PP1-3 Test Flashcards
a proposed explanation for phenomena to guide investigations
hypothesis
repeatedly tested hypotheses used to explain and predict phenomena or accepted explanation for observations, backed by scientific evidences
theory
Worked in 1830’s to 1850’s
In 1859, wrote his ideas about evolution (which at that point was a hypothesis) in a book called
On the Origin of Species by Means of Natural Selection
(basically a journal of his observations & questions), he didn’t call his ideas “evolution
charles darwin
3 word phrase for what Darwin called his hypothesis as proposed in his book…
this means that genes are modified (or changed/varied) & some of these changes are passed to an organism’s descendants & if it allows them to be better suited for their environments it leads to adaptations
“descent with modification”
Darwin’s ideas of evolution are now a ____ because of the repeated evidences that support it
theory
States that…“Organisms change gradually over time as a result of adaptations”
As the organisms change, their variation allows for differential survival and reproduction because nature selects, or allows, for the individual organisms that are best suited to their environment to pass on their traits to their offspring leading to adaptations and evolution of the species
Gradualism AKA Darwinism
change between species over time, one species replaces another, old species go extinct when replaced (will learn this later such as dinosaurs replaced by mammals)
macroevolution
change within species over time, see next slide, microevolution leads to macroevolution
Change within a species’
microevolution
microevolution ex.
Genetic variations occur for a variety of reasons If genetic variations are heritable and beneficial, then individuals pass on their traits to their offspring, if some survive “better” than other others then.. Natural selection (over many generations) allows members of the species that survived to produce more offspring and keep passing on these “variations” to their offspring Natural selection leads to an organism’s adaptations to their environment Evolution results
4 Principles of Darwin’s Theory of Evolution (by means of natural selection)
overpopulation, genetic variation, Struggle for existence/ Survival of the fittest, Natural selection
random variances or differences between individuals, the ‘why’ or ‘raw material’ for evolutionary change
genetic variation (heritable)
when individuals with heritable variations are better adapted they are chosen by nature to survive and reproduce, the ‘how’ or ‘mechanism’ for evolutionary change
natural selection
More babies born than can survive since so many things in environment can affect their mortality
overpopulation
Random differences or variations occur between individuals within the same species due to ________(exs. mutation or sexual reproduction and meiosis) but only heritable traits are passed onto offspring
genetics
Competition occurs between individuals such as predator with prey, male with male, or plant with plant. Competition occurs for living space, food, water, mates, etc. The organisms with the best heritable variations will survive due to being the most “fit” or best adapted to reproduce
Struggle for existence/ survival of the fittest
Natural selection allows those organisms with the most suitable heritable traits to survive and reproduce and pass those traits onto their offspring leading to adaptations BUT it does NOT produce perfection and does NOT have a goal and is NOT random, although variation is
Natural selection through differential survival and reproduction
Mutation, sexual reproduction, and genetic recombination during sexual reproduction lead to _______ ______
genetic variation
CAN lead to inheritance, if so then their can be a struggle for existence/survival of the fittest
genetic variation
Then _______ ________ occurs due to differential survival and reproduction which then leads to adaptations
natural selection
BUT if humans intervene then _______ _______ can have the same outcome
artificial selection
are “characteristics that result from natural selection when (heritable) traits are passed onto offspring resulting in organisms being better suited to their environment”
Often occur because of changes in organisms’ habitat
adaptations
Structural
way a structure looks
Anatomical (or morphological) adaptations
Functional
Helps a structure do something better
Physiological adaptations
If there is an anatomical adaptation, it is for a _______l reason
_______adaptations occur and result in anatomical changes as well
Physiological
Includes ‘instincts’ such as migration
behavioral adaptations
Adaptations lead to different types of _______
evolution
Unrelated organisms evolve similar adaptations but in different places due to similar habitats and niches
convergent evolution
Common ancestry leads to a diversity of species separating from a single point resulting in shared traits since all life originated from extinct ancestral species
divergent evolution
Divergence from a common ancestor, organisms separate due to isolation and adapt to changing habitats and niches
adaptive radiation and divergent evolution
Original species from which new species radiate
founder species
Formation of new species due to isolation of members from different populations resulting in not being able to interbreed, ONLY members of same species can interbreed
speciation
Isolation leads to _________(geographical, temporal, behavioral, mechanical etc)- populations of the same species living in different locations tend to evolve in different directions, as two populations become separated they become isolated so they can no longer interbreed and become different species (leading to new species being formed called speciation)
speciation
Natural selection causes change within ________- because traits of individuals allow the population to adapt to its environment due to genes, mutations and recombination of genes during sexual reproduction provide genetic variation upon which natural selection acts (microevolution)
populations
leads to species replacement- due to climatic changes and natural disasters some species become extinct and they are replaced by species that are better adapted (macroevolution)
extinction
his (Darwin) journey on the
(ship) as friend of the captain
HMS Beagle
raveled around the world and kept a journal of his questions
and observations, he was a naturalist, see next slide
Journey on the HMS Beagle
1831-1836
Plants and animals on these islands closely resembled those from the west coast of South America (where Darwin traveled)
Galapagos Islands
Darwin found many species that were _______ to certain areas only esp. Galapagos, but also found some species in one part of the world that were similar to species in other areas, also found extant species similar to fossils of extinct species???
