BIO FINAL EXAM Flashcards

Question

Poikilotherms

Answer 1

(most reptiles, amphibians, fish, invertebrates) lack physiological means to deviate from environmental temperature: their temperatures fluctuate Poikilotherms have lower energy requirements than similarly sized homeotherms because it maintaining constant temperature requires energy

Answer 2

must regulate heat balance to keep internal temperature within a narrow range: many traits contribute

Answer 3

Radiation: heat transfer by electromagnetic radiation Conduction: direct contact w substrat Convection: moving fluid (air or water) Evaporation: cooling from wet surfaces Redistribution: circulatory system redistributes head among body parts

Answer 4

Size matters to heat balance because of surface area to volume ratio Surface area determines equilibration rate - big SA:Vol equilibrates quickly Volume provides the inertia

Answer 5

Homeotherms tend to be larger at higher latitudes to conserve heat Shape matters: SA is needed for function - particular shapes Therefore the shape is a trade off and adaptive compromises

Answer 6

Homeotherms tend to have smaller appendages at higher,colder latitude

Answer 7

Insultion: more important than size and shape Fur, blubber, feathers Animals spend a lot of resources for insulation Convective cooling is enhanced by vascularization - Desert hares ears blood vessels Countercurrent circulation to limbs conserves heat: Arteries and veins should appressed (close together) in appendages to conserve heat Separated in appendages designed to shed heat Countercurrent flow maintains gradient so head is always flowing from outgoing blood to incoming blood Evaporative cooling Behavioral thermoregulation: seek out cooler places on a hot day

Answer 8

cause animals to not be perfectly adapted Being good at x may necessarily imply being bad y Weasels are the shape they are to be able to hunt for gophers Constrains Natural selection builds on what's already there

Answer 9

Plants cant evade stress by moving - But they make their own food - autotrophs - Photosynthesis light, co2, and water - Leaf stem and roots reflect adaptation Angiosperm flowering plant Hermaphrodites: have both and male and female parts - Anthers: pollen - male, stigma - women - Depend on animals to move pollen

Answer 10

they have little scope for behavior Are autotrophic and they need the same things to grow: light, Co2, water, soil nutrients

Answer 11

Enzymes need to be at a good temp Respiration turning carb and oxygen into co2 and h2o Carbon balance: for growth plants have to acquire more carbon through photosynthesis than they lose through respiration:

Answer 12

C gained via photosynthesis - C lost via respiration = NPP Photosynthetic structures embody adaptation to environment

Answer 13

PALO VERDE Photosynthetic bark on trunks and branches: can grow without incurring head load and water loss through Sometimes even sheds all its leaves as an adaptation Microphyll: super small leaves

Answer 14

Chlorophyll make plants green Plants take in CO2 through stomata but they also lose water through stomata (transpire) Leaf size and shape: SA:V ratio important again Large leaf surface: good for light and gaining CO2 Cost: easily transpire and therefore cause overheating Coping with overheating/water loss They use rubisco to carbon fix but it doesn't work at high temp Sometimes catches o2 instead of Co2

Answer 15

C4 photosynthesis: enzyme pepe carboxylase accepts CO2 CAM photosynthesis: close stomata during the day avoiding waterloos, open at night to let in CO2 and store that CO2 as maltate to be able to do photosynthesis during the light Large leaves grow in shady habitats and open and close their stomata by opening stomata cuz stomata releases water for evaporation cooling (hormone ABA is responsible) Trade off between water conservation and rapid growth Conserve water vs carry out photosynthesis seen on desert plants

Answer 16

VS TROPICAL Extensive but shallow because rainforests have a shallow of nutrient rich soil Root foraging Going roots into soil patches where nutrients are abundant Split root experiment to see how roots adapt Legumes also get nitrogen from nitrogen fixing bacteria Take Dinitrogen from the air and turn it into a form via nitrogen fixation Deciduous habit: leaves gone during cold or dry seasons to reduce water stress/ tissue damage

Answer 17

N - Number of individuals in absolute terms (y axis, time on x axis - Time Series) N/area - population density

Answer 18

Limnar: unimpeded moves like aerodynamic like moving over a car Cases a stagnant boundary layer of air to build up on the leaf surface: Prevents gas exchange Turbulent flow: ridges and irregular Does a better job at promoting gas exchange Morphological plasticity Epiphytes have their roots in the air or on trees so they can still be water stressed even in rainforest

Answer 19

Natural resource management: Ex size of fish stocks in ocean Abundance of outbreaking insect pests in forests How much damage they do to forests Conservation: Population declines of species Health: Monintstoring population or bacteria in humans Understanding and predicting human population growth Basic science question of what limits population growth

Answer 20

Predict the trajectory of population through time ie N as a function of t How many populations are in the population now? Nt Time advances by one so t - t +1: How many individuals are in the population one step later: Nt +1 General model: Nt+1 = f(Nt)

Answer 21

scientist said Human population cannot grow faster than food production

Answer 22

When using differential equation, time steps are infinitesimally small: use concept of limits and calculus growth is smooth and is best suited for species w continuous reproduction Ex population size of humans Difference equations: time steps are discrete (days, years), use it iterated recursion equations Best suited for episodic reproduction

Answer 23

Nt+1 = Nt x (lambda) Lambda: Nt+1/Nt the multipleive factors by which population changes over one unit of time Lambda > 1 births exceed dead population is growing

Answer 24

Therefore population growth starts at t = 0 therefore N0 or N(0) How can N change from Nt to Nt=1 (All happen in one time step) D = number who die B = number born E = emigrate I = immigration Nt+1 = Nt - D + B - E + I Births and immigration are equivalent, Death and immigration are equivocation Only model births and death and assume no immigration or emigration Treat birth and deaths during one time step per capita rates that are fixed constant - dont expect birth and death rates to be changing a lot

