Biology ch 54

a group of populations of different species living close enough to interact

• may be positive for one species (+), negative (-), or neutral (0)
• include competition, predation, and symbioses

• occur when resources are short in supply
• -/- interaction between the species

when 2 species are vying for a resource, eventually the one with the slight reproductive advantage will eliminate the other

the sum total of biotic and abiotic resources that the species uses in its environment

the niche potentially occupied by a species

the portio =n of the fundamental niche the species actually occupies

a +/- interaction between 2 species in which one species eats the other species

an organism is camouflaged by its coloring

a poisonous animal is brightly colored as a warning to other animals

refers to a situation in which a harmless species has evolved to mimic the coloration of an unpalatable/harmful species.

2 bad-tasting species resemble each other so that predators learn to avoid them equally

a +/- interaction in which an herbivor eats part of a plant or alga.

occurs when individuas of 2 or more species live in direct contact with one another

• a +/- symbiotic interaction in which the parasite derives its nourishment from its host
• may have a significant effect on the survivalm reproduction, and density of their host population

• an interspecific interaction that benefits both species (+/+)
• (Both pollinators and flowering plants benefit from their relationship)

• benefits one species, but neither harms nor helps the other (+/0)
• (a fern growing in the shade of another plant)

• measures the number of different species in a community (species richness) and the relative abundance of each speices
• (a community with an even species abundance is more diverse than one in which one or two species are abundant and the remainder are rare)

the feeding relationships among organisms

the links in the trophic structure of a community

the transfer of food energy from plants through herbivores through carnivores through decomposers (from one trophic level to another)

consist of 2 or more food chains linked together

have the highest biomass (most abundant)

the sum weight of all the members of a population

exert control on community by their important ecological niches

storm, fire, flood, drought, or human activity changes a community by removing organisms or changing resource availibility. Not always bad

states that moderate levels of disturbance create conditions that foster greater species diversity than low or high levels of disturbance

transitions in species composition in a certain area of ecological time

plants and animals gradually invade a region that was virtually lifeless where soil has not yet formed

an exisiting community has been cleared by a disturbance that leaves the soil intact

plant and animal life is generally more abundant and diverse in the tropics, becoming less so moving toward the poles

if all other factors are held equal, the larger geographic area of a community is, the more species it has

• because of their isolation and sixe
• also, land such as national parks surrounded by development work

• 1. rates of immigration and extincion are influenced primarily by the size of the island and the distance from mainland. The greater the sizes of the island, the higher the immigration rates and the lower the rates of extinction
• 2. As the distance from the mainand increases, the rate of immigration falls, and the rates of extinction increase

the differentitation of niches that enables similar species to coexist in a commuity

the tendency for characteristics to diverge more in sympatric populations of 2 species than in allopatric populations of the same 2 species

the formation of new species in populations that are geographically isolated from one another

the formation of new species in populations that live in the same geographic area

parasites that live within the body of their host (tapeworms)

parasites that feed on the external surface of a host (ticks, lice)

the number of different species in an area

the proportion each species represents of all individuals in a community

suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain