Exam 2 Powerpoint concepts Flashcards
what makes populations different?
natural selection
genetic drift
and mutations rates
what does gene flow do?
make populations similar
what happens when gene flow stops?
a population becomes genetically isolated
what leads to genetic divergence?
selection, drift, and mutation act independently in each population
genetic divergence + genetic isolation=
speciation
when does speciation occur?
when a single ancestral species splits into two or more descendent species,, and the populations egin to evolve independently
what is a species
an evolutionarily independent population
what is the biological species concept?
defines species as populations that do not successfully interbreed (reporductive isolation )
what does reproductive isolation do?
stops gene flow, causing gene flow
prezygotic isolation
prevents different species from even mating (fertilization doesnt occur)
post zygotic isolation
prevents different species from producing viable offspring
examples of prezygotic barriers
geographical,, separation by geographical barriers
ecological/habitat,, separated by habitat
temporal (time),, ex. flowers blooming at different times
behavioral,, different courtship behaviors
mechanical (incompatible geneitalia)
gametic,, the egg and the sperm are not compatible and the egg rejects the sperm
examples of post zygotic barriers
hybrid viability,, offspring do not develop normally and die as embryos
hybring sterility,, offspring mature but they are sterile
limitations to the BSC?
- typically limited to sexual organisms
- unknown to fossils,, only applies to living organisms
- difficult to know when closely related populations don’t overlap
-what about hybrids? Prizzly Bear
what is the morphospecies concept?
defines species as populations that appear different
(assumes that size, shape, and color differences are due to divergence)
limits of MSC
- very subject to human perception
(different researchers can come to different conclusions) - sometime species can look similar but they are genetically distinct
-sometimes two species can be identified even though it is only one
-cannot identify cryptic species
why is the MSC good?
0 it is good if you have a brand new species and have no idea where to start, gets a good start on identifying species
it is a good start
the phylogenetic species concept
identifies species based on the evolutionary history of populations
what are monophyletic groups?
contain an ancestral populatiom, all of its decendents and only those descendents
what are synapomorphies
- defines monophyletic groups
- homologous traits unique to a monophyletic group, genetic developmental or structural characteristics
why do synapomorphies occur?
genetic isolation
what are the benefits of the PSC?
- can be applied to any pop
-logcal
what are the disadvantages of the PSC
-synapomorphies are difficult to identify
- can lead to a huge number of species
mechanisms of speciation
allopatric and sympatric speciation
what is alloatric speciation
there is a physical barrier for speciation
what is sympatric speciation
what are the two ways that allopatric speciation may occur?
- dispersal
- vicariance
what is dispersal?
a population willingly disperses,, few ind. found a new isolated population
what is vicariance?
when a new physical barrier splits the population into two
example of allopatric speciation
- trumpeters in the amazon,, they are split by the amazon river and each population is isolated from each other
what prevents gene flow in sympatric speciation
- disruptive selection
- polyploidization in plants
what is disruptive selection
extreme phenotypes are favored by selection
example of disruptive selection
apple and Hawthorne flies,, they look the same but both of the flies prefer different fruits to feed off of. The are on their way to becoming a new species
what is polyploidization
chromosome duplication produces mismatched chromosomes between populations
(massive error in meiosis or mitosis)
- building a car with half chevy and half ford parts
- this stops geneflow through post zygotic isolation `
when does autopolyploidy occur?
when nondisjunction doubles the number of chromosomes in a species coming from the same parent
(asexual reproduction)
what does autopolyploidy result in?
sterile offspring due to gametes with uneven chromosome number
how do autopoly, and allopoly preven interbreeding
unpaired chromosomes
polyploidization is common in
self reproducing plants
what is secondary contact
- occurs when species that have undergone genetic isolation and divergence meet again
what are the 3 possible outcomes of secondary contact.
- fusion
-stability
-reinforcement
what is reinforcement?
strengthenign reproductive barriers,, hyprids cease to form
(when u get back together whth and ex and youre like omg I remember why I hate you)
what is fusion
weakening reproductive barriers,, the 2 species fuse
(when you meet back up with an ex and you decide to get back together again)(and then you have a baby)
what is stability
continued production of hybrid individuals, but the hybrids are not successful in either parents habitat they are only successful in their own little niche
what is hybrid speciation
when hybridization between two species produce a third species with new trairs
- the new traits may allow hybrids to occupy habitats the original parents cannot
go look at the charts in chapter 10
right now
how did life on earth begin?
