Ch 4

• Eukaryotic/eukaryotic cell - cell that is surrounded by a membrane and has a distinct nucleus.
• Prokaryotic/prokaryotic cell - cell containing no distinct nucleus or organelles.
• Species - group of similar organisms and for sexually reproducing organisms a set of individuals that can mate and produce fertile offspring.
• Biodiversity/biological diversity - variety of different species (species diversity), genetic variability among individuals within each species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional diversity).
• Species diversity - number of different species (species richness) combined with the relative abundance of individuals within each of those species (species evenness) in a given area.
• Species richness - variety of species, measured by the number of different species contained in a community.
• Species evenness - degree to which comparative numbers of individuals of each of the species present in a community are similar.
• Genetic diversity - variability in the genetic makeup among individuals within a single species.
• Biomes - terrestrial regions inhabited by certain types of life, especially vegetation.
• Edge effect - the changes in population or community structures that occur at the boundary of two habitats.
• Ecotone - transition area between two biomes.
• Functional diversity - biological and chemical processes of functions such as energy flow and matter cycling needed for the survival of species and biological communities.
• Ecological niche - total way of life or role of a species in an ecosystem. It includes all physical, chemical, and biological conditions that a species needs to live and reproduce in an ecosystem.
• Habitat - place or type of place where an organism or population of organisms live.
• Generalist species - species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions.
• Specialist species - species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or limited types of food.
• Native species - species that normally live and thrive in a particular ecosystem.
• Nonnative species - species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans.
• Indicator species - species whose decline serves as an early warning that a community or ecosystem is being degraded.
• Keystone species - species that play important roles in helping to sustain many other species in an ecosystem.
• Biological evolution/evolution - Change in the genetic makeup of a population of a species in successive generations. If continued long enough, it can lead to the formation of a new species. Note that populations, not individuals, evolve.
• Natural selection - Process by which a particular beneficial gene (or set of genes) is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions. See adaptation, biological evolution, differential reproduction, mutation.

• Fossils - Skeletons, bones, shells, body parts, leaves, seeds, or impressions of such items that provide recognizable evidence of organisms that lived long ago.

• Genetic variability - diversity in the genetic makeup among individuals within a single species.
• Adaptation/adaptive trait - any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions.
• Evolutionary tree/phylogenetic tree - branching diagram showing the inferred relationships among various biological species based on similarities and differences in their physical or genetic characteristics and arising from a common ancestor.
• Speciation - formation of two species from one species when different populations of a sexually reproducing species have been separated and exposed to different environmental conditions so long that their genetic makeup has changed; usually takes thousands of years.
• Geographic isolation - physical separation of populations of the same species into different areas for long periods of time.
• Reproductive isolation - situation where different populations of sexually reproducing species have been geographically isolated for such a long time that their genetic makeup has changed and they can no longer produce live, fertile, offspring.
• Artificial selection - process by which humans select one or more desirable genetic traits in the population of a plant or animal species and then use selective breeding to produce populations containing many individuals with the desired traits.
• Genetic engineering - insertion of an alien gene into an organism to give it a new genetic trait.
• Genetically modified organism (GMO) - organisms whose genetic makeup has been altered by genetic engineering.
• Synthetic biology - producing new sequences of DNA and using such human produced genetic information to design and create artificial cells, tissues, body parts, and organisms not found in nature.
• Extinction - complete disappearance of species from the earth. It happens when a species cannot adapt and successfully reproduce under new environmental conditions or when a species evolves into one or more new species.
• Endemic species - species that is found in only one area. Such species are especially vulnerable to extinction.
• Background extinction rate - normal extinction of various species as a result of changes in environmental conditions.
• Mass extinction - a catastrophic, widespread, often global event in which major groups of species are become extinct over a short time compared with the normal (background) extinction rates.
• Ecological diversity - the variety of forests, deserts, grasslands, oceans, streams, lakes, and other biological communities interacting with one another and with their nonliving environment.
• Invertebrates - animals without backbones.
• Vertebrates - animals with backbones.