Chapter 53: Population Ecology I Flashcards
Population (def.)
Group of individuals of a single species living in the same general area (real on same resources, influenced by same environment, interact and breed with one another)
Population dynamics (def.)
Examine characteristics of populations and how they change over time and space
Key characteristics of populations
1) Dispersion
2) Density
Population ecology (def.)
Study of populations in relation to the environment
Dispersion (def.)
- Pattern of spacing among individuals
- Reflects environmental conditions and interactions
- Clumped, uniform, random
Factors that affect dispersion
- Food, predators, competitors, microclimate, reproduction, age/sex
General patterns of dispersion
- Clumped
- Uniform
- Random
Population density (def.)
Number of individuals per unit area or volume
Population size equation
N = B + I - D - E
- N (population), B (births), I (immigrants), D (deaths), E (emigrants)
Demography (def.)
Study of vital statistics of a population and changes in these values over time
Vital statistics (def.)
Factors that affect present and future population size (e.g. births, deaths)
Life table useful for population ecologist?
- Age-specific summary of survival pattern of population
Survivorship curve (def.)
- Graphical representation of a life table; changes in survival over maximum life span
Type I (survivorship curve)
- Survival is high in early/middle life; survival decreases as organism gets older
- Elephant
Type II (survivorship curve)
- Survival rate is constant over organism’s life (gophers)
Type III (survivorship curve)
- Survival is low for young; mortality declines for survivors
Reproductive table
- Age-specific summary of reproductive rates in a population
Tradeoffs in patterns of reproduction?
- Many offspring = decreased survival probability
- Fewer offspring = increased survival probability
Degree of parental care in relation to survival rate of parent?
- Survival rate decreases with more involved parenting
Semelparity
- Big-bang reproduction (1x)
- Salmon, annual plants
- Semel: One time
Iteroparity
- Produces offspring repeatedly over course of life span
- Itero: Repeated
Growth rate + time equation
∆N / ∆t
Growth rate equation
bN - mN = N(b - m)
- b (birth), m (mortality rate)
Logistic population growth
- Exponential growth cannot be sustained for long in any population; population is limited by resource
- Growth rate changes as it approaches (K-carrying capacity)
Exponential growth
Constant rate of increase
Density dependence
Factors where effects on size or growth of population vary with density of population itself
Density dependent factors that influence birth and death rates?
- Competition
- Territoriality
- Disease (pathogens easier to spread with larger population)
- Predation