Answer 25

Main consequence of an exponential model growth is that when it increasing it will increase til infinity (exploding in an exponential way) All species have the potential for positive population growth under good conditions(lambda greater than 1) All species have the potential for negative population growth under good conditions less than 1 But no species has ever sustained lambda more than one or less than 1 for a long period Density-dependent regulation (growth depends on N) or Density independent reduction

Answer 26

Geometric growth N1 = lambda (N0) N2 = lambda (N1) = N2 = lambda ( lamda (N0) Therefore Nt = N0lambda ^t

Answer 27

assumes population growth is instantaneous Instantaneous, per captivate rate of population change = b-d = r (a constant) r= intrinsic rate of increase Differential equation = dN/dT = rN General continuous time: Nt = N0 e ^ rt Exponential growth if r > 0 Ln (lambda) = r

Answer 28

S-shaped growth = logistic growth (only happens when populationstarts low) Same as exponential growth with a new term added for breaks dn/dt = rN (1-N/k) K = carrying capacity - the size of the population that the resources in the environment can support General equation Nt = (KN0e^rt)/(K+N0 (e^rt - 1))

Answer 29

Inflection point at K/2 aPros: Mathematically tractable model of intraspecific competition and simple Can be expanded to consider multiple species competition

Answer 30

too simple Always a gradual approach to carrying capacity In reality density dependence is likely to be non linear

Answer 31

negative effects of low density Arise from social benefits ex mate finding, group living and group defense

Answer 32

But Fecundity and survivorship depends on age Species have diff life history strategies Life story : what age do events occur at

Answer 33

Start life small size Grow for a period without reproduction- resource accumulation When they have enough resources and become mature they prediction Some expend all resources at once some spread it out cuz they have various lifestyles Need to consider age structure and how birth and death rate depend on age

Answer 34

Still single population but now fecundity and survivorship vary w age Variation is summarized by life tables of age specific rates Important implication for: Evolution of life histories Conservations Understanding changings structure of human population

Answer 35

Stable age structure - instead of period it's gonna be a flat shape - roughly the same number of individuals in the same age

Answer 36

Life tables: summarize the life events that statistically expected for the average individual of an specific age in population Age of death and age of timing of reproduction

Answer 37

Age classes denoted subscript x Lx = probability of being alive at age x L0 = 1.0 cuz when a baby is alive its always 1 “Survivorship curve” graph of lx vs x Lx necessarily declines with x If mortality is constant then its gonna have an exceptionally curve: Usually use plot w log(lx) Type 2 - straight line Type 1 - survivorship high in early live and then declines rapidly at old age (ex humans) Type three - early mortality but after middle age survivorship is high

Answer 38

Higher growth rates = higher fitness Constraints and trade-offs: reproduction is costly. Longe reproductive periods allow for accumulate more resources Semelparity: ate in life reproduction Iteroparity: multiple years of their life reproduction

Answer 39

Age defined by x again Mx = number of daughters birth to a female of age x during the interval of x to x +1 Shape of mx is specific to species Reproductive period usually preceded by resource accumulation phase Fecundity - survivorship trade-offs = cost of reproduction

Answer 40

R0 = average number of daughters a female has in her lifetime R0 = Sum of lx mx Unit of one generation Generation time (Average age at which a female gives birth) T = sum of x lxmx/r0 X = female age r = ln(R0)/T = ln(lambda)

Answer 41

look at doc

Answer 42

Life expectancy = ex Reproductive value vx = expected number of future daughters left to an individual age x Fitness consequences of alternative life history straighteners and trade off between current reproduction and future Selection generally selects for early prediction so genes can be copied but u need to accumulate resources which can delay reprodction

Answer 43

Intraspecific competition (conspecifics): same species competition for resources Interspecific competition: different species Scramble/exploitative competition: depletion of a shared resource Ex squirrel eating bird food leaving less food for birds Contest/interference: direct interactions ex battle over territory Invasive ants fight harvester ants: Invasive often drive down population of native ants

Answer 44

dn1/dt = r1n1( 1 - N1/K1 - (a12N2)/K1) a= alpha aij = per capital effect on specifics one of individuals of species 2 “Competition coefficient” A is fixed for a pair of species Convert individuals into an equal number of individuals of species one because species are not equivalent competitors Possible outcomes Two species stably coexist Species 1 may always win (N1 = K1, N2 = 0) Species 2 may always win ( n2 = K2, N1 = 0) Indeed of winner may depend on starting N’s Outcomes depend on values of K’s and a’s Coexistence requires both species to inhibit their own growth more than they inhibit each other's Can expand to consider n species

Answer 45

Equilibrium = N’s no longer changing (dN/dt = 0) For a community: a community not changing over time meaning that all populations in a community at equilibrium Generally: constant species composition over time Stability : ability of a system to return to equilibrium following a disturbance Coexistence: two or more species have non zero population sizes at equilibrium

Answer 46

Principal competitive exclusion: LVM predictions that for two species to co-exist competition between species muscat be weaker than within species (Old idea - 1934 gause said)

Answer 47

Competitive exclusion seems false for plankton (also rainforesets cuz all the trees live together) WHY? Lotka volterra models too simple and ignores too much relative Real populations be ne kept below K

Answer 48

Lotka-Volterra models for predator-prey interaction tend to cycle Similar to competition models: two differential equations Repdicy couple lagged population cycles These cycles are hard to sustain in a lab - Most common result: predator and prey do not coexist, interaction is unstable But cycles in natural are unusual Additional factors Heavy browning regulates food available - hares may also be cycling w food Most natural cycles have complex causes

Answer 49

Coevolution = reciprocal adaptation Prey evolves defenses - predators counteract w new adaptations to get over defenses

Answer 50

unequal election pressures Prey should be under stronger selection to make defenses than predator to make counter defenses cuz life vs food

Answer 51

Human immune system Reply morphology, chemistry and behavior Plant secondary chemical Predation and community structure Competition decrease biodiversity = superior competitors exclude inferior

