PLB 115: FINAL EXAM
93 Cards in this Set
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Define evolution
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change in allele frequency over time
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What is the mechanism (agent of change) for evolution?
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Natural Selection
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Natural Selection
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process that brings about evolution by selecting which individuals will survive, reproduce, and pass on their genes:
1. acts on the phenotype
2.must affect reproductive success
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Who is responsible for the concept of natural selection?
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Charles Darwin
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What are the 5 tenets(requirements) for natural selection?
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1. over production- more offspring produced than can survive
2. variation in heritable traits
3.struggle for existence
4.differential survival and reproduction
5. favorable characteristics increase through generations
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what processes drive selection?
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1. differential survival(individuals with favorable traits survive)
2. differential reproduction(individuals best suited to the environment will produce more offspring)
3. differential mate selection(discriminate among mates)
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stabilizing selection
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elimination of individuals with extreme characteristics
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disruptive selection
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increase in the frequency of extreme types of phenotype
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directional selection
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increase in the frequency of one extreme type(occurs where there is a consistent change in the environment)
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directional selection
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increase in the frequency of one extreme type(occurs where there is a consistent change in the environment)
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Why are mutations important from an evolutionary context?
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Creates random variations so we can adapt to evironment
Can be good bad or neutral
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what causes allele frequencies to change in populations?
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1.mutations- random source of new alleles
2.immigration- bring new alleles in population
3.emigration-loss of alleles from the gene pool
4.genetic drift- chance change in allele frequencies
5.natural selection
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what is the result of natural selection?
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1.adaptation to the physical environment
*ecotype-a distinct phenotype in a habitat
*different forms in diff. habitats, maintained in common garden
2.adaptation to the biological environment
*co-evolution-population of 2 or more species interact so closely that each exerts a strong se…
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what is co-evolution?
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population of 2 or more species interact so closely that each exerts a strong selective force on the other
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what is speciation?
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process of generating new species
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How do new species originate over time
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One species splits into two or more species
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what is required for geographic isolation to result in a new species?
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-proportion of a population becomes geographically separated from the gene pool
-Requirements:
1. genetic divergence
2.reproductive isolation
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Give examples of reproductive isolating mechanisms. how do they affect speciation?
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1.change habitat use
2.change in timing of reproduction
3.behavioral isolation
4. mechanical isolation
5.biochemical isolation
*they can limit generating new species
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convergent evolution
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traits among unrelated organisms similar due to similar environmental conditions and selection agents
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divergent evolution
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species diverge, express less similar traits due to different selection pressures
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what is adaptive radiation? what conditions might lead to adaptive radiation?
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-rapid increase in the # of closely related species
-invading a new environment
-evolution of a new characteristic
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what is extinction?
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loss of a species
*99% of all species that have ever existed have gone extinct
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what factors affect the rate of evolutionary change?
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-generation time of the organism
-rate of environmental change
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what has the fossil record told us about species over long periods or time? Does the fossil record contain information on all species?
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-they show species that have gone extinct
-new species come into existence
-fossil record is factual, but not complete
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T/F: evolution happened a long time ago and does not occur now
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FALSE
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T/F: according to the theory of natural selection, the strongest are most fit
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FALSE
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T/F: according to Darwin, a giraffe that stretches its neck will produce offspring with longer necks
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FALSE
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T/F: evolution does not have a goal
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TRUE
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T/F: individuals evolve
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FALSE
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T/F: species have changed over time and continue to change today
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TRUE
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T/F: the fossil record contains all of the species that have ever existed
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FALSE
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T/F: increasing resistance to pesticides in insects is an example of natural selection
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TRUE
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T/F: charles darwin founded the theory of evolution based on his knowledge of genetics
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FALSE
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T/F: with respect to natural selection, "struggle for existence" only refers to conflict between organisms
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FALSE
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T/F: evolutionary patterns show divergence of species over time
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TRUE
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T/F: if a part of a population becomes geographically isolated, the isolated population will unconditionally become a new species
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FALSE
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T/F: most species that have ever existed have gone extinct
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TRUE
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T/F: selection acts on a phenotype, at the level of the individual
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TRUE
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Define: population
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All the indivduals of a species living in a specific area (only on especies in a particular area
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what are some characteristics of a population?
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-same species
-interbreed
-restricted in time & space
-dynamic
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what is meant by density?
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number of individuals per area
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what is meant by population distribution?
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the arrangement or spread of a particular species or organisms in a given geographical area
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what does sex ratio mean?
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ratio of males:females
*more females=more likely to increase
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How does age structure influence population size?
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-rapidly increasing pops have a greater proportion of young people
-slowly growing pops have a greater proportion of old people
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what 4 factors affect the rate of increase of a population?
