Study Questions Flashcards
- Distinguish between evolution, adaptation, and natural selection. Tell me how they differ, and use an example
Evolution is the change in gene frequencies in a population over time and it is a process for example a chang win how common certain traits are in a population
Natural selection is a mechanism of evolution that is a differential survival and reproduction of individuals within a population due to environment selecting the influences acting on heritable variation in traits and it is not a process but is heritability and environment. example individuals individuals with certain traits survive and have more offspring
An adaptation or a process increases the suability of a species for its environment due to natural selection leading to a better fit to the environment. example, organism with individual trait that better suits it to the environment
- Is producing lots of babies equivalent to having high fitness? Why or why not?
No, one needs to not only have lots of babies in one generation but over many generations those offspring must have lots more
- Colonial bentgrass (Agrostis capillaris, formerly A. tenuis) is a perennial grass from China that has been used to revegetate many industrial waste sites, including roadcuts, malls, and mines. The plant is widespread in much of the US. When A. capillaris grows on mine tailings (the soils left from spread mine wastes), it has to deal with high levels of copper. On mine tailings only plants with high copper tolerance survive.
a. Give two explanations for why some offspring from mine tailing populations might not have high copper tolerance.
b. What do we call populations adapted to particular environments or conditions?
a. 1) do not have the given trait that allow the individual organism to survive in that environment
2) do not have enough plants with the traits that allow them to survive on sipper and propagate
b. these populations could be considered ecotypes because they are locally adapted and genetically distinctive populations within the species created by disruptive selection towards one trait by adaptive evolution
with gene flow from other areas that were not selected for in that area.
- a. What factors affect the speed of evolution? Explain.
b. How does your answer fit with bacteria and our use of antibiotics?
c. How does your answer fit with changes we make in our daily routine based on changes in
weather, traffic, etc?
a. How much genetic flow or mutations how many new genes are coming into the population affecting the gene frequency of a population, increasing the gene flow can increase the spread of evolution and how fast species reproduction and life spans are
b. changing environments and the level of abrupt change or slow change favoring one genetic drift over another and stabilizing selection. bacteria were enticed to chang eby killing almost every bacteria not immune to the antibiotics changing the environment and creating directional selects towards one that is for a short period and they no longer work after a while if you don’t take all of the bacteria away some form resistance bringing it up to 100% as not all survive the same thing and any selective force will change it
c. small amounts of change in our environment from year to year, day to day does not overly affect the total evolution when it is looking at a large scale over time and generations are not forcing one trait as there are no major environmental changes and difference. as in behavior it does not affect genotypes, viruses can add genes to new one. adaptation not heritable and so no evolution or very slowly.
- A fictional island, with a population of birds and a second population of non-flying beetles, is split by a fault that creates a wide channel between the northern and southern portions of the island. There are now two small islands where previously there was one larger island. The channel between them is at least one kilometer. Would you expect this event to affect speciation for the birds or the beetles? Why?
Yes, speciation would depend upon the ability of the orgnaims’s populations ability to fly that distance most likely greater speciaition would occur for beetles given their size and the unlikelihood of the organisms to bridge that distance. there might be less speciaiton for birds if they could travel that distance easily. it also depend on environmental factors and assumes islands are seperate biography was similar in both parts before and after. much more likely for beetles to have geographic speciation
- Identify each of the following as “true” or “junk.” Explain your answer for anything you think is junk. a. We are in a temperate forest biome. b. Tropical dry forests have extremely fertile soils. c. Tropical savannas and temperate grasslands both experience frequent fires. d. Chaparral systems are limited to hot, dry areas. e. Desert systems require special adaptations because the highest availability of water and solar radiation are at different times of the year. f. Coral reefs thrive best near estuaries where rivers bring fresh water into the marine system.
a. True
b. Junk, the most fertile soil is in the temperate grassland. The tropical dry forests’ experience times of leeching and erosion because of the extended wet season; although, it has more nutrients than the tropical rain forest because of a couple of months during the year where there is a lack of growth.
c. True keeping woody plants out in both
d. Junk, chaparral systems have an unorthodox paradigm of hot and dry times of the year in the summer, with the other half of the year, cold and wet in winter.
e. True, but this depends on the desert. deserts require adaptation not because of different tmes of year but to water availability for all times chaparrals require for certain times of the year
f. Junk, coral reefs are not actually on the coast where estuaries would come out, but are somewhat in the ocean. Even if they were, they would most likely not be close to estuaries because of their need to maintain a steady temperature, turbidity and light for photosynthesis and environmental concentration of salt and nutrients and higher amounts of O2 than kelp , unlike areas where estuaries meet the ocean . they are usually in the neurotic attached to benthic and in photic.
nutrients and algal blooms bad for coral
- How might the earth’s tilt help to explain seasonal rainfall in tropical dry forests and tropical savannas? Think about air movement in cells between the equator and the poles.
