Genetics Exam 3
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Evolution is __?__ which means __?__.
- Descent with modification
- Changes in organisms that are padded from parent to offspring, through time, generation after generation
Evolution is the __?__ concept of biology and seeks to explain __?__ of the living world
- Central organizing
- every aspect (history of life on earth, processes)
Evolution is not __?__. (3)
- Increased Complexity
The 4 signs of evolution are __?__.
Fossils, Artificial selection, geography, homology
Examples of how fossil records show evolution include __?__. (3)
- Bird evolution (Birds [dinosaurs (teeth bony tail scales and feathers)--> present (no teeth, reduced tail, feathers) ]
- Whale evolution (Fully terestrial --> terrestrial/aquatic --> fully aquatic)
- Timing of appearance (anatomy suggests order of evolution)
Examples of evolution on short time scale include __?__.
- Resistance in disease causing organisms
- Insect resistance
- Plant resistance to toxins
- Lab experiments (fruit flys)
- Artificial selection
Examples of geographical distribution include __?__. (1)
Organisms closely related are often found in same geographic region ie Hummingbirds in North America
Vestigal structures are __?__.
- rudimentary structures that seem to habe lost some or all of their function
- ie tail bone in humans
Embryology is a good example of __?__ because __?__.
- similarities between organisms
- Organisms that are different as adults can have similar embryos (common ancestors use same embryological patterns)
DNA is an example of __?__ because __?__.
- Molecular similarities
- all organisms use the same material and mechanisms
Evolutionary biology is important because __?__ (1 idea) especially in the areas of __?__. (3)
- It helps us understand ourselves and natural world
__?__ is the scientific foundation of biology which is the foundation of Medicine.
__?__ are the four approaches to looking a medicine in an evolutionary context.
- Evolved defenses (Fever)
- Conflict with other organisms (co-evolution between pathogen and host + resistance)
- Dealing with new circumstances (Introduction to new enviornments + adaptation ie fatty foods and humans)
- Trade-offs (def. of "trade-off" ie sickle cell anemia
Evolution helps conservation efforts because it __?__. (4)
- Helps decide what a species is
- Helps pinpoint areas with greatest biodiversity
- Population genetics helps us prevent genetic deterioration of threatened species
- Evolutionary biology studies how organisms respond to change.
__?__ are the 5 main Historical contributors to evolution and __?__ are thier ideas.
- Aristotle - Scala Naturae
- Linnaeus -Scientific names and classification
- Cuvier - Extinction and catastrophism
- Lamarck - inheritance of acquired characteristics
- Darwin - Evolution and a mechanism (Natural Selection)
Scala of nature means __?__. It's flaw is __?__.
- Species evolve from imperfect to perfect
- Evolution is not progressive nor does it have a direction or goal
Carolus Linnaeus was the founder of __?__ and believed __?__.
- Modern taxonomy (placing life into order)
- species were permanent creations (non-evolutionary idea)
__?__ was the problem with Linnaeus's ideas.
Fossil record suggested there were species that do not exist anymore and there are new species that didnt exist before.
Georges Cuvier is the founder of __?__ and __?__.
- Comparative anatomy
Cuvier grouped animals into __?__ (#) distinct branches which were __?__.
Different layers of fossils suggested __?__ to Cuvier and he created his idea of __?__ to explain the layers. His idea explained the layers by saying __?__.
- Extinction (species were not fixed)
- Catastrophies occured which eliminated species who were then replaced by others
Lamarck was the first great __?__.
Lamarcks views of evolution were that __?__ (2).
- Use and disuse of parts (parts used often got bigger)
- Acquired characteristics were inherited
- ex. = giraffe necks
__?__ is the flaw in Lamarck's ideas.
Organisms do no inherit aquired characteristics
__?__ are the three ideas that allowed evolution to be discovered by Darwin and accepted by people.
- Plants and animals grouped
- Extinction was a fact
- Geological evidence showed the earth was old enough for evolution
Darwin's voyage on the HMS Beagle was influential for these three reasons?
