L17 Population Ecology Flashcards
define ecology
study of the relationships of organisms to one another and to the environment
biotic interactions
interactions among organisms
abiotic interactions
interactions between organisms and their non-living environments
what is the basic unit of ecology
population
define population ecology
study of populations in relation to the environment
what is a population
all the individuals of a single species that live and reproduce within a given area at a given time
what is population structure and what factors does it include
patterns in space and time: size, density, distribution, dispersion
what is population dynamics and what factors does it include
changes in structure over time: age structure, sex ratios, demography, survivorship curves
what does size relating to populations refer to
number of individual organisms present at a given time; doesn’t indicate area or volume
what does range relating to populations refer to
total area or volume occupied by the individual organisms belonging to the population (of one species)
what does density relating to populations refer to
number of individuals per unit area or volume
what are the problems if the population size and density is too low
- normal social behaviours are deficient (group foraging or defense)
- unable to find mates
- normal courtship and mating behaviours don’t occur
- genetic diversity falls (inbreeding)
- important community connections may be lost, affecting other species
what are the problems if the population size and density is too high
- social behaviours break down with overcrowding
- spread of disease increases
- food supplies are insufficient
- increased chance of conflict with humans
- damage to environment from overuse of resources
define distribution/dispersion, and what are the types
spatial arrangement of individuals within a space; random, clustered/clumped, uniform
what are the four factors affecting population growth
natality, mortality, immigration, emigration
growth under ideal conditions can be represented with what shape of model and why
exponential; growth continues with no limits
what is a more realistic growth model, why
s-shaped (logistic); as carrying capacity is reached, the population levels out and doesn’t overburden the environment
what is demography
describes dynamics of population change over time (such as age and sex)
what is a survivorship curve model
gives average timing of deaths of individuals in a population (types I, II, III)
What are the 2 types of regulation affecting the impact of population density
density-independent and dependent regulation
define density-independent regulation, and give examples
birth and death rates are not affected by population density but change due to other non-density related factors; weather, natural catastrophes, random events (extra terrestrial, terrestrial)
define density-dependent regulation, and give examples
birth rates fall and death rates rise with population density; competition for resources, territoriality, predation, health, toxic waste accumulation, intrinsic factors
r-selection refers to which selection, environment
density-independent (selects for life history traits that maximize reproduction); unstable environments
K-selection refers to which selection, environment
density-dependent (selects for life history traits that are sensitive to population density); stable environments
r-selected species have a _____ intrinsic growth
high
K-selected species have a ______ intrinsic growth
low
what is ecology
a field of study looking at relationships between organisms to each other and the environment, including distribution, abundance, and interactions
what is population ecology
a field of study looking at populations in relation to the environment
what are properties of populations
based on structure (size, density, distribution, dispersion) and its changes (age structure, sex ratios, demography, survivorship curves)
how do populations grow
by 4 factors: birth, death, immigration, emigration
how are populations regulated
through density dependent and density independent factors
