Special Topics in Evolution Terms
Get down with the lingo
AbiogenesisThe theory that biological life originated from a non-biological source (that is, through chemical reactions).
AlleleOne of two or more copies of a gene or gene region in an individual.
ArchaebacteriaAlso known as archaea, the 3rd domain of life, along with eukaryotes and prokaryotes. This domain contains many organisms that thrive under extreme conditions.
BiogenesisThe theory that life can only originate from other living things. Opposite of abiogenesis.
BiomoleculesBiological molecules such as amino acids and nucleic acids that are the building blocks for life on Earth. Think Legos on a much smaller scale.
ChemosynthesisThe conversion of chemical compounds (methane, nitrogen, oxygen, water) into organic matter such as amino and nucleic acids.
CladeA grouping of organisms on a phylogenetic tree.
CoacervateAn aggregation of particles (usually lipids) in an emulsion. Coacervates containing self-replicating ribozymes are believed to be the precursors to cellular life.
CyanobacteriaThe earliest bacteria to perform photosynthesis, the process of converting carbon dioxide and light into sugars for energy. They were the first to do photosynthesis, and have not shut up about it ever since.
EndosymbiontAn organism that lives within the body or cells of another organism.
EndosymbiosisThe process by which organisms are incorporated into eukaryotic cells producing organelles such as mitochondria and chloroplasts.
Extant TaxaOrganisms listed on a phylogentic tree, also known as "leaves" on the tree.
ExtremophileAn organism that lives life in the extremes (high salt, very cold temperatures, high sulfur). Not to be confused with organisms that live off of Mountain Dew.
GenotypeThe genetic sequence of an organism that leads to a certain physical characteristic, or phenotype.
GradualismThe theory of evolution that major phenotypic changes occur as an accumulation of minor phenotypic changes over several generations.
Half-lifeThe time required for a radioactive isotope to decay by half in number. If you have 100% carbon-14 in a substance, the half-life would be the time to 50% carbon-14.
IsotopeVariant of a chemical element that has the same number of protons, but different numbers of neutrons.
Local ExtinctionExtinction of a species in a certain location, while the species as a whole continues to survive in other locations.
Mass NumberThe number of protons and neutrons in an isotope of a chemical element.
MicrosphereSmall spherical particles, like a coacervate, which may have formed the earliest precursors to cellular life.
NodeA point in evolution where a hypothetical ancestor diverged into multiple taxa.
Non-synonymous MutationA mutation in a codon of DNA that affects the amino acid sequence.
OutgroupA reference organism (or group of organisms) that serves to determine the evolutionary relationship of other organisms.
OzoneA three-oxygen compound (O3) that forms a layer surrounding the Earth, protecting life from UV radiation from the sun. Ozone is only formed when there are a critically high number of oxygen molecules in the atmosphere.
PanspermiaThe theory that life originated from an extraterrestrial source. It still doesn't explain where THAT life originated from.
PhenotypeA physical feature that is easily observable on an organism. Eye color, height, and whether your earlobes are attached or unattached are all examples of phenotype. Go ahead, check your earlobes. We'll wait.
PhylogeneticsA process to measure the genetic relationships between various living organisms. It can use physiological features as well as DNA sequence information to determine these relationships.
PhylogenomicsA process to measure the relationships between genomic structures of different organisms.
PolytomyA point where the evolutionary ancestor of related species cannot be easily resolved. Not to be confused with the star of the film Biodome.
Radioactive DatingThe ability to determine how old something is based upon the amount of a radioactive isotope is present in the fossil, as a function of the half-life of that isotope. Radioactive dating is usually done with Carbon-14. Not to be confused with a couple that clearly like each other a lot.
Radioactive DecayThe loss of alpha-, beta-, or gamma- particles from an isotope, due to the instability of that isotope. Radioactive decay is sometimes followed by radioactive gentrification, if the isotope has a flourishing arts scene.
Radioactive IsotopeA form of an element that will spontaneously decay particles until it is in the natural elemental state.
RibozymeAn RNA polymer that is capable of catalyzing a chemical reaction. It's best to think of these as "RNA enzymes." Not to be confused with RNA molecules that play in some orchestras (ribozylophones).
SaltationThe theory that evolution occurs in major leaps, with morphological features evolving in single generations.
SelectionThe force of evolution that lets individuals with "advantageous" mutations survive in a population.
Sexual SelectionThe selection of specific traits that makes males or females appear more attractive to the opposite sex, or allows members to beat rivals for access to the opposite sex.
Synonymous MutationA mutation in a codon of DNA that doesn't affect the amino acid sequence.
Spontaneous GenerationAn archaic theory, first proposed by Aristotle, which holds that life emerges out of nothing, based upon two premises: abiogenesis (life comes out of nothing, such as rats can grow from wet paper), and xenogenesis (life originates from different forms of life, such as birds come from mollusks).
TaxonomyThe process of classifying organisms based upon shared characteristics and naming these groups.
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