- fossil collection during voyage
- Lyell's principles of Geology
- collection of animals and plants from different areas
__?__ are the three reasons why the Galapagos showed why evolution explains the patterns of speciation best.
- Islands are grouped closely together
- all islands are in the same climactic zone
- Very different species on each island
Darwin believed in natural selection for these four reasons?
- Individuals within a species vary
- Some variations are passed to offspring
- In every generation more offspring are produced than survive
- Survival and Reproduction are not random
Dawins 4 premises for natural selection are demonstrated by the giraffe as __?__.
- 1. Neck length varies
- 2. Offspring tend to have similar neck length of parents
- 3. More giraffes are produced than survive
- 4. Longer necked giraffes are more likely to survive
The modern synthesis of Natural selection states __?__.
Alleles that increase an organisms fitness are passed on more often/increase in frequency over time.
How do Darwins finches prove each of his postulates?
- 1. Beak size is variable
- 2. Beak size in offspring is similar to parents
- 3. Drought killed 84 % of pop.
- 4. Surviving birds had thick beaks (NOT RANDOM - fewer small seeds after drought)
The three modes of selection are __?__.
- 1. Directional - one extreme favored
- 2. Stabalizing - extremes are eliminated (suggests already well adapted)
- 3. Disruptive - selection for extremes (hard to maintain)
An example of Directional selection is the __?__ becuase__?__.
- Peppered moth
- Lichen on trees died from polution so dark moth was selected for
An example of stabalizing selection is __?__ because __?__.
- Gall-making fly
- larvae inside medium sized gall survived at highest rate
- Human birth weight
Examples of disruptive selection include __?__.
seedcracker finch (pyrenestes)
__?__ are the 5 forces of selection.
- Non-random mating
- Genetic drift
Genetic drift vs Natural selection.
- Genetic drift is the random sorting of heritable characters
- N.S. is the non-random sorting of heritable characters
Phylogenies are built and evaluated using __?__ and __?__.
- Characters (must be heritable)
Phylogeny: the evolutionary history of a group of organisms represented in a tree diagram
__?__ are the three things that can cause similarity.
- Common ancestry: Homolgy
- Convergence: independant ecolution of similar character in two or more lineages (Homoplasy)
- Reversal: Reversion to an ancestral form of a character due to selection or mutation (Homoplasy)
An example of homology is __?__
- Bird wings
- forearms of tetrapods
An example of convergence is __?__.
- wings in different taxa
- Shark and killer whale (shape, flippers and tails)
An example of reversal is __?__.
Archaeopteryx (first bird - claws) --> Most birds (no claws) --> Hoatzin (clawed bird)
Parsimony minimizes the number of __?__ which __?__.
the number of evolutionary changes that occur which limits the number of homoplasies.
Parsimony groups organisms based on characters that are __?__.
- Shared and derived
- Derived: evolution happens when an ancestral character evolves into a derived character
Synapomorphy: Shared, derived character
Define plesiomorphy, apomorphy, synapomorphy
- Plesiomorphy: Ancestral character
- Apomorphy: Derived character
- Synapomorphy: Shared, derived character
Parsimony defines __?__ groups which consist of __?__.
Monophyletic groups which consist of a common ancestor and all of its decendants
What are the modes of speciation?
- Allopatric "other place"
- Parapatric "beside place"
- Sympatric Hybridization
What is Allopatric speciation?
- Populations become seperated by a physical barrier and the evolve reproductive barriers
- Most common
What are two types of Allopatry + examples?
- Vicariant: pop divided into two widespread populations by a physical barrier - no dispersal - result = 2 large pop
- ex: freshwater fish and snapping shrimp (land bridge formation)
- Peripatric: A small colony disperses from a widespread population to a new area and evolves reproductive isolation Physical barrier - dispersal - 2 small pop.
- Usually caused by genetic drift/founder effect
What is secondary contact?
When species reconverge after speciation
How can you tell if a vicarian event ocured by looking at a phylogeny tree
Closest relative will be in different geographic area
Why are elephant seals and example of peripatric speciation?
- Hunted to samll number
- small colony near Mexico - Founder effect
- very small genetic diversity (population bottleneck)
- -conservation issue
What is Parapatric Speciation?
Strong selection causes a continuous population to divergePopulations are contifuousNo physical barrier (gene flow) speciation between niches within ecosystem
What is a Hybrid Zone?
