adaptation, or adaptive trait
any heritable trait that enables an individual organism to survive through natural selection and to reproduce more than other individuals under prevailing environmental conditions
background extinction
normal extinction of various species as a result of changes in local environmental conditions
biological diversity, or biodiversity
the variety of the earth's species, the genes they contain, the ecosystems in which they live, and the ecosystem processes such as energy flow and nutrient cycling that sustain all life
biological evolution
the process whereby earth's life changes over time through changes in the genes of populations
differential reproduction
phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits
ecological niche
total way of life or role of a species in an ecosystem
endemic species
Species that are found in only one area and are especially vulnerable to extinction
extinction
occurs when an entire species ceases to exist
fossils
mineralized or petrified replicas of skeletons, bones, teeth, shells, leaves, and seeds, or impressions of such items found in rocks
foundation species
species that plays a major role in shaping communities by creating and enhancing their habitats in ways that benefit other species
generalist species
have broad niches; can live in many different places, eat a variety of foods, and often tolerate a wide range of environmental conditions
geographic isolation
when different groups of the same population of a species become physically isolated from one another for long periods
indicator species
Species that provide early warnings of damage to a community or an ecosystem
keystone species
have a large effect on the types and abundances of other species in an ecosystem
mass extinction
is a significant rise in extinction rates above the background level
mutations
random changes in the structure or number of DNA molecules in a cell that can be inherited by offspring
native species
species that normally live and thrive in a particular ecosystem
natural selection
occurs when some individuals of a population have genetically based traits that enhance their ability to survive and produce offspring with the same traits
nonnative species
species that migrate into or are deliberately or accidentally introduced into an ecosystem
reproductive isolation
when mutation and change by natural selection operate independently in the gene pools of geographically isolated populations
specialist species
occupy narrow niches; may be able to live in only one type of habitat, use one or a few types of food, or tolerate a narrow range of climatic and other environmental conditions
speciation
two species arise from one through natural selection
species diversity
the number of different species an ecosystem contains (species richness) combined with the relative abundance of individuals within each of those species (species evenness)
species evenness
the relative abundance of individuals within each of the species in a community
species richness
number of different species contained in a community