Evolution Flashcards

Question

Genetic drift, bottleneck effect, founder's effect

Answer 1

In small populations, allele frequencies more likely to change stochastically (randomly) Example: allele frequency is 10% in two populations (1000 organisms vs 10) So, 100 alleles in first population, but just 1 allele in second By chance, allele much more likely to be eliminated from second population As a result, small populations undergo genetic drift Bottleneck is an example of genetic drift Bottleneck is a rapid decrease in population size, eliminates most alleles Bottleneck reflects adverse selective pressure (famine, disease, etc) Remaining survivors carry just a few alleles When population re-expands, low genetic diversity is dominated by “founder” alleles

Answer 2

heavy rain ponds become two ponds, that would be suddenly all alleles are able to mix together GENE FLOW

Answer 3

Separate populations have different gene pools Mixing of populations transfers alleles Genetic diversity increases within population, decreases between populations Example: flooding links two previously separate frog ponds

Answer 4

Bottleneck is an example of genetic drift Bottleneck is a rapid decrease in population size, eliminates most alleles Bottleneck reflects adverse selective pressure (famine, disease, etc) Remaining survivors carry just a few alleles When population re-expands, low genetic diversity is dominated by “founder” alleles

Answer 5

**Species is a population that can interbreed with itself but not other species** **All members can interbreed and produce viable fertile offspring** **One species placed in different environments → evolution and speciation** Two groups different species if environmentally isolated, cannot mate with eachother and produce fertile offspring; or can be in same place but not be able to reproduce with eachother\*\*\* speciation defined as: the formation of new and distinct species in the course of evolution.

Answer 6

categorized into prezygotic before fertilization maybe reproduce in differnt places, different courtship rituals, or gametes do not stick together properly maybe they do reproduce but progeny are steril or progeny die, so for whatever reason in process reproduction doesnt work properly ex mule sterile

Answer 7

Several barriers to interbreeding of species Barrier can be prezygotic = before fertilization Reproduction in different times and places (e.g., seasons) Different courtship rituals Mechanical incompatibilities in copulation Gametes may be incompatible (e.g., sperm cannot bind and get into egg) Barrier can be postzygotic = after fertilization Progeny may be sterile (e.g., female horse × male donkey = sterile mule) Progeny may not complete development Progeny in second or later generations may be inviable Gene leakage = gene flow between species

Answer 8

Barrier can be prezygotic = before fertilization Barrier can be postzygotic = after fertilization

Answer 9

Where an organism or population lives and reproduces Defined by conditions necessary for growth and survival (food, temperature, light, etc) Ecological niche includes competitive interactions among populations Populations indirectly compete for limiting resources or directly interact (e.g., predation) No two populations can occupy the same niche! One population will move out, die off, or evolve to occupy another niche Symbiotic relationships between species (mutualism, commensalism, parasitism)- living very closely with eachother, three kinds mutualism= ++ commensalism= +/0 one benefits other one doesn't care parasitism= +/- situation one species benefits other is harmed by interaction Just b/c cannot have two populations being in the same place in the same way

Answer 10

Idea from ecology that animals forage in such a way as to maximize their energy uptake per unit time- basically organsims are smart about foraging if can stay where they are eat little berries, low cal but plentiful and do not have to go anywhere will do that and not expend a lot of energy, if can get enough calories where they are they would only make a difficult journey if they needed to so if the bear runs a few 100 miles get better food or more nutrient rich food, but this theory says that organisms is aware of tradeoff will not run 200 miles for nothing if organism expending a lot of energy to get food has to be high calorie and worth it Organisms adapt strategies that encourage them to intake the most calories while exerting the least effort Different foraging strategies have evolved depending on both an organism’s environment and how much that environment has changed An unstable environment will lead to a more flexible diet

Answer 11

The application of game theory to understanding the strategies that organisms in a population use in competition Unlike in classical game theory, the goal is not the “best” strategy, but a strategy that is stable against others in a population Often used to explain phenomena between species such as co-evolution and cooperation Basically game theory scenarios ppl cooperate with eachother, choices individuals make in differnt scenarios if everyone cooperates everyone gets biggest reward if evyerone chooses to cooperate and you don't then you are screwed so it show you decide to relate to other players, cooperation vs competition in context of game theory some ppl tryign to apply this to evolution and talk about choice btw competion and cooperation

Answer 12

Most phenotypic traits are polygenic = controlled by many genes Most traits have a bell-curve distribution around a mean (e.g., height) Three different kinds of selection * Stabilizing selection * Directional selection * Destabilizing selection

Answer 13

eliminates extreme phenotypes, narrows curve around mean if environment really stable, whatever color most common see more and more mice with phenotype that is facored like in this case medium fur\*

Answer 14

* favors one extreme over the other, shifts mean value * now what happens is htere has been some kind of enviornmental change, maybe there are examples from industrial revolution buildings dirty animals darker coloration could hide better so did better, something changing what phentoype is most favored in this environemnt * so maybe going further dark phenotype more favored, most favored phenotype is shifting one direction or another!

