Biology :Evolution key terms
Complete List of Terms and Definitions for Biology :Evolution key terms
| Terms | Definitions |
|---|---|
| Classification | |
| Mimicry | Imitative behaviour |
| Symplesiomorphy | shared ancestral state |
| disruptive selection | favors extreme phenotypes |
| P.S. I love you! | |
| Inheritance/markers |
Mendelian (autosomal loci) -allozymes (proteins) - low levels variation (looking at protein) -microsatellites - neutral.. don't normally encode Uniparental 1)organellar DNA (no repair mechanisms... mtDNA/cpDNA -usually higher mutation rate 2)some sex chromosomes (ie Y chromosome) |
| directional selection | common - shifts phenotypes |
| Divergence | Accumulation of differecne between groups. |
| Dorudon | -fully aquatic using tail propulsion-pelvis was disconnected from the vertebral column and the hindlimbs barely projected from the body |
| Variation and Selection |
DNA polymorphisms -non-synonymous (dN)... changes a.a. -synonymous (dS).. do not change -dN/dS ratio tells us if evolution at a locus is due to: 1)drift... dN/dS=1 2)negative/purifying selection (<1) 3)positive/diversifying selection (>1) -"important" loci evolve slowly (low dN/dS) -neutral or unimportant loci evolve quickly via drift -few loci, diversifying selection (host antibodies, antigen proteins in viruses) |
| Unisexual Reproduction |
..there are 3 modes... Parthenogenesis -most common... asexual cloning Gynogenesis -Male sperm interacts with egg, trigers development, but does not fertilize -male genetic material not in zygote -goldfish/guppies Hybridogenesis -different species "mates" with female -genetic material is incorporated, but is not passed on... only female information passed on **divergence is 2%/million years b/w unisexual and closest relative ***nucleotide diversity (amount variation) increases in sexuals along with sequence divergence.. but this is not the case with unisexuals |
| Extinct | species that no longer exist |
| uniformitarianism | geological processes are uniform and have always occurred in earths history |
| Essentialism |
Aristotle, Ancient Greeks, The great chain of being |
| how are polygenic traits measured | quantitatively, numerically |
| Haplodiploidy | females more closely related to sistersthan to daughter (r = 0.75) |
| Character (characteristics) of organism | feature or trait |
| Chemical Selection | -New protobionts with enhanced enzymatic or replicating abilities would persist over those without-RNA probably served both an information storage and catalytic role |
| Behavioural adaption | Birds migrate south during winter |
| convergent evolution | organisms not closely related, resemble each other cuz they have responded to similar environments |
| macroevolution | Evolutionary change above the species level, including the appearance of major evolutionary developments, such as flight, that we use to define higher taxa. |
| the sun | came 9 billion years ago |
| Homologous Stucture | similar structures among related species |
| comparative embryology | evolutionary link based upon similar embryological development |
| homologous structure | structure that have different mature forms in different organisms but develop from the same embryotic tissues |
| paedomorphosis | a sexually mature adult that retains features that were juvenile structures in its evolutionary ancestors. humans are paedomorphs of chimps |
| Stabalizing selection | More of the same less extreams |
| Gene Pool | the combined genetic information of all the members of a particular population (all the different traits of a breeding population) |
| Charles Darwin: life |
-Born in England, 1809 -Started off as a medical student to follow in father's footsteps; didn't like the inhumanity of surgery (pre-anesthetic), so switched to studying as a minister. -Final career: as a naturalist on the HMS Beagle |
| Rhipidistians-lobed fin fishesIchthyostega- primitive amphibians | similarities: -five supporting basal bones in pelvic fin/hind limb-dermal skull bones of braincase-lateral line system of braincase-similar bones in skulls |
| Lamarck | Was correct in saying that evolution occurs, but incorrect in saying that it occured by acquired characteristicsSet the stage for Darwin by changing society's views |
| polymorphism | having multiple alleles of a gene within a population |
| Speciation and biogeography |
130spp Chameleons -did they speciate as Gondwana broke up? Hypothesis: If chameleons speciated as supercontinent broke up, order of speciation should correspond to order of break up -is allopatric speciation, but not vicariance!! -no single group in any clade -therefore dispersal RATITE BIRDS -originated on southern supercontinent -vicariance event -evolved in isolation through genetic drift, mutation and selection KEEP IN MIND>>... Organisms can spread out from their centre of evolutionary origin even if the continents are not connected, but limited by -the diserpsal capacities oft he organisms themselves (some fly, others walk) -the extent and types of barriers in their way -time -climate AND>>>.. Organisms can go extinct even in areas where they originated -eg. camels evolved N.America -no longer found here distribution is a dynamic phenomenon, changing through time - glacial events - everything new in recolonization Continents were not always in current configuration and clmate has changed. It is amazing that many aspects of distribution still bear the marks of ancient lineage originations and continents given the amount of time that has passed |
| big bang | major explosion 15 billion years agoresulted in the formation of the universe |
| Linked Loci |