Answer 52

Invasive species achieve high population size and have a negative effect Enemy release hypothesis: invaders impacts result from having fewer natural enemies in their new range compared to their native range

Answer 53

Single host spices = direct life cycle Many requires two or most host species to complete life cycle = complex life cycle Vectors are hosts that transport parasites to next host Zoonotic diseases: diseases transferred between animals and humans Often refer to other host species as reservoir Distribution, life history traits, and behaviors of hosts can affect parasite abundance and transmission

Answer 54

Dilution effect: for seieases that infest many host, host diversity can dilute disease risk to humans or animals - conserving host would be good Amplification effect: most host or vector species can support larger populations of disease causing organisms increasing risk to humans or animals

Answer 55

More species near the tropes at the equator than the poles Age or time the habitat has had accumulate species = most places near poles were under ice Maybe climate Relating back to predation - moew human pathogens are near the tropics and equator But a good part of this is based on government stuff ie healthcare spending

Answer 56

Nutritional mutualism Legumes and rhizome: exchange fixed c for fixed n Defensive mutualism ants and plants exchange protection for food Dispersal mutualisms Plants and animal seed dispensers: exchange seed dispersal for food Plants and animal pollinators: exchange gamete dispersal for food

Answer 57

Yao people in mozambique harvest wild honey so they use honey guides birds to get them to the nests because honey guides only eat the bees waxes Has been around for at least 500 years Playback experience: play a series of sounds to see how birds react Showed that the birds were able to understand and signal humans to where the bees next are

Answer 58

Strong intra-specific competition A third species or competitor Diminishing return to mutualism as the population grow Only mutualists when the population is small but not large

Answer 59

the process which two non-native species facilitate one another’s spread

Answer 60

Spring ephemerals Produce short-lived carpets of flowers which flow right after snow melts Seed dispersal between native anit vs invasive red ant Invasive red ant spreads a lot of seeds in europe so she wanted to see if it did the same Used a experimental mesocosms Invasive ant caused the invasive plants to move around more vs native and did more with native plants

Answer 61

But most mutuals are NOT tightly coevolved

Answer 62

Aphids feed on phloem sap that is rich on sugars but poor in essential amino acids Adapids have intracellular bacteria that provide their hosts w essential amino acids Buchera are vertically transmitted: passed on from mothers egg to off spring Vertically transmitted endosymbionts often have tiny genomes Buchnera has a much smaller genome than free living bacteria Other endosymbiotic bacteria also have tiny genomes mitochondria: - 17000 base pairs only codes dor 37 genes vs nuclear genes that have 3 billion Endosymbiotic bacteria lose genes that they no longer need Some functions are unnecessary cuz theyre no longer freelivig and are protected “Outsourced” to host genome

Answer 63

Partners are anew each generation Mutualisms are rarely one to interactions - usually many Current hot area of research: Understanding networks of interactions among large number of species Microbiomes: all the microbes living together or those collectives Most plants have many pollinator species; most pollinators visit many plants species

Answer 64

“population of populations” DIspersal connects populations A metapopulation is a collection of spatially distinct populations that are connected via dispersal We call each spatially distinct population a “patch”

Answer 65

colonization of new habitats Postglacial colonization depends on plant and animal dispersal

Answer 66

Metapopulation structure can allow population persistence even when individual populations are doomed Local populations can be re established by colonist by other populations after going extinct Source-sink dynamics “Sinks” are populations in a small habitat patches that would go extinct expect Migrants from”source” population “rescue” these populations

Answer 67

Predation keeping competitive exclusion from going to competition Non-equilibrium conditions, habitat patchiness, rescue by migration, variation in life history strategy

Answer 68

Colonization: a species can arrive on island from else Extinction: species can go locally extinct on island In-situ specification: a lineage can split in two on a island but its a slow process

Answer 69

Predict the number of pieces on an island from the island size and isolation (distance from mainland) Ignores in-situ speciation only colonization and extinction Graphical model rate on y number of spices on x Point where they cross is the equilibrium Near island is easier to colonization so it has a higher colonization rate therefore greater species Larger species have a smaller extinction rate so it has a higher equilibrium rate

Answer 70

Primary producer: plants Primary consumers = herbivores Second consumers = predators = carnivores who eat herbivores Tertiary consumers who eat secondary consumers Decomposers eat dead organic matter Higher biomass at lower trophic levels Decreasing biomass as you go up

Answer 71

Two interactions between two trophic levels cascade to a third trophic level When a predator eats a herbivore which lets plants grow solid line = direct dashed = indirect

Answer 72

Top down: advance kept low cuz of predation Experiment test = remove predator Bottom up control: abundance kept low because of resource limitation Experiment = resource addition

Answer 73

World is green because carnivores keep down herbivores now that herbivores don't limit plant growth Example of indirect effect to Trophic cascades involve effects across trophic levels Can drastically affect communities

Answer 74

Easy to be a carnivore: animal tissue easy to convert into animal tissue BUt plant tissue is hard to convert into animal tissue Cellulose and lignin tough indigestible without microbial symbionts Plant tissues heavily defended against herbivores Coevolution between plants insects herbivores is responsible for much biodiversity: specialization is common

Answer 75

Plant-herbivore interactions as an arms race Plants evolve toxins to reduce herbivory; insects evolve detoxification or other mechanisms to overcome plant defenses Very common (we think plants taste OK because our food crops have been artificially selected for low toxicity) Many types of secondary chemicals; alkaloids especially potent and prominent Chemicals often deleter generalist herbivores But no plant species is toxic enough to escape from specialist herbivores And special insects may evolve to use defensive chemicals such as feeding stimulation or defense compounds Results: escalation arms race

Answer 76

Interactions between organisms in the physical environaml producer wonder adaptations But physical environment isnt complex enough to produce extraordinary species diversity Interactions with other organisms can producer unlimited diversification

