biol 1011
What were the morphological features that helped vertebrates transition from water to land? How did microevolutionary forces contribute to speciation?
- limbs to allow movement (lobed fins) -breathing adaptions since gills collapse out of water -circulatory adaptions -lungs - tetrapods had to travel distances to get from one body of water to another so it had to adapt to navigate water and land to survive
-Explain why the statement "Humans evolved from chimps" is false and restate it more accurately (support your answer with a phylogenetic tree!). -State a hypothesis for why humans are hairless, unlike other mammals.
- Humans and chimps share a common ancestor - Allows humans to cool themselves more easily in extremely warm climates
-Describe the conditions that lead to speciation. -What are the reproductive barriers that keep species separate? -Draw a figure (a table, a spectrum, a venn diagram, etc.) that shows how pre and post-zygotic barriers contribute to species divergence. -Explain which microevolutionary force(s) are at play and how! Why are there so many different species on Honey creepers on the Hawaiian islands?
- There has to be an end of successful mating between the two populations. This could because of reproductive barriers. Once two populations are reproductively isolated there is no gene flow and each population will have other forces of microevolution working to produce more variation (natural selection, genetic drift, and mutation). If the two populations become varied enough from each other they cannot interbreed and produce viable, fertile offspring - pre-zygotic: -Temporal Isolation (mate at different times) -Habitat isolation (they could mate but don't meet) - Mechanical isolation (parts don't fit) - Behavioral isolation (difference in mating behaviors) Gametic isolation (Gametes of different species are incompatible) post-zygotic: -Reduced Hybrid Viability - egg is fertilized but embryo dies -Reduced Hybrid Fertility - produce offspring but it is not fertile (odd # of chromosomes -disrupts meiosis) Hybrid breakdown - Produces off spring but F2 generation is sterile
-What is a phylogenetic tree? -What goes at the tips of the tree? -Explain what happens at a branching point. -What is a clade? -What is an ancestral trait vs. a derived trait? -Given data about species (fossil or living) determine their phylogenetic relationship. Is there more than one way to depict the same phylogenetic relationship amongst organisms? Give an example!
- the mapping out of evolutionary relationships between a group of organisms - On the tips of the tree are species - Represents where a single lineage evolved into a distinct new one -a clade is a grouping that includes a common ancestor and all the descendants -Ancestral trait - the trait originally present in the ancestor group derived trait - more recent trait that differs from the ancestral trait
-What is a population? -How do the logistic and exponential growth models differ from one another? -In what ways are they the same? -How might you estimate population size if you cannot count every single individual in the population? - What is density-dependent population growth? What is density-independent population growth?
-All the individuals of the same species within an ecological community -Exponential Growth: G = rN or net increase/ starting pop (ideal environment w/ unlimited space and resources) Logistic Growth: rN(K-N)/K k = carrying capacity (idealized population growth slowed by limiting factors) -Mark recapture: marked individual sampling at time 1/ starting pop = marked individuals in sampling at time 2/total captured (marked and unmarked) in sampling 2 - Density- Dependent Factors: -lack of space -lack of food -increased disease -stress leading to decreased reproduction density-independent population : -just as likely to hit a populated vs unpopulated area. Natural disasters such as weather, flooding, fire
What evolutionary forces produced domesticated dogs? How can this be applied to explain domesticated cats? Or the food we eat (for example, broccoli and cauliflower)?
-Artificial selection
-How do we know if two organisms are from distinct species? -Explain each possible definition of a species. -What are the uses of the biological species concept of species and what are its limitations?
-Biological species concept: species = a group of populations who individuals have the potential to interbreed and produce fertile offspring Morphological species concept: Based on physical traits (shape, size, etc.) Ecological species concept: Based on adaptations to role in community - what they eat, where they live Phylogenetic species concept: based on common ancestry (uses morphology, DNA, or other comparisons to examine similarities and differences) - Only really works for species that are still living not those who are extinct
-Distinguish components of the theory of natural selection that are true vs. common misconceptions: -What is natural selection? How does it work? How is natural selection different from the theory of special creation? -What evidence do we have that that supports the theory of evolution vs. the theory of special creation?