- theory of chemical evolution
what is the theoyr of chemical evolution
-we went from simple chemical compounds
- those combined to form complex carbon compounds
- which then turned into the first proto-cell
what 4 things does all life contain?
hydrogen
carbon
nitrogen
oxygen
what percentage of organismal matter do these 4 atoms make up?
96%
how were the first molecules created?
spontaniously
what does the formation of complex compounds require?
energy
what is the first law of thermodynamics?
nergy cannot be created or destroyed.
what is energy?
the capacity to do work or supply heat can be potential or active
early earth was abundant in…
heat, loght, and radiation why?
- no ozone layer
the atmosphere of early earth was rich in
H2, Co2, N2, and water vapor
what are the two models of how life began?
- prebiotic soup model
- surface metabolism model
what is the prebiotic soup model
- certain molecules were synthesized from gases in the atmosphere or from meteorites
- they condensed with rain and accumulated in oceans
- the organic soup allowed for construction of complex molecules
1. simple molecules present 2. energy in sunlight drove reactions among the simple molecules 3. heat stimulated mire complex molecules
what is the surface metabolism model?
-extremely hot rocks contact deep seafloor cracks,, they are rich in dissolved gases and reactive minderals in deep sea vents
- it is a more concentrated smaller area
- acetic acid may have acted as a catalyst
who was stanley miller?
he tried to generated complex compounds from molecules present on early earth. Combined CH4 NH3, H2, H20, and electricity (detail of the experiment is in the book)
why did nothing happen in Stans experiment? what did he to to help?
- molecules were too stable to do anything,, he added electric shock
what happened when stan applied the shock in his experiment?
it turned red and contained some toxic chemicals that are important to more complex life, and it also contained amino acids which are the building blocks for proteins
what theory did stans experiment support?
prebiotic soup model
what happened when molecules became more complex in chemical ev.
complex molecules could self replicate, catalyze chemical reaction
what was the 1st molecule responsible for life?
RNA (less stable than dna so it is more reactive)
what do organic molecules contain and what are they?
Carbon,, building blocks of all life on earth
what do nucleotides consist of?
- phosphate group
- 5 carbon sugar
- nitrogenous bas
DNA and RNA are the same except…
you lose an oxygen molecule in DNA
whar are the pyrimidines>
cytosine, uracil, thymine
what are the purines?
guanine and adenine
what were the earliest nucleci acids
DNA and RNA
nucleic acids are made up of…
nucleotides
what did the hydrothermal vents do and why>
combined ribose and metals because the vents contained metals
hw did RNA ucleotides join together?
phosphodeister linages
what can catalyze the nucleotides combining?
metals in the vents
RNA carries information in the sequence of…
it’s bases
RNA can serve as it’s own…
template for replication
what can RNAs do? ( RNA is the swiss army knife of molecules)
- store information and replicate (mRNA and tRNA
- form bonds between amino acids (rRNA)
-edit and regulate other nucleic acids (miRNA)
DNA really can only…
store information
self replicating RNA is capable of
biolgical evolution
fatty acids combine to form
phospholipids
RNAs combine wiht fatty acids into
the 1st protocell
when new species gradually compound to produce higher taxonomic groupes
the same process that causes speciation (evolution)
microevolution happens over
years to centuries
macroevolution occurs over
millenia
what is a good analogy to describe species
islands, they appear al different from the surface, but underneath they are deepy connected
what are the two methods biologists use to study macroevolution>
phylogenetics and fossil record
cell theory and the theory of evolution by ntural selec assume that
all species trace back to a common ancestor
what is te tree of life?
the most universal of all phylogenies
literally a family tree of organisms
what does the tree of life do?
describes the genealogical relationships of organisms
what is at the bases and nodes of the tree of life
a single common ancestor (bases)
single common ancestor of branches (nodes)
what is phylogeny?
an actual genealogical relationships among all organisms
what does a phylogenetic tree do?
used to show relationships between species and their ancestry, and estimate their age
what do branches sharing a node show?
species/groups that are closely related
what do branches that do not share a node show?
distantly related groups/species
what are the practical applications of phylogenies?