endemic;
species native and unique to one area
endemic species (gal tort)
biblical idea, widely believed at time
Catastrophism
One of first to envision evolution
But did not believe in extinction
Believed the “need” of organisms drove evolutionary changes
Lamack
“ law of use and disuse”- if needed, use it and it evolves, if not used then doesn’t evolve
“inheritance of acquired characteristics”- he believed that if “need” drives evolution, then an organism will pass on traits acquired to offspring
Not accepted in scientific world
Darwin used same evidences for evolution as Lamarck did, but different arguments for it and not based upon “belief” but rather observable evidence
Lamackism
An Essay on the Principle of Population
Darwin read ______ and used the ideas for all organisms…. “overpopulation, competition among siblings, and genetic variation leading to slightly greater chance of survival”
Malthus
Principles of Geology
geologist who came up uniformitarianism - slow, gradual geological processes shape the earth
Darwin used the idea to explain fossil placement in rock and used to determine age of the fossils and when the organisms lived
In opposition to biblical idea of catastrophism
Oldest rocks on bottom, youngest on top since rocks laid down gradually
Lyell
Darwin used his observations and then read Lyell and learned about Lamarck, envisioned biological uniformitarianism similar to Lyell’s geological uniformitarianism; also believed that Malthus’ ideas pertained to all organisms, also influenced by Mendel’s ideas on genes too
“Evolution occurred over generations,
too slowly to be perceived”
effects on Darwin
Worked in South Pacific while Darwin was working in other parts of world
Corresponded with Darwin and shared his own theory of evolution with Darwin
Importance- Forced Darwin’s hand in publishing his book
In 1859, Darwin had to publish his book On the Origin of Species by Means of Natural Selection quickly so as to beat out Wallace, even though he wasn’t ready
Darwin’s book became a best seller eventually but it took the discovery of genetics to get the book to that point
Making similar observations as Darwin but in a different part of the world - Malaysia
Wallace
Not an influence on Darwin, rather Darwin was an influence on Gould - punctuated eq.
Gould
Species do not change for long periods then there are brief episodes of ‘fast’ speciation
Gould developed this idea because not all evolution and fossil records can be explained by gradualism
Ex. fossils from mass extinction events
Ex. Burgess Shale fossils showing
evolution during Cambrian explosion
Punctuated Equilibrium (P.E.)
