Glossary

acoustic Doppler current profilerA device that uses sound waves (SONAR) to record the speed and direction of water currents for a range of depths

adaptationA biological characteristic that improves the chance of survival of an organism and its descendants.

biodiversityThe variety and interdependence of all living things. Biodiversity includes all living organisms, the genetic differences among them, the communities, cultures, habitats and ecosystems in which they evolve and coexist, and the ecological and evolutionary processes that support them.

DNA (deoxyribonucleic acid)A molecule found in almost every cell that contains an organism's genetic code. DNA is made of two strings of bases wound in a helix, or spiral, shape.

evolutionThe scientific theory for how groups of living things change over time.

geneticsThe scientific study of heredity. Also, the genetic constitution of an individual, group, or class.

geographic isolation (allopatry)
When groups of organisms have entirely separate ranges that do not overlap. Biological populations that are physically isolated by a barrier can become reproductively isolated—they can no longer breed with one another and can evolve different features.

global positioning system (GPS)A system of satellites, computers, and receivers that can determine the location (latitude and longitude) of a receiver on Earth.

habitatThe environment where an organism can and does live.

hydrologyThe study of water.

morphologyThe form and structure of anything, usually applied to the shapes, parts, and arrangement of features in living and fossil organisms.

nucleotideThe basic structural unit of nucleic acids (DNA or RNA).

populationA group of organisms of one species, occupying a defined area and usually isolated from similar groups of the same species.

speciationWhen related groups of organisms have changed so much that they are different enough to be considered separate species.

speciesA group of individuals, usually identifiable by a set of distinctive features, with a unique evolutionary history. Classically, the members of a species can interbreed only with each other to produce fertile offspring.