The most direct sunlight is at the equator, throughout the year. Therefore, the air at these locations is heated up causing it to rise due to warm air having a lower density. Most air also has a lot of water vapor in it. In the upper atmosphere, as the air rises it cools causing the water in the air to form clouds. As it continually rises, the water condenses forming rain, which is why right along the equator it rains so much as it was too heavy to move very far. Once the air releases its moisture it is lighter and it travels toward the directions of the poles. In the tropical savannas and dry forests, which surround the tropical rainforest on the equator, they receive a large portion of this rain throughout the year as well. During the winter and summer solstices, the most direct sunlight is actually at the Tropic of Cancer and Capricorn with those areas receiving large amounts of precipitation and sun and it is drier when they are at the quinoxes. However, the seasonal changes that occur at the tropical dry forests and savannahs usually occur when the direct sunlight is on the hemisphere opposite of theirs and their location actually becomes a sink from all of the rising air at the centers of rising heated air that must come down. As the dry air comes down, it warms, and takes the moisture out of the area causing dryness during those times at the equinoxes.
The west side of the Sierra Nevada (mountain range between California and Nevada) gets lots of rain and snow, while the land to the east is dry with the best US examples of desert. Can you explain this difference?
The air over the ocean receives the evaporated warm wet air from the ocean currents, and moves, due to the coriolis affect from the earth’s spin, toward the coast. On the west of the mountain toward the coast, it experiences the greatest rain release as the warm air from the ocean currents, cools as it goes up the mountain. Due to the air-cooling, the water molecules become denser and stick together forming rain, releasing the moisture and water on that side and on the top of the mountain because of the height of the mountain. Then all of the air that was forced to rise, sinks down the other side and warms as it comes down. This air is dry and in order to equalize the amount of moisture in the air and land it takes the moisture from the land to the east of the mountain making the land dry called the rain shadow affect.
with the westerly coming from the west onto california
4.Are there fewer fish in the open ocean or along the coasts? Explain your answer.
Most along coasts, from nutrients from terrestrial run-off. That depends on many factors. 1st it depends on the vegetation that are present in the coast and open oceans. Along coasts where there are coral reefs, kelp and other seaweed mostly likely there are usually higher densities and more diverse fish groups compared to the middle of the ocean because of the higher availability of food stemming from the plant’s and animal’s ability to receive sunlight to grow. In coasts that have been destroyed, overfished or have toxic chemicals, there are more likely to be fish at a greater abundance in the middle of the ocean, in comparison. Many people think that coasts are the only places that support fish, whereas in fact many phytoplankton and zooplankton that have very little control of where they end up are much more numerous due to the space in the open ocean and these animals support many lives. This includes many types of fish, as well as large mammalian species such as sharks and whales. It also depends on many other factors but two to take note are salinity and temperature. In regions where the shoreline would have much colder water, there would be greater fluctuations in temperature due to the uncovering of certain areas and their exposure to air, and the animals would most likely not be able to sustain these harsh changes. Whereas, in the open ocean, the ocean waters stay a rather consistent temperature harboring life. However, in some areas along the cold coast nutrient upwelling occurs because of the thermohaline circulation systems movement making those areas warmer and more nutrient rich than otherwise expected of that area.
photosynthesis on surface of ocean although still a lot of life just less per square meter
- Which would you, expect to have wider salinity tolerance, deep sea organisms or intertidal organisms? Explain your answer.
Intertidal organisms would most likely have a wider salinity tolerance because of their daily fluctuations in the concentrations of salts. For instance, many freshwater streams and rivers run-off into the ocean and where they run off that part of the ocean would be slightly more diluted until the water diffuses. Also the contact with the sand and surrounding coast eroding the rocks etc. brings a lot of salt into the ocean in those areas, whereas in the deep sea the amount of salt does not range a great deal. Heavy rainfall changes, with the greatest saline areas having increased evaporation with the stratification left for certain periods.
