Term
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Definition
| number of individuals per unit area or volume |
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Term
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Definition
| pattern of spacing among individuals |
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Term
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Definition
1. count
2. count sample and extrapolate
3. proxy- nests, feeding damage, fecal droppings
4. mark-recapture: capture 1st sample of animals, mark those animals and then release, capture 2nd sample of animals and determine how many are marked (recaptured) |
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Term
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Definition
N=n1n2/m
n=population size
n1=# captured and marked
n2=# captured in 2nd sample
m= # recaptured |
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Term
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Definition
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Term
| What influences the spacing of individuals in a population |
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Definition
| environmental and social factors |
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Term
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Definition
one in which individuals aggregate in patches
-may be influenced by behavior
-caused by attraction between individuals or attraction of individuals to a common resource
-ex. wolves in groups=increased effectiveness of hunting |
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Term
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Definition
one in which individuals are evenly distributed
-may be influenced by social interactions such as territoriality
-antagonistic interactions between individuals or local depletion of resources
-ex. birds nesting on small islands such as king penguins
-ex. Creosote bush, distribution caused by competition for water |
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Term
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Definition
one in which the position of each individual is independent of other individuals
-neutral interactions between individuals and local ennvironment
-ex. dandelions grow from windblown seeds that land at random and later germinate |
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Term
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Definition
| the study of the vital statistics of a population and how they change over time |
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Term
| What is of particulate interest to demographers and why? |
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Definition
| death rates and birth rates; influence how selection acts to shape life histories |
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Term
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Definition
age-specific summary of the survival pattern of a population
-tool to understand population growth survivorship curves
-graphic description survival patterns |
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Term
| Survival data can be expressed as a |
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Definition
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Term
| 3 types of Survivorship curves |
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Definition
| Type I, II, III; all of which differ in the relative rates of juvenile and adult survival |
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Term
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Definition
| describes the reproduction patterns of a population |
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Term
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Definition
pattern of age-specific survival and reproduction of an organism
-life history traits = products of natural selection |
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Term
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Definition
'big-bang' reproduction
-produce many offspring once, and die |
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Term
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Definition
Repeated reproduction
-produce fewer well-provisioned offspring, offspring do so repeatedly over time |
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Term
| Factors that might favor semelparity |
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Definition
-low probability of surviving to reproduce additional times (e.g. annual plants, desert agaves, salmon)
-positive relationship between reproductive effort and reproductive success per unit effort |
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Term
| Factors that might favor iteroparity |
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Definition
-high adult survival
-reduced offspring success as the number offspring per reproductive episode increases |
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Term
| There are trade-offs between |
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Definition
offspring size and number
-ex. some plants produce a larger number of small seeds while other types of plants produce a moderate number of large seeds that provide a large store of energy that will help seedlings become established |
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Term
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Definition
resources
-of which may lead to tradeoffs between survival and reproduction |
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Term
| Populations change in size through |
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Definition
births, deaths, immigrations, and emigrations
delta N/delta T = B - D + I - E
B - D = r (rate of increase) |
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Term
| Exponential Growth Equation |
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Definition
dN/dt = rN
N= population size
r= intrinsic rate of increase
t= time interval
r > 0 (population growing)
r < 0 (shrinking)
r = 0 (population stable) |
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Term
| Zero population growth occurs when |
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Definition
| the birth rate equals the death rate and r = 0 |
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Term
| Exponential population growth results in what shaped curve? |
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Definition
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Term
| The J-shaped curve of exponential growth is characteristic of |
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Definition
| some populations that are rebounding |
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Term
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Definition
| algebraic solution of the exponential growth equation |
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Term
| Exponential Growth cannot be |
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Definition
| sustained for long in any population |
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Term
| A more realistic population model |
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Definition
| limits growth by incorporating carrying capacity |
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Term
| The Logistic Growth Model |
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Definition
the per capita rate of increase declines as carrying capacity is reached
-Carrying capacity (K) is the maximum population size the environment can support
N < K (population size increases)
N > K (declines)
N = K (growth rate is zero) |
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Term
| The logistic model produces what shaped curve? |
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Definition
| a sigmoid (S-shaped) curve |
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Term
| Density-Independent factors of Population Regulation |
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Definition
-Disturbance
-affect a species independent of its population size |
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Term
| Density-dependent factors of Population Regulation |
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Definition
-intraspecific competition for food
-density-dependent predation
-territoriality
-density-dependent disease spread
birth and/or death rates change with density |
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Term
| In crowded populations, increasing population density (Competition for Resources) |
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Definition
| intensifies intraspecific competition for resources |
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Term
| Life History traits favored by natural selection |
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Definition
| may vary with the type of population regulation acting on the organism |
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Term
| K-selection, or density dependent selection |
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Definition
| acts on organisms that are usually regulated by density-dependent factors |
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Term
| r-selection, or density-independent selection |
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Definition
acts on organisms that are often subject to density-independent population regulation
-Selects for life history traits that maximize reproduction |
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Term
| r-selected life history traits |
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Definition
| –High intrinsic growth rate. Many small offspring, good dispersal ability, small size, early age at first reproduction, poor competitive ability |
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Term
| k-selected life history traits |
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Definition
| -Long adult lifespans,large size, good competitors, few but high-quality offspring |
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Term
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Definition
| Focuses on the complex interactions between biotic and abiotic factors that cause variation in population size |
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Term
| Extreme Fluctuations in population size are typically more common in |
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Definition
| invertebrates than in large mammals |
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Term
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Definition
Are groups of populations linked by immigration
and emigration |
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Term
| Metapopulation structure can be a buffer against |
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Definition
extinction
-A particular population may go extinct from time to time but then be recolonized by immigrants from other populations
-This protects the entire system from extinction |
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Term
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Definition
| each population is genetically isolated and extinction of any population is permanent |
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Term
| The Global Human Population |
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Definition
-size, demography, age structure, carrying capacity
-increased relatively slowly until about 1650 and then began to grow exponentially
-though the global population is still growing, the rate of growth began to slow approximately 40 years ago |
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Term
| Two configurations that a regional human population can exist in |
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Definition
-Zero population growth = High birth rates – High death rates
-Zero population growth = Low birth rates – Low death rates |
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Term
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Definition
the relative number of individuals at each age
-represented by pyramids |
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Term
| Estimates of Carrying Capacity of earth |
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Definition
-The carrying capacity of Earth for humans is uncertain
-Increases in food production can increase the carrying capacity, but only within limits
-How many people the earth can support depends on the quality of life people wish to have or are willing to accept |
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Term
| Two Types of Population Growth |
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Definition
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Term
| Modes of Population regulation |
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Definition
-density dependence/independence
-population dynamics
-metapopulations |
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