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87 Cards in this Set
- Front
- Back
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Population |
A group of organisms of the same species occupying a particular space and is a self regulating system. It's one unit through which energy flows and nutrients are cycled. |
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Components of a Population |
Birth rate, death rate, growth form, density, age structure, and numerical dispersion in time and space |
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Population Ecology |
Study of the number of organisms and what determines their abundance and distribution |
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Density |
Size of a population in relation to a definite unit of space |
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Crude Density |
Density when referring to a population as so many per unity mile |
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Ecological Density |
Actual place in a mile that the organism lives, living space |
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Size and Density |
Smaller an organism is, greater its abundance per unit area and trophic level. Larger its size and the higher its population on trophic level, the less its density. |
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Demographer |
periodically makes a total count |
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Total Count |
counting all that is present |
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Sampling |
make inferences about a population, estimates of a population are determined |
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Random Sampling |
all combinations of sampling units must have an equal probability of being selected |
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Parameter Sampling |
characterize the population as a whole, certain constants are equal
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Estimate Sampling |
value of a parameter as estimated from the sample which is hoped to be accurate but often the estimate is biased |
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Quadrant |
determined by running a line through a point located on a transect line then randomly picking a quadrant |
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Plot |
used primarily in invertebrate work, especially in study of aquatic bottom fauna and soil fauna |
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Two Accuracy Enhancing Measures |
larger sample size, more parameters
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Mark-Recapture Procedure |
Mark animals trapped, let them redistribute back into population, take a sample, estimate population by ratio of marked to unmarked |
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Mark-Recapture Faults |
Assumes marked animals are as subject to sampling as unmarked ones, mortality of the two groups are the same, none of the marked lose their ID, populations remains relatively stable between the two trapping periods |
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Lincoln Index |
Wildlife |
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Peterson Index |
Fish |
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T/N=t/n |
number marked in pre-census/population estimate=total number of trapped marked animals/total number trapped |
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Indirect sample methods |
signs, tracks, droppings, songs, calls, strumming |
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Index of Relative Abundance |
An estimate of the relative size of an animal population calculated from counts of the number of individuals attracted to a standard bait or the number caught for each standardized unit of effort |
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Plant Populations |
Area above ground covered. Each layer of vegetation counted separately |
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Basal Area |
ground covered by the crowns or stems |
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What determines the number of organisms in a population |
Differences between birth rate and death rate and the balance between immigration and emigration |
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Natality |
Greatest influence on a population. Production of new individuals
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Physiological Natality |
maximum number of births under ideal conditions, the biological limit, little value to field biologist |
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Realized Natality |
amount of successful reproduction over time varies with species. Natural selection selects a max rate which are destined to reach adulthood. Size of yolk |
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Crude Birthrate |
natality expressed in terms of population size (50/1000) |
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Specific Birthrate |
Number of offspring produces per unit time by females of age X |
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Age Specific Birthrate |
Number of offspring born to females of age X |
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Gross Reproductive Rate |
mean number of females born in each female age group |
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Net reproductive rate |
adjustments made for mortality of females in each age group |
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Reproductive Rate |
Number of offspring per unit mature female that survive to the fledgling stage |
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Death Rate |
number of deaths during a given time interval divided by the average population |
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Probability of Dying |
number that died during a given time interval divided by the initial population |
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Probability of Living |
number of survivors divided by the initial number of the group |
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Life Table |
a table of statistics relating to life expectancy and mortality |
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Cohort Type Life Table |
data obtained by following a given group from birth until death |
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Wild Type Life Table |
constructed from a sample of animals taken at one place at one time assumes birth/death rate are constant with stagnant populations |
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Three Types of Suriviorship Curves |
Mortality rate constant at all ages, mortality high early in life, heavy morality at end of life span |
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Suriviorship Curves |
A graph comparing survivorship vs horizontal time |
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Two Weaknesses of Surviviorship Curves |
Lack of data of surivial young, assumption that curves are independent of crowding |
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Three Ecological Age Periods |
Pre-reproductive, reproductive, post-reproductive |
