AP bio unit 7
what does the root of a phylogenetic tree or cladogram indicate?
common ancestry
why is sexual selection called "nonrandom" mating?
(similar to natural selection) - called nonrandom mating because sexual selection in organisms in not just due to chance, there is a reason for why the mating between two specific organisms is taking place
what do + and - mean in a character table?
+ has trait - doesn't have trait
what does p stand for? what does q stand for?
-p stands for the frequency of the dominant allele -q stands for the frequency of the recessive allele
what is geological data and how does it show evidence for evolution?
-when organisms lived on earth -evidence: fossil records show how species evolved and when; evolution
what are some examples of structural and functional evidence shared across all domains?
-DNA (hereditary material) -proton gradient for ATP -cell membrane
how is divergent evolution different from convergent evolution?
-divergent evolution is when a species with a common ancestor who look different before of different environmental pressures -convergent evolution is when two species who don't share a common ancestor look similar because of similar environmental pressures
what is biogeography and how does it show evidence for evolution?
-geographic distribution of organisms -evidence: organisms speciated after being separated in pangea
what are the 4 main similarities between ALL tetrapods?
1 bond, 2 bones, little wrist bonds, and fingers
adaptive radiation vs divergent evolution
1. adaptive radiation: geographical isolation causes species to evolve on their own due to certain environmental pressures 2. divergent evolution: accumulation of differences between groups of organisms that lead to the creation of new, different varieties of species; speciation **both processes lead to speciation, but adaptive radiation is the first step of this process whereas divergent evolution is the final step
what are the three domains on earth?
1. bacteria and 2. archaea (prokaryotes) 3. eukaryotes
what are the two main parts of the definition of a species?
1. choose to mate 2. have viable, fertile, offspring
what are the structural features of eukaryotes that support common ancestry? (3)
1. genes that contain introns 2. membrane bound organelles 3. linear chromosomes
what are some cellular processes conserved across all organisms? (3)
1. glycolysis 2. DNA replication 3. protein synthesis
what are three mechanisms of evolution that are random occurrences?
1. mutations 2. genetic drift - bottleneck effect - founder effect 3. gene flow
what are five reasons why a population's allele frequency may change over the generations (evolve)?
1. mutations 2. sexual selection 3. natural selection 4. genetic drift 5. gene flow
what are five ways that a population can evolve?
1. natural selection 2. sexual selection 3. mutations 4. genetic drift - bottleneck effect - founder effect 5. gene flow
what are the steps that may lead to prezygotic barriers? (3)
1. population becomes isolated geographically or reproductively 2. isolated populations evolve (change) independently 3. once two groups are back in contact, they no longer choose to mate
what are the 3 keys to natural selection
1. variation 2. competition 3. differentiated success
what were the results of the miller-urey experiment?
15% of the carbon from methane had converted into other simple carbon compounds (like adenine found in nitrogen base and ATP)
what does it mean when q^2 is equal to 0.29?
29% of the population has the homozygous recessive phenotype
how old is earth? how is time measured?
4.6 billion years 4 eons divided into eras
what is kinesis?
A non-directional movement in response to a stimulus
natural selection
A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
what are the 7 major elements found in earths early atmosphere?
CO2, N2, NH3, H2, H2S, CH4, and H2O (H2O is in vapor form)
Microevolution
Change in allele frequencies in a population over generations.
what is the formula p^2 + 2pq + q^2 used for?
individuals/genotypes in a population (how often the genotype shows up in the population)
molecular data example
DNA sequence
what is an adaptation?
inherited characteristics of organisms that enhance survival and reproduction in specific environments
define taxis
movement of an organism in response to a stimulus
how to find total allele number?
mulitply alleles by 2 to get the total (allele only counts for one letter)
what does it mean if a population is IN hardy-weinberg equilibrium?
NOT evolving from one generation to the next; allele frequencies are not changing
what are the five requirements for a population to be IN hardy-weinberg equilibrium?
NO natural selection, sexual selection, mutations, genetic drift, gene flow and there should be a large population (this all only applies to the traits of the population being studied)
in addition to protein enzymes, what other macromolecule can catalyze chemical reactions and store genetic information?
