Cichlids: Common name for perch-like fish of the family Cichlidae, belonging to the suborder Labroidei, order PERCIFORMES.Perches: A common name for fish of the family Percidae, belonging to the suborder Percoidei, order PERCIFORMES.Africa, Eastern: The geographical area of Africa comprising BURUNDI; DJIBOUTI; ETHIOPIA; KENYA; RWANDA; SOMALIA; SUDAN; TANZANIA; and UGANDA.Lakes: Inland bodies of still or slowly moving FRESH WATER or salt water, larger than a pond, and supplied by RIVERS and streams.Fish Proteins: Proteins obtained from species of fish (FISHES).Fresh Water: Water containing no significant amounts of salts, such as water from RIVERS and LAKES.NicaraguaGenetic Speciation: The splitting of an ancestral species into daughter species that coexist in time (King, Dictionary of Genetics, 6th ed). Causal factors may include geographic isolation, HABITAT geometry, migration, REPRODUCTIVE ISOLATION, random GENETIC DRIFT and MUTATION.Territoriality: Behavior in defense of an area against another individual or individuals primarily of the same species.Jaw: Bony structure of the mouth that holds the teeth. It consists of the MANDIBLE and the MAXILLA.Tilapia: A freshwater fish used as an experimental organism and for food. This genus of the family Cichlidae (CICHLIDS) inhabits Central and South America (one species extends north into Texas), West Indies, Africa, Madagascar, Syria, and coastal India.Opsins: Photosensitive proteins in the membranes of PHOTORECEPTOR CELLS such as the rods and the cones. Opsins have varied light absorption properties and are members of the G-PROTEIN-COUPLED RECEPTORS family. Their ligands are VITAMIN A-based chromophores.Pigmentation: Coloration or discoloration of a part by a pigment.Mating Preference, Animal: The selection or choice of sexual partner in animals. Often this reproductive preference is based on traits in the potential mate, such as coloration, size, or behavioral boldness. If the chosen ones are genetically different from the rejected ones, then NATURAL SELECTION is occurring.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Evolution, Planetary: Creation and development of bodies within solar systems, includes study of early planetary geology.Microspectrophotometry: Analytical technique for studying substances present at enzyme concentrations in single cells, in situ, by measuring light absorption. Light from a tungsten strip lamp or xenon arc dispersed by a grating monochromator illuminates the optical system of a microscope. The absorbance of light is measured (in nanometers) by comparing the difference between the image of the sample and a reference image.Social Dominance: Social structure of a group as it relates to the relative social rank of dominance status of its members. (APA, Thesaurus of Psychological Index Terms, 8th ed.)Biological Evolution: The process of cumulative change over successive generations through which organisms acquire their distinguishing morphological and physiological characteristics.Evolution, Molecular: The process of cumulative change at the level of DNA; RNA; and PROTEINS, over successive generations.Malawi: A republic in southern Africa east of ZAMBIA and MOZAMBIQUE. Its capital is Lilongwe. It was formerly called Nyasaland.AfricaSpecies Specificity: The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.Color: The visually perceived property of objects created by absorption or reflection of specific wavelengths of light.Cone Opsins: Photosensitive proteins expressed in the CONE PHOTORECEPTOR CELLS. They are the protein components of cone photopigments. Cone opsins are classified by their peak absorption wavelengths.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)VenezuelaFishes: A group of cold-blooded, aquatic vertebrates having gills, fins, a cartilaginous or bony endoskeleton, and elongated bodies covered with scales.ColombiaRivers: Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).Caves: Geological formations consisting of underground enclosures with access from the surface.Central AmericaGuatemalaWood: A product of hard secondary xylem composed of CELLULOSE, hemicellulose, and LIGNANS, that is under the bark of trees and shrubs. It is used in construction and as a source of CHARCOAL and many other products.Aggression: Behavior which may be manifested by destructive and attacking action which is verbal or physical, by covert attitudes of hostility or by obstructionism.Animal Fins: Membranous appendage of fish and other aquatic organisms used for locomotion or balance.Hobbies: Leisure activities engaged in for pleasure.Gene Expression Profiling: The determination of the pattern of genes expressed at the level of GENETIC TRANSCRIPTION, under specific circumstances or in a specific cell.ParaguaySympatry: In evolutionary theory, overlapping geographic distribution of diverging species. In sympatric GENETIC SPECIATION, genetic diversion occurs without geographic separation.South AmericaTurtlesIndians, South American: Individual members of South American ethnic groups with historic ancestral origins in Asia.BrazilDielectric Spectroscopy: A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.Swimming: An activity in which the body is propelled through water by specific movement of the arms and/or the legs. Swimming as propulsion through water by the movement of limbs, tail, or fins of animals is often studied as a form of PHYSICAL EXERTION or endurance.Air Sacs: Thin-walled sacs or spaces which function as a part of the respiratory system in birds, fishes, insects, and mammals.Metronidazole: A nitroimidazole used to treat AMEBIASIS; VAGINITIS; TRICHOMONAS INFECTIONS; GIARDIASIS; ANAEROBIC BACTERIA; and TREPONEMAL INFECTIONS. It has also been proposed as a radiation sensitizer for hypoxic cells. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985, p133), this substance may reasonably be anticipated to be a carcinogen (Merck, 11th ed).Vacuum: A space in which the pressure is far below atmospheric pressure so that the remaining gases do not affect processes being carried on in the space.Body Water: Fluids composed mainly of water found within the body.Spirurida: An order of nematodes of the subclass SECERNENTEA. Characteristics include ventral or caudoventral papillae and an esophagus divided into anterior muscular and posterior glandular parts.Dracunculoidea: A superfamily of nematodes of the suborder CAMALLANINA. Its organisms possess a poorly developed buccal cavity and a rudimentary esophagus and intestine.Water Quality: A rating of a body of water based on measurable physical, chemical, and biological characteristics.