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Destination: Galapagos Islands Cyber Field Trip

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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