Evidence for evolution supports _____ Darwin’s view and Gould’s view
both
due to meiosis during sexual reproduction
genetic shuffling or genetic recombination
cell division that involves reduction in chromosome number, from diploid to haploid so a parent only passes on ½ of his/her chromosomes to offspring
meiosis
During meiosis, homologous pairs of chromosomes line up & genes switch from 1 chromosome to another before fertilization occurs
crossing over
fusion of 2 haploid gametes (sperm, eggs) to make 1 diploid zygote, each offspring has ½ of his/her chromosomes from each parent so each offspring is from his/her siblings depending on which gametes form the zygot
fertilization
Gregor Mendel: 1857
Discovered how genes work by studying genetics in pea plants by cross pollination (pollen from one plant to another) for desired traits= artificial selection
Dominant “T” Recessive “t” Genotype “TT” “Tt” “tt” Homozygous “TT” “tt” Heterozygous “Tt” Phenotype- physical expression ex tall, shortPunnett Square- given certain parental genotypes it provides representation of genotypes and phenotypes for offspring
Mendelian Genetics
used to explain the concepts from previous slide #6 …..Mendel discovered that 2 “alleles for a gene separate into gametes when they are made during meiosis, each gamete receives ONLY 1 of the 2 alleles
Depending which alleles combine during fertilization, the phenotypes of the offspring are varied from the parents and from each other, so the phenotype output illustrates genetic shuffling/recombination
law of segregation
As discovered by Mendel, when examining 2 traits/genes, “the alleles from the 2 or more different genes separate from one another and segregate independently of one another when gametes are made” and during fertilization, AGAIN illustrating genetic shuffling/recombination of the offspring
Law of independent assortment
genetics means that these inheritance patterns are different from what Mendel found where 1 trait is dominant & 1 is recessive
Non-Mendelian
more than 2 alleles for a trait, allows for more than 3 genotypes & 2 phenotypes of offspring (not just 1 dominant and 1 recessive)
Multiple alleles
2 of the multiple alleles from slide #9 are equally dominant and both are equally expressed when they are together in a genotype
Non-Mendelian genetics
Codominance
still 3 genotypes RR, Rr, and rr but
3 phenotypes- RR=dominant red, rr= recessive white, and Rr= intermediate (blended or mixed for heterozygous genotype) so pink
incomplete dominance
alleles available for offspring in a gene pool can be different for different populations of a species in different locations around the world & can change with migration
alleles available in a population’s gene pool
interbreeding members of a species
population
all genes/alleles available in a population for a trait
gene pool
alternative forms of a gene
alleles
movement of individuals from one place to another, can change alleles available, due to gene flow between gene pools
migration
% of an allele in a population
allele frequency
Because of genes available in the gene pool, allele frequency can be different in different locations of the world and at different times,_____ can lead to gene flow between gene pools thus result in changes in allele frequency
migration
jumping genes’
genes that can move from one area of a chromosome to another area of a chromosome, often within another gene, so that they inhibit the expression of those genes (interfere with the protein the gene codes for, thus changes the phenotype for that gene)
Barbara McClintock
discovered transposons in maize and won the Nobel Prize in Physiology or Medicine in 1983 for the discovery
transpsons
makes up genes, genes are found on chromosomes,
and genes code for proteins (gene expression= the protein the gene codes for and the phenotype it causes
background DNA
makes mRNA during transcription of protein synthesis, mRNA pairs with tRNA’s during translation of protein synthesis in order to assemble amino acids into a polypeptide and later a protein
background DNA
in DNA COULD affect or change the mRNA or tRNA as well as amino acids they code for, thus could affect or change the protein produced, but sometimes it does NOT change anything, see why on the next slide
mutations
Sometimes multiple mRNA ______ for the same amino acid so sometimes mutations in codons of mRNA (or DNA before it) do not cause changes in amino acids coded for or proteins made
codons
diploid body cells made from mitosis
somatic cells
haploid sex cells made from meiosis
gametes
in genes in somatic cells COULD affect the proteins made by those genes, these mutations could be inherited if they affect many cells in the body due to how they are inherited, and can lead to evolution in a bad way
mutations
based upon embryology)
discovered by Sean Carroll, evolutionary biologist
gametes of animals pass on master control genes to offspring that control the development of their body parts in the embryo during development, they are found in stem cells, the same master control genes are found in many animals
evolutionary development
All cells of embryo/fetus originate from 1 zygote stem cell that undergoes mitosis (cell division)
All cells begin as undifferentiated cells
Then, the stem cells begin to differentiate and develop specific functions (AKA specialize) due to DNA and genes that are turned on in each cell
Form skin cells, bone cells, brain cells, etc
Embryological Development
similar sequences of nucleotides in master control genes of different animals
Homeotic boxes (or homeoboxes)
same genes found in many animals that control development of same structures/functions in all the animals that have it
master control genes
examples of master control genes
hox genes
are found in different animals and they form the same body part in each animal, but the body parts are adapted differently for each animal
ex. all animals have appendages but in humans they are arms and legs, in insects they are legs and wings and the legs look differently in each
Same master control genes or Hox genes
Hox genes exist due to shared ______ ______ of animals during the Cambrian explosion when all animal species underwent divergent evolution, the same master control genes were inherited by all of them
common ancestory
eye development
pax 6
limb
development- antenna, legs, wings
Distal-less gene
heart
development
tinman
Mutations in _______ can be more serious than in somatic cells especially if they are in master control genes
gametes
mutation in a ______________ (ex. distal less- dll) could be dangerous or deadly to offspring
master control genes
are always inherited and thus can lead to evolution (in a good or bad way depending on the mutation and its effect)
Mutations in gametes and master control genes
________ evolve, individuals do not
populations
mutation
migration/gene flow
non-random mating- not included on CK-12 assignment but is in the video on the site
genetic drift/decrease in population size
As a result, these forces lead to…….
