, and thus have a whether alleles influence survival and relatively higher likelihood of making it Adaptive Evolution: Increase in the fitness of a population for its reproduction to the next generation environment Mutations Natural Selection Migration Fitness: how good a particular genotype is at leaving offspring in the Genetic Drift next generation relative to other genotypes Non-adaptive evolution can be followed by adaptive evolution to further shape populations 11 12 3  12/4/24 Homology reflects common ancestry Natural Selection Overview Homologous structures are resemblances that Over reproduction Mutation represent variations on a structural theme present in a of population common ancestor This is an example of descent with modification: evolution by natural Individual with traits diversity selection is a remodeling process where adaptations of preious (variation) best adapted to structures arise that are beneficial for a specific environment. environment Natural survive / leave more offspring selection competition environmental selection 13 14 ANALOGY – convergent evolution; does Mutation is a non- NOT reflect common ancestry adaptive mechanism of evolution N O R TH A M E R IC A Sugar glider M utations can lead to alleles A U S TR A LIA that are Deleterious (harm ful) Sugar glider Flying squirrel N eutral Flying squirrel Advantageous evolution of similar but analogous features in distantly related groups characters are not derived from a common ancestor 15 16 4  12/4/24 Migration is a non-adaptive form of evolution and results in the Genetic drift is a non-adaptive mechanism of flow of genes from one population to another (gene flow) evolution, and is important in small populations new alleles are transferred into or out of a population by the movement of fertile individuals or their gametes is the random change in allele frequencies from generation to generation. BB Bb Bottleneck effect bb bb is a sudden reduction in population size due to a change in the environment (fire, flood, human actions) Founder effect http://evolution.berkeley.edu What are the pros and cons of gene flow on may be important in the establishment of new populations in new niches evolutionary fitness? 17 18 Types of genetic drift: HOMEWORK 2 CONNECTION Bottleneck effect Founder effect 4. Two students are planning a research project as part of their Evolution course. The starting material is a population of bacteria where all the cells are genetically identical (i.e., they are clones). Students will divide the population in two and will grow them in separate flasks for 25,000 generations. DISASTER STRIKES! A FEW INDIVIDUALS FOUND A Students hypothesized that after 25,000 generations both populations will -by chance a few individuals survive NEW POPULATION differ. Explain the rationale that students used to make their hypothesis. -the surviving population may have a very different gene pool than the -the new population may have a very different gene pool than the Include the following terms in your answer: environment, mutations, original population original population genetic variation, and natural selection. [8 pts] 19 20 5  12/4/24 HOMEWORK 2 CONNECTION 1. The non-adaptive mechanisms of evolutionary In the early 1990’s, the population of the Florida panther consisted of only 20 panthers in poor health. At that time, it change are: was predicted that the population would be extinct in 20 years because of hunting and habitat loss. To try to save them, a conservation plan was initiated. According to the plan, in 1995 eight female pumas from Texas (a different subspecies of panther that can successfully mate and produce fertile offspring with the Florida panthers) were introduced in the A. migration (gene flow), mutation, and genetic drift. area where the Florida panthers lived. B. migration (gene flow), balancing selection, and genetic Table #1 shows the changes in the % Average Heterozygosity (a drift. measure of genetic diversity) before (values in italics) and after (values in bold) the initiation of the restoration experiment 1) How do you explain the lack of growth in the panther C. migration (gene flow), sexual selection, and genetic drift. with the Texas pumas. [Total 13 pts] population from 1985 until 1995 before the restoration plan was initiated? D. mutation, sexual selection, and genetic drift. Year % Average Heterozygosity E. mutation, genetic drift, and heterozygote advantage. 1990 16% 2) Why did the restoration plan work? Explain and be 1993 12% specific about the evolutionary mechanism(s) involved 2000 18% 2010 25% 21 22 2. Genetic drift is the _____ in allele 3. The only evolutionary process that leads to frequencies from generation to generation adaptive change is: and is especially important in _____ populations. A. random change; large A. mutation. B. change due to selection; small B. migration. C. change due to selection; large C. natural selection. D. random change; small D. genetic drift. E. none of these E. All of the answer options are correct. 23 24 6  12/4/24 4. Treatment of a bedbug population with the pesticide Bedbug Bully Speciation resulted in a population resistant to the treatment. ØModes of Speciation: allopatric vs. sympatric ØTaxonomy/Classification and reading This can be explained because the presence of the pesticide created resistant individuals. phylogenetic trees A. TRUE ØTiktaalik – transitionary fossils B. FALSE ØMass Extinction and Adaptive Radiation Explain! 