When a species diverges, but populations come back together. The area the two pop meet is the hybrid zone (secondary contact)
What does a hybrid zone indicate?
- Primary differentiation (parapatric speciation)
- Secondary contact between two formally isolated populations (Allopatric Speciation)
What is Sympatric speciation?
No geographic separation
What is Hybridization?
- Model of speciation
- Two parental species hybridize and produce offspring that can breed with each other, but are reproductively...
- Much more common in plants (rare in animals)
Speciation by polyploidy is caused by __?__.
- Errors in mitosis or meiosis resulting in diploid gametes instead of normal haploid gametes.
- Individuals with diploid gametes mate with each other and produce polyploid offspring
- Resulting individuals can not breed with progenitors (parents), but can breed with each other
Species concepts matter because they allow __?__ and __?__.
- Identification and understanding of biodiversity
- Taxonomic status often dictates conservaion priority
__?__ are the three steps to defining species.
- 1. Observe morphological or molecular variation
- 2. Group individuals into taxa
- 3. Rank taxa into hierarchy
Define the Biological Species Concept
BSC: Actually or potentially interbreeding populations that are reproductively isolated (lack of gene flow) from other such groups
Problems with the BSC include: (5)
- Asexual organisms
- fossil species dont apply
- Hybridization (especially plants)
- Evolution prior to reproductive isolation
- Isolated pop. cant be tested
Define Phylogenetic Species Concept
- PSC: The smallest diagnosable cluster of organisms within which there is a parental pattern of ancestry and decent
- Smallest monophyletic group
Define Diagnosable, Ancestry and decent
- Diagnosable: characters differentiate species (Synapomorphies)
- Ancestry and decent: share history
The PSC over comes which of the problems presented by the BSC?
Criticisms of the PCS include: (3)
- Phylogenies difficult to obtain
- Species specific trait may be trivial
- Will name too many species
BSC vs PSC
- BSC: reproductive isolation; predicting future; Based on morphological differences, groups individuals into taxa. If they hybridize = subspecies
- PSC: Characters are important, monophyly; reconstruct past; Morphology reveals groups with independant evolutionary histories, ranks species wither hybridizing or not
What is the giraffe example and what does it demonstrate?
- 6 different colors in different geographic regions, all can mate = 1 species in BSC
- Different species are adapted to different regions = 6 species in PSC
Define Ring distribution and problems + examples
- Ring distribution: Species occupy an area that forms a ring around a geographical location that overlaps at the ends
- Problem: all neighbors interbreed accept at ends - How should species be differentiated?
- Ex: salamanders and Greenish warbler (not ring, but hybrid zones dont breed)
What is the issue with recognizing killer whale species?
all interbreed, have low mtDNA seq divergence, but inhabit different regions and have character differences. Under PSC = 3 species
What issue does hybridization bring up? Give examples
- Is the hybrid a genetically unique individuals making them a new species or are they the same species because they can mate with the originals.
- Ex: orioles (interbreeding may be ancestral); Flickers (same thing); Red wolf
Is development part of modern synthesis? Why not?
- Geneticists and Developmental biologists do not communicate
Define Ontogeny; How does this relate to Haeckel's law? Who refuted this law and why?
- Ontogeny: development of an organism from embryo to dev
- Haeckel's law: is a hypothesis that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the evolution of their remote ancestors (Ontogeny recapitulates phylogeny)
- Von Baer: No functional equivalent of fish, amphibians, reptile stage in humans - all embryos are different
Changes in form by geometric transformation
__?__ are the two reasons evolutionists are interested in development.
- 1. Minor changes in regulatory genes can have major effects on phenotypes
- 2. Development may constrain morphological evolution
__?__ are the three patterns of morphological development.
- 1. individualization
- 2. Dissociation
- 3. Mosaic evolution
- 4. Heterochrony
- Individualization: When repeated structures become individualized; aquire distict identities
- Ex: Homodont --> Heterodont teeth
Individualization is often a result of __?__ which means __?__.
