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Galapagos Glossary
Use this glossary to help you understand some of the scientific terms found throughout the Destination: Galapagos Islands website.
abiotic: pertaining to those portions of an ecosystem that are non-living, such as temperature, light, soil, water, etc.
adaptation: a genetically controlled characteristic (behavioral, structural or physiological) that enhances survival and ability to reproduce among members of a population (Read more about Natural Selection)
adaptive radiation: an evolutionary pattern in which related species become dissimilar or less alike
archipelago: a large group of islands
autotroph: see producer
binomial nomenclature: a classification system developed by Carl von Linnaeus in which all organisms are assigned a specific two-word name (e.g., humans are Homo sapiens)
biochemical homologies: similarities in blood, proteins and DNA and RNA sequences that indicate species relatedness; the greater the similarities, the more closely related two organisms are thought to be
biological community: all the populations of different species occupying a single ecosystem
biotic: pertaining to, produced, or influenced by living organisms, especially as related to an ecosystem
calcium: (Ca); a macronutrient that makes up approximately 3% of the earth's crust and that is found in most plants and animals; calcium is the most abundant mineral present in the human body and is primarily responsible for
building strong bones and teeth
caldera: a large crater formed by a volcanic explosion
carnivore: an organism that consumes only animals
class: a taxonomic group subordinate to phylum; group of similar orders
climate: the weather conditions, such as temperature, precipitation and wind, normally experienced by a particular region
conservation: the protection of natural resources, such as air, soil, water, vegetation and wildlife
consumer: also known as a heterotroph, an organism that cannot make its own food and must eat producers or other consumers
convergent evolution: process by which unrelated species become more similar in order to survive in similar environmental conditions
detrivore: an organism that consumes dead and decaying organisms
dissolved oxygen: pure oxygen found in a body of water that may safely be used by marine organisms; the concentration of dissolved oxygen is largely determined by water temperature, salinity level and the amount of oxygen-consuming pollutants in the water
divergent evolution: process by which related species become less similar in order to survive in different environmental conditions
ecology: the study of the interactions of living organisms with one another and their environment
ecosystem: an ecological community that, together with its environment, functions as a unit
El Nino: a periodic warming of Pacific Ocean currents that occurs when changes in atmospheric pressure prevent cold water from rising to the surface
endemic: native or confined to a particular region
environment: the conditions that surround an organism and influence its growth, development and survival
Equator: the imaginary circle around the center of the Earth that divides the planet into the Northern and Southern Hemispheres
evolution: the theories concerning the processes of biological and organic change in organisms such that descendants differ from their ancestors; over time, species may change in structure and function
extinct: no longer existing or living
family: a taxonomic group subordinate to order; group of similar genera
fauna: a group of animals that live in a particular region
Five Kingdom System: a taxonomic classification system in which organisms are grouped into one of five kingdoms and are then further subdivided into increasingly specific groupings (phylum, class, order, family, genus and, finally, species)
flora: a group of plants that live in a particular region
food chain: the sequence of who eats whom within an ecosystem
food web: a complex feeding network made up of many different food chains
genus: a taxonomic group subordinate to family; group of similar species
habitat: the part of an ecosystem in which an organism lives
harvesting: the process of gathering a crop
heterotroph: see consumer
herbivore: an organism that consumes only plants
homologous: description for physical features that are formed in similar ways during embryonic development and that have a similar structure (e.g., the flipper of a whale, the arm of a human and the wing of a bat are all homologous organs)
Humboldt Current: a cold Pacific Ocean current that flows north from Antarctica to the western coast of South America (also known as the Peru Current)
hydrologic cycle: the cycle by which the water on Earth is constantly recycled and purified through the processes of evaporation, transpiration (the evaporation of water from the leaves of plants), precipitation, condensation, percolation and runoff
hydrosphere: a huge heat reservoir made up of all Earth's water (including ice and glaciers) that stores, absorbs and circulates the radiant energy striking the Earth
immutable: unable to change
introduced species: organisms that are not native to an area but have been accidentally or purposefully brought to the area by humans