- Give a one sentence explanation of how each of the following factors stratifies an aquatic environment. Provide an example for each factor. a. salinity b. temperature c. light availability
a. The differences in salinity will stratify an aquatic environment because higher salt concentrations increases density causing the salt to sink and the water with less salt to rise. For example, in the thermohaline circulation system the amount of salt present in the oceans varies at various depths due to the differing densities of the salt layer and their ability to be saturated by the salt present. lowest salinity at equator, highest salinity at desert band
b. Temperature stratifies an environment because cooler water is more dense than warmer water and will sink; however, when it gets too cold to around freezing temperature it forms at the top because ice is less dense than liquid. For example, in the thermohaline circulation system differing temperature stratifies the various layers due to cooler water having a higher density causing it to sink.
c. Light availability stratifies the ocean because only in the top 10m of the ocean can light can be absorbed because of the strained angles of refraction of sunlight which causes the appearance of more colors, and lighter blues as the rays are refracted in the upper layer, and below that line light cannot enter and is reflected up so even though the energy may diffuse down, light is still not available causing it to appear black. For example, the stratification due to light can be illustrated by the presence of phytoplankton and photosynthetic bacteria only in the top 10m of the ocean.
- Use four of the following terms to explain the differences in energy acquisition between plants and animals: condition, chemosynthesis, detritivore, autotroph, heterotroph, photosynthesis, ectotherm, resource. Some words are better choices than others. For all words that you choose, make sure that the definition is clear from your answer. It is safest to include each definition parenthetically or in a separate sentence.
Animals and plants differ by the fact that plants are autotrophs or the primary producer in the food chain. Autotrophs do not eat other organisms, but most plants although not all obtain energy by harnessing sunlight to make organic substances by photosynthesis. Whereas, all animals are classified as heterotrophs because they consume other organisms in order to satisfy their energy and nutrient requirements and they directly or indirectly rely on autotrophs as they rely on carbon that has originated from another living thing. They also differ in their requirements for conditions and resources, a condition that cannot be used up for animals are light, and air/O2, for instance. A condition for a plant, can be air and CO2 but some compete for air and very few others for CO2(not often) but not always light which is a resource because especially in a tropical rain forest with a canopy, plants are not able to move to receive more light unlike animals; therefore, other plants can use up light and not allow the lower ones in the canopy to have enough light. A resource that can be used up or for both plants and most animals would be food/nutrients and water as both can limit energy uptake.
They also differ in the way they acquire food, animals move plants don’t.
- Charles Krebs and his colleagues trained great tits (like chickadees) to eat mealworms off a conveyor belt. Faster conveyor belt speeds or decreased spacing increased food availability. They could also vary the speed of the belt to simulate a varying environment. Use optimal foraging to explain how you think the birds altered their consumption as food availability increased.
According to the theory, as the number of animals in the species increases they will have more energy intake per unit time available to them because the two variables are directly proportional in the equation and the animal may become more selective to better quality foods. For instance, as food availability increased the animals will have eaten more optimally as in larger pickier and choosier, and more calorie filled substances but they do not necessarily always eat perfectly optimally by always eating the highest calorie content as they will not always pass up the food that is either easier to get or comes more often. For instance, lower calorie food will still be eaten more than it should, as they do not do the math in their head but by is determined by behavior.
the decisions to eat lower quality foods are based on handling time as they are faster and more protected and are different between species although they are the same within.
- If torpor leads to lower metabolic costs, why don’t organisms spend all their time in torpor? Can you think of a rule of thumb to describe when torpor is useful?
Torpor is a state of low metabolic rate and lowered body temperature for short-term periods of time and is usually driven by ambient temperature and/or food availability. The rule of thumb may be that depending upon the food availability around, such as after times of great exertion like migration or especially in times where food is destroyed animals will go into torpor. They may not spend all of their time in torpor because over extended days or periods of time when they are in torpor it may not be beneficial to many of their organs especially when they are mating/reproducing etc. and may harm or hurt the fetus or themselves if their cells are limited in the amount of energy that they would normally absolutely need and so it should not be used a lot but only for emergency. Torpor also is not used for extended periods because animals still must use energy in the form of finding food, mating, or escaping predators and so living for extended periods will not be beneficial to them if they can’t find food in order to mate or if they are killed while in torpor with it difficult safe balancing survival and metabolism and are somewhat exposed and protected depending upon time to increase
hibernation are months reduced metabolic activity and inactivity over a long period in winter
aestivation- some in hot months, hot periods give advantage with a much more sheltered environment away from predators warmth or coolness undergone. and it takes longer to come out
- Butterflies are ectothermic and diurnal and are found from the tropics to the high temperate latitudes (even some polar zones). a. Would you expect butterflies to bask more in tropical or temperate zones? b. In an area with a wide temperature range for a single day, how would you expect basking to vary within a day?
