1.3 Diversity of Organisms

organism

any biological system that functions as an individual life form

population

group of organisms of the same species in the same area

communities

populations of two or more different species occupying the same geographical area at the same time

variation

differences between members of a group

discrete variation

traits that can be put into distinct qualitative categories

continuous variation

traits that vary along a quantitative continuum

intraspecies variation

variation within a species

morphological species concept

classified a species as a group of living things recognizably distinct from all others by their shared characteristics (shape + appearance)

biological species concept

classified a species as a population of organisms that are able to freely breed under natural conditions to produce fertile offspring

speciation

the splitting of one species into two or more species (usually happens gradually)

hybridization / cross-breeding

forming a cross between two distinct genetic species

biodiversity

the variety of life in all its forms, levels, and combinations

species diveristy

number of different species and abundance of each species that live in a particular location

species richness

the number of different species present in a particular area

species evenness

how close in numbers the different species are

genetic diversity

the variation in the amount of genetic information within and among individuals of a population, a species, an assemblage, or a community

ecosystem diversity

the number of different ecological niches found within an ecosystem

Simpson’s Reciprocal Index

quantifies diversity: the higher the DI, the greater the biodiversity