Chapter 53 - Population Ecology Flashcards
population
A group of individuals of the same species that live in the same area and interbreed, producing fertile offspring.
Describe density and its three main sampling techniques
The number of individuals per unit area or volume.
Three sampling techniques:
- Randomly selected plots
- Works best in homogeneous areas
- Indirectly
- Counting nests, burrows, tracks, fecal droppings
- Mark-Recapture methods
- Best for highly mobile species
dispersion
Pattern of spatial arrangement or distribution of individuals w/i environ.
- Largely det by patchiness of habitat
- Uniform, clumped, or random
mark-recapture method
A sampling technique used to estimate the size of animal populations.
- Capture random sample
- Tag/mark (m)
- Release
- Wait
- Recapture random sample
- n = total # of 2nd sample
- x = # marked recaptured
N = m*n / x
Assumptions of mark-recapture method
Assumptions of mark-recapture method:
- un/marked individuals have same probability of being captured
- marked orgs completely mix back into population
- no births/deaths or im/emigration during re-sampling interval
immigration
The influx of new individuals into a population from other areas.
emigration
The movement of individuals out of a population.
territoriality
A behavior in which an animal defends a bounded physical space against encroachment by other individuals, usually of its own species.
demography
The study of changes over time in the vital statistics of populations, esp birth and death rates; survival and reprod rates
life table
An age-specific summary of the survival pattern of a population.
cohort
A group of individuals of the same age in a population.
Describe how to build a life table
Life table:
- Calc # individuals that die in ea age-group (cohort)
- Calc proportion of cohort surviving fr one age class to next
- Typ, divide by total to calc proportion
survivorship curve
Plot of proportion/# in cohort still alive at ea age.
- One way to represent age-specific mortality.
Summarize the three main types of survivorship curves
reproductive table
An age-specific summary of the reproductive rates in a population.
- Simple view of demographics: females giving rise to females.
- Shows # of female offspring produced by ea age group.
zero population growth (ZPG)
A period of stability in population size, when additions to the population through births and immigration are balanced by subtractions through deaths and emigration.
exponential (geometric) population growth
Growth of a population in an ideal, unlimited environ, represented by a J-shaped curve when population size is plotted over time.
- E.g. bac in lab conditions
Formula for per capita rate of increase
r = b - d
rate = births - deaths
r > 0 → pop growing
carrying capacity
The maximum population size that can be supported by the available resources, symbolized as [italicized] “K.”
logistic population growth
Population growth that levels off as population size approaches carrying capacity.
- Not enough resources for reprod/survival → ↓ births/↑ deaths → ↓ rate
- # of additional individuals environ can support: K - N
- Fraction of environ avail for pop growth: (K - N) / K
Assumptions of logistic model of pop growth
Assumptions of logistic model of pop growth
- Populations adjust instantaneously to growth
- The approach toward carrying capacity is smooth
- Realistically, ‘lag’ time exists → over/undershooting K
life history
The traits that affect an organism’s schedule of survival/reprod.
- Trade-off b/w survival and reprod.
- When reprod beings
- How often org’s reprod
- How many offspring produced
- NOT a conscious choice
semelparity
Reproduction in which an organism produces all of its offspring in a single event; also known as big-bang reproduction.
iteroparity
Reproduction in which adults produce offspring over many years; also known as repeated reproduction.
K-selection [italicized “K”]
Selection for life history traits that are sensitive to population density; also called density-dependent selection.
r-selection [italicized “r”]
Selection for life history traits that maximize reproductive success in uncrowded environments; also called density-independent selection.
density independent
Referring to any characteristic that is not affected by population density.
density dependent
Referring to any characteristic that varies with population density.
population dynamics
The study of how complex interactions between biotic and abiotic factors influence variations in population size.
metapopulation
A group of spatially separated populations of one species that interact through immigration and emigration.
demographic transition
In a stable population, a shift from high birth and death rates to low birth and death rates.
age structure
The relative number of individuals of each age in a population.
ecological footprint
The aggregate land and water area required by a person, city, or nation to produce all of the resources it [he/she] consumes and to absorb all of the wastes it [he/she] generates.
What are the three D’s of population ecology?
Density
Dispersion
Demographics