-are loci on the same chromosome -they are inherited as a package -fewer map units separating them means less recombination (closer they are, the more likely they stay together) linkage equilibrium: loci are in linkage equilibrium when the genotype at one locus is independent of the genotype at a second locus -if A+a are 2 alleles for a locus, it is indepenent of whether it combines with allele B or b at a different locus linkage disequilibrium: loci in linkage disequilibrium means a non-random association between genotype at one locus and of genotype at a second locus -genotype at locus A affects genotype at locus B |
| artificial selection | The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits. |
| analogous structures | unrelated animals have organs with similar functions, yet are very different in structure and formex: butterfly wing and bird wing |
| polyploid | any species with multiple of the normal set of chromosomes. occurs when mitosis and meiosis makes a mistake. polyploids can mate w/ other polyploids and could form a seperate species. |
| Transcription (protein synthesis) |
-DNA unzips & complementary RNA transcribes the base pair sequence (uracil replaces thymine) -RNA travels our of nucleus to ribosome |
| divergent evolution | one species splits and each fraction different selective pressures - gradually evolve into different species |
| gene flow | esponsible for variation, it is an agent of evolution caused by the introduction of new genes into a population |
| Evidence for Evolution: other disciplines of biology |
Examples Include: Molecular Biology and Genomics 1. Shared DNA sequences: degree of similarity (more similarity = more recent divergence) 2. Shared non-coding DNA sequences: nucleotide divergence 3. Homologous Structures: five digit limbs in different proportions in mammals (similar morphology, different function) 4. Vestigial Structures: salamander non-functional eyes in dark caves, hind Limb Buds in fetal whales, tail in human fetuses 5. Biogeography: similarity of species correlated to geographical proximity, similarities between mockingbirds on Galapagos Islands |
| Previous Tree of Life | prokaryotes, protista, fungi, plants and animals |
| I definately know I will not be dressing up like snooki! | |
| Evolution | The idea that explains the change in species over time |
| evolution of female preference - benefit | no direct benefit |
| Absolute vs Relative Fitness |
For each genotype: -average absolute fitness W -relative fitness w -by definition, best genotype has w=1 -all others w=W/Wmax w=1 = zero selection w = 0.75 = 25% selection s=1-w -the rate of genetic change under selection depends on relative, not absolute fitness -relative fitness defines the fitness of genotypes relative to the best genotype and it defines the selection coefficient "s" |
| Mutations | occur constantly at a low rate and under normal conditions and can produce totally new alleles for a trait. Many are HARMFUL and are slow to be eliminated by natural selection. |
| genetic variation A | mutation in the DNA,crossing over independent assortmentoverproduction of offspringstruggle for existence |
| Monkeyflowers and QTL |
M. cardinalis and M. lewisii hybridized in lab M.c pollinated by hummingbird (red, long tube) -M.l pollinated by bee (need landing pad).. poor eyesight What genes are responsible for differences in floral traits? How many genes? Different effects? TWO SCHOOLS OF THOUGHT Fisher: alleles driven to fixation by natural selection have subtle effect on phenotype (most believe this) Orr: some of the fixed alleles have large phenotypic effects Used QTLs to determine what the effects were of different genes -took parental species.. F1 hybrids selfed.. F2 -many many types of F2 hybrids... huge range -screened 66 marker loci fixed in each species -markers randomly distributed throughout genome -if QTL and marker linked.. linkage disequilibrium (see correlation b/w trait and allele) -if unlinked, linkage equilibrium (no correlation) -association /w marker genotype and individual's phenotype -If M (marker) and Q (candidate gene) linked, what would F1 look like? -What if M and Q are not linked? In F2, if marker is linked to a QTL, phenotype will vary with marker presence/absence -If marker is not linked, phenotype will remain the same regardless of marker -This example supports Orr's view -Changing single allele at single locus makes M.lewisii 70 times more attractive to hummingbirds, and only 6 times less attractive to bees |
| Parallel evolution | evolution of similar traits in closely related species in response to the same selective agent |
| Cline | a graded series of changes in some characteristics of a species, coorelated with some gradual change in an environmental factor across the geographic range. ex: ear length in wolves. |
| geographic distribution | how plants and animals are organized in a given area |
| Adaptive radiation | a type of divergent evolution in which an ancestralspecies evolves into many different species to fit a number of diverse habitat. |
| Multidimensional species concept | A divsion of the BSC, dealing explicitly with populations that are allopatric and/or allochronic.By this definition, if a population has the potential to interbreed, then they are classified as the same species. |
| Possible heterozygote advantage: cystic fibrosis |
People with cystic fibrosis lack functional CFTR protein (found in lungs and intestinal tract), are susceptible to Pseudomonas bacteria (lung infection), early death However! Heterozygotes are protected against Salmonella typhi (typhoid fever) infiltration in the gut: 86% fewer bacteria. Thus, across 11 European countries, severity of typhoid outbreaks is correlated with frequency of ΔF508 in the next generation. (Allele is favored during times of typhoid outbreak.) |