Answer 77

Many insects complete development on a single well defended plants - they must overcome the plants defnseces Verbrates grazers often eat some plant tissue and then move on to another plants Vertebrates hervatoried often select mixed diets so theyere avoiding high doses of one toxin Some detoxification by microbes in fermentation chambers Guts between mammals - suggest how theyre processing plants is similar

Answer 78

Early or gradual exposure to environmental stress can reduce its negative impacts Porcelain crabs acclimated to cold temp functions better at colder temperatures But acclimation to warm temp increases high temp tolerance only minimally

Answer 79

Plasticity to changing conditions Student snow hares over 3 winters Radio collared hares and performed weekly measurements of coat color and snow around Is there enough sufficient plasticity to respond to the color of the environment In the fall they turn white regardless of the snow on the ground In spring there is more variation when there was more snow in one year they waited a little Not enough plasticity to avoid mismatches Plasticity alone in coat color change will not be able to respond to changes in conditions NOT ENOUGH FOR THEM TO ADAPT

Answer 80

Species are moving polewards Also moving up mountains but what if there run out of mountains Pikes are in trouble when itis hot in the summer

Answer 81

Any trait that makes an organism better able to survive in environment Evolutionary process that leads to origin and maintenance of such traits They create variation on earth

Answer 82

The elevational range of american pikas in great basin is greeting smaller Sites where pikas have gone locally extinct often hd temperatures above 26 c which can be lethal The american pima was considered as an endangered species in US But pikas in mountains in rocky mountains are fine

Answer 83

Determining the evolutionary relationships in terms of common ancestry Study long term patterns Use comparative data - looking at many species and different sub displences Ex molecular biology and genomics

Answer 84

First to use the term evolution First to provide a causal mechanisms: the inheritance of acquired characters Turned out ot be the wrong one tho Occurred characters: idea that over a course of an individual's life time you can accupure characters and pass them onto the next generation (girrafe thing)

Answer 85

Determining the particular microevolutionary processes for evolutionary change (eg natural sleetcion) Focuses primarily on the population level Ecpeirmeht and comparative studies the genetics and ecology of populatiosn

Answer 86

All organisms have descended with modification from common ancestors The process of leading to adaptation isn natural selection operating on variation a,ong individuals

Answer 87

Darwin read Lyell’s book on princicples of geology Lyell argued that present day geological processes can explain the history of the earth - gradualism Were not seeing giant new continents form in our life term or new species popping up The notion of a dynamic rather than a static world emerged in Darwin’s thinking

Answer 88

Darwin influenced by the botanist John S henslow at cambridge Voyage on HMS beagle around the world as ship’s naturalist Made numerous observations and collections of plants animals and fossils Returned to england and spend the rest of his life in seclusion at down house developing his ideas conducting experiments and writing books

Answer 89

Variation patterns of galapagos mocking birds Darwin doubts fixity of species There are similar species endemic to the islands descended from a south american mainland ancestor

Answer 90

Emphasizing human populations cannot continue to expand exponentially We cannot have unregulated growth forever

Answer 91

0 years taken up with accumulation of evidence for the theory of evolution 1844: wrote but did not publish an essay on natural selection - essay 1856: began work on natural selection book June 1858: Received “On the tendency of varieties to depart indefinitely from the original type” by A.R. Wallace July 1856: Linnean society presentation of Darwin-Wallace paper 1859: Publication of the “The origin of species by means of natural sleetcion or the preservation of favored races in the struggle for life” Sold out and became popular and impactful Why do we emphasize darwin more than wallace Cuz of the book

Answer 92

Inheritance only by germ cells gametes; somatic cells do not function as agents of heredity This genetics information cannot pass from soma to gametes onto the next generation Modern interpretation genetic information flows in one direction only from DNA to protein but never in reverse

Answer 93

Evolution occurs primarily at the population level (indidviduals do not evolve) Variation is not determined by the environment//is not directed You dont adapt when u need it 3 Most fit type depends on environment 4 Survival of the fitter: evolution works with available variations but it will not achieve perfection

Answer 94

Concept of a changing universe replaced view of static world What people thought at his time A phenomenon with no purpose Natural selection revealed how complex adaptations with important functions can appear through a blind, unplanned process

Answer 95

Treatment of the antibiotic gets more in with the resistant Antibody does not cause restsistant it just selected between the resistant that was already available

Answer 96

Show evolution Earth is very old Allows for immense amound of time for biological evolution Slow gradual evolutionary : evluition can be occurring even if we dont see it in our life time Intermediate forms Evidence for common ancestors linking features of living and extinct organisms Fossils in young increasingly resemble modern species in same region Older starts show increasing difference Evolutionary time points in the layers of fossiple finding

Answer 97

Clearly birds n have feathers but they dont fly Provided darwin w the question of why a designer put feathers on an organisms that doesnt fly? But this makes sense in terms of natural selection It descended from birds that used to flybut cant anymore but it still retained those traits WHY DOES IT NOT FLY? Maybe it was favoured not to fly: flying is costly In islands teher are fewer predators and more reason to swim and catch prey so theres no reason to fly

Answer 98

No function ex * ear muscles, tailbone, goosebumps, appendix

Answer 99

Olfactory receptor genes: allow us to smell diff types of odors Each gene allows us to smell diff types of odors More olfacry genes have become inactive in species that rely less on senses of smell We have a lot of dead genes (genes w mututaion) that are in our genes cuz were not as heavily reliant on smell Study results Over half of our genes are not working The common ancestor of humans, mammals, baboons etc developed trichromoatic color vision came along side losing a lot of olfactory genes cuz we weren't heavily dependent on smell Howler monkey indpentely evolved trichromatic color vision evolved

Answer 100

Organism features are consistent with modification of pre-existing structures Not expected of each organisms was individually optimally designed Provides the evidence that were related from the similarity Approx 500 genes share across all orms of life Storng shared constraints for genes involved in basic cellular functions We share the same mechanisms even with bacteria

