2A+Midterm Study Questions-2 PDF

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2A MIDTERM STUDY QUESTIONS FALL 2013 These study questions are designed to help you review for the midterm. Answers are not provided for a very good reason: actively answering these questions yourself is a much better way to prepare for a test than reading prepared questions and answers. Keep in mind that these are not comprehensive, nor will every concept addressed below appear on the midterm. They are simply meant to guide and supplement your studying. Good luck! LACTOSE • What is the Dual Inheritance Model? Apply it to the case of lactose. • What does it mean to be LA? Tolerant LM? Intolerant LM? What are their genotypes? • What hypotheses were discussed to explain the LM/LA polymorphism? • Compare and contrast the hypotheses that attempt to explain the prevalence and distribution of LA in the world. • Understand the two different mechanisms of calcium absorption and the requirements for each to function. • How can the mechanisms of calcium absorption explain the prevalence of LA in the world? Which population(s) are exceptions to this explanation and how can they be explained? • What evidence exists for the selection of cultural beliefs that promote milk-drinking behavior? EVOLUTION • What were Darwin’s inspirations for the ideas presented in Origin of Species? • What are the four drivers of evolution? What role does each play in the process of evolution? • What is fitness (Darwinian, modern, inclusive) and how does it relate to natural selection? What types of traits can natural selection act upon? • How does natural selection relate to evolution? Consider the level(s) at which natural selection and evolution act. • Distinguish between the different types of natural selection: environmental, sexual, kin. Can you think of an example of each? • Distinguish between the different modes of selection: stabilizing, directional, disruptive. Can you think of an example of each? • What can a cladogram tell you and how would you build one? What are the differences between a cladogram and a phylogeny? • Define and understand the similarities and differences between the following terms: adaptation, exaptation, spandrel, vestigial structure, homology, synapomorphy, analogy, and homoplasy. How do these terms relate to one another? How do they relate to cladograms? • Identify and understand the similarities and differences between the four major modes of speciation. Be able to identify how each could apply to a new example. • What are the different types of reproductive isolating mechanisms (RIMs)? How do they relate to natural selection and speciation? • What are the different species concepts? What are the limitations of each concept? • Compare and contrast gradualism and punctuated equilibrium. • What is anagenesis? What is cladogenesis? How do they relate to one another?

ECOLOGY • What is biodiversity? How do we measure biodiversity? What are the types of biodiversity? What is species richness and evenness? ● Biodiversity is the degree of variation of life ● 3 types of biodiversity → genetic diversity, species diversity, ecosystem diversity ● Can be measured/described by various scales o Species diversity, (richness (#) and species evenness) functional diversity, (important in communities) phylogenetic diversity, (diversification of a lineage, representation within a community) and genetic diversity (within or among populations). ● Species richness refers to the number of different species present in an environment ● Species evenness → how close in numbers each species in an environment are • How does fitness apply to ecology? What is a fundamental niche? A realized niche? When do these types of niches differ? Can niches change over time? ● Ecological fitness → poorly adapted organisms in a population die in grater numbers than those that are well adapted → measure by number of offspring an individual has during its lifetime ● Fundamental niche → the potential area and resources an organism is capable of using o Organism will tend to occupy less than this because of direct competition with other organisms or other limiting factors ● Realized Niche →the part of the fundamental niche that an organism occupies as a result of limiting factors in its habitat o These niches differ when the habitat is introduced to limiting factors (such as competing species) ● Can niches change over time? → Changing climate and environmental change can cause changes in a species’ niche (Ex: forest fire). The fittest members of the population will be able to survive by physiological and morphological adaptations. • Understand the types of interspecific interactions. How does each interaction affect each species? ● Competition between species, two different species living together + interacting → both species may experience positive, neutral, or negative benefits ● Four types: o Predation → harmful to one and beneficial to another o Competition → harmful to both o Commensalism → beneficial to one and neutral to the other o Mutualism → beneficial to both ● Outcomes of interspecific interactions o Competitive exclusion

