Short Answer Ecology Questions

What is meant by the term "trophic structure" in community ecology?

Whom eats whom. The food chain at the bottom are the primary producers (plants) Trophic structure refers to the way in which organisms use food resources. to get their energy for growth and reproduction, and is often refered to in. simple terms as the "food web" or "food chain". A healthy marine ecosystem. consists of trophic levels that have complex linkages to form a food web.

Your friend Bookie is confused about population ecology. He says "Dude, I'm confused. What's the difference between B and b? And M and m? And what is K? And how do I calculate "r" from information about B and M? I feel like my head gonna split open". Do Bookie a solid and help him out.

B is the number of births and little b is the number of births per capita B/N. same for M and little m. r=b-m is the per capita growth rate. K is the carrying capacity, the number of individuals an area can support indefintley.

You have been studying wombats, and you calculate the population r(max) = 0.0000001. Is this population a) growing exponentially, b) growing arithmetically, c) declining, d) stable?

. The population is growing exponentially (any r(max) above 0 will result in exponential growth) until something (like limited resources or whatever) slows the population down or causes it to crash.

You are studying a population of small mice in your attic. You estimate that the carrying capacity of your attic is 500 mice, and there are currently 200 mice up there. How many mice are added to the population per time-step if the r(max) of the population is = 0.07?

.007*200(500-200/500)=8.4

What is the difference between density dependent and density independent population regulation?

1. biotic factors, predation parastisim, depend on the population and are dependent on themselves(controlling birth and death rates.). like if more birds in a population then they will have less offspring due to lower resources to have them. 2. Abiotic factors are density independent do not depend on the density whatsoever to happen, natural diastsers, etc. vital rates (e.g., survival) depend only on the environment.

List three simplifying assumptions of the logistic growth model.

1. no immigration or emmigration. 2. All orgnaisims contribute equally 3. Enviorment is constant k is constant.

Your friend Fred conducts a mark-recapture study on badgers. In the first capture, Fred catches 20 badgers but only manages to mark 5 before the rest get away. On the second capture, Fred catches a total of 32 badgers, and there are two marked. How many badgers do you estimate are in this population?

5*(32)/2=80. Forumula is Numbermarked*totalcapturedin2ndone/numbermarkedin2ndcapture

Gaspard Coriolis is here to make our lives harder. But also, his notion of Coriolis forces help explain how tradewinds which blow from east to west (between 30 N and the equator, and 30 S and the equator) are generated. Explain this process in words.

As part of the Hadley cell circulation, surface air flows toward the equator while the flow aloft is towards the poles. A low-pressure area of calm, light variable winds near the equator is known as the doldrums,[7] near-equatorial trough,[8] intertropical front, or the Intertropical Convergence Zone.[9] When located within a monsoon region, this zone of low pressure and wind convergence is also known as the monsoon trough.[10] Around 30° in both hemispheres, air begins to descend toward the surface in subtropical high-pressure belts known as subtropical ridges. The subsident (sinking) air is relatively dry because as it descends, the temperature increases, but the absolute humidity remains constant, which lowers the relative humidity of the air mass. This warm, dry air is known as a superior air mass and normally resides above a maritime tropical (warm and moist) air mass. An increase of temperature with height is known as a temperature inversion. When it occurs within a trade wind regime, it is known as a trade wind inversion.[11] The surface air that flows from these subtropical high-pressure belts toward the Equator is deflected toward the west in both hemispheres by the Coriolis effect.[12] These winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.[13] Because winds are named for the direction from which the wind is blowing,[14] these winds are called the northeasterly trade winds in the Northern Hemisphere and the southeasterly trade winds in the Southern Hemisphere. The trade winds of both hemispheres meet at the doldrums.[7] So basically a hadley cell that is coming back towards the equator and the movement of the earth makes the trade winds.

You have two ponds, and each is full of algae. In one pond there are three trophic levels and in the other pond there are four trophic levels. Which pond is a better candidate for "top-down" control of algae, if you can only add more individuals of the 3rd trophic level to the first pond, or more individuals of the 4th trophic level to the second pond? (note: the trophic levels are, in ascending order, 1= algae, 2 = small zooplankton, 3 = large zooplankton, 4 = fish)

As we add more fish to the lake, this decreases the amount of large zoo plankton eating the small zoo plankton that eat the algae. If we added more of the zooplankton we would lower the amount of small zooplankton which would increase the algae rate. So we add more fish instead of adding more zooplankton

How are Hadley cells related to the presence of desert biomes at 30 degrees north and south latitude?

Because hadley cells lose all their moisture at the equator, as they move poleward they pick up the moisture off the land as they descend. Thus at 30 degrees the cloud is absorbing all the moisture from the land making it very dry.

