-
What is population and what does it suggest?
- Individuals of the same species in a given area at a given time
- Suggests that space and time are importatnt components
-
What are 5 attributes of population?
- Size - numbers (rarity, commonness)
- Density - distribution in space (per unit area or volume)
- Change in size over time ( increases/decreases in numbers, range)
- Age structure
- Genetic structure
-
What is range?
Overall Distributions in space - areal extent of a population or species
-
Name a species whoes range has expanded?
Zebra mussels
-
What do transplant experiments test? (2 things)
- wehter a popluation
- 1. never disperse there
- 2. Can't survive there
-
What are 3 patterns which populations are distributed within their ranges?
- Clumped or aggregated
- Random
- Evenly or overdispersed
-
What are the hypotheses for the distribution patterns?
Clumped?
Random?
Even?
- Clumped - resources clumped, social interactions, limited dispersal from parents
- Random - random dispersal, resources
- Even - Resources even, territorial interactions, competition
-
What is the definition and process of a random distribution?
- An individual has an equal probablitlity of occurring anywhere in an area
- netral interations between individuals and between individuals and local environment
-
What is the definition and process of regular distribution pattern?
- Individuals are uniformly spaced through the environment
- Antagonistic interactions between individuals or local depletion of resources - territoriality, competition, allelopathy
-
What is the definition and process for a clumped distribution?
- Individuals live in areas of high local abundance, which are separated by areas of low abundance
- Attraction between individuals or attraction of individuals to a common resource - sociality, resource clumping
-
How can the distribution of creosote bushes change through time? (3 steps)
- 1. Small shrubs establish in high densities and produce a cclumped distribution
- 2. Mortality as the shrubs grow reduces clumping and produces a random distribution amond medium shrubs
- 3. Competition enforces a regular distribution among large shrubs
-
How are body size and population size related?
- Because larger body size requires more resources such as food, space, etc. Then we expect that body size and population size should be negatively correlated
- Regressions of body size and population density of plants and animals support this prediction.
-
Who should know how population numbers change over time?
Economists, planners, farmers, insurance companies, school boards
-
what is the basis for population growth?
species interactions, evolution, etc.
-
What processes affect population size? ( 3 things)
- 1 Birth rates +
- 2. Death rates -
- 3. Immigration + , Emigration -
-
What is r in a population equation?
(birth rate - death rate) or (b-d)
-
What is N in a population equation?
population size
-
What is the equation for exponential growth?
- dN/dt = rN
- Or the change in numbers (dN) over time (dt) is equal to the growth rate (r) times the number of individuals (N)
-
What is dN in the equation dN/dt?
Change in number
-
What is dt in the equation dN/dt?
Change in time
-
What 3 things prvents continued exponential growth?
- External ( density independent factors)
- - weather, huricanes, floods, drought etc.
- - catastrophic events
- Self regulation (density dependent factors)
- - Resources becoming limiting ( competition)
- - Toxic build - up
- Interactions with other species (density dependent factors)
- - disease
- - predation
-
What is K in a population equation?
Carrying capacity of environment.
-
Explain the logistic or S - shaped growth?
- begining of time b>d, r>0
- Middle of time = maximum exponential growth
- end of time Growth rate slows (b + d) or (r =0)
-
What is another way to put dN/dt
r((K - N) / K)N or (1 - N/K)
-
What is ((K - N) / K)?
a term that slows growth as N approaches K, the carrying capacity or is equivalent to a competition term
-
What is intraspecific competition?
- The effect of individuals in a population on other individuals ( instantaneous effect )
- Acts to decrease birth rate or increase death rate
-
What is intraspecific competition in the logistic equation?
((K - N) / N) or (1 - N/K)
-
What shape does a density dependent graph have?
Logistic curve
-
What shape is a populaaion graph that is density independent?
Exponential growth
-
What are 5 population features?
- range
- numbers
- density
- age
- genetic structure
-
Growth of populations in ideal environments can be described with what growth model?
exponential growth model
-
What growth model shows a population in a limiting environment?
a logistic growth model
|
|