- identify species
- elucidate origins
- identify homologies
what do branch lengths mean?
-they show evolutionary time,, they are arbitrary
-genetic difference
-extent of evolutionary time between nodes
what makes for a bad phylogenetic tree
when the noses have more than two groups coming off of them
how do biologists estimate phylogenies
create a charcter matrix
what do you do to create a character matrix:
- determine characters to compare
- choose an outgroup
what does an outgroup do?
they determine if a trait is ancestral or derived
what are synapomorphies
same as a homology,, characters that are present in two or more taxa
how are macroevolutionary groups inferred?
morphological or dna data
ancestral traits=
common ancestor
derived trait=
descent with modification
species are grouped together based on
derived traits that they share in common
synapomorphies are used to define
monophyletic groups and homologies
what do homologous traits do?
they function similarly between two species due to common ancestry
where will homologous traits be found?
in any intermediate species as well as the common ancesty
what are hox genes
similar to homologous traits and synapomorphies
what is homoplasy?
similar traits due to something other than shared ancestry
what is homology
similar traits die to shared ancestry
what is homoplasy caused by?
convergent evolution
what does homplasy produce?
polyphyletic groups
homoplasious traits lilke body shape, look, and function can be similar between two species due to…
convergent evolution
convergent traits will be … from intermediate species as well as the common ancestor
absent
what is a polyphyletic group?
an unnatural group that does not include the most recent common ancestor
-viperid snakes are generally sluggish, thick body ambush hunters
- elapid snakes are quick active slender active hunters
- the A snake looks like viperid but is an elapid because it is in a similar environment to some of the viperids this is an example of…
convergent evolution
what is parsimony used for?
- distinguished similarity die to homology and similarity due to homoplasy
what is parsimony?
the pattern is the one that requires the fewest changes
what does parsimony assume?
homology is common and homoplasy is rare
what happens when a trait is lost?
may produce paraphyletic groups
when is a trait lost?
when a derived trait is lost in a descendent species
what is a paraphyletic group?
a group that includes an ancestral population and some of its descendants but not all
process of fossilization
- organism dies
- must be quickly buried
- soft tissues decay and hard tissues mineralize
- sediment is compacted into rock that is later exposed by erosion
other ways things can fossilize
covered in volcanic ash
tar pits
amber/sap
freezing
drying out/dessication
why are fossil records biased?
what is habitat bias?
locations of fossils,, sediment is important to fossilization so areas that do not have a lot of sediment will not have a lot of fossils
taxonomic bias
mineralization can be important and the record is biased to species that have harder tissues
ex) shark teeth are often found, but because they are mainly cartilege there are not many
temporal bias
older fossils are more likely to have been destroyed so it is biased toward younger fossils that are more easily discoverable
abundance bias
some species are more abundant than others and bc fossilization is rare the record is more biased to more abundant species
history of ife is divided into:
eons, eras, and periods
wat is the earliest era?
precambrian era
what happened during the hadean eon?
the earth formed
what occurred during the archarean eon?
unicellular life formed
what happened during the proterozoic eon?
o2 and multicellular life
when did the earth form?
4.6 billion years ago
when do fossils estimate life began on earth
3.5 billion hears ago
what was the first life form on earth? and whta were they
stromatolites (layers of algae and cyanobacteria that formed over thousands of years)
what is the phenerozoic eon?
coverd the rest of life
what was the paleozoic era
land animals and plants appear and begin to diversify then they are almost wiped out at the end of the permian period
what is the mesozoic era?
dinos and gymnosperms are dominant
what was the cenozoic era
mammals birds and angiosperms (flowering plants) are dominant
why are the continents constantly in motion?
plate tectonics
when did pangea form?
the mesozoic era
why is pangea important?
it explains why the same fossils can be found oceans apart
who is carl linneaus?
figured out how to name branches,, (1735) formed the two part name
how are organisms named?
genus and then species
scientific names are always written in
italics
the genus names are always written
capitalized
the species names are not
capitalized
classifications in descending order
domain,, kingdom,, phylum,, class,, order,, family,, genus,, species
go study the examples of the names on the powerpoint
now
families always end in..
idae
what is adaptive radiation?
