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BIO102 UNIT 1
unit 1: evolution
| Question | Answer |
|---|---|
| What 3 revelations make up our understanding of Earth? | 1. how continents have changed through geologic time, 2. how climate has changed over geologic time, and 3. how organisms changed through geologic time |
| Who proposed the continental drift theory and when? | Alfred Wegener in 1912 |
| What was the supercontinent Earth shifted from? | Pangea |
| What 2 climate states did Earth have? | 1. ice-house (like today) and 2. hot-house (Mesozoic) |
| Paleoclimate can be inferred from sediments. What can we infer from coal? | Wet terrestrial climate |
| Paleoclimate can be inferred from sediments. What can we infer from rock salt? | Dry terrestrial climate |
| Paleoclimate can be inferred from sediments. What can we infer from ice? | Glaciers or cold climate |
| What theory was created to understand how organisms have changed through geologic time? | Theory of Natural Selection |
| Who do we credit for an early view of evolution? | Jean Baptiste Lamarck (Lamarckism) |
| What WAS the early view of evolution by Lamarck? | environment influences your characteristics or traits / acquired genes cannot be inherited |
| What is the law of faunal succession? | Species change over time (faunal turnover) |
| Who is the founding father of paleontology? | George Cuvier |
| What did the founding father of paleontology establish? | He established extinction as a fact |
| Who independently discovered the theory of natural selection? | Alfred Wallace Russell (co-founded with Darwin in 1858) |
| What was the Wallace line? | Faunal divide of Asian and Australian species in Indonesia |
| What is stratigraphy? | The layering of rock sequences that allow us to track changes in environments and organisms through time |
| What is the law of superposition (Steno's law)? | Younger sediments overlay older sediments |
| Why was proving extinction so important? | The world was not as known, dinosaur discoveries by 19th century scientists: Mantell, Owen, Marsh, Cope, etc. |
| How many observations did Darwin have? | Four |
| How many predictions did Darwin have? | Two |
| What is variation? | Darwin's first observation: members of a species differ from each other |
| What is heritability? | Darwin's second observation: all organisms are able to pass some traits to their offspring |
| What is reproductive fitness? | Darwin's third observation: the "fittest" is an individual that is best adapted to survive (number of offspring that survive to reproduce |
| What was Darwin's fourth observation? | Species produce more offspring than the environment can support |
| Darwin's first prediction states that if these observations are true, over time...? | The population will resemble the organisms that have the most offspring |
| Darwin's second prediction states that populations change more rapidly (evolution is faster) if...? | If organisms are lost from the gene pool before they can reproduce |
| What is positive selection? | Natural selection that increases the frequency of a favorite allele |
| What is negative selection? | Natural selection that decreases the frequency of a harmful allele |
| What is balancing selection? | Natural selection that keeps an allele at an intermediate frequency, maintaining multiple alleles in the population |
| What is stabilizing selection? | Negative selection against extreme values for a specific character |
| What is directional selection? | Positive selection for a character value that is above or below the average value for that trait |
| What is disruptive selection? | It selects for extreme character trait values, or against intermediate values |
| Can individuals evolve? | NO, only populations and species can evolve biologically |
| What is a species? | A group of individuals that can exchange genetic material through interbreeding or share alleles through reproduction |
| What does a gene pool consist of? | All the alleles present in all individuals in a species |
| What is a population? | An interbreeding group of organisms of the same species living in the same geographic area |
| What mechanisms can cause the evolution of populations? | Evolution occurs when the allele frequencies of a population change over time |
| What is the founder effect? | A type of genetic drift, when few individuals become isolated from the larger population and establish a new population |
| What is the bottleneck effect? | A type of genetic drift, sudden change in the environment reduces the size of the population leaving only a small percentage of the initial allele diversity |
| What is nonrandom mating? | Individuals preferentially choose mates according to their genotypes |
| Does sexual selection increase or decrease an individual's chance for survival? | Decrease |
| What is artificial selection? | A type of directional selection where successful genotypes are selected by the breeder, not through competition |
| What is inbreeding depression? | A reduction in the offspring's fitness caused by homozygosity of deleterious recessive mutations |
| What is a gene? | A nucleotide sequence in DNA that codes for a protein in a specific location on the chromosome |
| What is an allele? | A variant of a gene in the same place among chromosomes for a trait |
| What is a genotype? | The genetic makeup of an organism |
| What is a phenotype? | The organism's expressed traits |
| Who used cross-breeding of pea plants to discover the basics of heredity? | Gregor Mendel (1822-1884) |
| What diagram is used to predict genotypes? | Punnett squares |
| What is the allele frequency formula? | Copies of an allele/total alleles in population = allele frequency |
| What is evolution? | A change in allele or genotype frequency from one generation to the next |
| What are the 2 equations for genotype frequency? | p + q = 1 and p^2 + 2pq + q^2 = 1 |
| In the genotype frequency equation which allele does p represent? | p = frequency of the dominant allele |
| In the genotype frequency equation which allele does q represent? | q = frequency of the recessive allele |
| What does p^2 represent in the second genotype frequency equation? | p^2 = frequency of the homozygous dominant genotype |
| What does 2pq represent in the second genotype frequency equation? | 2pq = frequency of heterozygous genotype |
| What does q^2 represent in the second genotype frequency equation? | q^2 = frequency of homozygous recessive genotype |
| What is molecular evolution? | The process of change in the genetic material of organisms over time |
| What is the biological species concept (BSC)? | Species are groups of interbreeding populations that are reproductively isolated from other groups |