RNA
what is the RNA world hypothesis?
The hypothesis that RNA was the first nucleic acid to evolve and early life was based on RNA rather than DNA or proteins, however DNA is more stable then RNA so as life evolved DNA took over this role.
what is darwin's second inference?
This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations
describe how antibiotic resistance develops
a bacterial mutation occurs that causes resistance to antibiotics
define punctuated equilibrium
a pattern of rapids change followed by stasis (no change) within a population **speciation occurs within a short time frame
how does geographic distribution of fossils give us clues about the past?
about evolution, how species evolved; aged *where species evolved from* example *we have found tropical organisms in antarctica which tells us more about the past*
what happens to the two different lizard populations while they are reproductively isolated?
after a while if the two lizard populations are ever reintroduced but don't breed, then speciation will occur
gene pool
all the alleles within a population
what do transitional fossils show?
an intermediate state between an ancestral trait and its later descendants, this ultimately shows how said organism has evolved over time.
tetrapods
animals with four limbs
when does life first appear on earth?
archean era
what is one of the main differences between artificial selection and natural selection?
artificial selection is when humans select desirable traits to be passed on to the next generation
which bacteria have low fitness? (in the bacterias case specifically)
bacteria that don't have a mutation that enables them to be resistant to antibiotics, because of this they are killed off and will reproduce at a much lower rate then bacteria that do carry that mutation that enables them to be resistant to antibiotics
how can convergent evolution lead to incorrect morphological interpretations?
because convergent evolution is when two species with no common ancestor look the same, and since morphological is only dealing with shape/structure, two organisms not related are going to look the same
why can morphological data be misleading?
because if convergent evolution occurred then fossil data can be misleading
in the example of sexual selection, why do you count the recessive individuals in the original population?
because it helps to find the q^2, and because these are the only phenotypes where we know the genotypes for sure
why does the biological species concept not always work when discussing species?
because it only works with living beings or organisms
why is molecular data a stronger source of evidence over morphological data?
because molecular data measures the genes of organisms whereas morphological data only looks at shape/structure so if two species only looked similar because of convergent evolution then that could throw off conclusions
explain why australia and north america have similar looking species that do not share a recent common ancestor
because of similar environments and selective pressures, they have evolved similarly because these are traits best fit to survive these environments
why do we start with the individuals with a recessive phenotype? what do they give us?
because once we have q (recessive) we can find p and then ultimately the answer
how can you solve for p and q from just looking at recessive individuals?
because q^2 is the number of recessive individuals divided by the total population
how is antibiotic resistance an example of evolution?
because the bacteria have developed mutations that lead to a higher fitness, they have developed in the population (higher fitness) and eventually this population of bacteria will grow so large that it has evolved from no mutation to a selected for mutation
if a river were to divide two lizard populations, why are they reproductively isolated?
because there is no gene flow occurring between the two populations and they are unable to reproduce or interbreed because they cannot reach each other
how can you tell if two species share a recent common ancestor or are distantly related?
common ancestor: little amino acid difference distantly related: large amino acid difference
why are different dog breeds considered to be the same species?
because they can produce fertile, viable offspring
why does genetic drift occur in small populations?
because they is where they have their largest impact; genetic drift can cause big losses of genetic variation for small populations
how come mules (result of a cross between two different species) are not a separate species?
because two mules cannot produce offspring; can't evolve
why are population with high variation more resilient to changing environements?
because when this environment changes and a species now has low fitness they may die off, but since this population has high variation there is more of a chance for the other species to actually be selected for in this new environment; if every species was the same and the changing environment made them selected against, this population would go extinct
why do you solve for q first?
because you are 100% sure of the genotype here when looking at the phenotype
what are the two changes in environment?
behavioral and physiological
what are two types of genetic drift?
bottleneck effect and founder effect
desirable traits
breeding of organisms with desirable trait in an attempt to produce offspring with similar desirable characteristics or with improved traits.
in general, how do postzygotic barriers prevent two species from hybridizing?
by preventing them from developing into viable fertile offspring
what is hardy-weinberg used for?