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1.birth rate
2. death rate
3.immigration
4.emigration
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what is exponential growth?
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change in numbers over a specific time period
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what is the exponential growth equation?
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dN/dt= rN
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what kind of curve represents this type of population change?
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J shaped curve
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what are limiting factors?
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what are limiting factors?
limits the growth or development of an organism, population, or process
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density dependent
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factors that regulate population growth as a population increases
*predation
*disease
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density independent
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factors that regulate population growth regardless of size
*climate
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categories of limiting factors
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1.raw materials
*water, nutrients, space
2. energy
*plants, herbivore.carnivores,decomposers
3.accumulation of waste
4.species interactions
*predators, pathogens, competitors
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the result of liming factors
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1. environmental resistance to exponential growth
2. carrying capacity of the environment to support a maximum sustainable population
3. logistic growth of populations
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Logistic Growth model equation
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dN/dt= rN((K-N)/K)
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what are the 3 phases of the logistic growth curve?
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1. population grows exponentially at first
2. growth slows down due to environmental resistance
3.population size levels off
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According to the logistic growth model, what happens to the growth rate of a population as the size of the population nears carrying capacity?
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A) The growth rate increases.
B) The growth rate abruptly drops to zero.
C) The growth rate slows to zero.
D) The growth rate slows but never reaches zero.
E) The growth rate remains unchanged.
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what type of growth curve does the human population show?
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S shaped
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what is a community?
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collection of species that interact in a general location
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habitat
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-where an organism lives
-determined by tolerance to biological and non-biological conditions
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niche/ components
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-the functional role a species in a community
-components are: diet, terrain and climate,vegetation, type of predators
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interspecific interactions?
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relations between species
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intraspecific interactions
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relations within a species
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predation (+)
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one organism kills and eats another organism
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parasitism (+,-)
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one organism living in or on another organism(host)
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commensalism(+,0)
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one species benefits while other neither benefits nor is harmed
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mutualism (+,+)
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both species benefit
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symbosis
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species unable to survive without each other
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competition(-,-)
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both organisms are negatively effected
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what is the principle of competitive exclusion?
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no 2 species can occupy the same niche; one will exclude the other
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resource partitioning
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evolutionary change in resource use caused by competition
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biodiversity
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the variety of species
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Ecosystem
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a biological community of interacting organisms and their environment
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Ecosystem Components
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Biotic: community of species occurring together
-interaction of all abiotic factors factors determine what biotic factors survive
Abiotic: climate, soil, water, humidity, etc.
-interaction of biotic factors among themselves determine what survives
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autotroph
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-producers
-organisms that make their own food
-plants
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heterotroph
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-consumers
-organisms that use carbon, produced by something else
-bacterial and fungal decomposers, animals
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Producer
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-Organism that makes its own food using energy and simple raw materials from the environment
-first trophic level
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Primary Consumer
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Organisms that feed on producers
-herbivores. (For example: zebra)
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secondary consumer
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-a carnivore that feeds only upon herbivores
-3rd tropic level
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Decomposer
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Organisms that get energy by breaking down dead organisms into simple materials like carbon dioxide and water.Examples: many bacteria and fungi.
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what is a tropic level?
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stages of energy flow
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How much energy is lost & transferred moving between trophic level?
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90% loss
10% transfered
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what happens to CO2 once it is fixed into plant biomass?
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- herbivores can eat it
-go through the food chain
-could eventully die
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how have humans altered the carbon cycle?
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-land clearing
-reduced productivity of oceans due to pollution
-combustion of fossil fuels
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how does CO2 get back into the atmosphere?
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decomposition
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what is the net result of increasing CO2 on global temperatures?
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-increased temps
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what are green house gasses
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water vapor, carbon dioxide, methane,
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Radiative forcing
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A change in the energy balance of the Earth system
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what is the global pattern for projected temperature change in the future?
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western regions
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what determines soil carbon storage?
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the balance between photosynthesis and decomposition
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how might the warming of arctic ecosystems result in positive feedback?
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reduce albedo to enhance regional warming
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what are some general biological responses to warming?
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1.disease
2.species loss
3.changes in distribution
4.asynchrony
5.changes in phenology
6.changes in physiology
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what is the projected change in biodiversity in response to increasing CO2 and global warming?
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-Increased CO2 in ocean water will interfere with
the ability of marine animals to make limestone
shells and calcification of corals.
– Coastal erosion will negatively impact coastal
diversity; 20% of coastal wetlands lost by 2080
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how is CO2 removed from the atmosphere?
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plant photosynthesis
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PLB 115: TEST 2