| Reversal + example | reversion to an ancestral form of acharacter due to selection or mutation. Example = Fish to Mammal to Dolphin |
| Adaptive Value (Adaptation) | Any trait that helps an organism survive and reproduce under a given set of environmental conditions |
| Fossil record challenges | most organisms consumed by animals or decomposers, sediments form in any one place episodically, fossils (rock ) must persist for millions of years, and rock must be accessible to paleontologists |
| Reproductive isolation | In order for speciation to occur, this is required. |
| primitive atmosphere | consister of the gases N2 CO2 water vapor H2 CO O2 was not prsent in the early atmosphere |
| biological species concept | Definition of a species as a population or group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but are not able to produce viable, fertile offspring with members of other populations. |
| immutability of species | species, once present, do not change over time |
| "ontogeny recapitulates phylogeny" | the development of an organism is a replay of the evolutionary history of the species |
| Second category of radiations | Second category consists of those that arise from annexation of new space via key innovations. It should be obvious that these events both increase N*max and N*, but without affecting the futures of existing lineages |
| Somatic Cell line | cells that make up your body so mutations in those cells aren't passed onto the next generation |
| Gene flow definition | the transfer of alleles of genes from one population to another |
| What are the five conditions to maintain genetic equilibrium? |
Random Mating Large Population No movement in or out of the population No Mutations No natural selection |
| Adaptations are often trade-offs! |
Horn size and survival of offspring (higher survival from bigger horned sheep)... but big horns are targeted by hunters... "Decline of the fittest" Flower number and size... Why do male and female flowers have a similar appearance? 1)for female flowers to attract bees (with pollen) -stabilizing selection male and female flower similar size 2)female flowers resemble male flowers most frequently visited by bees? -directional selected for larger flowers Found that bees prefer larger flowers, so why aren't female flowers larger than the male flowers A trade-off exists between flower size and number of flowers per inflorescence For flowers, more is better, but if small display has to still attract bees... CONSTRAINTS... -suchsiapollinated by hummingbird... different colors!! flower color changes to indicate when hummingbird shold come (when it is nectar producing)??? Is it a pollinator cue?? NO! -red attracts hummingbirds to flower to pollinate receptive, green flowers?? no... Physiological constraint?? YES! -pollen germination and tube develoment -from day 1 to day 4, 0-100% of tubes reach ovary |
| microevolution is a response to natural selection | Natural selection acts on an individual in one generation, and the result is the evolution of the population between generations. |
|
Determine Increase, Decrease, No Change (I, D, NC) in rate of random genetic drift for the following: a. change in mutation rate from .001 to .000001 per gamete per generation b. an increase in the rate of migration into a popn c. a change |
a. I (mutation slows RGD) b. I c. I d. I e. I look in book |
| uniformatariansim. who came up with it. | slow ongoing processes are responsible for present-day geologic features. lyell. |
| Stickleback have a rapid evolution of what traits? | armor and life history features |
| how are mutation rates measured? | # of independent origins pre gene per unit time. |
| what's the main question of irreducible complexity? | how can a complex structure be adaptive during transitional stages? |
| What are the 8 patterns of evolutionary change? | 1. most characters are homologous2. homoplasy is common3. rates of evolution differ (mosaic)4. evolution is gradual5. change form = change f(x)6. ontogeny - more similar as fetus7. need changes in development8. many show adaptive radiation |
| What are two methods for estimating levels of gene flow? List 3 disadvantages that each method has. |
Direct methods: For example, mark and recapture species Use marker traits/alleles -Migration does not equal gene flow -May not represent other populations, seasons, environments -Ignores rare, long distance events most difficult to detect Indirect methods: Infer gene flow from level of genetic differentiation -Assumes Fst reflects current gene flow: One can calculate gene flow for species that have been completely isolated but in the past were connected -Assumes island model of gene flow; unrealistic for many species. Isolation by distance is more realistic -Genetic markers are not under selection: selectively neutral; when tracking animals and where they end up using genetic markers if that genetic marker is under natural selection this will skew their results as it will affect Fst High Fst will result if favoring different alleles in different populations (+the genetic marker) is selected for Low Fst will result if selection for the same allele (our genetic marker) is favored for in each population *This can be used to identify traits under natural selection |
| What is a common descent? | A single "tree of life" that links all organisms |
| In what rare cases are somatic cell mutations inhereted? | When it is in vegetative propagation or asexual reproduction. |
| reduced pelvic expression tends to be greater on the | left side, Pitx-1 gene trying to fix the problem when spines are absent |
| How can the origin of any specied be described? | In terms of rates of origin and loss of species. Extinction rates tend to regular within lineages. |