law of tolerance: the law that states that the existence, abundance and distribution of species depends on the tolerance level of each species to physical and chemical factors
limiting factor: any abiotic factor that limits or prevents the growth of a population
macronutrient: an element required by a living organism in very large quantities
magnesium: (Mg); a macronutrient used by the green pigment of plants (chlorophyll) to trap sunlight and convert it to usable energy; magnesium is
also found in the bones, blood, cells and tissues of most animals
natural selection: the process by which those organisms that are best suited for their environment survive and reproduce (Read more about Natural Selection)
nitrogen: (N); a macronutrient that makes up 78% of the Earth's soil and is involved in virtually all biochemical processes that sustain plant and animal life
nitrogen-fixation: the conversion of unusable, free nitrogen to other forms -- such as nitrates or ammonia -- for utilization by plant tissues
omnivore: an organism that consumes both plants and animals
order: a taxonomic group subordinate to class; group of similar families
pH: the relative concentration of positive hydrogen ions (H+) and negative hydroxyl ions (OH-) in a solution; solutions with equal concentrations of these ions are neutral, while solutions with more hydrogen ions are acidic and solutions with more hydroxyl ions are alkaline
phosphorus: (P); a macronutrient found in soil that is essential for all animals and plants; phosphorus is an essential component of nucleic acids, which are present in all living systems
phylum: a taxonomic group of similar classes
Pliocene era: the period of geologic time marked by the appearance of most modern animals (about two to seven million years ago)
poaching: illegally fishing or hunting in a protected area
population: a group of interbreeding organisms that live in a particular location; population density is the number of individuals per unit of space
potassium: (K); a macronutrient found in soil that plays a vital role in the function of all plants, including the production of amino acids, which are utilized in protein synthesis, and the formation of chlorophyll
predator: an animal that actively seeks out other animals as a source of food
producer: also known as an autotroph, an organism that makes its own food, as green plants do
salinity: the amount of various salts in a given volume of water
shield volcano: a volcano with a gentle slope and regular shape that is formed by slow-flowing, basaltic (low in water content) magma
speciation: the formation of new species
species diversity: the variety of different organisms in a given area
species relatedness: the degree of similarity in the structure of organisms, which indicates common ancestry
species: a group of similar organisms capable of mating and producing fertile offspring
sulfur: a macronutrient concentrated in amino acids that promotes the detoxification and excretion of harmful substances; sulfur is found in virtually every cell of the human body, especially in hair, nails and skin
taxonomy: the science of classifying organisms into groups based on similar characteristics
temperature: the degree of hotness or coldness; one of the most important physical factors in the environment of any organism
trophic level: the feeding level to which every organism in an ecosystem is assigned, depending on whether it is a producer or consumer and on which type of consumer it is
Understanding Charles Darwin's Theory of Natural Selection
Charles Darwin's visit to the Galapagos Islands in 1835 inspired his Theory of Natural Selection -- an explanation of the very process of evolution. The isolation of the Galapagos Islands presented Darwin, and the many scientists who have followed in his footsteps, with an ideal environment to study the adaptations of species.
Darwin studied the islands' finch species, specifically the structure of their beaks and associated feeding behavior. Other examples of evolution in process in the Galapagos include the unique flightless cormorant, which gradually lost functional wings in an environment with abundant shoreline food sources and no predators. Scarcity of vegetation on the volcanic islands likely led the Pleistocene land iguana to seek food along the shoreline and gradually under water, leading to the development of the marine iguana.
The Charles Darwin Research Center in Puerto Ayora provides this outline that helps us understand Darwin's Theory of Natural Selection:
- In any population of animals, a relatively large number of young are produced. Since not all survive, there must be a struggle for existence.
- Within a population there is much variability. Some differences may confer an advantage in the struggle for existence. Those organisms that are best adapted for their environment will survive.
- Due to heredity, offspring tend to resemble their parents. Well-adapted organisms tend to have well-adapted offspring. Thus, certain traits become established in the population.
- If environmental conditions change, there may be selection for different traits. The variability within a population determines whether it will be able to survive these changes.
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Scientific American Frontiers
Fall 1990 to Spring 2000
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