- Dissociation: evolutionary change in development where features acquire more independent genetic control
- Ex: If bill length and thickness are under same genetic control, larger bill length will also give longer bill length. BUT if they are DISSOCIATED you can get longer bill withough a thicker one.
Define Mosaic Evolution
- Mosaic Evolution: When a region under tight genetic control undergoes dissociation, different parts can undergo evolutionary changes more independently
- What happens when dissociation takes place
Define Heterochrony and give examples
- Heterochrony: An evolutionary change in the timing or rate of developmental events
- Can affect may characters simultaneously or few characters
- Ex: Lower jaw sizes in horses over time got bigger
- Allometry: Different traits that grow at different rates
- Ex: babies head is large and grows slowly in relation to rest of body
- Ex: Irish Elk antlers - can predict antler size from body size
- Development: the means by which genetic change is translated into phenotypic change
- Knowing the rules of development allows the explination of many evolutionary novelties - what genes are responsible for evolutionary trait
Beak evolution in Finches is regulated by __?__ proteins.
- Calmodulin - length
- BMP4 - width
- + = wide long beak (positive gene for two prot.)
Hox genes are __?__. (3)
- Regulatory genes
- Each controls the trx of numerous other genes
- Do not encode structures, they provide positional information (tell cell where it is in body)
How do hox genes present in evolution of different species? (3)
- Many different species (Mouse, fruit fly, Jelly fish) have homologous hox genes.
- Not everyone is present, but the shared genes are in the same locations and appear in the same order.
- Within a species some hox genes may be missing (A single species does not have to have exactly the same Hox genes)
The change in number of hox genes allowed vertebrates __?__.
Greater morphological complexity
How does the change in Hox target gene relate to the hox gene itself?
- The target gene may change dramatically but the hox gene remains relatively unchanged
- Ex: The same hox gene controls the development of eyes for flys and mammals, but the two types of eyes are very different
What molecular change in the baleen whale tooth gene took place and what was the result?
- resulted in tooth loss
Sexual dimorphism is puzzling because __?__.
- It cannot be explained by natural selection
- Energy cost
- More visible to predators
Assymetry in sex means __?__.
- One of the sexes invests more in their offspring
- Usually female (eggs and pregnancy)
- 1. Males attempt as many matings as possible to increase reproductive success
- 2. Females are selective in their matings to insure reproductive success
- Ex: Few males become fathers while all Females have offspring
What is role-reversal and give an example.
- Role reversal: Males provide parental care and choose females. This means few females have most of the mates + offspring
- Conflict is driven by parental investment rather than gender
- Ex: Pipefish
Females prefer mates with exagerated traits that may be dangerous to the male because __?__.
- The trait is a signal of the males fitness
- Ex: Birds of Paradise
What is the Natural selection vs Sexual selextion conumdrum?
- Choose trade-off between individual survival or sexual selection
- Tungara frog mating call (attracts predators - bat)
Selection acts on __?__ of individuals.
Define Eusocial animals - This is an example of what kind of evolution? Give an example
- Eusocial animals: sterile or nearly sterile individuals rear offspring
- Ex: Ants and Bees
- evolved independantly in groups - Convergence
Define Kin selection and give an example (3)
- Kin selection: Relatives live in Eusocial society to help eachother look after one another or so one member can raise offspring
- Ex: Mear kat alarm calls - more frequent with closer relation; bloos sharing vampire bats; Naked mole rates (queen more agressive toward non-relatives)
Define Altruistic behavior
Altruistic Behavior: behavior benefits other individuals at the expense of the individual displaying the behavior
__?__ is the old explination for sexual selection which is __?__. The flaw with this idea is __?__
- Group selection
- behaviors evolve because they benefit the species or population as a whole "for the good of the species"
- Selection acts on the phenotype of the individual
The current explination for sexual selection is __?__.
Natural selection favors the spread of alleles that increase indirect fitness
Define Direct and Indirect fitness
- Direct fitness: individuals own reproduction
- Indirect fitness: reproduction of relatives (indirectly helping self)
What makes it difficult to determine what lifes common ancestor was like?
Difficult to tell from the fossil record because the oldest fossil is highly derived
The common ancestor for all had these 4 characters?