a. One would expect the butterflies to bask more in the temperate zones because of the high variation of the temperatures in the temperate forests including very low temperatures in the nights and high temperatures during the day. The low nightly temperatures would cause the butterflies’ temperature to decrease in the night and would require them to need to increase their temperatures in order to function during the day. Whereas, in tropical environments the daily variation are much lower and the temperature stays high and does not vary much throughout the day which means they do not need to bask as much to equalize their temperature.
b. In an area with a wide temperature range for a single day you would expect that in the morning when the sun is more direct but the earth has not heated up yet that they would bask and so in the afternoon they will hide in the shade after already being warmed to avoid extreme heat. there is no basking at night nor dawn and dusk bask in morning before heat of day with best sunlight with the east cooler than west.
- Are the differences in basking in question #4 an example of adaptation or acclimation? If you aren’t certain, explain what information you would want to collect to be certain.
I believe that basking is a form of acclimation as it is the process of an organism becoming adjusted to a new environment or situation that is done naturally by behavior. Acclimation is something an organism can do to adjust to its environment and allow them to change its rate of metabolism etc. to adapt to unfavorable environmental problems but it doesn’t pass on to its’ children. To test this if a young organism is separated from its parents and put in a new environment one can see if they don’t elicit behavior because they are not taught it or view others with the behavior. Whereas, adaptation is not naturally or normally done by the body and requires it to be inherited as a result of its genes becoming inherit in those species throughout generations. Placing an individual in a different environment could test this and still seeing if they have that behavior whether or not they need it.
cinoare behavior and switch around of siblings doing same thing adaptation. Don’t use adults because of environmental cues and developmental environment affecting phenotype before development.
- Identify each of the following as “true” or “junk.” Explain your answer (for both true and junk). a. A desert mammal will have issues more similar to a hypoosmotic organism than a hyperosmotic organism. b. Bergmann’s rule suggests that organisms will be smaller in colder climates. c. In a savannah plant roots will probably be longer than in a fertilized agricultural field in Kansas. d. Plants can control their temperature and water loss by following the sun. e. Small pointed tissues (e.g., hairs, spines) can be adaptations to extreme heat or cold. f. We would be more likely to find a C4 plant in a tropical rainforest than in a tropical savannah. g. Carnivores generally eat primary producers.
a. True, the desert organisms have more water in their body than the desert air and earth as they retain more water. An organism that is hypo-osmotic has a lower solute concentration than the external environment meaning more water, whereas hyperosmotic has a higher solute concentration than the surrounding air and earth. waters flows out of organism into the environment.
b. Junk, organisms will most likely be bigger in colder climates because of the need for excess fat and fur in order to keep them warm and when food is scarce they will have extra fat available for metabolism due to the harsh winter months. Also they will have a smaller surface area to volume ratio as they don’t require a large ratio for extra evaporative cooling which is usually seen in desert species.
c. True, in a savanna, the roots will have to dig deeper for water and nutrient etc. because of the lack of water and nutrients in the topsoil. Whereas in the fertilized area, the nutrients would most likely be at the top and require less growth of the roots.
d. Junk, plants maximize their photosynthesis by following the sun increasing their temperature and water loss, whereas, if they avoided the sun they would be more able to control their temperature and how much water they lost. They would also more likely be able to control their temperature and water loss by either spreading out their stems or wilting. can’t control water loss of following sunlight.
e. True, in warm climates, small hairs can allow for more convection and loss of heat to the wind and air and can reflect sunlight, whereas in cold climates these insulated leaves with slightly different hairs will trap this nonmoving air limiting convection keeping it warmer and having darker colors to absorb more light.
f. Junk, you would be more likely to find a C4 plant in a tropical savannah because of the elevated temperatures causing for a greater loss of water in the plant which coincides with the adaptation for a C4 plant, in a tropical rainforest it is mostly likely to have a C3 adaptation because there is so much water available that increased water loss due to its mechanism is not problematic and it maximizes the sugars produced allowing them to grow fast. with the CAM present in driest
g. Junk, carnivores usually eat other animals they never eat primary producers; herbivores eat primary producers.