Answer 101

The evolution of ecological phenotypic diversity within a rapidly multyling lineage as a result of speciation Orginaties from a single common ancestor The process results in an array of many species The species different in traits allowing expoliation of a range of habitats and resources Three features commonly identity an adaptive ration Recent common ancestry from a single species Phenotype environment correlation Rapid speciation

Answer 102

Geographically close organisms resemble each other Different groups organisms adapt to similar environment in different parts of the world convergent evolution Geographically isolated regions have unusual organisms

Answer 103

Distinct flora and fauna w high endusms (can only be found in that place) and many unique adaptations Biological uniqueness isa result of its long history of island form other land masses Shows lots of island characteristics

Answer 104

Vast amounts of heritable variation found within species This variation can be selected on,leading to dramatic changes over generations Artificial selection as the human imposed analog to natural selection in the wild Not exactly the same design just that if there are genetic variants favored taht are better to survive and reproduce in the environment you can get rapid changes just like how when humans domesticate eplants and animals

Answer 105

Mutuaion is an inevitable phenomenon Despite ceeular mechanisms to correct errors during DNA replication Mutation is not directed toward an outcome by the organism or by the environment Not like u move to a hot environment and then change ur cells to adjust Random respect to effects on fitness Not summoned to make things better Rate depends on the type of mutation Can vary among genes Environment can affect mutation rate EG mytagens, high temperature But its not directing the organism - can a role but not affecting it directly

Answer 106

Mutation, Degreation, recomination

Answer 107

Point mutations Changed G to a C - single nucliotoid mutation Insertions/deletions (”indels”) Change in repeat numbers Chromosomal rearrangements (eg inversion)

Answer 108

1) Inheritance is determined by discrete particles * Genes 2) Each diploid organism carries two copies of each gene * Alleles can exhibit dominance / recessivity 3) Gametes fuse to make offspring * Sperm / pollen with egg / ovule * Gametes contain only one allele per gene 4) Offspring inherit one gamete from each parent at random * One allele per gene at random from each parent

Answer 109

3) Gametes fuse to make offspring * Sperm / pollen with egg / ovule * Gametes contain only one allele per gene 4) Offspring inherit one gamete from each parent at random * One allele per gene at random from each parent

Answer 110

Segregation + independent assortment of chromosomes generates diversity Independent assortment and segregation during meiosis generates diversity Allows different combinations of parental chromosomes Recombination during meiosis furthers contribution to variation

Answer 111

Genotype: genetic consiture Phenotype: observed traitGenome: organism's entire DNA Polymorphisms: common in nature Direct correspondence between rait and its genetic basis Easy to track selection and evolution 2 or more phenotypes Phenotype variation in mumatls: most traits vary continuously not with discrete actegorgies

Answer 112

Continuous variation and darwinian natural selection are fully consistent with mendel’s laws

Answer 113

Quantitative traits often are affected by many factors Complex polygenic = many gene interaches Environmental interaction BUT It is very hard to study quantive genetics in humans Very difficult to control for environmental differences in humans Simple connections between genotype and phentupe extremely unsual

Answer 114

‘Mendelian’ genetics * Genes of major effect, dominance and recessiveness * Spread of alleles, change in allele frequency Continuous variation * Quantitative genetics * Many genes each with alleles of small effect, important environmental effects * Selection response as change in average trait value

Answer 115

Mutation Presents an increase in genetic variation Minor one because its one base in millions but its what causes a series Increases genetic variation Ultimate source of genetic variation Caused by errors during replication (Not directed) Recombination Working w the existing variation that exist thru mutual and creating new combinations Random genetic drift: Caused by random sampling effects in each varination May not be due to genetic differences in an organism's fitness/reproduction/survival Smaller the population size - the stronger the affects of genetic drift

Answer 116

Natural selection: Negative (Purifying) selection Decreases genetic variation Mutuals that reduce fitness are removed by natural selection Positive (directional) selection (adaptations) Decreases genetic variation in populations Mutations that increase fitness will become fixed in a population Selection favoring diversity Increases or retains genetic variation in populations Natural selection can act to maintain diversity over the long term (eg heterozygote advantage) Selection should be favoring to keeping both allele around MIgration (gene flow) If they don't interbreed - it doesnt affect genetic variations Two populations taht have been somewhat isolated - two different variations in the population Creating variation in the C allel that wasnt there before (slide pic) Increases genetic diversity in populations Migration influences the structuring of diversity over a large spatial scale

Answer 117

Heterozygosity (H) Fraction of individuals that are hetergozygous averaged across gene loci Loci: one site that were focused on (relative ex it can be a base or a large sequence) Recall from mendelain genetics Heterozugotes indidvials have bpth alleles & Polymorphism (P) Proportion of gene loci that have 2 or more alleles in the population A locus can be polymorphic without being heterozygous

Answer 118

1. Mutual-selection balance Less fit types reintroduced by mutation Followed by selection acting to remove them 2. Selection maintaining variation Heterozygote advantage Frequency-dependent selection A rare type has a an advantage over a common type EX pathogen - if you are a pathogen and u have a rare antigen you might be favored because they might not respond quickly Fitness variables in space or time All of these are under the umbrella term “balancing selection”

Answer 119

Morphological colour polymorphism Cytological Chormonse inversions Looked under a microscope Saw plenty of genetic variations

Answer 120

Rather than focus on mendelian discrete trails, focus on continuous polygenic traits Selection experiments on different groups of organisms Involves controlled breeding of individuals with particular trails for many generations ARTIFICAL SELECTION

Answer 121

Demonstrates existence of heritable variation in fitness-related phenotypes Due to many underlying genes

Answer 122

Selection responses demonstrate that abundant genetic variation exists for polygenic quantitative traits But often no information on P&H as key populatio genetic traits Also: comparative studies difficult as traits studied often are group specific Still no solution to the question: what maintains genetic variation

Answer 123

Many loci can be examined * Can be used in nearly any organism * Loci co-dominant, heterozygotes can be identified * Variation examined close to DNA level * Provides genetic marker loci for other studies