- Most likely like bacteria
- Contained DNA
- Fairly complete metabolism
- More like bacteria than Eukarya/Archaea
When did the common ancestor most likely appear?
- Sometime between 4.5 billion years ago (Earths age) and 3.5 billion years ago ( first fossil evidence of life)
- Appeared soon after formation of earth
The evolution of Eukarya involved what 2 major innovations?
- Linear DNA
- Organelles (most likely through endosymbiosis)
The first multicellular life was seen when?
565 million years ago
Define Cambrian explosion
Cambrian Explosion: 565 MYA + 40 MY experienced an explosive radiation of forms representing different body plans
What forms of life were represented during the cambrian explosion?
What major genomic evolution occured during the Cambrian explosion and what does it mean?
- All including arthropods and chordates
- Development of Hox Genes - shows common ancestry for all life
Mass extinction vs Normal extiction
- Mass: large numbers of related and unrelated species die off at a high rate
- Normal: Is a law - small number of species, and slowly
When did the first terrestrial vertebrates appear?
400 million years ago
When did the dinosaurs appear? When did mammals appear and from what?
- 250 MYA
- Soon after from mammal-like reptiles
When did modern homosapiens appear?
__?__ are the three macroevolutionary patterns.
- Adaptive radiation
How many periods of mass extinction have occured?
The end-permian extinction happend __?__ years ago and had these 5 characteristics:
- 245 M
- quickly - 1 million years
- biological disaster
- 50% of families - 90% species
- dominant amphibians were replaced by ancestors of mammals and dinosaurs
__?__ were the 4 cause of the End-Permian extinction.
- sea-level change
- climate change
- change in ocean/atmosphere chemistry
- Multiple volcanic eruptions
The End-crecaceous extinction occured __?__ years ago and had these 5 characteristics:
- 65 Million years ago
- between 60-80% of species extinct
- dinosuars and pterosaurs wiped out
- marine plankton severely effected
- many marine invertebrates
- amphibians, crocs, mammals, turtles no affected as much
What caused the End-crecaceous extinction, what are the evidence (2) and what were the effects of the mechanism? (5)
- chemical and mineral change in soil (uradium) and found 180 km diameter crater off coast of mexico
- affected climate and atmosphere chem
- SO2 + water vapor create acid rain
- dust blocks sun
- massive earthquakes trigger volcanic activity
- huge tidal waves
What was seen in speceis after the extinction of dinosaurs?
Huge increase in numbers of placental mammal species
What is causing the next mass extinction and what are the evidence? (3)
- pleistocene megafauna extinction (wooly mammoth saber-tooth tiger... hunted) - timing coincides with human migration
- South Pacific birds - major extinction of species in last 2000 years (about 20% of species)
- Historical evidence since 1600 (fossil and archeological digs)
__?__ are the two most studies groups for extinction and conservative estimates say __?__% are threatened with current extinction rates at __?__ to __?__ times higher than normal.
- Birds and Mammals (1% ext. 11% threatened [both])
- 100 - 1000
Examples of extinct moderns species include: (4)
- Carolina parakeet
- Ivory-billed Woodpecker
- Chinese River dolphin
- Dusky Seaside Sparrow
Define Adaptive radiation and give an example
- Adaptive Radiation: Ancestral species diversifie into large number of highly specialized descendant species
- Ex: Darwins finches - came from common ancestor and specialized (beaks for different seeds)
Adaptive breakthrough is __?__ and __?__ is an example.
- Evolutionary innovation allowing a new mode of resource exploitation
- Ex: wings for flight in birds; Jointed appendages in arthropods
Define Stasis; what controversy did it lead to?
- Stasis: Long period of no change in a lineage
- Phyletic gradualism vs Punctuated equilibrium
__?__ are the 4 characteristics of Phyletic gradualism.
- Suggested by Darwin
- Natural selection operating over long periods of time
- Gradual change in lineages
- Traditional view
__?__ are the 3 characteristics of punctuated equilibrium and __?__ is an example.
- Proposed by Eldredge and Gould '72
- Fossil record shows stasis
- Periods of stasis "puntuated" by rapid change and splitting of lineages (think of tree differences)
- Ex: Caribbean bryozoans - detailed fossil record
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