Ecology Flashcards
What are important biotic factors that can affect the structure and organization of biological communities?
Predation and competition
What are abiotic factors that can affect the structure and organization of biological communities?
Precipitation and wind
Nutrient availability, soil pH
Temperature and water
Light intensity and seasonality
Generalized global air circulation and precipitation patterns are caused by:
Rising, warm, moist air cools and precipitates as it rises and at high altitude cool and sink as dry air
What is true about oligotrophic and eutrophic lakes?
Eutrophic lakes are richer in nutrients
Oligotrophic lakes have high O2 levels
Rate of photosynthesis is higher in eutrophic lakes (algal bloom)
Sediments in oligotrophic lakes contain low levels of decomposable organic matter
An ecologist recorded 12 white-tailed deer per square mile in one woodlot and 20 per square mile on another woodlot. What was the ecologist comparing?
Population density
What group would most likely exhibit uniform dispersion?
Red squirrels, who actively defend territories
What assumptions have to be made regarding the capture-recapture estimate of population size?
Marked and unmarked individuals have same probability of being trapped
The marked individuals have thoroughly mixed with population after being marked
No individuals have entered or left the population and none have been added by birth or eliminated by death during course of estimate
The three basic variables that make up the life history of an organism are:
Age when reproduction begins, how often reproduction occurs, and how many offspring are produced per reproductive episode
What is a conclusion that can be drawn from this graph?
(Bird graph)
There appears to be a negative correlation between brood enlargements and parental survival
What can contribute to density-dependent regulation of populations?
Intraspecific competition for nutrients
What can contribute to density-independent regulation of populations?
Removal of toxic waste by decomposers
Earthquakes
Floods
Weather catastrophes
What graph illustrates the population growth curve of single bacterium growing in a flask of ideal medium at optimum temperature over a 24-hour period?
Exponential graph
Population growth, no limit on resources
What graph illustrates the growth curve of a small population of rodents that has grown to reach a static carrying capacity?
Half a hill
Population collapse
Field observation suggests that populations of a particular species of herbivorous mammal undergo cyclic fluctuations in a density at 3-5 year intervals. What is a plausible explanation of these cycles? #1
Periodic crowding affects the endocrine system, resulting in increased aggressiveness
Increases in population density lead to increased rates of predation
Field observation suggests that populations of a particular species of herbivorous mammal undergo cyclic fluctuations in a density at 3-5 year intervals. What is a plausible explanation of these cycles? #2
Increases in rates of herbivore lead to changes in the nutritive value of plants used as food
Increases in population density lead to more infestations of parasites to host animals
The sum total of an organism’s interaction with the biotic and abiotic resources of its environment is called its:
Ecological niche
Two barnacles, Balanus and Chthmalus, can both survive on the lower rocks just above the low-tide line on the Scottish coast, but only Balanus actually does so, with Chthamalus adopting a higher zone. Which of the following best accounts for this niche separation?
Competitive exclusion
A species of fish is found to require an certain water temperature, a particular oxygen content of the water, a particular depth, a rocky substrate on the bottom, and a variety of nutrients in the form of microscopic plants and animals to thrive. These environments describe its:
Ecological niche
White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees. The Downy woodpecker searched for insects by hunting from the bottom of the tree trunk to the top, while the White-breasted nuthatch searched from the top of the trunk down. These hunting behaviors best illustrate what ecological concepts?
Resource partitioning
Prairie dogs once covered the Great Plains. Their grazing made the grass more nutritious for the huge herds of bison, and a variety of snakes, raptors, and mammals preyed on the rodents. In fact, the black-footed ferret specialized in prairie dog predation. Today, growing housing and agricultural developments have covered many prairie dog towns. What is true abt prairie dogs?
Their fundamental niche is changed
Food chains are sometimes short because:
Most of the energy in a trophic level is lost as it passes to the next higher level
Suppose you are studying the nitrogen cycling in a pond ecosystem over the course of a year. While you are collecting data, a flock of 100 canada geese land and spends the night during a fall migration. What could you do to eliminate error in your study as a result of this event?
Find out how much nitrogen is consumed and eliminated by a canada goose over a 12-hour period and multiply this number by 100; enter this value into the nitrogen budget of the ecosystem
For most terrestrial ecosystems, organisms of numbers, biomass, and energy are essentially the same—they have a broad base and a narrow top. The primary reason for this pattern is that:
At each step, energy is lost from the system as a result of keeping the organisms alive
The high levels of pesticides found in birds of prey is an example of:
Biological magnification
