Eco Lab Final

Population size is a fundamental feature of any population. You and your lab partner will estimate the size of a population using a mark-recapture technique. Although we will not be doing a true "census" (= complete head count), the lab exercise uses this term repeatedly in describing population estimates. A mark-recapture technique can be based on the Petersen index, which has a single "census" period, and it uses a mathematic formula involving several symbols. Which symbol has not been correctly identified? -M = the number of animals marked during a post-census period -R = the number of marked animals recaptured during the census period -N = estimate of the population size -C = the number of animals captured during the census period

-M = the number of animals marked during a post-census period

Direct gradient analysis is a technique for measuring species' adaptations to natural environments in which both biotic and abiotic factors are at work. In this technique, ecologists determine species' performances along sizable environmental gradients in which abiotic factors (e.g., soil moisture and nutrients) change gradually and continuously. How well any species "performs" in any particular part of the gradient is a clue as to its adaptations. Measures of performance for trees include leaf cover, basal area, and relative density. In a nutshell, direct gradient analysis is a good way to directlymeasure: -Leidbig's law of the minimum -species' realized distributions -the importance of biotic factors versus abiotic factors -species' potential distributions

-species' realized distributions

How long does it take for the climax forest to be reached during old-field succession on uplands in the Piedmont of North Carolina? -25-250 years -150-175 years -it can never reach the climax -50 years -in less than a century

150-175 years

Secchi disks are routinely used to determine water clarity and the depth to which net primary productivity can proceed. If you were using a Secchi disk and you measured the compensation point to be 2.25 meters, to what depth would the euphotic zone extend? -2.25 meters -2 meters -1 meters all depths greater than 2.25 meters -it is not possible to know the depth of the euphoric zone based on the information given here

2.25 meters

An ecologist decides to use a mark-recapture approach and the Petersen index to estimate the population size of fox squirrels The number of squirrels marked in a pre-census is 82. The total number of squirrels captured the second night (or during the "census" period) is 78, and the number of previously marked squirrels that is recaptured is 19. What is the correct estimate of the population size? Note, that the estimate (value) should not be rounded. It should simply be truncated. -326 -334 -337 -8 -335

326

In a mark-recapture study of bird population size, C = 56, M = 72, and R = 11. Based on the Petersen index, what is the estimated size of the population? -9 -345 -371 -64 -382

345

During a previous lab exercise, you and your lab partner used deer jaws to age white-tailed deer. To create a survivorship curve, you used a sheet of semi-log paper and converted the Y-axis to decimal fractions for percentage survival. Which value for percentage survival has not been converted to its correct decimal fraction? -34%=0.34 -96%=0.96 -4%=0.4 -15%=0.15 -2.5%=0.025

4%=0.4

An ecologist decides to use a mark-recapture approach and the Petersen index to estimate the size of a population of flying squirrels in longleaf pine savannas of North Carolina. The number of squirrels marked in a pre-census is 36. The total number of squirrels captured the second night (or during the "census" period) is 28, and the number of previously marked squirrels that is recaptures is 11. What is the correct estimate of the population size? Note, that the estimate (value) should not be rounded. It should simply be truncated.

88

Ecologists sometimes make the distinction between a species' realized distribution and its potential distribution. How do these two concepts differ? -Any species' realized distribution results from adaptations to limiting factors, whereas the potential distribution results from adaptations to a range of physical factors. -Any species' realized distribution is the result of biotic interactions and its adaptations to abiotic factors in the environment, whereas the potential distribution results from adaptions to abiotic factors alone. -Any species' realized distribution is the result of adaptations to abiotic factors alone, whereas any species' potential distribution results from interactions with other organisms. -The realized distribution occurs under optimal conditions, whereas the potential distribution occurs under harsh conditions.

Any species' realized distribution is the result of biotic interactions and its adaptations to abiotic factors in the environment, whereas the potential distribution results from adaptions to abiotic factors alone.

