Chapter 53 Flashcards
population ecology
the study of populations in relation to their environet. explores how biotic and abiotic factors influence the abundnace, dispersion, and age structure of a population
density
the number of individuals per unit area or volume
dispersion
pattern of spacing among individuals within the boundaries of the population
mark-recapture method
determingin population size
carrying capacity
maximum population size the environment can support, varies with abundance of limiting resources
when does population meet its maximum
half carrying capacity
traits that affecst organisms reproduction and survival
age of repro, how often repro, how many offspring produces
semelparity
reproduce once and die, highly variable and unpredicatable environments
iteroparity
produce offspring repeatedly, more dependeable environments,
r selection
density independent selection, selects for life history that maximize reproduction, smaller animals
k selection
density dependent selection, slects for life history traits that are sensitive to population density
survivorship curve
plot of the proportion or numbers in a cohort still alive at each age
trade off for survival and reproduction
some species will reproduce rapidly to maxmizmie population and then die immediatley
density dependent regulation factors
predation, negative feedback loop, disease, competition for resources, territories, intrinsic physiological factors
population dynamics
fluctuations from year to year or place to place, focuses on the complex interactions between biotic and abiotic factors that cause variation in population sizes
exponential growth
occurs when there are ideal conditions, abundant food, free to reproduce anywhere, means the population grows at a constant proportion
logistic growth
growth with a limit (carrying capacity), the rate of population growth as it reaches zero as the population size nears the carrying capacity, rate of population decreases as population size approaches K
surviviorship curves
percentage of an original population that survives to a given age
type one survivorship
mortality rises in post reproductive age (humans)
type ii surviviorship
mortality is constant thoruhgt age (birds)
type iii surviviorship
mortality is low after establishment, large decline in young (mice)
density independent
a birthrate or death rate that does not change with population density
density dependent
a death rate that increases with population density or a birth rate that falls with rising density
