Chapter 19- Introduction to Ecology

Question 1

Define ecology.

Answer 1

is the scientific study of the interactions between

organisms and their environment.

Question 2

Distinguish among organismal, population, community, ecosystem, landscape, and global ecology.

Answer 2

1. Organismal ecology: is concerned with the behavioral, physiological, and morphological ways individuals interact with the environment.
2. Population ecology: examines factors that affect population size and composition, and how the number of individuals in a population changes over time.
3. Community ecology:examines the interactions
   between species and considers how factors such
   as predation, competition, parasitism, disease, and disturbance affect community structure and organization.
   ( A community consists of all the organisms of all the species that inhabit a particular area. )
4. Ecosystem ecology studies how energy and chemicals flow and cycle among organisms and between organisms and their surrounding environment.
   (An ecosystem consists all the organisms that exist in a certain area along with of all the abiotic, or non-living, components.)
5. Landscape ecology deals with arrays of ecosystems and their arrangement in a geographic region.
   (A landscape or seascape consists of several different ecosystems linked by exchanges of energy, materials, and organisms.Each landscape or seascape consists of a mosaic of different types of patches.)
6. Global ecology focusses on the entire biosphere - the sum of all of the planet ’s ecosystems.

Question 3

Distinguish between abiotic and biotic components of the environment.

Answer 3

• Biotic factors are all the living organisms in an environment.
• Abiotic factors are the nonliving chemical and physical factors such as temperature, light, water, and nutrients that influence the distribution and abundance of organisms.

Question 4

Describe the three key physical factors that influence an aquatic environment, and how they do so.

Answer 4

1. Nutrient availability: limits growth rates of photosynthetic species, which form base of aquatic food webs.
2. Water depth: dictates how much light reaches the organisms in a particular region.
3. Water movement: pattern, speed, and amount of water movement present a physical force/challenge.

Question 5

Explain how upwellings and seasonal turnover bring nutrient rich waters from the deep to the surface in oceans and lakes respectively

Answer 5

1) • Upwelling is a process that draws deep salty water, that is typically rich in nutrients, up to the surface, replacing warmer waters that have been pushed away from an area by prevailing winds.
• Due to the rotation of the Earth, when winds blow parallel to the coastline, they can move water at right angles to the direction the wind is blowing (= Coriolis effect).
• Upwellings typically occur along the west coasts of continents and around Antarctica where prevailing winds thus blow the surface water offshore.

2) Many temperate lakes undergo a semi-annual mixing of their waters as a result of changing temperature profiles.
• This seasonal turnover sends oxygenated water from a lake’s surface to the bottom and brings nutrient rich water from the bottom to the top in both spring and autumn.

Question 6

Differentiate between marine biomes and freshwater biomes

Answer 6

• Marine biomes generally have salt concentrations that average 3%.
• Freshwater biomes have salt concentrations of less than 0.1%.

Question 7

Explain how the conditions of estuaries, the intertidal zone, and the headwaters of streams present challenges for the organisms that live there .

Answer 7

• The pattern, speed, and amount of water movement
also shape an aquatic environment.
• For example:
• Organisms that live in fast flowing streams have to cope with the physical force that constantly threatens to displace them.
• In intertidal habitats, organisms need to cope with both wave action + exposure to air.
• Water movement also influences nutrient and oxygen availability.
• For example, fast moving streams are high in oxygen, but low in nutrient availability.

Question 8

Define the following characteristics of lakes: thermocline, photic zone, aphotic zone, benthic zone, pelagic zone, littoral zone, and limnetic zone.

Answer 8

Thermocline – narrow layer of abrupt temperature change that separated warm upper layers from colder deep layers.
Photic zone- near the top
Aphotic zone- underneath
Benthic zone - bellow
Pelagic zone- put together 
Littoral zone- shallow
Limnetic zone- deeper

Question 9

Define the following characteristics of oceans: thermocline, photic zone, aphotic zone, benthic zone, pelagic zone, abyssal zone, intertidal zone, neritic
zone, and oceanic zone.