▪ Gause’s law ▪ One of the two competitors will always overcome the other, leading to either the extinction of the competitor or an evolutionary/behavioral shift toward a different ecological niche ▪ Complete competitors cannot coexist o Niche partitioning ▪ National selection drives competing species into different patterns of resource use or different niches → so that one species does not out-compete the other ▪ Can coexistence because of the differentiation of their ecological niches o Character displacement ▪ When ranges overlap, selection favors individuals with less similar resource use • What is a keystone species? What are some examples of keystone species? ● Keystone species → species that has a larger impact on the community than you would guess (based on the abundance of that species) ● Examples o Palm trees o Toucans → clean seeds and carry them to different areas that have been disturbed, big part of the regeneration cycle • How do character displacement and niche differentiation affect competition? ● Character displacement favors individuals with less similar resource use, and selectively drives individuals to change their behaviors so they can coexist with their competitor species that are in their niches. Niche differentiation is driven by natural selection driving people to select different resources or different niches entirely in order to avoid confrontation with their competitors and coexist better. • What is an evolutionary arms race? ● Evolutionary struggle between competing sets of co-evolving genes that develop adaptations and counter-adaptations against each other → positive feedback ● Co-evolving genes may be in different species (predator vs. prey) or between members of the same species (sexual conflict between the sexes). • What are the three types of survivorship curves and how do they relate to life-history strategies? What is an example of a species that fits each curve? ● Type 1 → high survival in early and middle life followed by rapid decline in survivorship in later life o Example: Humans ● Type II → intermediate between I and III, constant mortality rate regardless of age o Example: birds ● Type III → greatest mortality experienced early in life, low rates of death for those surviving this bottleneck o Species that produce a large number of offspring o Example: Octopus

• What different assumptions are made in the exponential and the logistic growth models? ● Population will grow exponentially if unchecked ● Resources grow linearly ● Exponential growth model assumptions o No immigration or emigration o Constant birth and death rates → constant r o No variation among individuals in genetics, size, or age o No time lags • Understand the following terms conceptually and know how to calculate/determine them for a population: population size, population growth rate, intrinsic rate of increase, carrying capacity, and competition coefficients (α and β) ● N = population size → number of individuals of a species (N = b – d) when there are no limits/checks on population growth ● N-hat → equilibrium population size of a species under competition ● Exponential growth → dN/dt = rN o OR N(t) = N(o)e^rt ● Logistic model of population growth → dN/dt = rN (K-N)/K o K = carrying capacity (growth slows down as the population size approaches is limit ● Population growth rate → r o B-d o If r>0 population has intrinsic potential to grow because births exceed deaths (intrinsic rate of increase) ● Competition coefficients o Alpha → Effect that species 2 has on the growth of species 1 o Beta → effect of species 1 on the growth of species 2 o When a or ß are >1 → per capita effect of between species competition is greater than within-species competition • What is density dependent growth and when does it apply? How does density affect survivorship? What is carrying capacity? Can carrying capacity vary? ● Density dependent growth → population growth rates are regulated by density of a population o Population growth regulated by crowding, predators, competition o Density dependent inhibition → weather or environmental conditions that may affect populations carrying capacity o Birth rate falls as competition increases ● How it effects survivorship o Predation affects survivorship → resource competition leads to lower growth rates, survivorship and/or birth rate (fertility/fecundity) ● Carrying capacity (K) → maximum population size of the species that the environment can sustain indefinitely (given food, habitat, water, other necessities)

Environmental changes can therefore change the carrying capacity of an environment (famine, natural disaster) o Humans can also increase their carrying capacity through technological innovation (Boserup) • How does the logistic rate of population growth compare to the exponential rate? How does this vary at different population sizes? Understand graphs of these models and how they differ. o