Answer 124

Mutatio-selection balance Less fit types maintained by epatestd mutational input Selection maintaining variation Herterozyogote advantage Frequency-dependet selection Ditness varies in time or space Selectively neutral variation Different types do nto differ in their fitness relative to one another New mutations neither eliminated or retained by selection

Answer 125

Negative selection rapidly eliminates detrimental mutations * Positive selection rapidly fixes beneficial mutations * The only mutations left to create genetic variation are selectively neutral

Answer 126

Asexual Making clones of themselves Violation of mendel's law Sexual Can have species w separate sexes like humans Or hermaphrodites such as plants Mating w others: cross-fertilization Mating w self: self-fertilization

Answer 127

Sexual reproduction: 2 paremt contribute genetic material to offspring Meiotic, reductive division to form gametes Fusion of gametes Asexual reproduction 1 parent contributes genetic material No meitoic reductive division Offspring are genetic replicas (conlones) of parents

Answer 128

Time and energy to find and attract mates (“dating cost”) Increased energetic costs of mating Risk of predation and infection Cost of producing males 50% less genetic transmission Break up of adaptive gene combinations Segregations

Answer 129

The big question “The paradox of sex” Can it overcome the costs

Answer 130

Compared to asexual females, sexual females contribute only 5-% of her gene copies to the next generation This transmission bias favors asexuals in competition with females Should see that asexual form should be favoured

Answer 131

Bringing together favorable mutations Eliminating harmful mutation

Answer 132

“Lottery models” given environmental unpredictability Creating all these diff combinations - like lottery tickets Spatially heterogeneous environments “Tangled bank hypothesis” Temporally heterogeneous environments “Red queen hypothesis” Many theoretical models, but limited experimental evidence Can be hard to distinguish and test these hyptheises FAVORABLE COMBINATION SOF MUTATIONS BROUGHT TOGETHER MORE RAPIDLY BY SEX

Answer 133

30% of Oenothera species are functionally asexual Can we find consequences of these in their genomes? Many independent transitions ADVANTAGES OF SEX IN EVENING PRIMROSE: Elimination of harmful mutations Asexual oenothera have: More “premature” stop codon mutations Leads to dysfunctional proteins Higher rates of proteins sequences evolution Implies greater accumulation of deleterious mutations

Answer 134

Asexuality by parthenogenesis: * Sporadically distributed across the animal kingdom * More common in invertebrates, rare in vertebrates Asexuality by clonal propagation: * Much more common in plants * Few species (if any) are exclusively asexual Asexual species are usually at the tips of phylogenies * Macroevolutionary pattern indicates higher extinction rate * Low chance of long-term evolutionary persistence * Probably due to extremely low genetic variation & accumulation of deleterious mutations

Answer 135

Who mates with who, and how often? Mates are less closely related than random = outbreeding Mates are more closely related than radom = inbreeding In pratice there is a continuum between outbreeding and inbreedting

Answer 136

Mating w someone else Either by outbreeding or inrbeeding Fusion of gametes from 2 parents Gametes derive from eiotic reductive division

Answer 137

Most extreme form of inbreeding but not asexual repridction Fusion of gametes from 1 parents Gametes derive from meiotic reductive division

Answer 138

Large,showy flowers attract pollinators Timging offset between male and female reproduction Pollen vs ovule maturation within a flower When a male vs female flower open Diverse morphological and physiological mechaimss to avoid selfin g Self-icompatiablity

Answer 139

Dispersal by one sex Delayed maturation Extra paur copulation Kin recognition and avoidance

Answer 140

Changes genotype frequencies Increases homozygosity Decreases heterozygosity Does not directly change allele frequencies Does not change polymorphism (p)

Answer 141

Genetic contribution of individuals to next generation relative to others as a result of differences in viability and fertility Darwin fitness A relative quantity not absolute survival or offspring number

Answer 142

The amount by which some individuals of a given genotype are better adapted to a given environment Reflects relative differences in fitness

Answer 143

Monitors correlations of allele or traits with environment over space and time Track a populations phenotype over multiple generaiosn and see if its changing Are there changes in population that leads to evolutionary change? Is it related to any environmental change? Analyze genomic diversity Gene targeted by selection ought to show distinct pattens Parts of the genome that are subjected by slectionshould show a pattern Experimental manipulation Differneces in environment w evolution overtime

Answer 144

Positive direction selection (adaptation) Even tiny selection advantages can spread through populations with enough time Gonna make the population adapt Turns out it doesn't even take that much time for these allele to spread Negative purifying selection Variation maintain selection (balancing)

Answer 145

Disruptive selection: favours Both extremes Stablizing selection on human birth weight Directional selection: favours one extreme

Answer 146

As seed abundance decrease, population fell but as seeds became harder average beak size increased Due to the drought of seeds - before seeds wre less hard but now they were harder

Answer 147

Disruptive selection leads to trait divergence In some cases, may lead to speciation Requires spatial heterogeneity or discrete resources

Answer 148

Research through today shows: Thousands of measurements of selection Demonstrates fitness differences and evolutionary change in traits And yet: Many fewer convincing cases document the mechanisms agent of selection in natural populations Linking evolution to ecology is difficult

Answer 149

Evolution of industrial melanism in peppered moths Pepper moths Before 1850, dark mothers were rare but as indtural population balckented tree trunks near cities, the dark variant of pepper moths replaced light forms in polluted areas Lighter one were still in rural areas Before1850 the allele that caused the darkness was rare Hypothesis: Mechanism of selection due to selection by birds Differences in moth crypsis (camouflage) depend on trunk coloration Light form on a dark tree trunk - ur visible to predation Experiments in the field test this After introduction of the UK “Clean air act” in 1956 There was a decline in the frequency of the dark form There was a lag in the revolutionary response shows the time required for foresets to return to a more natural (unpolluted state) as well as low initial frequency of the recessive allele for typical coloration

