Chapter 53: Population Ecology Flashcards
(29 cards)
Population
- Group of individuals of a single species living in the same general area
- Rely on the same resources
- Influenced by similar environmental factors
- Likely to interact / breed with one another
Population Density
Number of individuals per unit area or volume
Dispersion
Pattern of spacing among individuals within the boundaries of the population
Mark-Recapture Method
- Used to estimate size of wildlife population
- x/n = s/ N or N = (sn)/ x
- x = # of marked animals in 2nd sampling
- n = total # of animals in 2nd sampling
- s = # of animals marked and released in 1st sampling
- N = population size
Immigration
Influx of new individuals from other areas
Emigration
Movement of individuals out of a population and into other locations
Territoriality
Defense of a bounded physical space against encroachment by other individuals
Demography
Study of the vital statistics of populations and how they change over time
Survivorship Curve
Plot of the proportion or number of members in a cohort still alive at each age
Type I Curve
- Flat at start : low death rates in middle & early life
- Drops steeply as age increases
Type III Curve
- Drops sharply at start : high mortality rate when younger
- Flattens out with age increase
Type II Curve
- Intermediate
- Constant death rate
Reproductive Table
- Fertility schedule
- Age-specific summary of the reproductive rates in a population
Zero Population Growth (ZPG)
When per capita birth and death rates are equal (r= 0)
Exponential Population Growth
- Growth of a population in an ideal, unlimited environment
- Represented by a J-shaped curve when a population size is plotted over time
- Free to reproduce at physiological capacity
- There’s abundant food
Carrying Capacity
- K
- Max population size that a particular environment can sustain
Logistic Population Growth
- Per capita rate of increase approaches 0 as the population size nears the carrying capacity
- S- curve
Life History
- Traits that affect an organism’s schedule of reproduction and survival
- 3 main variables:
- When reproduction starts
- How often the organism reproduces
- How many offspring are produced per reproductive episode
Semelparity
- Reproduction where an organism produces all of its offspring in a single event
- Also called big-bang reproduction
Iteroparity
- Repeated reproduction
- Provide for offspring better and reproduce less and larger offspring
K-Selection
- Density-dependent selection
- Selection for traits that are sensitive to population density and favored at higher densities
- Big organisms
- Fewer babies
- Increased care
R- Selection
- Selection for traits that maximize reproductive success in uncrowded environments (low densities)
- Density-independent selection
- Small organisms
- More babies
- Less care
Density Independent
Birth rate / death rate that doesn’t change with population density
Density Dependent
- Death rate that increases with population density
- Birth rate that falls with increased density