-Components that are true: Evolution is not entirely "chance." There are non-random evolutionary processes. Evolution is observable and testable through scientific experiments. Evolutionary theory deals with mainly how life changed after its origin. Components that are false: Natural selection gives organisms what they need to adapt to an environment. Evolution is a theory that is losing strength because it is debatable whether evolution took place. Evolution is like a climb up a ladder of progress; organisms are always getting better. - Natural Selection = differential reproductive success. Individuals whose characteristics best adapt them to their CURRENT environment are most likely to survive and reproduce. vs Theory of Special Creation: All living things came to be made individually. -"Belief" implies faith vs Science which is not about faith or belief it is testable
-What is microevolution? How is it measured? -Describe all possible microevolutionary mechanisms and explain which ones are random and which ones are not random. -Find examples other than those given in class or your textbook that are representative of the various microevolutionary forces so that you can practice recognizing which form of microevolutionary force is a driving evolution. Explain how genetic drift, mutation, gene flow and natural selection affect allele frequency in a population.
-Microevolution - a change in allele frequency over time. -Forces of microevolution - random forces: Mutation/ Gene Flow (Immigration/Emmigration between existing populations/ Genetic Drift (change in gene pool due to chance- Bottleneck effect -large pop to small pop due to catastrophe Founder Effect: a new pop is just starting out) nonrandom forces: Natural Selection- differential reproduction Stabilizing: middle range is selected Disruptive: Selecting for extremes Directional: Shift to one extreme Sexual: Intrasexual - 2 males compete for female. Intersexual - between sexes
-What is natural selection? -Why has our understanding of natural selection improved when combined with Mendel's work? (your answer should include an explanation of Mendel and the significance of his work, too).
-Natural Selection = differential reproductive success. An editing process, contingent on time and place. Significant evolutionary change can occur in a short time (few generations). - 4 process of evolution not just natural selection but also gene flow, genetic drift, and mutation. -recognizes that "traits" are =genes -NS acts on individuals but the effect is a change in the population -population is a group of organisms of the same species living at the same time/place -Microevolution - a change in allele frequency over time
-What are the conditions under which evolution is not expected to occur. What does it mean for a population to be in Hardy-Weinberg equilibrium? How do we know if evolution is occurring (describe in detail) in a population?
-No mutations (mutations create genetic variation) - Very large (avoiding genetic drift) -No immigration/ Emmigration - Gene flow -Mating is random -Reproductive success is equal - no natural selection -The population is not evolving -New mutations present themselves
-What is the difference between phenotype frequency, genotype frequency and allele frequency? -How do we calculate each one? -How do you calculate allele/genoytype/phenotye frequency if you do not know if a population is in Hardy-Weinberg equilibrium? -What are p and q? -What is the relationship between the Hardy-Weinberg equation and calculating genotype/phenotype/allele frequencies?
-Phenotype frequency: frequency of certain physical characteristics like color genotype frequency: the frequency of certain genes in the population like homozygous dominant and homozygous recessive allele frequency: the frequency of either the dominant or recessive allele - allele equation : p(dominant) + q(Recessive) = 1 genotypic equation: p^2 + 2pq + q^2 = 1 -calculate frequencies and see if it fits the Hardy-Weinberg prediction
-What is science? -How can we apply the scientific process to the study of evolution? Consider the questions researchers ask and the evidence they might use. -Give examples of evolutionary studies and explain the outcomes of those experiments.
-Science is testable and falsifiable. -Predict what the scientists find when they compare PitX Dna coding sequences between marine (w/spine_ and freshwater (w/o spine) sticklebacks: The same coding regions (no differences in sequence) - (hypothesis) : If loss of PitX expression in the pelvis of freshwater sticklebacks is the reason they don't have pelvic spines, then putting PitX into freshwater sticklebacks will cause: these fish to develop pelvis spines. (test) -Why do stickleback of Alaska make a good model for evolutionary studies? Isolated lakes where fish could not mix and breed (no gene flow) and short generation time and fossil record
How would you use the Hardy-Weinberg equilibrium to determine if a population is evolving or not?
Starting Pop. There are 1,000 butterflies 490 AA butterflies dark-blue wings 420 Aa butterflies medium-blue wings 90 aa butterflies white wings genotype frequencies? 490/1,000 = 0.49 dark blue 420/1,000 = 0.42 medium-blue 90/1,000 = 0.09 aa white Allele frequencies? There are 1,00 butterflies (each with two copies of each allele) --> 2000 alleles A: 490 + 490 +420 = 1400/2000 = 0.7 a: 420 + 90 + 90 = 600/2000 = 0.3
List and describe the five different kinds of community interactions. What does it mean to partition resources?
competition (negative for both species) parasitism, predation, herbivory (positive for species one, negative for species 2) mutualism (positive for both)