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a group of individuals of a single species that occupy the same general area

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population

question

the number of individuals of a species per unit area or volume (ecologists use sampling techniques to estimate)

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population density

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the way the individuals are spaced within their area

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dispersion pattern

question

when individuals are grouped in patched ex. a school of fish (most COMMON in nature, results from unequal distribution of resources in the environment)

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clumped dispersion pattern

question

when individuals are dispersed in an even manner ex. king penguins (results from interactions between the individuals of a population)

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uniform dispersion pattern

question

when individuals are spaced in an unpredictable way ex. dandelions (varying habitat conditions and social interactions make this dispersion patter RARE)

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random dispersion pattern

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plots survivorship as the proportion of individuals from an initial population that are alive at each stage

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survivorship curves

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track the chance of an individual in a given population surviving to various ages

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life tables

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What are the 3 types of dispersion patters?

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Clumped, uniform, and random

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What is the relationship between a population and a species?

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A population is a localized group of individuals of species.

question

What dispersion pattern would you predict in a forest population of termites, which live in damp rotting wood.

answer

Clumped inside fallen logs or dead trees

question

How dies the chance of survival change with age in organisms with a Type III survivorship curve?

answer

Chances of surviving is initially low but increases after an individual reaches maturity.

question

average contribution of each individual to population growth

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per capita rate of increase

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an idealized picture of unregulated population growth; the rate of population increase under ideal conditions, no restrictions on the organism to live, grow, and reproduce

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exponential growth model

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environmental factors that restrict population growth

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limiting factors

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a description of idealized population growth that is slowed by limiting factors as the population size increases

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logistic growth model (S curve eg fur seals)

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the maximum population size that a particular environment can sustain

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carrying capacity

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In logistic growth at what population size is the population increasing most rapidly? Explain why.

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When N is 1/2 K (population = 1/2 carrying . At this population size there are more reproductive individuals than at lower population sizes and still lots of space or other resources available for growth. (N=population size, K=carrying capacity)

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declining birth rates and rising death rates in response to increasing population density (increased density causes population grown rate to recline by reducing birth rate and/or increasing death rate

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Density-dependent rates

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List some of the factors that may reduce birth rate or increase death rate as population density decreases.

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Food and nutrient limitations, insufficient territories, increasing in disease and predation, accumulation of toxins

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Produce few offspring but take good care of each one increasing the likelihood that they will survive to maturity (eg humans - high survivorship)

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Type I curve

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Produce a medium amount of offspring and cares little for each one with survivorship constant over the life span - no more vulnerable at one stage of life than another (straight line eg squirrels, lizards, rodents)

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Type II (2) curve

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Produce many offspring and takes care of none with low survivorship for the very young followed by high survivorship for those few individuals that live to a certain age (eg oysters, nile perch produce 16 million eggs but most die young)

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Type 3 curve

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How would a population grow rapidly?

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If there are no influencing factors the population will rise rapidly then even out when a factor appears.

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What is the shape of exponential growth on a graph?

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A j-curve; when a population rapidly rises causing the data on a graph to be shaped like a J

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What is the equation for the exponential growth model?

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G = rN

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What is the equation for the logistic growth model?

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G = rN x (K - N)/K

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What are the 3 types of population cycles?

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Boom and bust, predator-prey, and herbivore-producer

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harvesting a resource as a level which can be sustained without population decline

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Maximum sustained yeild

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have same effect on population growth regardless of density

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Density-independent

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the traits that affect an organism's schedule of reproduction and death make up its _______________

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life history

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In one experiment, increasing food supply to hares increased their population density, but the population continued to show cyclic collapses. What might you conclude from these results?

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Hare population cycles are not primarily caused by food shortage

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harvesting a resource without damaging it

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Sustainable resource managment

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Explain why managers often try to maintain populations of fish and game species at about half their carrying capacity.

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To protect wildlife from overharvest yet maintaining lower population levels so that growth is high and mortality from resource limitation is reduced

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a shift from zero population growth in which birth rates and death rates are high but roughly equal to zero population growth characterized by low birth and death rates

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demographic tranistion

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used to predict a populations future growth; it is the number of individuals in different age groups

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age structure

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in a population in which r = 0, the continuation of population growth as girls in the reproductive age group reach their reproductive years [an age structure with a broad base has a high proportion of children and a high birth rate because on average, each woman is substantially exceeding the replacement rate of two children per couple. When this occurs, the proportion of women of childbearing years increases and now a situation called __________________ exists. }

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population momemtum

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One life history pattern is typified by small-bodied, short lived animals that develop and reach sexual maturity rapidly, have a large number of offspring, and offer little or no parental care AND/OR plants like dandelions that produce thousands of seeds. Ecologists hypothesize that selection for this set of life history traits occurs in environments where resources are abundant permitting exponential growth. What is this called and why?

answer

r-selection because r (the per capita rate of increase) is maximized

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One life history pattern is typified by large-bodied, long lived animals that develop slowly and produce few but well cared for offspring AND/OR plants like coconut palms that produce few seeds that are well stocked with nutrient rich material (the plant's version of parental care). Ecologists hypothesize that selection for this set of life history traits occurs in environments where population size is near carry capacity. What is this called and why?

answer

K-selection because carrying capacity K is maximized. Population growth limited by density dependent factors.

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During the demographic transition from high birth and death rates to low birth rates and death rates, countries usually undergo rapid population growth. Explain why.

answer

the death rate declines before the birth rate, creating a period when births greatly outnumber deaths. this also sets up population momentum

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an estimate of the amount of land required to provide the raw materials an individual or a nation consumes including food, fuel, water, housing, and waste disposal; it is one approach to understanding resource availability and usage

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ecological footprint

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the study of how and why population changes

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population ecology

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the average contribution of each individual to population growth

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per capita rate of increase (factor r in G=rn, per capita means per person)

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the curve is known as the logistic growth model curve, idealized population growth that is slowed by limiting factors as the population size increase

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S Curve

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dramatic fluctuations in density; rapid exponential growth that is typically followed by population falls to a minimal level (eg lemmings)

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boom-bust cycle

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The rate at which a population increases in size if there are no density-dependent forces regulating the population

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intrinsic rate of growth

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Refer to Module 36.3. Which type of survivorship curve would you expect to find in a population experiencing r-selection? K-selection?

answer

Type III for a population experiencing r-selection; Type I for a population experiencing r-selection.

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harvesting should be done at a level that produces a constant yield without forcing a population into decline.

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maximum standard yield

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Point out an example of population momentum in figure 36.10

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The 1981 "boomlet" is a consequence of rapid reproduction in 1946-1965, as girls born during the baby boom entered their reproductive years

Biology Ch 36 – Flashcards

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