Chapter 54: Introduction to Ecology (Part 1, Week 3)

Question 1

[Start 54.1 Scale of Ecology]

What are the main threats to a species?

Answer 1

Main causes are introduced species, direct exploitation, habitat destruction, pollution and climate change.

Question 2

Why did two-thirds of the 110 species of harlequin frogs in Costa Rica die off?

Answer 2

The culprit identified as a disease-causing fungus, but researchers blamed global warming since the increase in temperature allowed the fungus to thrive.

Disease is the bullet killing frogs, but climate change is pulling the trigger.

Question 3

What is the study of interactions among organisms and between organisms and their environments?

Answer 3

Ecology

Question 4

What is the term used to describe interactions among organisms?

What is the term to describe interactions between organisms and their nonliving environment?

Answer 4

Biotic

Abiotic

Question 5

What governs the numbers of species in an area and their population densities?

Answer 5

The interactions.

Question 6

What does climate have a large influence on?

Answer 6

Biomes

Question 7

What exactly are Biomes?

Answer 7

A major type of habitat characterized by distinctive plant and animal life. Essentially, the place where organisms are found.

Question 8

What is a good analogy to remember the difference between ecology and environmental science?

Answer 8

Ecology is to environmental science as physics is to engineering.

Both physics and ecology provide the theoretical framework on which more applied studies are based.

Engineers rely on the principles of physics to build bridges. Environmental scientists rely on the principles of ecology to solve environmental problems.

Question 9

How does ecology range in scale of studies? (4)

Answer 9

• Individual organism
• Populations
• Communities
• Ecosystems

Question 10

What is the study of the ways in which individual organisms meet the challenages of their biotic and abiotic interactions within their environments?

Answer 10

Organismal ecology

Question 11

What are the two sub disciplines of organismal ecology?

Answer 11

Physiological ecology and behavioral ecology

Question 12

What is the discipline that investigates how organisms are physiologically adapted to their environment and how the environment impacts the distribution of species?

Answer 12

Physiological ecology

Question 13

What is the discipline that focues on how the behavior of individual organisms contributes to their survival and reproductive success, which, in turn, eventually affects the population density of the species?

Answer 13

Behavioral ecology

Question 14

What focuses on the groups of interbreeding individuals, called populations? AND what is the primary goal of this?

Answer 14

Population ecology and the goal of this type of ecology is to understand the factors that affect a population’s growth and determine its size and density.

Question 15

Even though population ecology will be focusing on the population of a particular species, the relative abundance of that species is often influences by its interactions with other species. With that said, what does this type of ecology include the study of?

Answer 15

Species interactions, such as predation, competition, and parasitism.

Knowing what factors affect populations can help us lessen species endangerment, stop extinctions, and control invasive species.

Question 16

What is a species that is moved from a native location to another location, usually by humans?

Answer 16

Introduced species

Question 17

What is a species that sometimes spreads so aggresively that they crowd out native organisms?

Answer 17

Invasive species

Question 18

What is the use of an introduced species’ natural enemies to control its proliferation?

Answer 18

Biological control

Question 19

In the example of the invasive eurasian plant and the experiment to see why it was killing native plants around it, what did it excrete?

Answer 19

An allelochemical… A powerful plant chemical, often a root exudate, that kills other plant species.

Question 20

What studies how populations of species interact and form functional communities?

Answer 20

Community ecology

For example, a forest is a community of trees, herbs, shrubs, grasses, the herbivores that eat them, and the carnivores that prey on the herbivores.

Question 21

What is the focus of community ecology?

Answer 21

It focuses on why certain areas have high numbers of species (that is, are species-rich), but other areas have low numbers of species (that is, are species-poor).

Question 22

What does community ecology also consider other than the numbers of species?

Answer 22

It considers how species composition and community structure change over time and, in particular, after a disturbance, a process called succession.

Question 23

What is the biotic community of organisms in an area, as well as the abiotic environment affecting that community?

Answer 23

Ecosystem

Question 24

What deals with the flow of energy and materials within an ecosystem, which in turn, affects the production of biomass?

Answer 24

Ecosystem ecology

Question 25

[Start 54.2 Ecological Methods]

What are some topics that ecologists would use to understand the oak winter moth and the factors that could affect its population size? (4)

Answer 25

Abiotic factors such as temperature and rainfall.

Natural enemies, including bird predators of adult moths and caterpillars, insect parasites, bacterial parasites, and pupal predators.

Competitors like other insects and larder vertebrae grazers feed on leaves.

Host plants that may increase or decrease in the quality or quantity.

Question 26

What is the five-stage process that involves hypothesis testing?

Answer 26

1. Observations
2. Hypothesis formation
3. Experimentation
4. Data Analysis
5. Acceptance or rejection of the hypothesis

Question 27

What is used to determine whether or not two variables are significantly related to one another?