Answer 15

* eliminates intermediate phenotype, splits distribution in two * Destabilizing selection may promote speciation * environemnt becomes pathcy, if light fur can go to one place, dark fur can go ot another place, but if medium fur stuck * so here get two distinct phenotypes within population favored, destablizing selection can in some cases lead to sepciation * if light colored mice hang out in one environment adn dark colored mice hang out in another area and stop interacting with eachohter can no longer breed with eachother that point down teh line refer to them as different, they will no longer interact with eacother remember speciation is defined as: Speciation is how a new kind of plant or animal species is created. Speciation occurs when a group within a species separates from other members of its species and develops its own unique characteristics. the formation of new and distinct species in the course of evolution.

Answer 16

Evolution yields two evolutionary strategies for species When environment is far from its carrying capacity, less competition for resources. Some organsims are r-selectd some are k-selected species Evolution will favor “r-selected” organisms r-selected species have: many offspring, rapid development, little parental care, small body size, short lifespan, high mortality (e.g., insects, amphibians) THINK INSECTS, have lots of offspring develop rapdily with very little interaction help from parents, strategy is to put lots and lots of offspring out in world and let them go When environment is near or at carrying capacity, more competition for resources

Answer 17

Evolution will favor “K-selected” organisms K-selected species have: few offspring, long gestation, more parental care, larger body size, longer lifespan, lower mortality (e.g., humans, primates) Very few offspsring, large gestational period, don't die as much can see how the lists go together, how having many offpsring without much invcestment in them versus few offspring with high investment is another strategy With few offspring makes sense those offspring would be larger, live longer better cared for, see organisms that adopt one or the other of these approaches

Answer 18

Divergent evolution is evolution of two species away from a common ancestor Divergent evolution = adaptive radiation Homologous anatomical structures have a common evolutionary origin Example: dog foreleg, human arm, whale front flipper Implies common ancestor or common ancestor structure, can identify homolgous structures that A and B have, big example of this some ancestoral structure gives rise to forearm of human, front flipper of whale, wing of a bat, all of those are derived from a common ancestoral structure adnd they are called homoglous structures\*\* they have a common ancestor\* but the structures have different functions in present like whale front flipper for swimming, dog foreleg for running, bat for flyign but homolgous come from common acnestoral structure

Answer 19

Convergent or parallel evolution Unrelated organisms may evolve similar anatomical structures Structures can arise in parallel = more than once, in different evolutionary lines Similar structures that evolve from different ancestors = analogous Example: bird wing, insect wing NO homolgous strucrures because no common ancestor, but get insect wing and bat wing not both derived from acnestoral wing, just that being able to fly which is a HUGE advntage from evolutionary poitn of veiw so tehy are analgous same function in present but do not imply an evolutionary relationship

Answer 20

common acnestor derived homologous structures for divergent evolution ex. darwin finches all started on mainland, adapted to other islands once flew out differnt beaks became differnt from eachother that is another example of adaptive radiation all started on mainland and then the finches moved out to island all adapted\*

Answer 21

know all life forms use the same genetic code! and there are some genes that are highly conserved, i fyou want to make inferences about how closely realted differnt organisms are or different species are the best thing to do is look at how much dna they have in common, how much sequence is in common

Answer 22

Evidence for evolution is present in fossils and DNA Fossils provide evidence of anatomical relatedness and alterations over time DNA sequence data indicates genetic similarity of species All life forms share universal genetic code Genetic code evolved once, was conserved (maintained) in all life forms Sequence and function of many genes is also conserved across species Key genes are highly conserved and do not change much over evolution Evolutionary distance is indicated by degree of sequence homology More evolutionarily distant = more sequence changes Assumes mutation rate is generally constant “Horizontal” swap of DNA among species can complicate evolutionary trees

Answer 23

Ontogeny = embryonic development when embryo developing goes through all evolutionary stages, not always true when human embryo is developing not fast fowarding through all of human evolution going through phase reflecting lower animals, but it is true human has tail for a while so there are other less advanced evolutionary forms that embryos do go through, cornel of truth to this not strictly true but lot can see about evolution when look at embryos Homologous structures look really similar when preparing embyos

Answer 24

Ontogeny = embryonic development Phylogeny = evolutionary development of a species During development, embryo passes through developmental stages Developmental stages resemble evolutionary predecessors Anatomical structures shared by related species tend to develop earlier Example: backbone in fish and mouse Homologous structures look similar in embryo Anatomical structure specific to one species tend to develop later Example: human cerebrum Anatomical structures that are lost during evolution are lost later during development Example: leg bones in snakes and whales Anatomical evolution generally occurs by modifications of developmental plan Changes in DNA affect morphology of embryo and its development