| What qualifies an individual to be a member of a species? | They must be reproductively compatible and produce offspring that are also fertile |
| What is reproductive isolation? | Barriers that prevent members of 2 species from interbreeding and producing viable, fertile offspring |
| What 2 kinds of barriers cause reproductive isolation? | Prezygotic and postzygotic |
| What are prezygotic barriers? | Isolating factors that prevent fertilization from taking place |
| What are postzygotic barriers? | Isolating factors that lead to the failure of the fertilized egg to develop into a fertile individual (genetic incompatibility) |
| What are the 6 prezygotic barriers? | Geographic, temporal, ecological, behavioral, mechanical, and gametic |
| Describe the geographic and temporal prezygotic barriers | Geographic: the physical environment can isolate gene pools; Temporal: the timing of activity of reproduction does not overlap |
| Describe the ecological and behavioral prezygotic barriers | Ecological: closely related species occupy different niches within the same area; Behavioral: courting rituals that are species specific |
| Describe the mechanical and gametic prezygotic barriers | Mechanical: structural variation between species prevent reproduction; Gametic: gametes are incompatible and do not fuse to form a fertilized egg |
| What are the 3 postzygotic barriers? | Reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown |
| Describe the reduced hybrid viability postzygotic barrier | Reduced hybrid viability: hybrid offspring fails to develop properly or dies early |
| Describe the reduced hybrid fertility postzygotic barrier | Reduced hybrid fertility: hybrid offspring survives and grows, but is sterile (gene flow ends) |
| Describe the hybrid breakdown postzygotic barrier | Hybrid breakdown: first generation (F1) hybrids are viable and fertile but F2 have problems (or later generations) |
| What is the morphological species concept (MSC)? | Distinguishes species by body shape or other structural features |
| What is the ecological species concept (ESC)? | Defines species by its ecological niche (how members interact w/nonliving and living parts of the environment) |
| What is the phylogenetic species concept (PSC)? | All members of a species all share a common ancestry and fate |
| What is hybridzation? | The process of an organism breeding with an individual of another species |
| What are hybrid zones? | Regions in which members of different species meet and mate |
| What are the 2 types of speciation? | Allopatric speciation and sympatric speciation |
| Describe allopatric speciation | When populations become geographically isolated, preventing gene flow and leading to the formation of new species |
| Describe sympatric speciation | Where a new species arises from a surviving ancestral species while continuing to live in the same area |
| What is dispersal? | When individuals colonize a new area |
| What is vicariance? | Where a geographic barrier arises, a population splits into 2 populations |
| What is a type of allopatric speciation? | Peripatric speciation |
| What is peripatric speciation? | A type of allopatric speciation where a small population evolves into a new species, descent from its main ancestor |
| Can speciation occur without natural selection? | Yes, speciation can still happen to due to random processes, especially in isolated or small populations (genetic drift) |
| What is punctuated equilibrium? | The hypothesis that evolutionary development is marked by isolated episodes of rapid speciation between long periods of little or no change |
| What is gradualism? | Evolution happens slowly and continuously over long periods of time |
| When did the first single-celled prokaryotes appear? | 3.5 billion years ago (3.5 Ba) - Archean era |
| What are stromatolites? | Fossilized layered structures of bacteria and sediment |
| When did the Great Oxidation Event occur? | 2.4 billion years ago (2.4 Ba) - Proterozoic era |
| Which organisms were the likely source of early atmospheric oxygen? | Cyanobacteria |
| When did the first single-celled eukaryotes appear? | 1.8 billion years (1.8 Ba) - Proterozoic era |
| What key structures distinguish eukaryotes from prokaryotes? | Nucleus, membrane-bound organelles, and the cytoskeleton |
| What does the endosymbiotic theory propose? | Mitochondria and plastids evolved from engulfed prokaryotes |
| When did multicellular eukaryotes originate? | 1.2 billion years ago (1.2 Ba) |
| What is the Ediacaran fauna known for? | Soft-bodied multicellular animals (~600 million years ago/~600 Ma) |
| What major evolutionary event occurred during the Cambrian Explosion? | Rapid diversification of animal forms (~535-525 million years ago/~535-525 Ma) |
| What is the Burgess Shale? | A Cambrian fossil site (~505 million years ago/~505 Ma) |
| When did eukaryotes begin colonizing land? | ~500 million years ago (~500 Ma) - Ordovician era |
| When did tetrapods evolve from lobe-finned fish? | ~375 million years ago (~375 Ma) - Devonian era |
| What key adaptation evolved around 312 million years ago (312 Ma)? | The amniotic egg |
| What caused the K-Pg extinction event? | Bolide (asteroid) impact (~65 million years ago/~65 Ma) |
| What is adaptative radiation? | A period of evolutionary change when groups of organisms form new species to fill ecological niches (roles) |
| What is fossil preservation? | The process by which an organism becomes a fossil |
| What are fossils? | The remains of once-living organisms, preserved through time in sedimentary rocks |
| What are body fossils? | The actual physical remains (or shape) of an organism |
| What are trace fossils? | Preserved behaviors or other biological activities of an organism that shows how the organism functioned in an environment |
| What is taphonomy? | The study of death and post-death processes of an organism and how they become preserved in the geologic record |
| What are the 4 D's of taphonomy? | Death, decay/decomposition, disarticulation/dispersal, and diagenesis |
| Explain the first D: death of taphonomy? | The organism dies; necrology |
| Explain the second D: decay/decomposition of taphomomy? | Breakdown of the body |
| Explain the third D: disarticulation/dispersal of taphonomy? | Separation of pieces of an organism caused by natural events (floods, scavengers) |
| Explain the fourth D: diagenesis of taphonomy? | The physical and chemical changes occurring during the conversion of sediments to sedimentary rock - the body is completely decomposed |
| What is the biostratinomy? | The study of what happens to an organism after it dies but before final burial |
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