Answer 27

Statistical tests. For the oak winter moth larvae and larval parasitism by Cyzenis albicans, it is called a significant correlation.

Question 28

What is one way ecologists could test the hypothesis of whether or not pupal predation by beatles and shews was an additional control of the population size of the oak winter moths?

How would this be conducted?

Answer 28

They could remove the pupal predators and examine subsequent survival rates of the moth pupae.

They could catch the predators by putting out traps or by applying a pesticide to the soil in July to kill predators prior to the moths’ pupation in the fall.

Ecologists could then measure survival rates of the pupae during the fall. If predators are having a significant effect, then removing them should cause moth pupal populations to substantially increase.

Question 29

How would this experiment be conducted about the pupal predators and oak winter moth population?

Answer 29

This experiment would be conduted using two groups with equal numbers of trees: a group of trees in which the predators had been removed in the ground beneath (the experimental group)

And a group of trees with predators still present (the control group).

Any differences in oak winter moth pupal survival over the fall would likely be due to differences in predation.

Question 30

What word describes performing an experiment several times?

Answer 30

Replication

Ecologists might replicate the experiment involving the removal of predators of the oak winter moths five or ten times, or even more.

At the end of the replications, the researchers would sum the total number of emerging moths, divide the sum by the number of replications, and calculate the mean.

Question 31

[Start 54.3 Environment’s Effect on the Distribution of Organisms]

In addition to natural enemies, what else has powerful effects on population sizes in most ecological systems?

Answer 31

Physical (abiotic) factors

Question 32

What is the distribution patterns of organisms and their abundance are limited by? (5)

Answer 32

Physical features of the environment such as temperature, wind, availability of water and light, salinity, and pH.

Question 33

Give examples how temperature, wind, water, light, salinity, and pH effect organisms?

Answer 33

• Low temperatures freeze many plants; high temperatures denature proteins. Some plants require fire for germination.
• Wind amplifies effects of cool temperatures (wind chill) and water loss; creates pounding waves.
• Insufficient water limits plant growth and animal abundance; excess water drowns plants and other organisms.
• Insifficient light limits plant growth, particularly in aquatic environments.
• High salinity generally reduces plant growth in terrestrial habitats; affects osmosis in marine and freshwater environments.
• Variations in pH affect decomposition and nutrient availability in terrestrial systems; directly influence mortality in both aquatic and terrestrial habitats.

Question 34

What prehaps is the most important factor in the distribution of organisms because of its effect ob biological processes and because ______ ?

Answer 34

Temperature.

Because of the inability of most organisms to regulate their body temperature precisely.

Question 35

What is an isotherm?

Answer 35

A line on a map connecting points of equal temperature.

Question 36

What is the effects of lower temperature waters and coral reefs?

Answer 36

There are organisms that secrete calcium carbonate shells that form coral reefs and they are suppressed by cold waters. And that is why they are abundant in warmer waters.

Question 37

What is probably the single most important factor limiting the geographic distribution of tropical and subtropical plants?

Answer 37

Frost.

Cold temperatures can be lethal because cells may rupture if the water they contain freezes.

Question 38

How are higher temperatures also limiting for many plants and animals?

Answer 38

Most species cannot survive internal temperatures more than a few degrees above their metabolic optimum.

The symbiotic algae that live within coral die and are expelled causing a phenomenon called coral bleaching.

Question 39

T/F Some plants are actually dependent on low-intensity fires like the jack pines and their serotinous cones, which remain sealed by pine resin until the heat of a fire melts them open and releases seeds.

Answer 39

True.

Giant sequoias also require some fires.

Question 40

Why are some fires very destructive to natural systems?

Answer 40

In some areas when fire is prevented, fuel, in the form of old leaves and branches, can accumulate. When a fire eventually occurs, it can be so large and hot that it destroys everything in its path, even reaching high into the tree canopy.

Question 41

What type of proteins help organisms cope with the stress of adverse conditions like heat or freeze and act as chaperones to prevent the denature of proteins?

Answer 41

Heat shock proteins (HSPs)

HSPs normally constitute only about 2% of a cell’s soluble protein content, but this can increase to 20% when a cell is stressed, whether by heat, cold, drought, or other conditions.

The genes that encode HSPs are extremely common and are found in the genomes of all organisms.

Researchers have produced transgenic tobacco plants that grow better than normal plants under higher temperatures.

Question 42

What is created by temperature gradients as air heats up and it becomes less dense and rises? As hot air rises, cooler air rushes in to take its place?

Answer 42

Wind.

For example, hot air rising in the tropics is replaced by cooler air flowing in from the temperate regions, thereby creating northeryly or southerly winds.

Question 43

How does wind affect living organisms in a variety of ways? (3)

Answer 43

• Increases the rate of heat loss by convection (the transfer of heat by movement of air next to the body (the wind chill factor).
• Also contributes to water loss in organisms by increasing the rate of evaporation in animals and transpiration in plants.
• Wind also intensifies oceanic wave action. For example, on the rocky shore, seaweeds surve heavy surf by relying on a combination of holdfasts and flexible structures. Animals of this zone have powerful organic glues and muscular feet to hold them in place.

