53.1-5

the study of population in relation to their environment, including environmental influences on population density and distribution, age structure, and variation in population size

population density, dispersion, and demographics

a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring

the number of individuals per unit area or volume changes as individuals are added to or removed from a population

the pattern of spacing among individuals within the boundaries of a population

a sampling technique used to estimate the size of wild animal populations

from number of nests, burrows, tracks, fecal droppings

the influx of new individuals into a population form other areas

the movement of individuals out of a population

clumped uniform random

the most common pattern where individuals are aggregated in patches plants and fungi are often clumped where factors favor germination and growth

evenly spaced pattern of dispersion may result from direct interactions between individuals in the population, such as territoriality

a behavior in which an animal defends a bounded physical space against encroachment by other individuals, usually of its own species

unpredictable spacing the position of each individual in a population is independent of other individuals occurs in the absence of strong attractions or repulsions among individuals or where key physical or chemical factors are relatively constant across the area ex: plants by windblown seeds

the study of changes over time in the vital statistics of populations, especially birth and death rates uses life tables and survivorship curves

an age specific summary of the survival pattern of a population

to follow the fate of a cohort

a group of individuals of the same age in a population

a plot of the number of members of a cohort that are still alive at each age one way to represent age specific mortality three types: type I, II, III

flat at the start, reflecting low death rates during early and middle life, and then drops steeply as death rates increase among older age groups many large animals including humans that produce few offspring but provide good care

drops sharply at the start, reflecting very high death rates for the young, but flattens out as death rates decline for those few that survive the early period of die off usually organisms that produce large amounts of offspring but provide little to no care, such as long lived plants, fishes, and marine invertebrates

intermediate, with constant death rate over the organisms life span (straight line) squirrels, rodents, annual plants

an age specific summary of the reproductive rates in a population

population growth in an idealized, unlimited environmnet

the difference between the per capita birth rate and per capita death rate, which is the per capita rate of increase

a period of stability in population size, when additions through population through births and immigration are balanced by subtractions through deaths and emigration

growth of a population in an ideal, unlimited environment, represented by a j-shaped curve when population size is plotted over time assumes resources are unlimited with unlimited reproduction

some populations that are introduced into a new environment or whose numbers have been drastically reduced by an event and are rebounding

the logistic model describes how a population grows more slowly as it nears its carrying capacity

the maximum population size that can be supported by the available resources, symbolized as K

energy shelter refuge from predators nutrient availability water suitable nesting sites

population growth that levels off as population size approaches carrying capacity the per capita rate of increase approaches zero as the carrying capacity is reached produces a sigmoid(S-shaped) growth curve when N(population size) is plotted over time

natural selection

the traits that affect an organisms's schedule of reproduction and survival

when reproduction begins how often the organism reproduces how many offspring are produced per reproductive episode

reproduction in which an organism produces all of its offspring in a single event; also known as big band reproduction example: salmon and agave plant

reproduction in which adults produce offspring over many years; also known as repeated reproduction produce few but large offspring

survival rate of the offspring and the likelihood that the adult will survive to reproduce again when survival rate of offspring is low, semelparity is favored because adults are also less likely to survive in such environments iteroparity is more favorable in dependable environments, where adults are more likely to survive to breed again and where competition for resources may be intense

selection for life history traits that are sensitive to population density; also called density dependent selection favored at high density

selection for life history traits that maximize reproductive success in uncrowded environments; also called density independent selection

density dependent

referring to any characteristic that is not affected by population density ex: a birth or death rate that does not change with population density

referring to any characteristic that varies with population density acts as a negative feedback between population density and rates of birth and death ex: death rate that rises as population density rises

competition for resources predation intrinsic factors toxic wastes territoriality disease

increasing population density intensifies competition for resources, reducing reproductive rates

can be important if a predator captures more food as the population density of the prey increases predators may feed preferentially on that species if population builds up

intrinsic physiological factors sometimes regulate population size reproduction may drop at high population densities

organisms produce wastes, and too much waste is toxic

territoriality can limit population density when space becomes the resource for which individuals compete maintaining territory increases likelihood that animal will capture enough food to reproduce surplus means territoriality is restricting population growth

diseases have a higher transmission rate in higher crowded areas

the study of how complex interactions between biotic and abiotic factors influence variations in population size

a group of spatially separated populations of one species that interact through immigration and emigration