calculate and see if allele frequencies changed; if the population evolved
what does p + q= 1 tell us?
calculates allele frequencies to tell us if the population is evolving
what elements and molecules need to exist for cells to form?
carbs, lipids, protein, and nucleic acids so, CHONPS
what is earths most basic element?
cells
what is evolution?
change in allele frequencies in a gene pool over generations
evolution definition
change in allele frequencies in a population over generations/time
microevolution vs. macroevolution
change in the gene pool of a population over several generations / large scale changes in a population that leads to the evolution of a new species
describe the DNA content in prokaryotes
circular chromosomes in nucleoid surrounded by plasmids
what does ecological stress refer to?
climate change, volcanic eruptions, ocean pH changes
following a bottleneck, where does NEW variation come from?
comes from the remaining population that then reproduces and has mutations occur within that reproduction
behavorial isolation
dancing or mating calls (courtship rituals) lead to reproductive isolation because they develop behaviors that are not recognizable by other populations; two birds with different chirping "songs" would not mate
what are vestigial structures? + example
describe something that is no longer in use in a present day organisms, but did serve a function in a ancestor example: tailbones in humans
competition results in...
differentiated reproductive success
what do distantly related genes tell you about the ancestor?
distantly related and a common ancestor but further back then closely related genes between organisms
individuals __ evolve
don't -generations evolve/change over time
why is it that populations evolve and not individuals?
evolution is a change in trait/gene frequencies over time. An individual's traits/genes do not change, but the trait/gene frequencies in a population may change from one generation to the next.
what do phylogenetic trees and cladograms show?
evolutionary relationship between species
what happens to different populations once they have become reproductively isolated?
evolve independently of each other
gene flow
exchange of genes between populations
do bacterial populations grow exponentially or logistically?
exponentially
t or f: genetic drift and gene flow are based on fitness?
false
t or f: organisms can adapt by creating new phenotypes
false, organisms cannot create new phenotypes; only can act on existing ones
t or f: being constantly exposed to pesticides on a daily basis caused pesticide resistance in the population over time
false, pesticide exposure did not cause pesticide resistance in the population, it only killed off low fitness organisms and high fitness (to that environment) organisms reproduced increasing their prevalence
how do bacteria reproduce?
fast because they double every 20 minutes or so through binary fission (asexual reproduction; organisms can reproduce on their own or one parent)
adaptive characteristics
favorable traits that result in increased survival and reproduction which causes organisms within a population to differ in their reproductive success
describe the first cell membranes and early cells
first cells weren't composed of phospholipids but actually composed of fatty acids
speciation
formation of new species
what kind of data can be used to draw a cladogram?
fossil record, morphological data, DNA/amino acid sequences
what can you "see" in the fossil record?
fossils; record of life one earth
founder effect vs. bottleneck effect
founder effect is when a small number of individuals colonize a new area but they represent the old population, the bottleneck effect is when a large population shrink due to natural disasters or like hunting or something
founder effect vs. gene flow
founder effect: a few individual from a population start a new population with a different allele frequency than the original population; results in reduced genetic diversity gene flow: few individuals with the same allele frequency as the population flowing in and out of the population; results in a change in allele frequency but not diversity
why does gene flow cause evolution to occur?
gene flow is caused from migration--when individuals move into/out of a population, they bring their alleles with them-- and if evolution is a change in allele frequency then the arrival of these new alleles into a population will change the allele frequency and ultimately allow for said population to evolve
what is the founder effect?
genetic drift that occurs after a small number of individuals in a population move to a new area where they reproduce
what will most likely happen to an individual who lacks variation and environment changes occur?
going to go extinct
define gradualism
gradual change in species; evolution over time
what math can you do to determine if evolution has occurred or not?
hardy-weinberg formulas and theory
explain the peppered moth example of natural selection
has the best camouflage, therefore the highest fitness, and are more likely to pass that trait onto future generations
describe how herbicide resistance is an example of evolution
herbicides kill of pests however the ones resistant to this will survive. so as the weak die off and the resistant become more prevalent in the population or evolve, humans will develop a stronger herbicide that the pests will eventually evolve again to most likely because of a mutation.