Answer 9

Thermocline – narrow layer of abrupt temperature change that separated warm upper layers from colder deep layers.
Photic zone- near the top
Aphotic zone- underneath
Benthic zone - bellow
Pelagic zone- put together
Abyssal zone- deepest region of ocean
Intertidal zone- where the waves flow
Neritic zone- near the shore
Oceanic zone- ocean

Question 10

Describe the characteristics of the major aquatic biomes: lakes, wetlands, streams, estuaries, and oceans

Answer 10

Lakes: Canada has the highest percentage of surface area covered by lakes, water movement is driven by wind and temperature. The littoral and limnetic zones are much warmer and better oxygenated than the nethic zone, simply because they receive so much more solar radiation and are in contact with oxygen in the atmosphere. Benthic zone is more nutrient rich because dead and decomposing bodies sink and accumolate there, lake is dependent on seasonal turn overs

Wetlands: shallow water only; water flow non-existant to slow and steady; supports emergent vegetation adapted to water-saturated soild.( “indicator plants” and emergent vegetation)

Streams: are bodies of water that constantly move in one direction (creaks are small streams and rivers are large streams). Major physical variables: speed of the current and availability of oxygen and nutrients. Sunlight isnt a limiting factor, Streams are dependant on nutrients from falling leaves, or organic matter. rare to find photosynthletic organisms

Estuaries: Nutrient rich, shallow water; water flow fluctuates daily and seasonally; among the most productive environments on earth, form where fresh water meets ocean

Oceans: form a continuous body of salt water and are remarkably uniform in chemical composititionincludes intertidal and nertic zones amongst others

Question 11

Describe the characteristics of the major terrestrial biomes: tropical forest, desert, savannah, chaparral, temperate grassland, coniferous forest, temperate broadleaf forest, and tundra.

Answer 11

Tropical forest: found in equatorial regions, High annual temperature that shows very little seasonal variation; high annual precipitation that shows high season variation (though even at lows remains very high); extraordinary diversity of plants

Desert: found 30 degrees north and south of equator, mean monthly temp. varies more then in tropical wet climates,

Savannah: Rainfall seasonal; dry season can last 8-9 months; warm year-round; trees are scattered and have small leaves; fires common; ground cover vegetation is tolerant of grazing by large herbivores

Chaparral: an area of dry land especially in southern California that is covered with bushes and short trees. Chaparral is found in regions with a Mediterranean climate, characterized by hot, dry summers and mild, wet winters.The fires that commonly occur during this period are necessary for the germination of many shrub seeds, and they clear away dense ground cover, thus maintaining the shrubby growth form of the vegetation by preventing the spread of trees. New chaparral growth provides good grazing for domestic livestock, and chaparral vegetation also is valuable for watershed protection in areas with steep, easily eroded slopes.

Temperate grassland: pronounced annual fluctuations in temperature; annual precipitation low; conditions generally too dry to support tree growth; frequent fires, plant life dense

Temerate Broadleaf Forest: annual fluctuations in temperature that drop below freezing ; moderate to high precipitation, with low variation, most common biome in north america, western europe and new zealand

Tundra: Short growing season, very low precipitation, very low temperatures; ttreeless, low-growing plants an dlichens cover the ground surface

Boreal forest: very cold winters and short cool summers, temperature variation is extreme, (rages 70 degrees!!) low precipitation, so cold evaporation is minimal, abuntent in cold-tolerant treets, low species diversity, just a tree layer and a ground layer

Question 12

Define climate and weather

Answer 12

• —> Climate: the prevailing, long-term weather conditions found in the area.
• —>Weather consists of specific short-term atmospheric conditions of temperature, moisture, sunlight, and wind.

Question 13

List the four abiotic factors that are the most important components of climate, and state how/why each component influences where terrestrial biomes exist.

Answer 13

• Temperature?- enzymes ectothermic, dessication
• Moisture?- all organisms need to balance H2O in and H2O out
• Sunlight?- photosynthesis
• Wind?- influence on organisms, flyin insects, airborne sperm

Question 14

Define disturbance and explain how latitudinal biome patterns can be modified by disturbance.

