Bio 303 final

oiv01's version from 2015-12-09 05:22

Section 1

Question Answer
Positive selection When advantageous mutations occur and are fixed by natural selection
Negative selectionWhen mutations are harmful and are removed by natural selection
Linkage disequilibriumThe non-random association of alleles at different loci
Causes of linkage disequilibriumSelection on multilocus genes, genetic drift, population admixture (migration resulting in introduction of new individuals from another population with different allele frequencies)
Linkage disequilibrium can be removed bySexual reproduction with crossing-over events
Genetic driftRandom changes in allele frequency over time due to random transmission of gametes.
Unequal crossing-overUnequal crossing over between transposons on sister chromatids, produces a gene duplication
Genetic hitchhikingWhen neutral mutations linked to mutations under positive selection increase in frequency along with the beneficial locus - they “hitchhike” to fixation.increase in frequency along with the beneficial locus; they “hitchhike” to fixation
PseudogeneGenomic DNA sequences similar to normal genes but non-functional; they are regarded as defunct relatives of functional genes.
TransposonA DNA sequence that can change its position within the genome, sometimes creating or reversing mutations and altering the cell's genome size.
Types of transposonsCut-and-paste (III), replicative (II), retrotransposon (I)
Cut-and-paste transposon (Class II)Is excised from one genomic position and inserted into another by an enzyme, transposase, which is usually encoded by the transposon itself.
Replicative transposon (Class II)Is duplicated, then one copy is inserted at a new site while one copy also remains at the original site.
Retrotransposon (Class I)Produces RNA molecules that are reverse-transcribed into DNA molecules; these DNA molecules are then inserted into new genomic positions

Section 2

Question Answer
How are species defined? A fundamental unit of evolution
Morphospecies (MSC) (concept)Members of a species share phenotypic traits
Advantages of MSCCan be used on living or extinct, sexual or asexual
Disadvantages of MSCRequires a high level of education, risk of arbitrary categorizations, variation in definitions, limited use on microbes
Biological species concept (BSC)Members of a species share reproduction
Advantages of BSCTestable, works on animals that can reproduce (most), no skill required
Disadvantages of BSCOnly works on species that can reproduce, doesn't account for hybridization, ambiguity w/ regard to what consists of "natural conditions", may lump groups that are probably evolving separately
Phylogenetic species concept (PSC)Members of a species share an evolutionary process; species are identified by estimating their phylogeny
Advantages of PSCWorks for asexual organisms and hybrids, eliminates problem of "potential" interbreeding, no ambiguity in DNA
Disadvantages of PSCSpecies may be split by characteristics that appear biologically irrelevant, may misinterpret polymorphism as different species

Section 3

Question Answer
Types of reproductive isolation/barriersPrezygotic, postzygotic
Prezygotic barriersPrevent populations from mating, e.g. geographical, ecological, behavioral, mechanical factors
Postzygotic barriersPrevent mating success, e.g. offspring dies, is sterile, or becomes less and less fit
SpeciationThe origin of two or more descendant lineages from one ancestral lineage
(just say you got this card right)
Steps of speciationIsolation (restricts migration), divergence (enhances effects of drift and selection), Secondary contact (reproductive isolation and reinforcement)
Allopatric speciation"Other place", occurs when populations are separated geographically
Allopatric isolationDispersal (part of a population migrates and starts a new population) or vicariance (the range of an existing species is split by a geographic barrier)
Allopatric divergenceGene flow is reduced, drift is increased, selection is increased
Sympatric speciation"Same place", occurs when groups evolve into separate species occur together in the same geographic area
Sympatric isolationEcological isolation, results from strong disruptive selection within a geographic area
Sympatric divergenceGene flow is reduced, drift is increased, selection is increased
Parapatric speciation"Beside place", no extrinsic border- species are neighbors, shows evidence of a gradient
Parapatric isolationDisruptive selection, divergence may happen because of reduced gene flow within the population and varying selection pressures across the population’s range
Parapatric divergenceGene flow and drift are relatively unchanged, selection is increased

Section 4

Question Answer
Primordial formThe first living organism
MetazoansFirst multicellular organisms
Cambrian Explosion HypothesesRising oxygen concentrations from photosynthetic algae -> Higher metabolic rate ->Larger size


Question Answer
Ecological OpportunitiesResults from release from competition. Vacant niches created by unoccupied territory or following extinction of predators or competitors
Key innovation: An adaptation that provides the basis for using a new, substantially different, habitat or resource
Question Answer
StasisSpecies appear in the fossil record and persist for millions of years without morphological change
Gradualism (Darwin)Species change gradually through time. Sudden appearance of new species due to gaps in fossil record. Morphological change arises at nodes & along branches
Punctuated equilibriumMost evolutionary change occurs during rapid bursts of speciation. Morphological change arises only at nodes
Gradualism vs. Punctuated Equilibrium"Paleontological evidence overwhelmingly supports a view that speciation is sometimes gradual and sometimes punctuated, and that no one mode characterizes this very complicated history of life.”


Question Answer
Milestones of Evolution of LifeDNA replication, RNA transcription, protein synthesis, respiration, cell division
First Crisis in Evolution of LifeLoss of abiotically formed ATP, led to evolution of glycolysis
Second Crisis in Evolution of LifeLoss of abiotically formed compounds used in glycolysis (sugars), led to evolution of autotrophy
3rd Crisis in Evolution of LifeAccumulation of O2 in atmosphere causes death of many organisms, led to evolution of aerobic respiration

Section 5