(follows mass extinction)
- adds branches to the tree of life
- rapid exploitation of many different niches
- when a single lineage rapidly produces many descendent species with a wide range of adaptive forms
what are two processes that can happen to the tree of life?
growth and pruning
what is an example of small scale adaptive radiation?
speciation across islands
what is adaptive radiation?
when a single lineage splits into may descendent species with different adaptive features
what do adaptive radiations exhibits?
monophyly, rapid speciation, and ecological diversificatin
what causes adaptive radiation?
ecological opportunity and morphological innovation
morphological innovation
when mutations occur which creates new morphologies that allow exploitations of new niches and resources
(evolution of a new trait)
sepection promotes…
new species that can exploit new resouces
ecological opportunity
availability of new resources and habitats
ecological opportunity allows for
morphological innovation
example of morphological radiation
angiosperm radiation (the speciation of flowers,, different flower types)
example of large adaptive radiation?
the Cambrian explosion
hat happened in the Cambrian explosion>
simple bilateral sponges morphed into larger complex animals.
early life was all…
unicellular
what was the firsy multicellular animals
ediacaran fauna (sponges and corals
camrbian species examples:
sponges, jellies,
what came before cambrian>
edicarian
what triggered the cambrian evolution
- higher o2 levels in the atmosphere
- makes aerobic respiration more efficient, which supported larger bodies - rise of algae
- high quality food source for early animals,, better reproduction quality and better growth - evolution of predation
- selection for defensive adaptations drove morpho. divergence - new niches present more niches
- once animals could move off of the seafloor, they could exploit new iches - hox genes
- important during the development and body plans of an organism
hox genes
may have been a morphological innovation that promoted the cambiran evolution
when does mass extinction occur
when at least 60% of species on earth go extinct within 1 million years
what is a mass extinction
temporary catastrophic events
what id background extinction
normal rate of extinction
what was the biggest mass extinction?
the end- permian extinction (90% of species on earth went extinct) wiped out multicellular life
most recent mass extinction
end cretaceous extinction,, wiped out the dinos and gradually mammals begin to dominate the earth
- mos tlikely caused by the chichxulub metoer
why did the dinos go extinct
- they were thought to be mesotherms so they
are we in a mass extinction and why?
yes,
- habitat loss
- pollution
- overexploitation
- etc.
what are the three domains
- bacteria
-archaea - eukarya
what are eukaryotes
plants, fungi, and animals
what were the contents of the oldest fossils?
bacteria (3.46 billion years ago)
characteristics of bacteria and archaea
- microscopic
- unicellular
- ## prokaryotic
what is the difference between a prokaryote and eukaryote
prokaryotes lack a membrane bound nucleus
(not as many organelles) go look at the pictures on the slides
how are bacteria and archaea diferent
- different protein synthesis
- different ribosomes
!!! bacteria have a unique compound called peptidoglycan in their cell wall
bactera have what type of link?
ester llink
archaea have what type of link?
ether link
what are prokaryotes?
small unicellular flagellated with circular genomes and simple proteins
what are the characteristics of archea cell walls?
they have ether linkages and phospholipids (little peptidoglycan)
what are the characteristics of bacterial cell walls?
they have ester linkages and peptidoglycan
peptidoglycan is associated with…
bacteria
what does a blue gram stain indicate?
peptidoglycan
what does a pink gran stain indicate?
phospholipids
Blue gram
Bacteria
why do biologists study prokaryotes
- biolofical impact
- extremeophile nature
- medical importance
- commercial value
what is biological impact?
- prokaryotes are the earliest forms of life (euks have only been around for half of that time)
- millions of species have evolved to fill every conceivable habitat
- there is a high abundance of prokaryotes
(tells us about how life began) - habitat diversity (extreme and normal environments)
what constitutes an extremeophile
can life in acid, salt, ice, high heat, and anoxic habitats
why are extremeophiles important?
important for studying the origin of life, extraterrestrial life implications, and commercial applications
prokaryotes were the first to introduce what to the atmostphere?
oxygen
pros run what cycle?
global nitrogen cycle
procaryotes are the only organisms responsible for what
atmospheric nitrogen
mutural paristism
nitrogen fixing bacteria in a plant that help the plant grow
what is the medical importance of pros?
- pros constitute a large portion of your body
- they aid normal functions like digestion but some can be pathogenic and can contribute to antibiotic resistence
what are some commercial values to pros
- create biofuels and used in bioremediation