Answer 150

Gene flow: adds to homogeny Natural selection will be acting to drive them apart If theyre in diff environment Drift will do the same

Answer 151

Difficult to observe and measure Potential (dispersal ) vs actual (interbreeding) Gamete vs individual Even a little can affect this - youre looking for any little change Use experimental approaches Use neutral genetic markers Polymorphic genetic variants that arent tagrtes of selection Let us infer non-selective processes affecting genetic diversity of populations

Answer 152

Most gene flow occurs over a short distcnace but a small amount occurs as far as 1km Combined effects of selection, geneflow and genetic dift on population divergence

Answer 153

Stochastic (inpredicble or random) evolutionary forces Mutuation Random w respect to fitness Recombination Shuffling genes randomly Geneftic dift Very much like rolling a dice Good w mathematically modelling cuz we know propbabliyu Deterministic (predictable or non-random) evolutionary force Natural selection

Answer 154

Genetic dift Stochastic changes in allele frequency due to random variation in fecundity and mortality - some survive some dont just by chance Most important when populations are small Population bottle necks: A single sharp reduction in abudance, usually followed by rebound Causes a loss of diversity Founder events: Colonization by a few indidviuals that start a new population Colonixing group contains only limited diversity compared to the source population

Answer 155

Genetic dift is more prounched in small populations More drastic flucnations each generation More rapid loss of genetic diversity Faster time to allel fixation or loss Less consistency across replicate populations

Answer 156

Humans show a loss of genetic variation with increasing distance from east africa Reflects serial founder events as humans migrated from source populations

Answer 157

Genetic differentiation among populations is often observed across a geographic range DIfferent allel frequencies in different populations Phenotypic differentiation may be: Adaptive (“local adaptation”) or Due to genetic dift or Phenotypic plasticity Evidence for local adaptation: Reciprocal transplant studies Genomic analyses

Answer 158

The ability of a genotype to modify its phenotype in response to changes in the environment Occurs through modifications to growth and development and behavior Under genetic control Common in sedentary organisms - plants corals Also in animal behaviour Behaviour itself is a type of plasticity Ohnotypic plaasticty often is an adaptation to unpredictable neivornments But not all phenotypic plasticity results from adaption Some of it might be maladaptive - sometimes when species evolve in enironments that they werent exposed to

Answer 159

Growth of equivalent genotypes in contriasting environments and comparisons of their relative performance Can separate phenotypic variation into genetic and enviornmental compoents Enables measuremnts of selection against non-local genotypes Provides evidence of local adaptation

Answer 160

High UV radiation: Interferes w folate Very important vitation May have selected for increased pigmentation Low UV radiation Redcued Vitiam D syntesis Mau have selected for reduced pigmentation No single “best” phenotype across globes due to trade-offs Was there a history of local adaption on skin Pigmentation Numerous genes known to affect skin pigmentation Allele of these gens show rapid allel frequency change over time using ancient genomes (indicates natural selection) Allele of these gens show higher between population differentiation than most other genes Evidence supporting a history of local adaptation Only evidence in local adaptation in humans Diseases resistance (ex malaria) Lactose tolerance Natural selection associated with history of agriculture/pastoral societies

Answer 161

raditionally defined by phenotypic similarity Fairly easy to dindetify within a region (symatric) In one location if theres a number fo plants that look similar then youre like oh theyre the same Symatric - look within a habitat BUt problem arises from gradual differences across regions Popilations can diverge from eachother - how do we deicide if theyre different around Allopatric - different populations..? Watch video Genetic similarity also used to identify and define species (phyologenitic species concept) Where do you cut things out

Answer 162

Taxmonix (or morphkogical) Often based on phenotype Based on primarily on dictint measurable differences Biological Based on interfertility among individuals Concepts vary amgong organisms: NO UNVIERSAL SPEICES CONCEPT Ex bacteria dont interbreed sao we cant use this idea for them

Answer 163

A group fp interbreeding natural pooulations that are reproductively isolated from other such groups If they can breed together then theyre the same The BS Chelps frame the species problem as tractable research question

Answer 164

Focuses on the PROCESS Process of speciation in a way that we can study it Geopgrahic isolation alone is not suffient Just bc they live in geographic iolandt doesnt mean theyre diff speices Isolation does not have to be obsolete Question of what cutoff Must be possibly interbreeding in the wild DOes not apply well for bacteria, asexuals, highly self fertilizing species or fossils PROF VIEW: BSC is the mots useful species oncept we have, leads to the best research on the speciation

Answer 165

Allopatirc speciation much more common and easier to evolve due to evolution with minimal gene flow Symatic - same location

Answer 166

Pre-zygotic barriers prevent mating or fertilzation so no zygote gets formed Geogprahical, ecological Temporal, behavoural Mate recognition Mechanicals Genutal structure compatibility Eboltional divergnence Cellular Sperm-egg compatibility

Answer 167

Host shift from hawthorns and after arrival of domesticated apples in 1800s Differences in timin of host planting frituing (app;e vs hawthorne) DIfefrent timing of fly mating on preferred host plant Reduces fly gene flow by 94% in sympatry (same region)

Answer 168

POst-zygotic barriers prevent proper functioning of zygotes once they are formed

Answer 169

taxonomic unit (taxa plural) Kingdom, phyla, clSSES, ORDER, FAMILIES, GENERA, SPECIESS

Answer 170

The founder of taxnoony Binomial nomenclature Hierarchical system of classification Even before darwin's day it was clear that things were more similar and diff than others Kingdoms

Answer 171

Name is key to shared info on an organism Predictive power Enables interpretation of origins and evolutionary history

Answer 172

Terminal nodes: taxa Terminal branches: accumulated evolutionary change Internal nodes: common ancestors, speciation Interbranches: accumulated evolutionary change

Answer 173

Molophysleyic group: includes the complete set of species from a common ancestor Paraphyletic group: contains some but not all species derived from a common ancestor Non evolutionary commonness in the pairing

Answer 174

Understand history of life Large scale patterns ofevoltion Understand how many times traits have evolved, how fast, underwhat conditions Practical: Where and when did parasites spread? Which flu strain was most successful last year Adaptive evolution - what are they key mutations that help these things evolve What are the driver mutations as SARS COV-2 evolves?

