Populations - Distribution and Growth Flashcards
What are the properties of populations (5)?
Geographic range, abundance, density, dispersion, dispersal
How are populations measured?
Census, quadrat, mark-recapture
What are the types of population growth models?
Density independent (exponential) and density dependent (logistic)
Why are population dynamics important for conservation and resource management?
If how populations change in response to their conditions is understood, then populations can be managed by manipulating the conditions
How can you distinguish individuals from populations?
Can be difficult to distinguish, so must be defined by the study.
Genetically identical individuals may be linked by runners. Genets are composed of ramets.
What can the spatial distribution of a population tell us about its behaviour and ecology?
Spatial distribution tells us where the specie’s favourable habitats are - favourable as in close to good foraging spots, protected, beneficial interactions with other species.
Populations can be either ________ or ________, and measured at ________ or ________ time intervals.
Populations can be either open or closed, and measured at discrete or continuous time intervals.
Density-independent
Exponential growth, population size limited by chance abiotic factors (ex. flooding, fire)
Density-dependent
Logistic growth, population size limited by competition for resources
Population
Individuals of the same species co-occurring in time and space, dynamic
Population dynamics
Models that predict how populations will change over time and space
Genet
Genetically distinct individual, composed of ramets
Ramet
Genetically identical sub-individuals of a genet
Geographic range
Area encompassing all individuals of a species. Limited by temperature, rainfall, geographic boundaries (ex. mountains, oceans)
Geographic range: distribution
Presence or absence of a species depending on environmental conditions
Geographic range: scale
Spatial extent that is relavent to study
Abundance
Count of individuals (function of density)
Density
Abundance per unit of area
Dispersion
Spacing of individuals in relation to one another in response to abiotic/biotic factors
Types of dispersion (3)
Random, clumped, uniform
Dispersal
Movement of individuals between places… but not migration
Census
Counting every individual
Quadrat
Count every individual in a smaller area
Mark-recapture
Number of recaptures proportional to the population size
N = (M x C) / R
population estimate = (1st captures x new captures) / recaptures
Define these equation terms:
N =
b =
d =
t =
i =
e =
N = number of individuals
b = number of births
d = number of deaths
t = time
i = immigrants (entering)
e = emigrants (leaving)
Closed population
Isolated from other populations. Only affected by b and d
Open population
Individuals may leave, enter, or stay in the population. Affected by births, immigration, deaths, and emigration.
Is it reasonable to assume a closed population?
Usually, yes. Emigration and immigration are tiny factors compared to births and deaths.
Continuous time scales
Births and deaths are recorded all the time
Discrete time scales
Births and deaths are recorded at discrete intervals
Intrinsic growth rate
r
Ideal/maximum growth rate
Density independent model
Define the two types
Exponential, ideal growth rate, determines doubling rate, J-shaped curve
r is used in continuous time models, and lambda is used in discrete time models (accounts for seasonal effects)
Density dependent model
Logistic, limited by carrying capacity (k), S-shaped curve