E. natural selection
yeah
Mutations in DNA nucleotide sequences, especially of master control genes in gametes (ex Pax 6, Tinman, distal-less genes) lead to heritable changes such as legs growing from head, deformed heart, etc. (also mutations in other genes in gametes)
Mutations in DNA nucleotide sequences of regular genes of somatic cells CAN sometimes lead to heritable genetic variation too
Mutation is NOT a common thing to happen, so it does not significantly change allele frequency of a population, but is source of variation for the other forces of evolution
leads to genetic variation
mutaions in individuals
(NOT included on the CK-12 site but is in the video on the site) does NOT necessarily lead to genetic variation but can still impact evolution
Random mating is different… Individuals choose mates regardless of how they look which leads to variation
When individuals choose mates that have the same phenotypes as them
This leads to inbreeding which leads to more individuals who are homozygous rather than heterozygous which maintains allele frequencies
non-random mating
Sometimes individuals choose the mates with only certain phenotypes that are most “attractive” to them, sometimes this exaggerates phenotypes to the point of the trait becoming detrimental but can also lead to better “fitness”
random mating
leads to genetic variation, sometimes in a bad way
andom drastic reduction in size of a small population
greatly affects small populations even if only 1 individual is lost since alleles may not be present in many individuals
Bottleneck effect- small number of individuals survive, thus choice of mates is greatly reduced, thus can cause change in allele frequencies
Population size dramatically decreased due to unusual event or reason such as chance events like epidemic, flood, overhunting, landslide, earthquake, fire, etc
Since population is quite small, if disease strikes after genetic drift, less ability to adapt and could become extinct
Can lead to inbreeding or interbreeding which decreases genetic variability and diversity, can bring out “bad genes”
genetic drift
Surviving individuals repopulate which can change the allele frequencies especially if alleles or genes present in the population are already mutated
Then the allele frequency of future generations changes
results of genetic drift
a few individuals start a new population in a different location
but the founder species could be have different allele frequencies than the population they left
founder effect
mechanism’ for evolution in which nature ‘allows’ individuals that are best suited (most “fit”) with most favorable heritable variation to survive and reproduce and pass on genes and traits to their offspring thus leading to adaptations
Can increase or decrease allele frequency depending on its effects on survival and reproduction
Natural selection leads to microevolution of a species including divergent evolution, convergent evolution, adaptive radiation, etc
Can lead to macroevolution and speciation eventually though
natural selection
leads to differences in “fitness” among individuals in a population
allows for adaptations to occur within the population
changes allele frequencies in the gene pool of the population
ex sickle cell anemia slide #21 in PPT 3 & slides #37-48 in PPT 6
natural selection
natural selection depends on:
the phenotypes of the traits
the environment
traits controlled by many genes
Exs. skin color, hair color, peppered moth wing color
Data represented as a “normal distribution”
polygenic traits
is graphed as bell shaped curve
Mean= average values, includes middle values of graph
normal distribution
One “extreme” from
normal bell shaped curve
is eliminated/selected against, other extreme is selected for
So curve moves to
the extreme that is
selected for, thus the “mean” shifts towards that extreme
directional selection
Ex. Mammoths
with largest tusks selected for due to survival of the fittest
But tusks became so large that it could have lead to their extinction so then selected against large tusks
Ex. Spines of a cactus
More spines cactus has more likely to not be eaten by pig