K selected

By contrast, K-selected species display traits associated with living at densities close to carrying capacity, and typically are strong competitors in such crowded niches that invest more heavily in fewer offspring, each of which has a relatively high probability of surviving to adulthood (i.e., low r, high K). In scientific literature, r-selected species are occasionally referred to as "opportunistic" whereas K-selected species are described as "equilibrium".[8]

Write a short paragraph describing how El Ninos occur; make sure to include the concepts of westerly-winds, warm water "pile-up" in the western Pacific, coastal upwelling, and fisheries collapse.

El ninos occur in the Pacific ocean, when the tempature of the water on the US west coast isn't its normal cool temperature and it is usually hot on the Australia side. What happens is usually the cold water slushes down the winds to go from east to west making an easterly wind, but in an el nino, the water is warm on both sides and mainly very warm in the west pacific, and can stop the wind of make it go the other way producing a westerly wind. So due to the cold water coming up and pushing the trade winds, it also helped bring up nutrients from deep in the ocean to support fish higher in the surface. When this doesnt happen and el nino occurs it causes the fisheries at the top to not get nutrients from the bottom and to start dying

How are hadley cells formed?

From at the ICTZ on the equator, The Hadley cell, named after George Hadley, is a tropical atmospheric circulation that features air rising near the equator, flowing poleward at 10-15 kilometers above the surface, descending in the subtropics, and then flowing equatorward near the surface. The Hadley cell circulation produces strong latitudinal patterns of precipitation. As water molecules in the tropics (most notably the oceans) absorb the intense sunlight there, they evaporate, so the air that rises in the tropics is rich in water vapor. As this warm, moist air expands and cools, fewer water molecules are moving fast enough to bounce apart after they collide. Instead, they form droplets of liquid water (or ice crystals), which grow and—when massive enough—fall to the ground as precipitation. Thus the warm, rising air of the Hadley cells drops most of its moisture near the equator as rain. The high-altitude air that eventually descends near 30° N and 30° S is largely depleted of water; moreover, because it warms as it descends and is compressed, the little water that remains stays in a gaseous state. Earth's great deserts are located around these latitudes.

Can a large and a small island have the same predicted equilibrium species richness? Why or why not?

If the large island is far, and the small is near (as above), they could possibly have the same species richness.

What is the difference between r and r(max)?

In the exponential model they are the same thing. But in the logisitic model, rmax =b-d and is constant (also called intrisinic rate of increase) (The realized is the same as the maximum rate of increase because the population is unlimited by resources.), and r=rmax*(k-n/k) This "adjustment" takes into account changes in b and d that happen as density changes. So r is a changing variable with carrying capacity and R max doesnt change and assumes maximum unlimeted resources and growth etc. r(max) is the highest potential per capita rate of growth for a population, which only occurs when the population is at 0 individuals (unlimited resources, no competition, etc). As soon as individuals are added to the population, the actual rate of increase of the population (r) begins to get smaller than r(max), because of the growth rate modifier term in logistic growth (K-N/K).

What does it mean when one says "this species displays a life-history that seems more r-selected"?

It means that the species tends to reproduce at a young age, make lots of offspring, give those offspring little or no parental care. Think weeds, think houseflies, think yucky bugs of various sorts.

If a giant forest hog eats 2500 joules of energy, and uses 900 joules towards all maintenance (respiration) and excretion, what is the giant forest hog's production efficiency? Does that seem high or low for such a creature?

It seems high for an endo-therm. Usually they have to use a lot for respiration and heating their body up. But the hog is using 1600 Joules of energy towards growth. Which is very high, and his production efficiency is very high. the amount of meat he makes (1600/2500). Generally production efficiency for endo therms is between 1-5% for endotherms. so this is massive. So the biomass stored for this animal is very high and they have a lot of meat.

You take a field trip and you go out to two different prairies, and collect all the grasses there, and weigh them up. Amazingly, both prairies have the exact same total weight of grasses (150,000 pounds in each). Is it true then that both prairies have the same NPP? GPP? Explain your answer.

Nope, NPP and GPP are rates, and all we've done is measure biomass (or standing crop). We have no information about their relative rates of productivity

Your friend is very curious about the following observation: Two different areas on the globe have exactly the same annual rainfall, but one area is dry and scrubby and the other is very green and lush. Drop some knowledge on this friend regarding how this can be.

One area could have a high amount of disturbances that keep it from becoming green and lush. Like a rain forest vs a savanna. They both can have a high amount of rain but in the Savannah animals can trample down and eat all the vegetation and also fires can be started. Could be animals eating it. Also it's all about the temporal distribution and intensity of the rainfall (does it drizzle constantly or come down in buckets?), and how much solar radiation the area receives (remember evapotranspiration? A function of water and solar energy)

What results did the experiment in the intertidal zone with those blue and brown mussel species (Balanus and Cthamalus) show? Use the terms "fundamental niche" and "realized niche" in your answer, as well as "competitive superiority".