Answer 14

Latitudinal patterns are modified by disturbances (e.g., storms, fire, or human activity) that change a community.

Disturbances can keep a biome from becoming another type of biome that might otherwise be supported by the given climate of the region.
• Example: Frequent fires can prevent a savannah from becoming a woodland.

Question 15

Describe a climograph and use it to distinguish between two different biomes.

Answer 15

Climograph: a plot of the annual mean temperature and

precipitation of a region.

Question 16

Define ecotone.

Answer 16

Ecotone: area of intergradation between biomes; may be narrow or wide.

Question 17

Provide 3 examples of how global climate change is having a profound effect on the environmental conditions of aquatic and terrestrial biomes

Answer 17

Global climate change: increase in temperature and change in weather patterns due to rising concentrations of carbon dioxide in the atmosphere.
• Is having a profound effect on the abiotic conditions that
characterize aquatic and terrestrial biomes.

For example:
• Runoff from melting glaciers and pole ice is changing water depths around the globe.
• Warming ocean waters are changing long-established patterns in ocean currents, which in turn influence climate.
• On land, higher air temperatures are altering growing season and water availability in various biomes.

Question 18

Distinguish between macroclimate and microclimate.

Answer 18

• Macroclimate patterns are on global, regional, or local levels.
• Microclimate patterns are very fine patterns, such as the conditions experienced by a community of organisms under a fallen log .

Question 19

Explain why the tropics are warm and wet, why deserts are located around 30 degrees latitude north and south, and why the poles are cold and dry.

Answer 19

1. Earth’s curved shape causes latitudinal variation in intensity of sunlight.
   • Sunlight strikes regions around the equator most directly –>more heat and light per unit surface area.
   • At higher latitudes, sunlight strikes the Earth at an lower
   angle —> less and less energy is received per unit area as you move away from equator.
2. Intense sunlight near the equator initiates a global pattern of air circulation and precipitation
3. High temperatures in the tropics evaporate water from the Earth’s surface and cause warm, wet air masses to rise.
   • Warm air can hold much more moisture than cold air because water remains as vapor rather than forming droplets.
4. As the air masses rise, they begin to cool, their ability to hold water declines, and they release much of their moisture.
   • Results in abundant precipitation in the tropics.
5. As more air is heated along the equator, the cooler air masses are pushed poleward.
6. Once the air mass has cooled enough, its density increases, and it begins to sink back
   towards the earth.
7. As it sinks, it begins to absorb more and more heat radiating off the Earth and begins to warm, again gaining water-holding capacity.
   • Because these sinking air masses hold onto moisture, little rain occurs in these regions of the globe, resulting in deserts around latitudes of about 30 degrees north and south.
8. Some of the air then continues poleward, and at about 60 degrees latitude, the air masses, now warm again, begin to rise and release abundant precipitation.
9. Some of the now cold and dry rising air continues on towards the poles, where, once cool enough, it again descends towards the Earth, resulting in the relatively rainless and dry polar regions.

Question 20

Explain the cause of seasonality at higher latitudes

Answer 20

• Due to the tilt of the Earth, the Northern Hemisphere faces the sun most directly, and thus receives the most amount of solar radiation per unit area, in June and July, creating a warm summer.
• During this time, the southern hemisphere is tilted away from the sun, resulting in a steep angle for incoming light and thus cooler temperatures.
• In November + December the reverse is true.
• During March + Sept equinox all regions receive equal hours of daylight and darkness.

Question 21

Explain, with examples, how a body of water and a mountain range affect regional climatic conditions.

Answer 21

Because of the high specific heat of water, oceans and large lakes tend to moderate the climate of nearby terrestrial environments.

Ocean currents influence climate along the coasts of
continents by heating and cooling overlaying air masses
that pass across land.

