Chapter 5: Biodiversity, Species Interactions, and Population Control

interspecific competion

occurs when members of 2 or more species interact to gain access to the same limited resources such as food, water, light, and space.

ecological niche

an organisms role in an ecosystem.

resource partitioning

occurs when species competing for similar scarce resources evolve specialized traits that allow them to share resources by using parts of them, using them at different times, or using them in different ways.

predation

occurs when a member of one species (predator) feeds directly on all or part of a member of another species (prey).

predator-prey relationship

relationship between two different species where one feeds on the other.

camouflage

an adaptation that allows predators and/or prey to hide in plain sight.

chemical warfare

using poisons to paralyze prey or to deter predators.

warning coloration

brightly colored advertising that helps experienced predators/prey to recognize and avoid them.

mimicry

where nonpoisonous organisms gain protection by looking like poisonous ones.

behavioral strategies

prey attempt to scare off predators by puffing up, spreading wings to look bigger, or mimicking the behavior of the predator.

coevolution

when populations of 2 different species interact in such a way over a long period of time develop changes in the gene pool of the other. It allows both sides to become more competitive, or to avoid or reduce competition.

parasitism

occurs when one organism (parasite) feeds on another organism (host), usually by living on or in the host.

mutualism

the interaction that benefits both species by providing each with food, shelter, or some other resource.

commensalism

the interaction that benefits one species but has little or no effect on the other.

echolocation

a way to navigate and locate prey using pulses of high-frequency and high-intensity sound which bounces off objects, and the returning echoes tell them where their prey is located.

ecological succession

the normally gradual change in species composition in a given area.

primary ecological succession

involves the gradual establishment of biotic communities in lifeless areas where there is no soil in a terrestrial ecosystem or no bottom sediment in an aquatic one. Ex.: on a newly formed island.

secondary ecological succession

where a series of communities or ecosystems with different species develop in places containing soil or bottom sediment. Ex.: after a fire

pioneer species

species which colonize previously uncolonized land, usually leading to ecological succession.

ecological restoration

bringing back an ecosytem to its original form after being degraded. Secondary ecological succession after a fire is natural restoration.

facilitation

one set species makes an area suitable for species with different niche requirements, and often less suitable for itself.

inhibition

some species hinder the establishment and growth of other species.

tolerance

plants in the late stages of succession succeed because they are not in direct competition with other plants for key resources. Ex: shade tolerant plants

climax community

is a biological community of plants and animals which, through the process of ecological succession — the development of vegetation in an area over time — has reached a stable state.

inertia or persistence

the ability of a living system to survive moderate disturbances. Ex.: rainforest

resilience

the ability of a living system to be restored through secondary successioin after a more severe disturbance. Ex.: grassland

population

a group of interbreeding individuals of the same species.

clumped distribution

populations that live in packs, schools, or flocks live in this distribution pattern. Most populations live in this pattern.

uniform distribution

a pattern of distribution most commonly seen when resources are scarce. They are evenly distributed like the creoste bush in the desert.

random distribution

a population distribution pattern seen where a population is plentiful, such as dandelions in a field.

age structure

distribution of individuals among various age groups

prereproductive stage

organisms not mature enough to reproduce

reproductive stage

capable of reproduction

postreproductive stage

organisms too old to reproduce

range of tolerance

range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. When plotted it is usually a bell curve.

limiting factors

the number of physical or chemical factors that determine the number of organisms in a population. They regulate a population size.

optimum level or range

the part of a range of tolerance where a particular species does the best.

limiting factor principle

states that too much or too little of any physical or chemical factor can limit or prevent the growth of a population, even if all other factors are at or near the optimal range of tolerance.

population density

the number of individuals in a population found in a particular area or volume.

dissolved oxygen content (DO)

the levels of oxygen gas in water.

salinity

the amounts of various inorganic minerals or salts dissolved in a given volume of water.

environmental resistance

the combination of all factors that act to limit the growth of a population. It largely determine's an area's carrying capacity.

carrying capacity

the maximum population of a given species that a particular habitat can sustain indefinitely.

exponential growth

growth that starts out slowly, but then accelerates as the population increases because the base size is increasing. When plotted it looks like a "J". Ex.: world populaton, bacteria growth

logistic growth

when exponential growth decreases steadily with time as the population approaches the carrying capacity. When plotted it looks like an "S".

overshoot

when populations use up their resource supplies and temporarily exceed the carrying capacity of their environment.

reproductive time lag

the period needed for the birth rate to fall and for the death rate to rise in response to resource overconsumption. It allows for an overshoot in population growth.

dieback or population crash

when a population suffers a sharp decline.

density-dependent population control factors

the factors that limit population growth and have a greater effect as the density increases. Ex.: parasitism, infectious disease, competition for resources.

density-independent population control factors

factors that kill members of a population that do not depend on density. Ex.: severe freeze, floods, hurricanes, fire, pollution, and habitat destruction.

stable population

a species whose population size fluctuates slightly above and below its carrying capacity.

irruptive population

a species whose population size may occasionally surge, then crash. Ex.: algae or some insects

cyclic population

species whose population has boom-and-bust cycles every so many years. Ex.: lynx and snowshoe hare

irregular population

populations whose size has no regular pattern.