Unit 8: Ecology

• Population: a localized group of individuals of the same species that can interbreed, producing fertile offspring
• Community: all the organisms that inhabit a particular area; as assemblage of populations of different species living close enough together for potential interaction
• Ecosystem: all the organisms in a given area as well as the abiotic factors with which they interact
• Biotic: pertaining to the living organisms in the environment
• Abiotic: nonliving; referring to physical and chemical properties of an environment
• Biosphere: the entire portion of earth inhabited by life; the sum of all the planet's ecosystems
• Niche: the sum of a species' use of the biotic and abiotic resources in its environment
• Clumped Distribution: individual aggregated patches, some organisms group together where food is abundant
• Uniform Distribution: evenly spaced, some organisms maintain evenly distributed spacing to avoid aggressive interactions between neighbors
• Random Distribution: unpredictable spacing, some plants grow in random groups if their seeds were windblown across an area
• Population Ecology: the study of populations in relation to their environment, including environmental influences on populations, on population density and distribution, age structure, and variations in population size
• Birth Rate: rate of annual birth within a population
• Death Rate: rate of annual death within a population
• Sex Ratio: ratio of females to males within a population
• Immigration Rate: the rate of influx of new individuals INTO a population from other areas
• Emigration Rate: the rate of movement of individuals OUT of a population
• Carrying Capacity: the maximum population size that can be supported by the available resources, (symbolized by K)
• Density Dependent: any characteristic that varies according to an increase in population density
• Exponential Growth: growth of a population in an ideal, unlimited environment, (represented by a J-Shaped curve when population size is plotted over time)
• Logistical Growth: population growth that levels off as population size approaches carrying capacity
• K-Selected: stabilize around carrying capacity, have fewer offspring later in life, mature later, live longer and invest more parental care
• R-Selected: reside in unstable environment, have many offspring early in life, mature earlier, shorter life span, no parental care
• Survivorship Curve: the plot of the proportion or numbers in a cohort still alive at each age
• Type I Surivorship Curve: low death rates during early/middle life then increase among older age groups (humans)
• Type II Surviorship Curve: constant death rate over the organism's life span
• Type III Surviorship Curve: very high death rates for the young and then declines for those few individuals that survive the early period (insects)
• Symbiosis: an ecological relationship between organisms of two different species that live together in direct and intimate contact
• Commensalism: a symbiotic relationship in which one organism benefits but the other is neither helped nor harmed
• Mutualism: a symbiotic relationship in which both participants benefit
• Parasitism: a symbiotic relationship in which one organism (the parasite) benefits at the expense of another (the host) by living either within or on its host
• Intraspecific Competition: interactions between the same species competing for resources
• Interspecific Competition: competition for resources between individuals of two or more species when resources are in short supply
• Predation: an interaction between species in which one species (the predator) eats the other (the prey)
• Aposematic Coloration: the bright coloration of animals with effective physical or chemical defenses that acts as a warning to predators
• Batesian Mimicry: a type of mimicry in which a harmless species look like a species that is poisonous or harmful to predators
• Cryptic Coloration: camouflage that makes a potential prey difficult to spot against its background
• Mullerian Mimicry: a mutual mimicry by two unpalatable species
• Pioneer Species: the first species to colonize previously disrupted or damaged ecosystems, beginning a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem
• Climax Community: in a community of organisms in a specific area there is one state of equilibrium controlled solely by climate
• Succession: the process by which the structure of a biological community evolves over time