Which species dominates the field in the second year?

Aster

The oxygen concentration of freshwater ecosystems varies from surface to bottom, especially during warm months in deep lakes in temperate parts of the world. Where would oxygen gas concentration typically be lowest in a freshwater lake? -At the surface because of the loss of oxygen gas from the surface. -At the bottom because the activity of decomposing bacteria is greatest at the bottom. During decomposition, these bacteria consume oxygen gas by way of cellular respiration, which depletes oxygen in the bottom substrate. -At the bottom, because bacterial decomposition releases carbon dioxide. -At the bottom because photosynthesis at the bottom releases oxygen gas. -none

At the bottom because the activity of decomposing bacteria is greatest at the bottom. During decomposition, these bacteria consume oxygen gas by way of cellular respiration, which depletes oxygen in the bottom substrate.

The oxygen concentration of freshwater ecosystems varies from surface to bottom. Where would the oxygen gas concentration typically be greatest in a freshwater lake? -At the bottom as net photosynthesis is likely to occur here; hence, oxygen gas is produced. -At the surface because of physical mixing between the surface water and the atmosphere. -At the bottom because decomposition produces oxygen gas, and decomposition is greatest at the bottom. -At the surface because of the loss of carbon dioxide from the surface. -none

At the surface because of physical mixing between the surface water and the atmosphere.

Examine the illustration of a lake below. Which letter in the figure represents the littoral zone? -A -D -B -C

B

Distance sampling can be used in place of strip-census techniques, such as the Hayne Estimator. The two techniques are similar and have all the following in common except: -Both methods can use footprints, droppings, or some evidence of the species under study, instead of actual sightings of the animals. -In both methods, the perpendicular distances between the animals sighted and the transect are recorded. -Both methods rely on transects for sighting animals. -Both methods rely on the number of animals sighted inside some smaller, imaginary rectangle within the area occupied by the species

Both methods rely on the number of animals sighted inside some smaller, imaginary rectangle within the area occupied by the species

Which species dominates the field in year three to six?

Broomsedge

As compared with the Petersen index approach, the Schnabel estimator should theoretically give a more accurate estimate of the true population size during mark-recapture studies. Why? -It uses more sophisticated technology than does the Petersen. -It uses more reliable marking techniques as compared with the Petersen. -By including multiple mark-recapture (or census) periods, the Schnabel should provide a more representative sampling of the population under study. -Unlike the Petersen index, it does not require that every animal in the population is captured. -Its equation is less biased than is the Petersen index equation.

By including multiple mark-recapture (or census) periods, the Schnabel should provide a more representative sampling of the population under study.

An ecologist decides to use a mark-recapture approach and the Petersen index to estimate the size of a population of flying squirrels in longleaf pine savannas of North Carolina. The number of squirrels marked in a pre-census is 36. The total number of squirrels captured the second night (or during the "census" period) is 28, and the number of previously marked squirrels that is recaptures is 11. Using the Petersen index, the number "28" would be represented by this symbol: -R -M -C -CM -N

C

An ecologist decides to use a mark-recapture approach and the Petersen index to estimate the size of a population of fox squirrels in the Sandhills of North Carolina. The number of squirrels marked in a pre-census is 82. The total number of squirrels captured the second night (or during the "census" period) is 78, and the number of previously marked squirrels that is recaptures is 19. Using the Petersen index, the number "78" would be represented by this symbol: -M -R -C -CM N

C

The word "plankton" means wanderer. This term is appropriate, as these minute organisms simply float or drift in the water column of aquatic ecosystems. Photosynthetic plankton are called phytoplankton, while the heterotrophic plankton are called zooplankton. All organisms below are components of plankton. Which organism belongs to the zooplankton? -Spirogyra -Chara -Algae -Cladoceran -Diatom

Cladoceran

Which community (or species) would appear on the field in year 0?

Crabgrass

In the old-field secession in the Piedmont of North Carolina, which four species would be pioneer species in this succession? -hickory -crabgrass -aster -broomsedge -hardwood -oak -pine -horseweed

Crabgrass Aster Broomsedge Horseweed

Which annual species produces toxins that inhibit the growth of its own seedlings? Hence, this species disappears by the second year?

Horseweed

Some of the most important work on secondary succession has occurred in North Carolina. Much of this work has focused on a special category of secondary succession, called old field succession, which is initiated by the abandonment of farmed land. Studies of old-field succession have focused on uplands in the Piedmont, areas that drain well. After a crop has been harvested and the field abandoned (left fallow), crab grass is typically the first species of plant to dominate the field. During summer a year later (Year 1), a tall plant called horseweed dominates the field. By summer of the next year (Year 2), horseweed becomes less abundant, and aster begins to dominate the field. Why does horseweed begin to disappear? -Horseweed plants cannot tolerate full sunlight. -Horseweed plants are annual plants that depend on seed regeneration, and yet they produce toxins that harm their own seedlings. -It cannot tolerate the shade under aster plants. -Aster plants produce toxins that inhibit the growth of horseweed plants. -It does not compete well with aster plants for soil moisture and nutrients.

Horseweed plants are annual plants that depend on seed regeneration, and yet they produce toxins that harm their own seedlings.

What is the euphotic zone of aquatic ecosystems? -it is the light zone that typically coincides with the metalimnion. -It is the zone below the compensation point in freshwater ecosystems. -It is the region of maximum decomposition in lotic and lentic ecosystems. -It is defined as the zone where cellular respiration exceeds net photosynthesis. -It is the upper layer of water where ample sunlight allows net photosynthesis.

It is the upper layer of water where ample sunlight allows net photosynthesis.

Many lakes undergo fall and spring overturns. What is the temperature of the water column immediately following a spring overturn? -It is not possible to know the temperature without sampling the lake. -It is 4oC at the top and 0oC at the bottom. -It is uniformly 0oC throughout the water column. -It is 0oC at the top and 4oC at the bottom. -It is uniformly 4oC throughout the water column.

It is uniformly 4oC throughout the water column.

The Petersen index and the Schnabel estimator are based on the same concept, except the Petersen index involves a single census, whereas the Schnabel includes multiple census periods. Consequently, the equation (or formula) for the Schnabel is really just a longer version of the Petersen, and the number "1" is added to the denominator to make the Schnabel equation unbiased. Which symbol or factor in the equation for the Schnabel estimator has not been correctly identified? -Ci = the number of animals captured during a given census period -Mi = the number of marked animals at the end of all census periods -simga=the sum of -Ri = the number of animals recaptured during a given census period -N= the population size

Mi = the number of marked animals at the end of all census periods

Mark-recapture studies can be used to estimate population sizes. Which equation (or formula) is the unbiased equation for the Petersen index?

N=((C+1)(M+1)/R+1)-1

Which species would be an intermediate species in this succession? This same species does not appear in the climax.

Pine

Oak trees and pine trees commonly live in close association with root fungi, which enhance their ability to absorb water and nutrients. Hence, they are able to inhabit nutrient-poor soils that would not support them in the absence of their fungal partners. In this situation, it is clear that: -Oak trees and pine trees have greater ecological amplitudes than do red maple trees. -The ecological distribution of oak and pine trees in the wild is mainly shaped by Shelford's law of tolerance. -Potential distributions for oaks and pines are smaller than they would be in the absence of biotic interactions. -Realized distributions for oaks and pines, in this case, are greater than they would be in the absence of biotic interactions. -Root fungi are affected by abiotic factors more so than by biotic factors.

Realized distributions for oaks and pines, in this case, are greater than they would be in the absence of biotic interactions.

The ecological distributions of species are affected by biotic and abiotic factors. One of the few laws in ecology states that for every abiotic factor in the environment, an organism has an upper and lower limit of tolerance. The optimum tolerance lies somewhere within that range. This law is known as: -potential niche -Simpson's index -Liebig's law of the minimum -Optimal tolerance law -Shelford's law of tolerance

Shelford's law of tolerance

Relative to mark-recapture techniques, the Petersen Estimator and the Schnabel Estimator are based on a similar concept. How do they differ? -The Petersen attempts to capture every animal in the population, whereas the Schnabel attempts to capture only a subset of the total. -The Petersen Estimator uses multiple census periods, and the Schnabel Estimator has a single census period. -The Schnabel attempts to capture every animal in the population, whereas the Petersen attempts to capture only a subset of the total. -The Petersen Estimator uses a single census period, and the Schnabel Estimator has multiple census periods. -The Petersen is based on a true census, whereas the Schnabel is based on estimates.

The Petersen Estimator uses a single census period, and the Schnabel Estimator has multiple census periods.

Liebig's law of the minimum is often cited in regard to soil nutrients, and Shelford's law of tolerance is often cited in regard to a range of temperatures or a range of other physical factors to which organisms are typically exposed. Species differ in their adaptations to environmental factors, and hence, together these two laws help explain the tremendous diversity of life on Earth. What is the main idea behind Liebig's law of the minimum? -The resource that is least available to an organism, relative to the organism's needs for that resource, will be the resource that most limits that organism's distribution and growth. -No two species that compete for the same limiting resource can coexist indefinitely. -No two species can have the same realized distribution. -A species' realized distribution is likely to be narrower or smaller than its potential distribution. -Any organism has an upper and lower limit of tolerance for every abiotic factor.

The resource that is least available to an organism, relative to the organism's needs for that resource, will be the resource that most limits that organism's distribution and growth.

Many lakes undergo fall and spring overturns. How do overturns affect lakes? -They reduce the euphotic zone of the lake. -They increase the compensation point of the lake. -They cause a temperature inversion, whereby the warmest water is at the bottom of the lake, and the coldest water is at the top of the lake. -They cause uniform mixing of oxygen gas and temperature throughout the body of water. -They cause nutrients to sink to the bottom.

They cause uniform mixing of oxygen gas and temperature throughout the body of water.

Despite its value in recognizing species' adaptations, direct gradient analysis has important limitations, such as: -Better performance in parts of the gradient does not necessarily mean that the species is benefitting from those abiotic factors present. -Some factors that are important for any one species' distribution may not examined within the gradients studied. -Organisms perceive their environments as a complex set of interacting factors, making it difficult to study the influence of any single abiotic factor. -Abiotic factors interact in complex ways that make it difficult to interpret which factors are at work. -all of these

all of these

Successions are orderly and predictable changes in the communities of plant and animal species that occupy a site following a disturbance that is either catastrophic or that removes some or all the dominant vegetation. Which factor below is likely to trigger secondary succession? -fires -farming and then abandoning the farm field logging strong winds that topple many tress -all of these

all of these

The term ecological distribution is also called the geographic range. This is a fundamental aspect of the natural history of any species. Both abiotic and biotic factors shape any species' ecological distribution. Which factor below potentially influences the distributions of species of trees? -soil moisture -soil pH (or acidity) -availability of sunlight -competition with other species of plants -all of these

all of these

Live traps (e.g., Sherman live traps) are used in many mark-recapture studies. What is a major consideration of any mark-recapture study and the use of traps? -animals will not be starved while captured in the traps -animals will not lose their marks during the period under study -animals will not bite or scratch the researchers -animals will not be harmed during marking or capture -all of these are considerations

all of these are true

On April 6th, our lab exercise will cover direct gradient analysis. What is an environmental gradient? -any change in soil nutrients that occurs throughout the soil profie -an area in which the environment changes abruptly -a change in biodiversity with elevation -an area in which environ mental conditions (e.g., nutrients, soil moisture, sunlight, etc.) vary gradually and continuously

an area in which environ mental conditions (e.g., nutrients, soil moisture, sunlight, etc.) vary gradually and continuously

Realized and potential distributions may be quite different in extent. Because of competition and other negative interactions with other species, -abiotic factors, such as air temperatures, are unlikely to affect species in their realized distribution. -any species' potential distribution may be more restricted (narrower) than its realized distribution. -a greater range of biotic interactions are likely to occur in any species' potential distribution. -any species' realized distribution may be more restricted (narrower) than its potential distribution. -species are more likely to flourish and occupy more habitats in their realized distributions.

any species' realized distribution may be more restricted (narrower) than its potential distribution.

Many deep lakes at higher latitudes experience temperature inversions. During a temperature inversion, where is the coldest water located? -at the surface of the lake -the lake uniformly cold throughout the water column -in the middle of the lake -at the bottom of the lake

at the surface of the lake

During a previous lab exercise, you created a survivorship curve for white-tailed deer, using a sheet of semi-log paper. Before hunting began, 100% of the deer under study were alive. The decimal fraction for 100% is 1.0. The decimal fraction for 100% survival is something of a "placeholder." Even so, it must be graphed. Where should "1.0" be placed on the semi-log paper? -at the very bottom of the Y-axis -at the very top of the y-axis -where the top of the y-axis intersects with the 1.5-2.5 year age class -at the intersect of the x-axis with the y-axis -any place along the y-axis where the number "1" occurs on the original semi-log paper

at the very top of the y-axis

Lake and pond ecosystems typically have distinct habitat zones that support different aquatic organisms. Which habitat zone is often inhabited by flatworms, clams, phantom midges, and bloodworms? -benthic zone -metalimnion -limnetic zone -profundal zone -littoral zone

benthic zone

Both consumers and producers (plants and phytoplankton) occur in freshwater ecosystems. The consumers can be divided into functional feeding groups, based on the ways in which they obtain food. The larvae of many species of caddisflies use silken nets to capture organic particles and tiny organisms on which they feed. Thus, these larvae belong to the functional group known as: -predators -collectors -shredders -detrivores -scrapers

collectors

In thermally stratified lakes, the euphotic zone typically coincides with the: -metalimnion -thermocline -epilimnion -profundal zone -hypolimnion

epilimnion

In thermally stratified lakes, which layer of water is warmest and most oxygen rich? -secchi zone -hypolimnion -metalimnion -epilimnion -profundal zone

epilimnion

When lakes are thermally stratified, what term is given to the coldest layer at the bottom of the lake? -epilimnion -hypolimnion -metalimnion -profundal zone -secchi zone

hypolimnion

Freshwater ecosystems that are characterized by standing water, as in lakes and ponds, are known as _______________ ecosystems: -lotic -tranisent -littoral -lentic -profundal

lentic

In lakes and ponds where distinct habitat zones occur, this habitat zone includes the euphotic zone, and here phytoplankton are abundant, while fishes are the most abundant of free-swimming animals (i.e., nekton): -metalimnion -limnetic zone -epilimnion -hypolimnion -profundal zone

limnetic zone

This habitat zone of lakes and ponds is recognized by "open water" that extends from the surface to the depth at which light can penetrate. It's inhabited by fish and plankton: -profundal zone -limnetic zone -metalimnion -benthic zone -littoral zone

limnetic zone

Lake and pond ecosystems typically have distinct habitat zones that support different aquatic organisms. Which habitat zone typically supports the greatest diversity of aquatic life? -limnetic zone -profundal zone -benthic zone -littoral zone -metalimnion

littoral zone

In deeper lakes, the water column may be thermally stratified, meaning that distinct layers of temperature occur from top to bottom. In some lakes, the middle layer of water may display a rapid drop in temperature of more than 1oC per meter in depth. This middle layer is called the thermocline, and it typically coincides with the: -hypolimnion -metalimnion -limnetic zone -littoral zone -epilimnion

metalimnion

Which community (or serial stage) will become the climax community?