Answer 175

Speices that share a more recent common anector tend to be more similar Descent with modification We can begin to shape evolution based on who shares what traits

Answer 176

got to udenifty and distinct btween ancestor and derived traits Ancestral trait = A trait shared w common ancestor Derived trait = A trait that differs from the ancestral trait

Answer 177

The independent evolution of structures that resemble one another and perform similar functional roles due to the shared ecology of unrelated organisms

Answer 178

Gens can be sequenced Species can be assessed for changes in the sequence of nuelcotides CHanges can be used to infer relationships in a branching diagram (phylogeny)

Answer 179

Key innovations: origin of a novel trail resulting in adaptive radiation Carriers of the trait can expoiut new resources or set of habits SUsually associated with rapid evoluirontary divsersifciation (adpative raidtaions)

Answer 180

Diversification = speciation - exicition Key inncoation could increase speculation ordecrease ecteiion to ufluence In the pic maybe the key innvolation is what lead to the thing

Answer 181

Use replicate sister groups compression WIth one phyilogeruc comparison it is difficult to say key innviatio is involved but w more repetition then tehres more evidence

Answer 182

Coevolution between insects and plants drives a higher rate in speciation in herbabtives

Answer 183

Secual reproduction allows us to have more genetic varion = more diversiation Outcrossing species * Animal pollination in plants * Increased dispersal

Answer 184

A small number of events lead to a major changes in how inherence worked Previously idpenitnt evolving nuts merged leading to higher level complexity and specialization through division of labor

Answer 185

Most pheotipuc traits we study in orgiams arose due to selection that increases the fitness of individuals May of may not be good for psieces Ex selection for color for mating but it might be bad Inddviual selection is usually stronger than group selection

Answer 186

High relatedness * Genes that lead to helping relatives can spread via natural selection 2) Reciprocal altruism * In cases where organisms repeatedly encounter each other * Mutual cooperation can lead to highest fitness 3) BUT: Cooperation sometimes breaks down * E.g. selection for ‘cheaters’

Answer 187

Because genes are the unit of inheritance ultinaekty the target of selection is the gene

Answer 188

Genones are composed of uenlated geens and allele that have been inherent from different places Seergation, recomiabtion, and random mating ensures that they are mostly passed on indietely

Answer 189

1) Mitosis and meiosis * Ensures that alleles don’t compete within an individual * Fair representation of gene variants among daughter cells 2) Development and multicellularity * Starting from a single cell prevents initial competition among cell lineages 3) Uniparental inheritance of organelles * Chloroplasts and mitochondria replicate asexually * Prevents competition within cells of different organelle genome

Answer 190

If an allels can bias iys own ttanstmisson Then it can spread to higher freuence wven while reducing individual fitness Selfish genetic element relative to organisms fitness interests

Answer 191

Meiotic drive can RAPIDLY ELIMINATE alleles that have higher individual fitness Sometines when meotic drive happens but it gets reduced by natural selection

Answer 192

Self replicating segments of DNA THE Replication separated from cellular replicayopn Ensure their own over representation in offspring

Answer 193

Allele airing elsewhere in genome that sielce TE will be faviorusd Mechiams controlling DNA and hsitione methylaition - probably evolved as a way of regulating piRna and RNA interference may have evolved as silencing mechanisms Tranpsotion Trabsotion is a form of mutation that can dispruot a gene ransposition increases TE abundance * Natural selection against harmful effects on the organism reduces abundance of chromosome copies with most TEs – Overall abundance results from a balance between these opposing forces 30© BIO120 Fall 2023

Answer 194

MITOCHORIA STAY COOPERATIVE BY: Uniparental plastid inheritance strongly reduces competition within individuals * Consistent with hypothesis that it evolved to maintain cooperation – e.g. active exclusion of sperm mitochondria at fertilization COnflict of ntrest: Material ingtericayion of cyptasmic genmonic Bipertanl inherical of nulacear genome MItochondrial mutations that enhance material fitness can spread *even if the cost is serve to male fitness

Answer 195

* New mutations in the mitochondria that make hermaphroditic plants “male sterile” can spread – “Male sterile” hermaphrodites = “female” – Because they favour mitochondrial transmission – Can reduce fitness of plant as a whole * Leads to evolution of nuclear ‘restorer’ alleles that re-enable fertility through pollen – Arms-race co-evolution of CMS & restorer genes

Answer 196

Starting from a single cell reduces competitionwithin individuals Sepration of germline with limited numbers of cell division inhibits transmission of selfish cell lineages Tumor supporsos, other features inhibit unregulated cell division

Answer 197

CANCER: selfish cell liengaes evolving within an vidual Many features ensure that the natural selection within an individual is limited (minimize genetic variation within individuals) * Ensures that many genes succeed by enhancing the fitness of the organism (‘group’) * BUT: countless ways to evade cooperation * Presence of strong selection on rest of genome (‘policing’) seems essential to maintain higher-level cohesion!

Answer 198

Strong, prolonged selection pressures using the same chemothreapity drugs trong, prolonged selection pressures using the same chemotherapy drugs – May not be the best solution – Selects for resistance * Cycling drugs, multidrug cocktails, lower doses of drugs – A better option? – Ethical considerations make tests of theory for human application challenging

Answer 199

Stagies for reduing ib pr in small cative animal specuces FOunding indidvuauls Ex like rhinos w only 17 left What will allow animals to adapt before exiction How likely is evolutionaly rescuxe Depends on population size, beenfical mutation rate, and how much fitness was reduced - basis on model

BIO FINAL EXAM Flashcards

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