● Exponential growth model exists when rate of growth has ideal conditions ● Logistic is more realistic to actual population growth in not ideal conditions → rate of growth is proportional to the amount but there is a damping factor due to competition and limited resources o As the population reaches the carrying capacity, it starts to level off o When population reaches its equilibrium state, rate of growth is zero and population will stay constant if there are no interruptions (natural disasters) • What are the meanings of α and β? Which equations use these variables? How do you determine equilibrium population size? ● Alpha → effect species 2 has on growth of species 1 ● Beta → effect of species 1 on growth of species 2 ● Greater than 1 means between-species competition is greater than withinspecies competition ● Two equations that model population growth using equilibrium population sizes and alpha/beta coefficients (look at equation sheet cause they’re long as shit and I’m not about to type that up). • How does N-hat differ from K? When is N-hat < K? When is N-hat = K? ● N-hat → equilibrium population size of a species under competition ● K → carry capacity as in the single-species population growth models

● N-hat < K when population growth rate is positive so populations increase in size ● N-hat = K when the growth of population has stopped and equilibrium population size is stable • What factors influence community diversity? ● Abiotic Factors ● Size of habitat → affects number of species which can live in it ● Harshness of habitat → also affects the number or species that are able to survive in the community ● Disturbances in a habitat → effect population size or allow other species to colonize the space ● Isolation of habitat → fewer diversity of species can colonize is ● Biotic Factors o Age of community type → time community has existed species diversity (longer the species has existed the more species will have had time to join the community) o Community structure → complex community structure means community will have more niches o Competition → competition between species can alter species richness • What is the difference between primary and secondary succession? How does disturbance relate to biodiversity? ● Primary succession → occurs in environment in which new substrate devoid of vegetation and usually lacking soil (lava flow or area after melted glacier) is deposited o Gradual growth of an ecosystem over a longer period ● Secondary succession → occurs on substrate that previously supported vegetation before an ecological disturbance from things like floods, hurricanes, or other natural disasters destroyed the plant life ● Disturbances o Effect population size and/or allow other species to come in and colonize the space and increase biodiversity o Can create different patches of communities that makes the area able to support a greater variety of species • How does ecology and ecological communities relate to the human microbiome? What trends in diversity (both functional and phylogenetic) do we see between different areas of the body? ● Microbiome → genes of all the microbial species in a community o Secondary succession ▪ Antibiotics often kill important microbes in your body that aid in digestion and cause bad side effects while your body tried to restore your microbes o Primary succession ▪ Microbiome of new babies → baby passes through mother’s vaginal microbiome community

Efferent locations on the skin (different ecological communities) can create diversity and different species composition of bacteria on our skin POPULATION DYNAMICS • Compare the opinions of the following people: Malthus; Marx; Boserup. -What did they say (if they said anything at all) about population growth? Scarcity? Technology? ● Malthus → population size grows faster than resources (exponential population growth vs. linear resource growth) o Population size determines scarcity (once population exceeds K) o Law of diminishing returns → population catches up with the carrying capacity ● Marx → Scarcity caused by unequal distribution/allocation of resources o Majority of resources controlled by small portion of population ● Boserup o People respond to population pressure with technological innovation and can raise the carrying capacity allowing for availability of more resources o More population density = more innovation o Scarcity is not inevitable -What evidence (presented in lecture) is there to support each of their views? What evidence is inconsistent with their views? ● El Salvador for Malthus and Marx -How do their views relate to the population growth models we have learned? How do humans complicate our attempts to model population growth? ● Exponential growth model → consistent with Malthus (but logistic is even more consistent because it talks about how resources check population growth ● Humans complicate these growth models o Technological innovations → allow us to increase the amount of resources we can extract from our environments and increase the efficiency with which we use these resources o Culture → cultural ideas/norms impact K by changing standards of subsistence ▪ Difference cultures around the world have different standards of living which translate into different resource use patterns and different local carrying capacities -How are their views reflected in contemporary events in the real world? ● Contemporary Demographic transition model o (High stationary) Remove groups → high birth and high death rate ▪ Children needed for family o (Early expanding) Egypt, Kenya, India → High birth rate, rapidly falling death rate ▪ Children needed for family, no family planning o