what is the difference between high and low fitness?
high fitness: survive and reproduce low fitness: have a hard time surviving and reproducing
homologous vs analogous structures
homologous - traits inherited by two different organisms from a common ancestor (divergent evolution) analogous- similarity due to convergent evolution, not common ancestry (convergent evolution)
what is reduced hybrid viability?
parents have incompatible genetics and the hybrid offspring fail to develop
describe the conditions of early earth
hostile; fluctuated between extreme heat and extreme cold; hit with multiple meteors
what do "amino acid differences" actually tell us?
how closely related two organisms are
What does frequency mean?
how often an allele shows up in the gene pool
what does "differential survival" mean?
how organisms manage to successfully survive changes to their environment or fail and die out
homids
humans and other creatures that walk upright
explain how sexual selection can lead to a change in allele frequencies over time
if a certain trait makes an organism more likely to be reproduced with then said trait along with the genotype will be more prevalent in the population and that trait will continually be choose for to reproduce with making it even more prevalent (kind of like an amplifying signal)
how does natural selection lead to a change in allele frequency?
if a trait no longer has high fitness--reproductive success--in an environment, then said trait will be less frequent meaning that the said allele will also be less frequent
how can you tell if speciation has occurred or not?
if after being isolated two groups choose to mate or not (if they choose to mate then speciation did not occur)
how did variation in the peppered moth population help it survive a changing environment?
if all the moths were peppered and the black ash covered the tress, then the whole species would die off, but since black moths were also present, the species was able to survive
what are postzygotic barriers?
if mating does occur then this barrier prevents viable fertile offspring, keeping them as two separate species
how do you know if a population evolved or not?
if the allele frequencies between the two generations studied changed
why is a large population important as a requirement of hardy-weinberg equilibrium?
important so any random events (genetic drift) don't effect allele frequencies
what two things do adaptations or inherited traits do for an organism?
increase chances of surviving and reproducing
what does "selected for" and "selected against" mean?
individuals survive or don't survive, individuals reproduce or they don't
what is darwins first inference?
individuals with traits better suited to their environment survive and reproduce
compare and contrast intersexual and intrasexual selection
intersexual selection (female choice): can drive the shift in allele frequencies over generations intersexual selection: when the males of the species compete for the females
geographic isolation
isolation between populations due to physical barriers
if the allele frequency does not change from one generation to the next, is that population evolving?
it is not, in respect to what the gene is
why is genetic drift "random" and not "selective"?
it is random and not selective because it is based on fitness
what is a outgroup?
least closely related to the remainder of the organisms
what determines if an individual survives in a particular enviornment?
phenotype of an individual (genotype determines phenotype)
describe the genetic variation in the founder effect
loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population
what does the bottleneck effect create?
low genetic variation
what does low variation within a population indicate?
low survival rates in the presence of changing environments
what are postzygotic barriers?
mating occurs but offspring is not viable or fertile; species are unable to come together
how can fitness be measured?
measured by reproductive success; how many offspring they have
what is the most reliable type of data to use when studying evolution?
molecular data, the numbers are more accurate
diverged most recently in a phylogenetic tree or cladogram indicates what?
most related
which of the 5 fingers of evolution leads to adaptations?
natural selection
**explain how some mechanisms of evolution are adaptive evolution while some are random occurrences
natural selection and sexual selection are adaptive evolution because they are determined by fitness. whereas mutations, genetic drift, and gene flow are random occurrences because they do not rely on fit
how are mutations related to natural selection?
natural selection relies on variations and mutations create variation. also, when a mutation occurs in an organism this expressed trait can either give the organism high or low fitness (reproductive success), then natural selection will take it's course and depending on the organisms high or low fitness the trait will die out; go extinct (low fitness) or take over as the populations main phenotype (high fitness)
can an individual choose to change its phenotype?
no
if hybrid breakdown is present, can a species occur?
no
was there always oxygen on earth?
no
will these two lizard populations that are geographically isolated develop the same mutations and variations?
no because there is no gene flow between the two
mutations create variation. Are mutations always bad? explain how a mutation can increase an organism's fitness.