- For fourteen North American bird species at the northern edge of their geographic ranges, Terry Root found that the minimum metabolic rate necessary for survival was about 2.5 times the basal metabolic rate at the portion of their range where they were at highest abundance. a. Explain how this increased metabolic rate might contribute to their range limits. b. Think of a plausible, testable, alternative hypothesis for a factor that might limit these birds at this northern range limit and explain how you would test your hypothesis.
a. This increased metabolic rate means that more heat is produced through metabolism allowing them to survive in this environment. The increased metabolic rate means that the animals break down more food than usual and therefore require more food in order for them to survive in that environment. The rate means that the animals require 2.5 times as much food available for them to survive. A range limit suggests that even though it is metabolically more difficult for them to survive at this range, it has enough resources available for them to survive but beyond that point there is not enough for them to survive. Therefore they cannot eat enough to counteract this metabolic loss at certain areas
b. An alternate limitation might be in the availability of nesting for some bird species. For instance, some trees may not be able to survive in such harsh environments and the specialist species that use these specific trees therefore also would not be found there. A way to test this hypothesis would be to have two plots of land in these temperatures at the edge of the bird species range. In one of the plots introduce the nesting tree while protecting the tree from the environment so it is able to grow. Then if they are not already present introduce the test bird’s species into the nearby area and observe whether the bird species expands. If they expand in the area it is very likely that the nesting limits it and not necessarily the temperature to their bodies. able to live in a wide range without turning on engine. or the limitation of young as extremes may be limiting to egg hatching
- You collect and mark 80 caddis fly larvae in Lower Lake and go back the next day and catch 120 caddis fly larvae, 20 of which are marked. a. What is your estimate for how many caddis fly larvae are in the lake? b. Would you trust your estimate more or less if your second sample had come 8 weeks after the first?
a) 480.
b) I would trust my estimate less because of the variability in the population of flies seasonally and daily. For instance, when the fly population was highest, their predator species such as birds could be low and eight weeks later the birds could be more numerous. Also, if the fly population became adults in that time frame some individuals may have emigrated and new individuals immigrated. birth death, behavior, emigration, and immigration
- a. What is the difference between λ and rmax? b. How does the population size change over time when λ>1? When λ =1? When λ
a) λ is the finite rate of increase, or the geometric rate of increase and the fundamental rate per capita of increase with the probability of the survival of existing individuals. It describes things overall through a period of time. rmax is the instantaneous rate of change and the change happens at a distinct and short set of time.
b) When λ>1 the graph exhibits a geometric growth and when the λ
- Which factors below can lead to density-dependent mortality or birth rates? Explain. a. a cold winter that wipes out half of a population b. a refuge that allows a fixed number of individuals to survive c. a sexually transmitted disease d. a disease transmitted by casual contact
a. It does not lead to density-dependent mortality because it does not matter how many individuals the cold wipes out whether in a large or small population if it is too cold they won’t survive.
b. The sheltering of individuals given the fixed number is considered density dependent because if there is a limitation of a resource such as shelter it is based upon how many individuals can use it; therefore, it is density- dependent.
c. It will not create density dependent mortality because it does not matter how many individuals are within the population as it does not rely on contact and will affect individuals within large or small population no matter what. However, it may be slightly density dependent because within a large population it is less likely that all will die from the diseases because there is such a large population to transmit them to. Whereas, in a small population everyone is more likely to get it easier if they are all interbreeding, again these depend upon the behavior of the individuals within the population as well.
d. Casual contact is more likely to happen in environments in which there are more individuals in an area.
- Using the following data, determine whether this population shows density-dependent birth or death rates or both. Illustrate your answer using graphs with correctly labeled axes (You won’t be able to put your graph into Moodle, but tell me what your axes are and what the plots look like).
The data exhibits density dependent birth rates as the rates decrease from .7 to .11, but there are density-independent death rates because the rates stay relatively the same at around .1. The graph has population size on the X-axis and the number of individuals who were born and died on the Y. However, the graph does exhibit positive linear slopes for deaths because at low population sizes there were very few deaths. As for births there was a negative linear slope with a lot of births at low population size. However, at high population size there was the same amount of deaths as births with the births much lower than previous.
- a. Describe and draw the four possible outcomes of discrete-time logistic population growth (in the quiz, just describe). b. Explain how time lags play a role in this equation and in these dynamics.