▪ Improvements in medical care, water supple and sanitation so fewer children die o (Late expanding) Brazil → falling birth rate and slowly falling death rate ▪ Improved medical care and diet, fewer children needed for work o (Low stationary) USA, Japan, France, UK → low birth and low death rates ▪ Family planning, good health, improving status of women, later marriage, good health care, reliable food supply o (Declining) Germany →very low birth rate, low death rate ▪ Family planning, status of women, later marriages, health care, food supply ● Other examples o England ▪ Real wages and population size inversely correlation ▪ Malthus believed increase in wages would drive population growth but in England we see a non-Malthusian exogenous shock (Black plague) which decreased the population leading to greater availability of resources for the remaining survivors o El Salvador ▪ Small farms are numerous but account for less than half o total farmland, large farms (only a few) account for vast majority of farmland ● Supports Marx’s explanation for unequal land distribution driving scarcity o China ▪ Population doubles in 150 years despite no increase in total cultivated land area ● Supports Boserup’s theory that innovation can increase K and allow for population growth o USA ▪ Age of first marriage increased and total marriage decreased during Great Depression ● Malthus ideas still relevant in modern world ● Decline in overall marriage rate/increase in age at first marriage are preventive checks which Malthus would have predicted to occur during times of great scarcity like the great depression -What other factors might help explain trends in population growth? Consider: -Exogenous checks ▪ Exogenous checks → outside of society o Volcanoes, Climate change → affect populations regardless of the population density -The Demographic Transition ▪ See above

• What drives scarcity in El Salvador? -Which theorists’ views help to explain this scarcity? ▪ Marx and Malthus → we get it… -What roles did commercial and household production play? • Know how to interpret key graphs presented in lecture. For example: -How do we interpret the Lorenz Curve? How does this relate to GINI coefficients? ▪ Area between line of absolute equality and the Lorenz curve gives you the GINI coefficient which is a measure of inequality -How do we interpret the Marx and Malthus “D curve” graphs presented by Professor Durham? ▪ D-curve → Depression of fitness of curve o Malthus → As Population increases, distribution of resources stays the D curve shows this o Marx → Average is the same, but distributional change causes scarcity for most o We should look at these more -Which graphs support or refute the views of a given theorist? (ADDENDUM) GENETICS • Understand the phases of mitosis. In what order do they occur and what happens in each step? ● Mitosis → nuclear division plus cytokinesis o Produces two identical daughter cells during its phases ● (1) Interphase o Cell engaged in metabolic activity to prepare for mitosis o Chromosomes are not yet clearly discerned in the nucleus ● (2) Prophase o Chromatin in nucleus begins to condense and becomes visible as chromosomes o Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres (some fibers cross the cell to form mitotic spindle) ● (3) Prometaphase o Nuclear membrane dissolves o Proteins attach to the centromeres creating kinetochores o Microtubules attach at the kinetochores and chromosomes begin moving ● (4) Metaphase o Spindle fibers align the chromosomes along the middle of the cell nucleus on the metaphase plate o Ensures that when chromosomes are separated each new nucleus will receive one copy of each chromosome ● (5) Anaphase o Paired chromosomes separate at the kinetochores and move to opposite sides of the cell o Microtubules help move them

● (6) Telophase o Chromatids arrive at opposite poles of cell and new membrane form around daughter nuclei o Chromosomes disperse and are no longer visible o Cytokinesis (partitioning of the cell) may begin during this state ● Cytokinesis o Pinches cell into two daughter cell → each with one nucleus • Understand the phases of meiosis. In what order do they occur and what happens in each step? ● Meiosis → reduces number of chromosomes in half (making the daughter cells haploid) ● Meiosis 1 → most of genetic recombination occurs o **Similar to mitosis but instead of tetrads lining up and separating rather than chromosomes like in mitosis o (1) Prophase 1 ▪ DNA condensation occurs → nuclear envelope and nucleoli disappear, spindle starts to form ▪ Difference between mit...