Some species are not able to occupy their entire niche because of the presence or absence of other species. Interspecific competition occurs when two different species attempt to utilize the same resource and there is not enough of the resource for both species. Observation of this phenomenon in nature has led to the concepts of fundamental and realized niches. Fundamental niche: the set of resources a population is theoretically capable of using under ideal conditions Realized niche: the resources a population actually uses The realized niche may be smaller than the fundamental niche because of interspecific interactions such as: Competition Predation Two species of barnacles live in a stratified distribution in the intertidal region along the Scottish coast. Observations: Balanus is most concentrated in the lower intertidal area. Chthamalus is most concentrated in the upper intertidal area. The free-swimming larvae of each species can settle anywhere on the rocky shoreline, and presumably be able to grow to be an adult. Question: why don't we see Balanus and Chthamalus growing together? Experiment 1: Connell removed Chthamalus from the upper area, and no Balanus replaced it. Inference: Balanus could not survive in an area that experienced so much desiccation (due to low tides). Conclusion: Balanus's realized niche was the same as its fundamental niche. Experiment 2: Connell removed Balanus from the lower area and Chthamalus replaced it. Inference: Balanus was a more successful competitor in the lower intertidal zone. Conclusion: the fundamental niche and realized niche for Chthamalus were not the same—its realized niche was smaller due to interspecific competition. Conclusion: competition occurs in nature and can explain the distinction between a fundamental niche and a realized niche. and Balanus is a superior competiter lower in the water.

What is the "facilitation" model of succession? Can you remember the example we talked about in class?

That's the one where organisms make the environment favorable for other species, which "facilitates" those very species coming in an opening up a can of whupping on the facilitator species. Remember the nitrogen-fixing alder trees making things good for the spruce trees?

Why are parcels of air moving towards the equator from higher latitudes deflected? What direction are these parcels of air deflected?

The corriolis force relates to the movement of the trade winds throughout the earth. As the air moves from the poles to the equator it is moving into an area that is moving faster at the center then higher up, it moves from east to west. So as air comes toward the eqautor it appears to be deflected to the west. the trade winds. As air moves from a slower moving part of the globe (at 30 degrees north and south) towards the faster moving equator, the air is deflected westward because of the differential speeds of the earth's surface (along with some friction)

Climate change gonna kick yo a**. Explain how the greenhouse effect works. How much warmer is the planet these days, on average, than historical temps? How many of the 14 hottest years on record have occurred since the year 2000?

The greenhouse effect is a natural process by which some of the radiant heat from the Sun is captured in the lower atmosphere of the Earth, thus maintaining the temperature of the Earth's surface. The gases that help capture the heat, called "greenhouse gases," include water vapor, carbon dioxide, methane, nitrous oxide, and a variety of manufactured chemicals. Some are emitted from natural sources; others are anthropogenic, resulting from human activities. So an increases in these gases causes the temperature to increase. 15 of the 16 hottest years since 2000. hotter by .8 degrees.

Draw an X-Y graph showing what you think the relationship would be between average dispersal distance of a species and the degree of inbreeding (mating with more related individuals) experienced by that species.

The higher the inbreeding the lower the dispersal distance due to them all having sex with each other, they wouldn't go out to other groups to make offspring and would just stay in their own little area.

Note that while there are biomes that are very warm and wet, biomes that are very warm and dry, and biomes that are very cold and dry, there are no biomes that are super cold and super wet. Why do you suppose that is?

There are no places on earth where those exist. If its really cold preciptation has to be low due to it being too cold and outside the headley cells area. so its incredibly dry. The Arctic is a cold desert because it gets very little precipitation (rain or snow) - about the same amount as the Sahara - but it is so cold that the snow that does fall doesn't melt, so deep snow covers the land and ice Heavy rainfall usually happens when hot air rises, and as the air rises, it cools and loses moisture. If it's really really cold, there isn't a lot of air rising, right?

from your rock-solid near-cyborg-like memory, construct the island biogeography curves, labeling each axis, each of the two curves, and the points S"hat" and P. Make sure you know what each of these components represents.

Total number of species on mainland = P and S is the equilibrium species richness

Which island will have higher species richness, a large far island or a near small island? Is it possible to tell? If you need more information, what information do you need to be able to answer the question?

We don't have enough information...it could go either way depending on the specifics. We need to know the shapes of the immigration and extinction curves for each island, so that we can see where those two lines cross for each island. The one that crosses at a higher equilibrium species richness will be, uh, the one with the higher species richness