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38 Cards in this Set
- Front
- Back
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What is a population |
A group of individuals of same species occupying the same area at the same time also known as breeding groups |
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What is a community |
It is Made up of the populations of all organisms occupying an area |
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What is a habitat |
It is the physical area the species lives in |
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What is an ecological niche |
The role of the species in the environment |
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What is population size |
The number of organisms. represented by N |
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What is population density |
It is the number of organisms per unit of space. Represented as Dp. Dp= N divided by A(area) or V (volume) |
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What is dispersion of populations |
How populations are distributed over an area. there are three main dispersion patterns |
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What is uniform dispersion |
It is when the population is evenly spread out because of competition |
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What is positive and negative growth rate |
Positive growth rate means population is increasing Negative Growth rate means population is decreasing |
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What is per capita growth rate |
Represented by cgr, the amount population has changed in relation to its original size per unit time. Cgr= (new - original N) dividided by (original N) |
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What is an open population |
It changes as a result from natality, mortality, immigration and emigration and is considered natural and more common than a closed population |
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What is a closed population |
It changes as a result from natality and mortality only. there is no immigration or emigration and is considered rare |
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What is exponential growth |
It is represented by r which is the rate of population increasing during exponential growth. It occurs in ideal conditions when population is growing at it’s biotic potential. on graphs it appears as a J shaped growth curve |
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What is logistic growth |
It is represented by K for carrying capacity. It is common in nature and caused by limited resources so the size of the population stabilizes. On graphs it appears as an S shaped curve |
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What are the three phases of logistic growth |
Log phase: exponential growth period lag phase:increasing slowly stationary phase: carrying capacity reached |
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What are limitations against population growth |
Low food supply low oxygen disease predators limited space |
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What are limitations or environmental resistance |
Both abiotic and biotic factors that limit population size.These limiting factors can be density dependent or density independent |
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What does density dependent mean |
It is factors affected by the size of the population and is usually biotic examples are food predation and disease |
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What is clumped dispersion |
It is when the population is grouped in favourable patches |
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What does density independent mean |
Usually the abiotic factors that are unaffected by the size the population examples are drought temperature and humidity |
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What is the k selected strategy |
Live close to carrying capacity in a stable environment they have a low birth rates, long lifespan, slow growth rates, and require parental care An example is large mammals like humans whales and elephants |
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What is our selected strategy |
They take it vantage of good conditions in an unstable environment they exhibit exponential growth and individuals are small in size, have a high reproduction rate, fast individual growth rates, little paternal care, and a short lifespan an example would be insects |
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What are the population histograms |
Young populations / \ stabilize population /\ declining population () |
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What is intraspecific competition |
It is within a species for a common resource |
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What is interspecific competition |
It is between different species using a common resource |
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What are two types of interspecific competition |
Interference competition which is a physical fight over resources exploitative competition which is sharing resources |
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What is gauses principle of competitive exclusion |
Two species cannot compete for the same niche forever competition leads to resource partitioning (specific non-overlapping niches) |
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What is predation |
It is when predators eat pray |
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What is the predator prey relationship cycle/sinusodial curve |
Less predators means more prey survive More prey means more predators survive More predators means less prey Less prey means less predators |
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Random dispersion |
It is when there is neither an attraction or repulsion among individuals and it is unaffected by biotic factors |
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Predator population ____ behind the prey population |
Lags |
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What is biotic potential |
Represented by R. maximum reproductive rate under ideal conditions |
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What is carrying capacity |
It is represented by K. the maximum number of organisms that ecosystem can support at one time and is dynamic (constantly changing) |
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What is natality |
The number of births |
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What is mortality |
The number of deaths |
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What is immigration |
The number of individuals moving in |
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What is emigration |
The number of individuals moving out |
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What is growth rate |
It is represented by gr. It is how quickly a population size is changing. Current-old N is divided by current-old time = gr |