Answer 25

Structures that serve no purpose! Vestigial structures/organs serve no obvious or useful function = evolutionary relic Related to useful structures in other species Indicative of common ancestry, followed by evolutionary specialization Human coccyx, appendix, snake limb bones, eyes of blind cave-dwelling fish Like snakes have limb bones but obviously do nto need those and dont' walk but can see verstiage of evolutionary history, some fish live in really dark vaces still have eyes because evolved from fish that dif have vision\*

Answer 26

we are in phylum chordata, we are chordates which includes all vertebreates Chordates have four basic features: Notochord\* remember only for a little while as embryos, mesodermal structure gives rise to neural tube that gives rise to brain and spinal cord, some features common to all chordates are only present in embryo; part of being a chordate\* Dorsal nerve cord (dorsal to notochord) dorsal= back Pharyngeal pouches/gill grooves **(in land animals, lost during embryogenesis) somethign have briefly in embryos which we do not have after** Post-anal tail: extension of notochord, lost in humans and frogs; humans lost tail, purely found in embryos, stil qualifies us as chordates Within phylum of chordates all vertebrates are included In contrast, arthropods (insects, crustaceans), annelids (worms) have ventral nerve cord

Answer 27

Animals are either invertebrates or vertebrates Invertebrates lack a backbone (e.g., sponge, fruit fly) Vertebrates have a backbone (e.g., humans, mice, crocodile) Main classes are fish, amphibians, reptiles, birds, and mammals **Warm blooded organisms can actively regulate body temperature = birds, mammals, if we go somewhere really cold do not just equilibirate with environment we are able to regulate** Cold blooded organisms cannot regulate body temperature = fish, reptiles, amphibians Temperature of cold-blooded organisms dictated/controlled by surroundings On a hot day, lizard sits in shade to cool off

Answer 28

Fish were the first vertebrates **Fish have 2-chambered heart (one atrium, one ventricle)** Amphibians evolved from fish, are able to breathe air w/ lungs, but still inhabit water **Amphibians have 3-chambered heart (two atrium, one ventricle)** Reptiles evolved from amphibians, live mainly on dry land **Reptiles have 3-chambered heart (two atrium, one partially divided ventricle)** Birds thought to have evolved from reptiles **Birds have 4-chambered heart, are warm-blooded** **Mammals thought to have evolved from reptiles** **Mammals are warm-blooded, have 4-chambered heart, mammary glands for nursing**

Answer 29

idea very early atmosphere had no molecular oxygen, water present so oxygen in water; ammonia present, so idea is that the high energy lightenign storm UV light bombarding early atmosphere jolted all these inorganic moelcules ttogether to form orgnaic moelcules amino acids and nucleotides of RNA ## Footnote All current life forms are genetically similar Life probably evolved only once, from simple chemical molecules Early earth: no oxygen, but simple organic molecules and energy Miller experiment: inorganic molecules + energy → organic molecules, took ammonia and water zapped them like crzy and showed yes randoly can get organic molecules and amino acids from doing that So the idea is that the first "organisms" ppl with reproduction would have been squiggles of rna becuase can act as catalyst for interactions, code information, squiggle with RNA genome, can reproduce itself, self replicaitng RNA may have been earliest life form some ppl refer to RNA world as world of rna squiggles Water, ammonia, methane, hydrogen + spark → amino acids, nucleotides

Answer 30

After chemical evolution, possibly and RNA world RNA can be a catalyst, RNA can encode information Self-replicating RNA may have been earliest “life form” After RNA world → eventually organisms Eventually dna developed from RNA, and cells evolved from that point on life was DNA based Last common ancestor is theoretical ancestor to all present life forms First cells were anaerobes, then photosynthetic autotrophs → oxygen Once photosynthetic autotrophs evolved suddenly oxygen in atmosphere, once there was oxygen heterogrphs many animals were able to develop from there know the order this happens: inorganic molecules-- organic molecules--\> RNA--\> DNA--\> photosyunthetic autotrophs--\> heterotrophs the inorganic source of carbon peope thing of is methane\*\*\*\* organic molecules can think of as amino acids

Answer 31

King KINGDOM- broadest Phillip PHYLUM Came CLASS Over ORDER From FAMILY German GENUS e.g. Homo Soil SPECIES e.g. sapiens So when we say homo sapiens, homo is our genus sapeins is our species how they test- if two organisms are in the same genus, they must also be in the same family, order\*\*\* SAME EVERYTHING ABOVE BUT NOT BELOW\*\*\* so not same species same class, same phylum, but not same order family genus species