Ex. Greyhounds
Artificially selected (bred) for greyhounds that are the fastes
ENVIRONMENTAL FORCES… LEAD TO EVOLUTIONARY CHANGE
Overuse of antibiotics causes bacteria to become resistant to them so now some antibiotics cannot protect us
‘The Rise of Antibiotic-Resistant Infections’
Directional Selection and specialization
Problem with antibiotic resistant bacteria
MRSA
Both “extremes” of bell curve are eliminated/selected against, “mean” or average phenotype is selected for
bell curve becomes more narrow since both extremes selected against and “mean” is selected for so “mean” gets larger
Ex. Human baby birth weights
Low birth weights and high birth weights are bad, both selected against and mean birth weight is selected for
ex. number of eggs a bird lays
stabilizing selection
“Mean” of bell curve is selected against and “extremes” are selected for
graph ends up with two curves since both extremes selected for and “mean” gets lower since it is selected against
The more that palatable, or tasty, African butterflies mimic distasteful butterflies, the better chance the tasty butterflies have of surviving
Ex. sexual dimorphism- there is usually a difference in appearances between males and females in some species, males one extreme and females other extreme
disruptive selection
fossils are preserved remains (bone, tooth, shells) or traces (footprints, burrow, or imprint) of an organism that lived long ago
fossil records
are dated using radiometric dating (using half lives) (K-Ar or Ur-Pb or C14) so provides actual record of the evolution of Earth’s 3.5 billion yrs of life
fossils
Can determine when the organism lived using the
Precambrian era, Paleozoic era, Mesozoic era, Cenozoic era and their respective geological periods
geological time scale
an be used in addition to the fossil record to determine where organisms lived in the past ex Pangaea
plate tectonics
which are fossils of extinct organisms found between ancestors to 2 groups of modern day groups, with traits of both, however some parts of the fossil record is incomplete
Missing links (or intermediate or transitional forms)
using DNA’s nucleotide sequences and genes- look at how many amino acids are different between two species to determine relationship between proteins in those species
Ex hemoglobin
Amino acid sequences of proteins
can be used to determine the similarity of DNA sequences between species especially those that share recent common ancestors
Ex gorillas and chimps with humans
DNA
what? is a circular DNA plasmid inside the mitochondria
How it arose- mitochondria arose due to endosymbiosis of bacterial cells
Inherited from mother to children
mutates slower because plasmids replicate by binary fission when mitochondria replicate so DOES NOT change from one generation to the next except by spontaneous mutation (unlike nuclear DNA which genetically recombines every generation due to meiosis and sexual reproduction)
Use number of nucleotide changes (mutations) in DNA or amino acid changes in proteins to determine divergence between species
mtDNA can be used to: date or determine how long ago two individuals or species diverged from one another
Can be used to find common ancestors
mtDNA can be used to trace migration “Out of Africa” and for relationship between 2 species
called a “molecular clock” because it can be used to “tell time” when divergence of species occurred- used as a dating method
Each species’ mtDNA mutates at a fairly constant rate
Thought to have occurred very slowly??
Mitochondrial Eve- once thought that human mtDNA mutation occurred once every 200,000 years, now thought to be once every 6500 years
Problem is it cannot be directly (absolutely) measured
mtDNA
Different animals have similar genes and thus similar body parts due to common ancestry
ex. hearts, eyes, and limbs of all animals and brains of vertebrates
Master control genes
same basic pattern of parts due to similar embryological origins of the organisms
Similar basic structures (due to common ancestry), however… the functions MAY BE different or….. may be the same function too.