no, if the mutation results in a trait that benefits said organism in an environment, then their fitness will increase
is high fitness always good?
no, it is just based on reproductive success, not if said trait is stronger or weaker in an environment
does an environment cause mutations to occur? explain.
no, just because the environment changes does not mean a mutation has to show to help that species survive
can an individual choose to adapt to a new environemnt?
no, the change in traits is due to inheritance
are common traits in sharks, dolphins, and penguins due to common ancestry?
no, these traits are due to similar environmental factors; they have evolved similarly because they need similar traits to have high fitness
do character tables only show traits that have to be "gained"?
no, they can also show lost traits (like snakes used to have feet, we know this because they have the correct bone structure to have legs
in convergent evolution, do the species that are being compared share a recent common ancestor?
no, they have similar traits because of similar environmental pressures
nocturnal vs diurnal
nocturnal: active at night diurnal: active during the day
do scientists know for certain how life began on earth? what are the two current hypotheses?
not completely. 1. extraterrestrial origin 2. primordial soup model
directional selection
occurs when individuals with traits on one side of the mean in their population survive better or reproduce more than those on the other
how and when did oxygen enter the atmosphere?
once cyanobacteria were able to photosynthesize; once photosynthesis developed, they released oxygen into the atmosphere as a waste product and this built up over time
allele
one part of a gene
which organisms contribute offspring to the next generation?
ones that are better suited to survive their environment; ones who survive long enough to reproduce
how does a population change over generations?
ones who are best fit to survive and reproduce will, and ones who are not best fit to survive will die off, and we will see less and less to almost nothing of their traits within a population
how many carbon compounds have been produced form the miller-urey experiment and repeats?
over 30 different carbon compounds
hardy weinberg: if a question is asking about the frequency of a homozygous dominant or recessive trait, what formula would you use?
p^2+2pq+q^2=1
what do each of the following symbols represent? p^2 2pq q^2
p^2: homozygous dominant individuals in a population 2pq: heterozygous individuals in a population q^2: homozygous recessive individuals in a population
in natural selection, what is changing over time?
phenotypes, due to environmental changes
mechanical isolation
physical differences will prevent two species from mating
*stabilizing selection
population mean of a trait stabilizes; genetic diversity decreases as this occurs
what are two examples of taxis?
positive taxis: movement towards a stimulus negative taxis: movement away from a stimulus
what does life come from?
pre-existing life
what are prezygotic barriers?
prevent mating or prevent a zygote from forming
what does "prezygotic barrier" mean?
prevents a zygote from forming between two species keeping them as two separate species
Hardy-Weinberg equilibrium
principle stating that the genetic variation in a population will remain constant from one generation to the next in the absence of disturbing factors.
what are molecular clocks?
rate of mutations
what do closely related genes tell you about the ancestor?
recent ancestor
what does "morpological" mean?
refers to an organisms shape/structure
what do mutations create?
results in genetic variation, which provide phenotypes on which natural selection acts
what is strata?
rock layers
What can sexual selection result in?
sexual dimorphism; marked differences between the sexes of an organism
what is "morphological" data based on?
shapes/structures *applies to living species mostly*
what do vestigial structures show us about evolution?
shows us how present day organisms have evolved since their ancestors
*diversifying selection
similar to sexual selection; describes changes in population genetics in which extreme values for a trait are favored over intermediate values.
explain the heterozygote advantage using sickle cell anemia as an example
since sickle cell anemia is co-dominant and said person is heterozygous they will have half normal red blood cells and half sickle cell red blood cells, this is survivable up to the reproductive age so this could potentially supply high fitness (reproductive success) to said person, also malaria for example can only effect normal RBC so if said person has sickle cell alleles that are heterozygous only half of their RB cells will be effected
what is the founder effect?
small number of individuals colonize a new area, but they represent the old population
what does a split in a phylogenetic tree indicate?
speciation
biological species concept
species is a group of populations whose members have the potential to produce fertile offspring
gametic isolation
sperm from one species is unable to fertilize eggs from another species
if species evolve to live in different parts of their environment is
sympatric because the species originally started on the same land
what is fitness?