The four possible outcomes of discrete-time logistic population growth are plotted as time versus the number of individuals in the population. The first of the four possible outcomes are monotonic damping where the rdiscrete is less than 1 and is illustrated by an exponential growth curve with a large increase in population from a slow one then tapering off at the end reaching a stable population. The second outcome is damped oscillation where the rdiscrete is between 1 and 2. This graph illustrates exponential increase once again from a slow increase to a rapid increase and then overshoots the carrying capacity of the population. There is then a slight drop and a few small overshooting bumps then the population remains stable at that population afterwards. The third outcome is the stable/limit cycles where the rdiscrete is between 2 and 2.692. The graph increases exponentially starting out the same as the two previous graphs and then overshooting and dropping by equal amounts. Then the graph oscillates between these two points and does not keep a consistent population size. The last outcome possible is chaos with the rdiscrete larger than 2.692. Its graph illustrates a steady exponential increase very similar to the others but when it overshoots and undershoots around the carrying capacity it does not oscillate between these two points and instead the populations are random. The time lag is the time difference between the organism eating all the food and the effect of having no food left acting on the population. The time lag causes some of the populations to overshoot the carrying capacity with larger time lags causing the stable/limit cycles and the largest creating chaotic cycles
- Furbish’s lousewort (Pedicularis furbishiae) is a federally endangered plant in the Scrophulariaceae (same family as snapdragons) that grows in floodplain areas, specifically on slumped river banks in Maine and New Brunswick. P. furbishiae is a perennial species that takes up to three years to reach reproductive maturity. The non-reproductive form is a small, flat plant called a basal rosette, but the mature, reproductive plant is fairly big because of a flowering spike about 1m tall. The size of plants is strongly positively correlated with seed production, meaning that bigger plants tend to produce more seeds, so plants often produce more seeds after their first year of reproductive maturity. Each plant can also self-pollinate so that a single plant can produce seeds. The seeds disperse primarily through river currents and wind and often end up far from the parent(s) in large clumps at river bends where the current slows. Each population does not live very long because the plants do not compete very well without floods, and with floods they get scrubbed off the banks within a decade or so. We only see new populations in places where floods have removed most other species and created empty spots along the bank.
a. How does P. furbishiae experience r-selection or K-selection? This is a species that does not fit the dichotomy very well, or that could fit either side. Try to come up with at least two characteristics of r and two for K.
b. Is there another life history classification system that works better than r vs K? Explain your answer.
a. r-selected attributes- not good competitors, smaller non-reproductive form to maximize the number that initially grow, good dispersers that allows their range to be far away, and producing a lot of offspring. ruderals
K-selected attributes- larger reproductive body size, disturbance adapted especially to floods, does not live very long
b. The periodic life history model is more fitting because it combines the low juvenile survival, which most likely occurs because of competition among the species for room and nutrients at the un-reproductive stage. There is also high fecundity created from bigger plants and more seeds, and later maturity. Also, the Grimes Triangle was created for plants and illustrates that the low stress, and competition nature of the plants allow them to be disturbance adapted.
Life table questions
b. Find the size of the population after 10 years, given that N0=1000 and assuming that lx and
mx do not change.
d. Can you think of a species that might fit this life table?
e. If this example described a perennial species with discrete breeding in the spring and with
the ages being 0, 1, 2, 3, 4, and 5 years, what would the population size be in 10 years? (Hint: Remember to convert between Ro and λ)
b, λ=R0
Nt=N0* λt. Nt=1000*.8593210= 219 individuals.
d. A species with a very small life-span of around fifty days although its entire life stage is completed in a year and that undergoes a sort of adolescent or larval stage for 1/5 of their life after which they can produce many babies most likely semelparous if it is an annual plant and then slowly die off. ex. most likely to be a plant to live one year and have one group of offspring then die, like a daisy.
e. T=(Σxlxmx)/(Σlxmx). T=(2.38864)/.85932. T=2.779686264 days
λ=R01/T. λ=.859321/2.779686264 = .946917289
Nt=N0λt. 1000*.94691728910= 579 individuals
- Life tables assume a constant rate of population growth.
a. What would the problem be with constructing a life table for an organism with density dependent population growth? Explain.
b. In the real world populations do not grow forever without limit, so when are life tables useful?
a. It would be extremely difficult to make a chart for a population that is so dynamic and continually changing. Therefore, finding the amount of individuals produced and dying one day versus the next would not only be difficult to actually do but would not represent that data as a whole such as in winter many more individuals die than births but there are births and in the spring there may be more births than deaths. This is because they are not only continually dying as the other model, but continually reproducing throughout the year.
b. When a population or species is increasing or decreasing in number when they are below their populations carrying capacity. They give us important information about the death and birth of individuals with certain ages in the population.