Question 44

What performs many vital functions in all living organisms and acts as a solvent for chemical reactions, takes part in hydrolysis and dehydration reactions, AND is the means by which animals eliminate wastes, AND is used for support in plants and in some invertebrates as part of a hydrostatic skeleton?

Answer 44

Water, BABY! GLUG GLUG

Question 45

What are some examples of distribution patterns of many plants limited by the available water?

Answer 45

1. The density of creosote bushes in the Mojave Desert increases in wetter areas.
2. Alpine trees stop growing at a point on the mountainside where they cannot take up enough moisture to offset transpiration losses. This point, known as timberline, is readily apparent on many mountainsides. (typically, you see a gradual decline in the size of trees versus an abrupt line)

Question 46

When it comes to cold climates, how can water that is present be locked up?

Answer 46

Water can be present as permafrost, and therefore, be unavailable.

Question 47

T/F Other than plants, animals face problems of water balance, too, and their distribution and population density are strongly affected by water availability.

Why or why not? Provide an example too! (Think Toto)

Answer 47

True.

Because most animals depend ultimately on plants for food, their distribution is intrinsically linked to those of their food sources.

This such phenomenon regulates the number of buffalo in the Serengeti area of Africa. In this area, grass productivity is related to the amount of rainfall in the previous month. Buffalo density is governed by grass availability, so a significant correlation is found between buffalo density and rainfall.

The only exception occurs in the vicinity of Lake Manyara, where groundwater promotes plant growth.

Question 48

Other than wind, water, and temperature, what else is necessary and can be a limiting resource for plants?

Answer 48

Light (photosynthesis)

Plants may differ.

Example: Hemlocks grow in the understory of a forest in the shade and need on 1/4 of full sunlight. Sugarcane, however, increases in photosynthesis as light duration increases.

Question 49

At what depth in the water is light absorbed completely and prevents photosynthesis?

Answer 49

100 meters

Question 50

What is a fairly narrow zone close to the surface of an aquatic environment, where light is sufficient to allow photosynthesis to occur?

Answer 50

Photic zone

Question 51

What varies widely in aquatic environments and have a great effect on osmotic balance in animals?

Answer 51

Salt concentrations (think hypertonic, isotonic, and hypotonic)

Question 52

Why do oceans contain considerably more dissolved minerals than rivers?

Answer 52

Oceans continuosly receive the nutrient-rich waters of rivers, and the Sun evaporates pure water from ocean surfaces, making concentrations of minerals such as salts even higher.

Question 53

What is the difference between saltwater and freshwater fish?

Answer 53

Freshwater fishes are hypersomatic (having a greater concentration of solutes) relative to their environment and tend to gain water by osmosis as it diffuses through the thin tissue of the gills and mouth. TO COUNTER THIS, the fish continually elminate water in the urine.

However, to avoid losing all dissolved ions, many ions are reabsorbed into the bloodstream at the kidneys.

Many marine fishes are hypo-osmatic (having a lower concentration of solutes) relative to their environment and tend to lose water as seawater passes over the mouth and gills. They drink water to compensate for this losee, but the water contains a higher concentration of salt, which must be excreted at the gills and kidneys.

Question 54

What is a plant that can tolerate higher than normal salt concentrations and can occupy coastal salt marshes or saline deserts?

Give an example of a plant (think of home)

Answer 54

Halophytes

Spartina have salt glands that exude salt onto the surface of the leaves, where it forms tiny white salt crystals.

Question 55

What are the different pH levels of water called?

Answer 55

Acidic, alkaline, or neutral.

Question 56

Why is normal rainwater, having a pH of about 5.6, slight acidic?

Answer 56

Because of the absorption of atmospheric carbon dioxide (CO2) and sulfur dioxide (SO2) into rain droplets that forms carbonic and sulfuric acids, respectively.

Question 57

What pH level do most plants grow best in?

Answer 57

pH of 6.5

Rhododendrons and azaleas can live in soils with a pH of 4.0 or less!

Question 58

In general, what type of soil will consist of chalk and limestone which gives it a higher pH and sustain much richer flora (and associated fauna)?

Answer 58

Alkaline soils

Question 59

What is the optimal pH for most freshwater fishes and bottom dwelling invertebrates?

Answer 59

6.0 - 9.0.

Acidity in lakes increases the amount of toxic metals, such as mercury, aluminum, and lead, which can leach into the water from surrounding soil and rock.. This can interfere with fill function, causing fishes to suffocate

Question 60

What is the precipitation with a pH of less than 5.6 and results from the burning of fossil fuels?

Answer 60

Acid rain (SO2 and NO2 in the atomoshere)