Exam 2 Powerpoint concepts Flashcards
what makes populations different?
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=
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
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?
what are the benefits of the PSC?
- can be applied to any pop
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?
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
what does autopolyploidy result in?
sterile offspring due to gametes with uneven chromosome number
how do autopoly, and allopoly preven interbreeding
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.
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
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?
what percentage of organismal matter do these 4 atoms make up?
how were the first molecules created?
what does the formation of complex compounds require?
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…
what did the hydrothermal vents do and why>
combined ribose and metals because the vents contained metals
hw did RNA ucleotides join together?
what can catalyze the nucleotides combining?
metals in the vents
RNA carries information in the sequence of…
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…
self replicating RNA is capable of
fatty acids combine to form
RNAs combine wiht fatty acids into
the 1st protocell