- For the survivorship curve to the right, please a. label the axes; b. identify the curve as a Type 1, Type 2, or Type 3 survivorship curve.
This is a type 1 survivorship curve because the juveniles survive very well and then there is a constant population and then a huge die-off at the older age. The x-axis is age, and the y-axis is log(survivors).
- If everyone in the world started having a maximum of 2 children/couple would population growth cease immediately? Explain your answer.
No, because population growth is not just about the number of births but also deaths. So if in that time right away the current death rate stands the population would still be growing, as there are not people leaving the world population through deaths. However, after a period of time growth of the population will cease, as the number of individuals in the world will be completely replacing those that are dying.
- Identify which of the following involve competition. If there is competition, tell me if it is interference competition:
a. Garlic mustard (Alliaria petiolata) is a non-native species spreading through New England. It takes over new areas by killing native plant species with chemicals that it exudes through its roots.
b. Lions attack a pair of hyenas and steal a gazelle that the hyenas have killed.
c. Lions enter a new area, and their predation lowers gazelle population densities. Subsequently, hyena densities in the same area decrease. The lions and hyenas never encounter each other.
d. Male frogs call from breeding ponds in the spring, and predators home in on these sounds, often capturing and consuming both male and female frogs.
e. In the west, ground squirrels and tiger salamanders will use burrows at different times of the day or year, with tiger salamanders out in breeding ponds at night and in the wet spring when ground squirrels are in burrows.
a. This is interference competition because the one species is directly excluding the other species and is interfering with the other specie’s acquisition of resources.
b. They are physically excluding the other species from resources and so they are exhibiting interference competition.
c. This is not interference competition because they are not physically or directly keeping another species from acquiring of the resources. Instead, they are indirectly exploiting the resources exhibiting exploitative competition with the other species by taking the resources from the area.
d. This is not competition between two predators so there is no interference.
e. This is not interference competition or competition in general these animals have no niche overlap as described and so are not in competition with each other.
with resource portioning as the squirrels make them and the salamanders benefit it could be commensalism.
- Ecologist Jared Diamond argues that fruit eating bird communities on South Pacific Islands are structured by (i.e. strongly affected by) competition. If he is right,
a. how much rotten fruit will there be on the ground?
b. What will happen to fruit densities and resource utilization curves if a new competitor invades?
c. What will happen to fruit densities and resource utilization curves if a native frugivorous (fruit-eating) bird goes extinct?
a. There would be very little fruit on the ground because if there is strong competition between species there will not be that much fruit left over on the trees. Any species that would leave food on the trees would be decreasing their chances of survival and reproduction. Also, if fruit fell by accident one would expect a niche to include these fallen fruits in order to utilize their nutrients with better fitness of these individuals who can access these resources.
b. If a new competitor invades, the food densities will decrease initially then level off and there would be less food available for each individual in a species therefore making the curve for each species taller in height with more utilization of one type of food that is different than the other species decreasing competition.
c. The food densities would possibly increase initially then level off but there would be more food available per individual and as a species overall allowing for the species to increase feeding and increasing the width of the curve of things they could possibly utilize due to decreased competition for those resources.
- Species 1 and 2 compete. Using the Lotka-Volterra competition equations, express the outcome of competition between such species, and draw the phase plane diagrams if K1 = 100 and K2 = 50 and
a. α21 =α12 =0.25.
b. α21 = 0.75, α12 = 0.50.
a. There is stable coexistence because the K1/α1,2 point is larger than the carrying capacity for species 2, and the K2/α2,1 is larger than the carrying capacity for species b. Species 1 wins because its carrying capacity and K1/ α1,2 are both greater than the carrying capacity and K2/α2,1 of species 2.
- For each phase plane diagram below, state whether the species coexist. If they do not, who survives?
a. The equilbirum point is at K2 where both species do not coexist and only species two is present as it is at its carrying capacity.
b. At this center position there is an unstable equilibrium position where both species can coexist but beyond that point there is a split in the outcomes that depends on the initial conditions and can either have the equilibrium point at species one or species two carrying capacity.