25 26 Modes of speciation Summary Speciation Overview If a single population is split into two populations that are unable to interbreed, different mutations will appear by chance in the two populations. 27 28 7  12/4/24 Taxonomy: science of describing, naming, and Homework 3 Connection classifying species 3a. Why is the mutation that led to larger body mass only present in population B, but not The most inclusive Taxonomic Aloe vera Number of present in population A? (largest) taxon is the group classification species domain. Domain Eukarya Several million 3b. What is the evolutionary mechanism that led the neutral mutation (the change in The least inclusive Kingdom Plantae ~375,000 pigmentation) in population A to become fixed? Do you expect this evolutionary taxon is the species. Phylum Anthophyta ~235,000 mechanism to have a stronger effect on a fish population with 50 fish or one with 50,000 fish? Explain your answer briefly. Class Liliopsida ~65,000 Order Liliales ~1200 3c. A scientist is studying these two fish populations to determine whether speciation has Family Asphodelaceae 785 occurred. They decide to mate fish from population A with fish from population B. They Genus Aloe 500 discover that these fish do produce offspring, but they conclude that these fish are two different species based on the biological species concept. Give one possible reason that the Species Aloe vera 1 scientist might arrive at that conclusion. 29 30 The tree of life includes three domains a Species are b broadly categorized into one of three c domains d 31 32 8  12/4/24 Transitional Fossil: Fish to Tetrapod Vertebrates Fish Traits Fins Fishlike heads Gills Mixed Traits Fins Scales Gills -Wrist bones -Fingers -Amphibian-like skull with eyes Tiktaalik on top of head -True neck http://research.uchicago.edu/highlights/resources/media/shubin/shubin_package_VO.mov?prog=true 33 34 Speciation Patterns from Fossils: Mass Extinctions Adaptive radiations occur after a mass extinction Major environmental changes can kill off many species at once. Surviving organisms can exploit new resources in the changed environment, so they diversify after others die. Adaptive radiation: rapid diversification of a lineage when niches open up 35 36 9  12/4/24 HOMEWORK 4 CONNECTION Explain why the number of animal Human Evolution genera increases following the mass extinction at the end of the Permian Period, which lasted from 299 to 251 million years ago. The end of this ØHuman’s place in the primate phylogeny period marked the largest extinction event in Earth's history—far bigger ØFossil evidence for major transitions in human than the more famous Cretaceous extinction when the dinosaurs evolution disappeared. Scientists estimate that more than half (53%) of all taxonomic families were lost in the Permian Period. In your answer, incorporate your knowledge about what drives speciation events. 37 38 Humans and chimpanzees share a recent Hominin species common ancestor Key trends to compare: 5 – 7 mya Bipedalism Brain size Migration Tool Use/ Culture 39 40 10  12/4/24 The pelvis is extensively Becoming Bipedal required substantial reconfigured for an shifts in basic anatomical characteristics upright posture, with internal organs over it. Legs are longer to Legs enable long stride The foramen magnum, the hole length for efficient Foramen in the skull through which the locomotion and their magnum spinal cord passes, is anatomy altered so the repositioned so that the human legs are directly under skull balances directly on top of the body. the vertebral column. Feet Spine The foot is narrower and has a more The human spine is developed heel and larger big toe, S-shaped so weight which contributes to a springier foot. is directly over the pelvis. 41 42 Homework 4 Connection Cranium Size Increase The picture below shows an anatomical comparison of chimpanzees, early hominins (Ardipithecus, Australopithecus, Homo erectus) and humans (Homo sapiens). For each anatomical comparison listed below, describe the observed changes across the five species. Explain how these changes are related to one another and might have been adaptive during the evolution of modern humans. BRAIN SIZE, BIPEDALISM, TEETH, ARBOREAL LOCOMOTION Can look also at our skull collection Ardi’s foot 43 44 11  12/4/24 Simplified tree of life diagram Key evolutionary transitions – part I ØProkaryotes vs. Eukaryotes – key differences Life’s ancestral ØEvolution of eukaryotic organelles from prokaryotes condition – endosymbiosis 45 46 Eukaryotic features evolved from prokaryotic features: both Phylogenetic analyses based on DNA sequences mitochondria and chloroplasts evolved via endosymbiosis strongly support the endosymbiosis hypothesis Contain their own DNA that is most closely related to bacteria Experiment: use molecular sequence data to generate phylogenetic trees Structures physically resemble bacteria Cyanobacterial DNA and Reproduce like bacteria within the cell chloroplast DNA are related Photosynthetic Chloroplast Prokaryotic Cell Photo- synthetic Eukaryote Mitochondria DNA and aerobic alpha- Mitochondrion Aerobic Non-photosynthetic proteobacterial DNA Prokaryotic Eukaryote are related. Cell Mitochondrion h ttp s :/ / w w w.n a tu r e.c o m / s c ita b le / c o n te n t/ th