West moisture-laden air blows onshore from pacific ocean, air rises over mountains, cools and releases water (rain) , after over the mountain east dry air creates desert conditions

At any given latitude, air temperature declines 6C with
every 1000m increase in elevation

Question 22

Explain how the current rate of global warming may impact species abundance and distributions.

Answer 22

Many species can adapt to slight changes in their environment; however, the expected changes due to global warming are expected to occur too quickly for species to adapt by normal
evolutionary processes, such as natural selection.
• Distributions of many species could be reduced and extinctions may occur.
• Example: Plant species cannot simply migrate north or south to newly created climate regimes that will be suitable for them – i.e., climatic zones will likely shift faster the plants can migrate via seed dispersal .
• Conversely, the ranges of other species could expand.
• The northward limit of European butterfly species has expanded by 32-240km since the beginning of the 20th century.
• Receding sea ice in the arctic has increased the flow of water from the Pacific to the Atlantic, allowing a species of diatom to colonize the Atlantic ocean for the first time in 800,000 years!!!

Question 23

Define biogeography.

Answer 23

the study of how organisms are distributed
geographically.

The most fundamental observation about the geographical range of a species is that no one species can survive the full range of environmental conditions present on Earth.

Question 24

Describe the questions that might be asked in a study addressing the limits of the geographic distribution of a particular species

Answer 24

Does dispersal limit its distribution?
Does behavior limits its distribution?
Does biotic factors (other species),,,
Does abiotic factors…

Question 25

Define dispersal and explain how dispersal may be limited for a given species.

Answer 25

• Dispersal refers to the movement of an individual from its place of origin to the location where it lives and breeds as an adult.
• If a species is missing from an area it could potentially inhabit, it is likely that a physical barrier such as an ocean, a river, or mountain has blocked its dispersal.
• Human activity has greatly affected the dispersal of species in a number of ways -e.g., air travel, invasive species introductions.

Question 26

Provide an example of how human activity has affected the dispersal of a species.

Answer 26

Human activity has greatly affected the dispersal of species in a number of ways -
e.g., air travel, invasive species introductions.

Question 27

Describe the problems caused by introduced species and illustrate with a specific example.

Answer 27

• Some of the most “impressive” examples of biotic limitation occur when humans accidentally introduce exotic species, which then proceed to wipe out native species.
• Example: Rabbits and cane toads in Australia.
• Rabbits are believed to have caused the extinction of several small ground-dwelling mammals in Australia, and have contributed to the decline of many native plant.

Question 28

Describe, with examples, how biotic factors may affect the distribution of organisms.

Answer 28

• Biotic factors
• Interactions with other species can limit the distribution of an organism.
• Example: Negative interactions between predators and prey or herbivores and plants can restrict the ability of a species to survive and reproduce.
—>Can you think of any other examples of biotic interactions that may limit species distributions?
• Absence of a pollinator.
• Absence of a food resource.
• Presence of a pathogen or parasite.
• Presence of competing organisms.

Question 29

Describe, with examples, how abiotic factors may affect the distribution of organisms.

Answer 29

Abiotic factors
• Temperature, water, oxygen, salinity, sunlight, soil…etc. may also limit a species distribution.
• In short: if the physical conditions at a site do not allow a species to survive and reproduce, then the species will not be found there.
—>How can each of these abiotic factors limit a species’ distribution?
• Temperature (enzymes, ectothermic, dessication)
• Water and oxygen (all organisms need to balance H2O in and H2O out)
• Salinity
• Sunlight photosynthesis
• Rocks + soil

Question 30

Explain how habitat selection behavior may limit the distribution of a species within its range of suitable habitats.

Answer 30

When individuals seem to avoid certain habitats, even when those habitats are suitable, the organism’s distribution may be limited by habitat selection behavior.
• Habitat selection is a hierarchical process involving a series of decisions made by an animal about where in the environment to move, how much effort to exert in
doing so, and what habitat to use.
• Habitat may be selected for cover availability, food quality and quantity, availability of nesting or resting sites…etc.
• Habitat selection is one of the least understood of all ecological processes.