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Most Vulnerable Groups |
Young and old |
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Old and Birthrate |
When old are caught more fall into reproductive class thus increasing birthrate |
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Game Population Ratio |
2:1 young to adults. Increasing population should have increasing young. |
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War |
population may be decreasing and have high percentage of young |
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Living Longer |
Population may be stationary and show decreasing percentage of young |
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Sex Ratio Favoratism |
Favor males at first in vertebrates. Deer=male, Squirrel=female, Muskrat=either |
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Polygamous Species Population |
Large population of males can be killed without much effect on population. If females are reduced, population tends to produce more females. |
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Population growth |
when a population first colonizes an unoccupied area, when resources are excessive, species response increase exponentially |
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Limit to Population Increase |
carrying capacity, may fluctuate or crash after this point
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Carrying Capacity |
maximum population size of the species that the environment can sustain indefinitely, given the food, habitat, water, and other necessities available in the environment |
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Thomas Malthus |
carrying capacity
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Changes to Birthrate R |
Positive when birthrate exceeds death rate, negative when death rate exceeds birthrate. |
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Increases in R |
female reproducing at a young age, size of litter, and longevity |
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J-Shaped Curve |
Density independent growth. Vertical asymptote |
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Exponential increase |
geometric increase due to reproducing individuals in which environment is unlimited. J shaped curve. Insects, mammals |
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Verhulst |
French mathematician equation for population growth in limited environment |
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Verhulst Equation |
rate of increase in population is equal to the potential increase of the population times the proportion of the carrying capacity of the habitat unexploited. S shaped curve |
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S-Shaped Curve |
Density dependent growth. Horizontal asymptote |
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Verhulst Equation Problems |
Eliminates age structure and assumes all have a chance to give birth or die. Lab animals follow this
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Three Causes of Negative R |
Females remain unfertilized, increase in death rate, individual chance of predation |
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Causes of Reduced Growth
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Disease, strife, famine, war |
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Result of Overcrowding |
Increase death rate, poor reproduction, killing young, physiological derangement due to hypoglycemia, disease/parasite, sexual egg |
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Density Independent Influences |
annual or seasonal changes in environment are irregular changes food accessibility, moisture, temperature. Winter kills population, spring reach reproduction, large fall population |
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Man's Influence |
Hunting for hides/feathers, destruction of forest=bird decline, DDT concentrate in food chain |
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Density Dependent Influences |
Animals regulated by density so to not exceed carrying capacity. Balance of population and resources. Oscillations or regular fluctuations feedback. |
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Intraspecific Competition |
Animals of the same species utilize a common resource in short supply like food and space |
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Scramble Competition |
individual gets small portion of the food but cannot survive to help the population maintain. Large waste, violent oscillations due to environment, density below carrying capacity due to waste. |
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Contest Competition |
Requisites for maintenance and reproduction, without requisites no food or space. Eliminates food waste and oscillations of scramble competition due to hierarchy. |
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Territory Behavior |
Tolerance and intolerance between individual control population by controlling breeding |
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Territory Hierarchy |
limit animals in a habitat, food supply, or breeding area. Contest to area ownership |
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Territory Losers |
poor breeders and surplus members are put in poor feeding areas |
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Density and Territory size |
larger at low density, lower at high density end of breeding season. Larger animals=large territory |
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Social Hierarchy |
Animals group in flocks, bands, herds, schools, etc based on intraspecific aggressiveness and dominance of one individual over another. |
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Opposing Forces to Groups |
Gregariousness, aggressiveness |
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Gregariousness |
mutual attraction toward one another, remain in group |
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Aggressivness |
As population increases, so does the need for space |
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Home Range |
Area over which an animal habitually travels. Related to weight of animal. Hunters have large home ranges. Food, water, shelter, rest, and young rearing |
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Sex/Age Home Range |
Female home range is small when defending young, males are curious and search for mates |
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Endocrine Balance |
Social stress can cause endocrine physiological feedback via pituitary and adrenal glands |
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Endocrine and Large R |
suppress somatic growth, curtail reproduction, delayed or canceled female maturation, uterine abortion, cannibalism |
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Snowshoe Hare Shock Disease |
hypoglycemia and low liver glycogen |
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Adrenal Problems in Deer Overcrowding |
adrenal weight increase, zona glomerulosa fluid imbalance.
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