e -o r ig in -o f-m ito c h o n d r ia -a n d -c h lo r o p la s ts -1 4 7 4 7 7 0 2 / 47 48 12  12/4/24 How did prokaryotes pave the way for Relationship between atmospheric O2 and Evolution of eukaryotic evolution and multi-cellularity? Multicellularity formation First humans of Earth (11:59:40 P.M.) The human impact on mammal size: first flowers first Earth rocks invasion of land by plants first prokaryotes Photosynthetic Algae MIDNIGHT (Protists) first TODAY animals billions of first years ago multicellular organisms NOON first eukaryotes Aerobic cellular respiration: 1 glucose yields 32 ATP energy free oxygen begins Cyanobacteria to accumulate Anaerobic cellular respiration: 1 glucose yields 2 ATP energy 49 50 COMPLEX MULTICELLULARITY EVOLVED AT LEAST 6 TIMES IN EUKARYOTIC GROUPS The evolution of multicellularity in both plants and animals is most likely an example of A. homology B. allopatric speciation C. vestigial structures D. convergent evolution E. artificial selection 51 52 13  12/4/24 Both plants and terrestrial animals (invertebrates and vertebrates) Key evolutionary transitions – part II evolved from aquatic ancestors. ØTransition to life on land from aquatic ancestors: Life on land: challenges? 1) Vertebrate animals (features that aided in this transition) 1. Structural support 2) Land plants (features that aided in this transition) 2. Movement (animals only) 3. Gas exchange and bulk flow 4. Desiccation (drying-out) a) of gametes during fertilization b) of embryo c) of key structures/internal organs 5. Dispersal of offspring (plants only) 6. UV exposure (haploid gametes can sustain mutations) 53 54 Life on land: vertebrate animal solutions? Life on land: vertebrate animal solutions? Evolution of the Vertebrate Lung: Evolution of walking limbs: descent with modification descent with modification Lungfish Lung Trout Swim Bladder Fin webbing; bones at base Ray-fin fish fin Single bone at base of limb, like in tetrapod limbs Lungs Lungs Lungfish fin Walking Bones that resemble Walking Legs tetrapod forearm and wrist Legs with fully formed digits Amniotic Amniotic Tiktaalik egg; egg; keratin keratin 55 56 14  12/4/24 Life on land: vertebrate animal solutions? Life on land: vertebrate animal solutions? Evolution of the Amniotic Evolution of the 4- Egg: descent with chambered heart: modification descent with modification Chick Human Lungs Walking Legs Amniotic egg; keratin 57 58 Alternation of Generations Life Cycle in Land Plants Life on land: plant solutions? Features Two Multicellular Phases Fertilization and dispersal of offspring became increasingly independent of water during land plant evolution from aquatic ancestor (green algae) Plant life cycle: two multicellular phases – 1) gametophyte (haploid, n); 2) sporophyte (diploid, 2n) Fertilization Fertilization gametophyte Animal life cycle: one multicellular phase (diploid – 2n) sporophyte 59 60 15  12/4/24 Alternation of generations – an evolutionary adaptation that allowed plants to colonize the Non-vascular and vascular plants land! describes the basic life cycle of all land plants. Bryophytes (non-vascular) includes mosses, liverworts, and hornworts. Sporophyte is the diploid multicellular generation gives rise do not actively control their hydration. to spores à this life cycle stage is specialized for dispersal of “offspring” (in this case, spores) do not form roots and are totally dependent on the surface water to keep their photosynthetic cells hydrated Gametophyte is the haploid multicellular generation gives rise to gametes à this life cycle stage is specialized for Vascular plants fertilization Includes ferns, gymnosperms, angiosperms actively control their hydration by drawing up The resulting life cycle where a haploid gametophyte and a water from the soil through root system diploid sporophyte alternate is called alternation of make up more than 95% of all land plant species generations. 61 62 Where do Bryophytes thrive? Land plant dispersal mechanisms: seed diversity and advantages of seed dispersal over spore dispersal Grass Seed = multicellular diploid structure Spore = single cell, haploid Turf Tree Seed is more likely to form a new, photosynthetically Trunk self-supporting plant after dispersal because: It can store resources that the embryo contained Moss inside can use during germination Seeds can exhibit dormancy and avoid germinating until the conditions are favorable 63 64 16  12/4/24 Angiosperm (flowering plant) reproduction through flowers Angiosperm adaptations: Flower to Fruit As the fertilized egg develops to form an embryo, the ovary wall develops into a fruit Fruits serve two functions: 1. They protect immature seeds from being preyed upon by animals. 2. They enhance dispersal of The evolution of flowers is what allowed progeny once the seeds are mature. angiosperms to use animals to transport pollen instead of just wind-based transport (as seen in gymnosperms). 65 66 Practice with mapping Homework 7 CONNECTIONS adaptations in land plants 1) Name the 4 groups shown 5b. What evolutionary advantage(s) do pollen, seeds, in the image to the left. flowers, and fruit each offer? 2) Decide where in this d phylogeny each of the c below adaptations evolved: - cuticle and stomata b - fruit and flowers - alternation of generations a - fertilization without water - pollen and seeds - vascular tissue 67 68 17