- Common mynas have been introduced to Australia and use similar nesting sites to those preferred by Rosella’s (an Australian parrot). Mynas will perch on rosella nests and harass breeding rosella, occasionally pecking at incubating eggs. Rosellas’ preferred nesting sites are tree hollows, but they will avoid hollows in Eucalyptus trees when mynas are in the area. Explain how the following terms fit or do not fit this situation:
a. Character displacement
b. Competitive release
c. Niche shift
d. Fundamental niche
e. Realized niche
f. Resource partitioning
a. Character displacement is where differences among similar species whose distributions overlap geographically are accentuated in regions where the species co-occur, but are not present where the species’ distributions do not overlap. Where they do occur evolution commonly happens due to competition leading to a change for an adapative trait. They are experiencing character displacement due to the competing species because Rosella’s will utilize the hollows of Eucalyptus trees when myenas are not present but will not when they are and this could be due to evolution or lead to it due to interference competition.
b. This is the shift from the realized niche to the fundamental niche with the removal of a competitor, which usually changes population size. This is not occurring because the myena’s were added changing the rosella’s fundamental niche to realized niche and not vice versa. If the myena’s were removed this would most likely happen.
c. Is when species shift resource use from their fundamental to realized niche and it usually is associated with a smaller population size of that species. Although there was no indication that there was a change in population size, it would be expected. However, there does appear to be a shift in the utilization of resources for Rosella’s at least in order to avoid the Myena shifting the Rosella’s fundamental niche where they utilize all of the resources to one with a smaller amount of resources by not including eucalyptus trees as nesting sites.
d. The fundamental niche is the full range of environmental conditions and resources an organism can possibly occupy and use, especially when limiting factors are absent in its habitat. In this case the fundamental niches of these two species cannot be utilized, because they overlap too much. Although, we are unsure whether myenas actually are in a realized niche they could possibly be in their fundamental niche because they are better competitors.
e. The realized niche is the part of fundamental niche that an organism occupies as a result of limiting factors present in its habitat. So it is a different niche with different resources centered on and utilized. This is the niche that the Rosella’s now definitely occupy by utilizing their resources differently than before in order to maximize their survival and lessen negative competition.
f. This is when species divide up resources and it does not necessarily happen in this case because even though the Rosella’s avoid the eucalyptus hollows there is no indication that the Myena’s have also changed their behavior according to this. They are not dividing up resources and instead are competing almost entirely for the same resources.
6 a. What happens to the strength of competition with a niche shift?
b. What happens to the strength of competition with character displacement?
c. How do the two differ?
d. How would you distinguish between them?
a. The strength of competition decreases with a niche shift because they are shifting from using the same resources in their fundamental niche to their realized niche. This will create resource partitioning so there is less competition and niche overlap in order to more fully utilize the available resources in order for the species to survive. strength increases compeition as intersection point decreases
b. With character displacement it creates evolution due to competition which inadvertently leads to an adaptive trait that separates one species from the next and it could possibly increase competition by increasing the species’ ability to better compete for that item or it could decrease competition by allowing that species to shift its niche and function by taking advantage of other resources less competed for.
c. Niche shift is the change of one species to a different niche allowing them to utilize resources better in another area decreasing competition. Whereas, character displacement would not always necessarily decrease competition it could also increase competition by allowing them to better compete for resources in that environment. genetic basis phenotypic difference physical or behavioral.
d. A niche shift would be more of a behavioral shift of a niche decreasing competition and is not necessarily heritable, whereas a character displacement may more likely be a physical attribute or a new ability to do something different increasing or decreasing competition for aloquated resources and can be heritable. remove competitor and spread out with inch shift if they didn’t spread out it is character displacement
- A researcher in New England observed that two Norway maples in her backyard kept their leaves longer than the red maples in her yard.
a. Based on this observation, come up with one question (that differs from the one below) and a related hypothesis.
b. The researcher asked whether this longer leaf retention led to different growth rates of small trees of both species. State specific hypotheses related to this question and frame an experiment to test your hypothesis.
a. I wonder whether this longer retention of leaves allows the trees to store more food and last through longer periods of cold weather or longer winters? I hypothesize that this increase retention of leaves allows for more photosynthesis creating more sugars for the tree, which are stored allowing the trees to utilize this sugar over longer periods of time.
b. I hypothesize that the longer leaf retention exhibits different growth rates of the two species and the trees that kept their leaves and photosynthesize longer growing slower due to increased resources needed for growths. Therefore, at the end of the year they will have grown the same amount but just at different rates. To test this one should grow the trees under the same conditions and after a period cut hundreds of small trees of both species at varying ages and different times of the year and measure the rings to see how much they grew during that time and at what past age.