embo studies - Similar vertebrate embryological development due to common ancestry and divergent evolution
Results in homology
divergent evolution
Homologous structures
Structures that have become reduced in size and function due to evolution
Evidence of common ancestry- creatures with that trait have a common ancestor that once used that organ
Evidence of homology and common ancestry
Ex halter(e)s in flies (hind wings)
Vestigial structures
Structures are adapted to perform the same function in different organisms if they live in similar habitats but in different parts of the world
But structures evolved independently of one another because organisms not closely related
Ex. wings of animals all used for flight but made of different things
Analogous Structures
Results in analogous structures
No evidence of recent common ancestry
Similar adaptations due to similar habitats in different places but evolve in different organisms independently
Demonstrates the power of natural selection
convergent evolutioon
Evidences for Microevolution
‘change within a species’
Peppered moths
Sickle cell anemia
is a protein that controls coloration of wings
Melanin is from a multigene family- many genes and many alleles control the production of melanin
Amount of melanin determined by the amount of alleles present
more alleles present for that gene, the more melanin is produced so the darker the moth
the less alleles present, the less melanin is produced so the lighter the moth
9 shades of peppered moths due to variations of melanin
If moth is camouflaged due to coloration, it is better adapted to the environment thus survives and reproduces and passes on genes for same number of alleles for melanin to offspring
melanin
before 1850’s (prior to Industrial Revolution)= tree trunks were lightly colored
moths with most alleles for melanin were the darkest and were eaten due to lack of camouflage
So moths that had least and medium amts of melanin and #’s of alleles for melanin survived and reproduced
after 1850’s (due to Industrial revolution)= tree trunks became dark because of pollution from Industrial Revolution thus affected which moths survived which was called ‘industrial melanism’
moths with least alleles, had least melanin so were the lightest & were eaten due to lack of camouflage
moths with more alleles, had more melanin were darker thus were not eaten thus survived & reproduced
color of moths natural selection
where is hemoglobin found? human RBC’s
normal RBC’s are anucleated in order to hold hemoglobin which carries oxygen
hemoglobin
Inherited recessive trait due to mutation in one nucleotide of beta- hemoglobin gene
Causes RBC’s to sickle thus clogging vessels so oxygen does not get to cells
sickle cell amenia
normal RBC’s (homozygous dominant)
normal RBC’s- no sickle cell anemia, but get malaria
AA
normal RBC’s but carry sickle cell anemia trait (heterozygous)
ormal RBC’s but carry sickle cell anemia gene, but no malaria either
AS
have sickle cell anemia (homozygous recessive)
sickled RBC’s so have sickle cell anemia, but no malaria
SS
Since sickle cell anemia is fatal, then why hasn’t natural selection eliminated it’s alleles from the human population?
Having only one allele for sickle cell makes a person resistant to malaria in some parts of the world and malaria is more deadly than sickle cell
If malaria is endemic
to certain areas…..
natural selection works on sickle cell allele in opposing ways
Natural selection in areas where malaria is NOT endemic…
ickle cell allele is selected against in “SS” only, since it is deadly
“SS” allele frequency decreases in sickle cell homozygous (SS) individuals and they become less common
The most “fit” can be either “AA”
or “AS” since neither results in sickle cell anemia, (the sickle cell allele is maintained in the “AS” individual only even though “AS” is a carrier for sickle cell anemia)
Directional Selection- p 263
Natural Selection in areas where malaria is endemic…
when malaria is present, “AA” and “SS” are selected against, and “AS” is selected for since it is most “fit”
Natural selection maintains both normal hemoglobin allele AND sickle cell allele in the “AS” individuals because…..
he sickle cell allele in “SS” homozygous individuals is selected against and eliminated because sickle cell disease is lethal and “AA” is also eliminated or selected against because malaria is deadly
BUT….the sickle cell allele is preserved only in the heterozygous individuals (“AS”) because it provides resistance to both malaria and sickle cell anemia
Natural selection works in opposite directions= BALANCING SELECTION
Natural Selection in areas where malaria is endemic…
Natural Selection in areas where malaria is endemic…
The allele frequencies balance out, only good to be “AS”
Balancing Selection - pp.262-263
When microevolution occurs within many species that are interrelated, it causes macroevolution between the species where one of the interrelated species replaces another
evolution