oak-hickory

Strip-census techniques are intuitive and have been used by ecologists in the past to estimate population size within an area smaller than the area occupied by the entire population. The Hayne Estimator, as described in your lab manual, however, is subject to some erroneous assumptions. A more accurate replacement is an approach called Distance sampling. Like strip-census techniques, in Distance sampling a person travels a straight line (transect) and tries to sight individuals on either side of the transect. The data that are recorded and later used to estimate population size are: -number of animals sighted in half of the area occupied by the species -number of animals observed during multiple mark-recapture events. -perpendicular distances between the animals sighted and the transect -number of animals sighted inside some smaller rectangle within the area occupied by the species -number of animals observed during a single mark-recapture event

perpendicular distances between the animals sighted and the transect

This habitat zone of lentic ecosystems, such as lakes and ponds, lies beneath the euphotic and limnetic zones, but above the bottom mud: -limnetic zone -metalimnion -littoral zone -benthic zone -profundal zone

profundal zone

Ecological distributions of species are affected by biotic and abiotic factors. Biotic factors such as competition and predation affect species' distributions. The actual ecological distribution that any species experiences in the presence of biotic factors is known as the: -realized distribution -ecotype -potential distribution -niche partitioning -niche differentiation

realized distribution

All mark-recapture techniques work on the assumption that a certain percentage of the population was marked during the pre-census period and that this proportion will later be reflected in the ___________ rates of previously marked animals in later census periods. -capture -Petersen -Schnabel -recapture -censused

recapture

Many different types of freshwater ecosystems exist, and they all have almost no salt content (less than 0.05% salt). Both lentic(standing bodies of water) and lotic (flowing bodies of water) ecosystems exist. Because movement of their waters allows physical mixing between the surface water and the air, lotic ecosystems tend to have greater concentrations of dissolved oxygen gas as compared with lentic ecosystems. Which freshwater ecosystem below is a lotic ecosystem? -river -lake -marsh -swamp -pond

river

Ecologists have assigned several terms to aquatic insects and invertebrates based on the manner in which they obtain food. In effect, these constitute functional feeding groups. Which group obtains its food by removing algae and biofilms from surfaces? -Scraper -Mincer -Shredder -Collector -Predator

scraper

Both consumers and producers (plants and phytoplankton) occur in freshwater ecosystems. The consumers can be divided into functional feeding groups, based on the ways in which they obtain food. Which functional feeding group has not been correctly represented? -shredder - shreds leaves or organic matter for food -predator - feeds on other organisms -collector - filter feeder, such as larvae of some species of caddisflies -scraper -- eats benthic, particulate organic matter -all have been correctly represented

scraper -- eats benthic, particulate organic matter

Red maple (Acer rubrum) is one of the most common and abundant species of trees in the southeastern United States. It is "ecologically ample," or it is said to have a broad ecological amplitude, because it tolerates a wide range of abiotic conditions, including soil types, soil moisture, topography, and climatic conditions. This certainly is not true for all species of maples. For example, your lab manual mentions that, in North Carolina, sugar maple (Acer saccharum ssp. saccharum) is most abundant in the mountains, rarely found in the Coastal Plain, and found on just a few rich sites in the Piedmont of North Carolina. This is because sugar maple's distribution is largely limited by: -competition with red maple -soil texture and soil moisture -topography and growing season -temperature and precipitation -none of these

temperature and precipitation

In deeper lakes, the water column may be thermally stratified, meaning that distinct layers of temperature occur from top to bottom. In some lakes, the middle layer of water may display a rapid drop in temperature of more than 1oC per meter in depth. This middle layer is called the: -epilimnion -compensation point -hypolimnion -thermocline -metalimnion

thermocline

Which type of disturbance is most likely to initiate primary succession? -hurricanes -volcanic eruptions -floods -fires -logging

volcanic eruptions