the ability to survive and reproduce
which bacteria have high fitness? (in the bacterias case specifically)
the bacteria that provide resistance to antibiotics because they are going to survive and reproduce at higher rates then bacteria that did not have a mutation so it was just killed off by antibiotics.
t or f: if a certain trait is more likely to survive and reproduce in a environment then over time the allele frequency in the population will change
true, + the allele frequency change is what causes evolution
give one example of artifical selection
the domestication of plants and animals
bacteria dominated the earth until....
the endosymbiotic theory cam about (created multicellular organisms; eukaryotes)
what are transitional fossils?
the fossils of a same species, tell us how said species evolved
what do you think reproductive isolation means?
the inability of a species to breed successfully with related species due to certain factors
what is the background rate of extinction?
the natural rate a species will go extinct
what occurs during hybrid breakdown?
the offspring of two different species cannot mate with the offspring of those same two species (a mule can't mate with a mule)
what drives the change in allele frequencies? (sexual wise)
when the mating is not a random event
explain "natural selection can only amplify or diminish heritable traits"
the traits are already there, but high fitness organisms will have traits that amplify, and low fitness organisms will have traits that diminish
what does it mean that the genetic code is "universal"?
the universal code applies to all organisms; base pairing rules don't change regardless of the species
what is the other hypothesis of how macromolecules evolved on earth?
they arrived from outer space by being transported to earth through meteors
how did a wide diversity of mammals evolve?
they could move into all the land space after dinosaurs went extinct and because of this they were able to kind of separate from their formerly small land area and evolve
how did 13 finch species evolved from one common ancestor?
they were separated geographically so they evolved separately
in a cladogram or phylogenetic tree, what do the lines represent?
time passing
converge
to come together
what are shared derived traits? what do they help to show?
traits that indicate common ancestry, help us derive hypotheses of how these species evolve
temporal isolation
two groups mate a different times of day or seasons
sympatric speciation
two population live in the same geographic region but different isolating mechanisms prevent gene flow
allopatric speciation
two populations are living in different geographic regions, preventing gene flow
what is convergent evolution?
two species not related have evolved and now look similar due to their similar environments/selective pressures
how does carbon-dating work? which fossils can be analyzed with carbon dating?
use it to see the age of the fossils by how much carbon is present in the fossil samples *zero carbon-14 = old this is applied to newer fossils mostly
what did darwin notice about variation in a population? what did he notice about the amount of offspring in a population?
variation exists in populations, and variation is an inherited trait. what darwin noticed about the amount of offspring in a population is that more individuals are born then can survive
difference between reduced hybrid viability and reduced hybrid fertility?
viability: no survive fertility: survive
how do we affect the variation in other species?
we choose the species with the traits that we favor more and breed that with traits of another species we favor to create a new breed of said organism
what drives the change in allele frequencies in intrasexual selection
what drives the change in allele frequencies is the fact that the mating here is not a random event
what happens to the population size and genetic diversity during a bottleneck event?
what happens is the population size for atleast one generation has reduced resulting in a loss of genetic variation; this reduction in population size is random; due to chance
why is it called a bottleneck?
when a population size is greatly reduced due to chance; randomness
in the fossil record, what clues would imply that a mass extinction occurred in the past?
when there is a lot of biodiversity in one layer and much less in the next
habitat isolation
when two groups of one species lives in different habitats, this can lead to speciation because habitat isolation leads to a loss of gene flow which leads to reproductive isolation and possibly speciation
what does reproductive isolation mean?
when two groups of the same species do not breed together
what is divergent evolution?
when two species have a recent common ancestor but have evolved to look different (ex. humans evolved from fish)
how can you identify the outgroup on a "number of amino acid differences* table?
which column is the most different from the others
how is fitness determined during sexual selection?
whichever organism has more reproductive success over the other has higher fitness example: a female dolphin chooses between two other male dolphins to mate with, whomever she chooses to mate with will have higher fitness because they are reproducing or passing their traits on whereas the other dolphin is not
does sexual selection effect fitness?
yes
is gene flow random? what does gene flow lead to?
yes, and it leads to evolution