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Special Topics in Evolution Terms

Get down with the lingo

Abiogenesis

The theory that biological life originated from a non-biological source (that is, through chemical reactions).

Allele

One of two or more copies of a gene or gene region in an individual.

Archaebacteria

Also known as archaea, the 3rd domain of life, along with eukaryotes and prokaryotes. This domain contains many organisms that thrive under extreme conditions.

Biogenesis

The theory that life can only originate from other living things. Opposite of abiogenesis.

Biomolecules

Biological molecules such as amino acids and nucleic acids that are the building blocks for life on Earth. Think Legos on a much smaller scale.

Chemosynthesis

The conversion of chemical compounds (methane, nitrogen, oxygen, water) into organic matter such as amino and nucleic acids.

Clade

A grouping of organisms on a phylogenetic tree.

Coacervate

An aggregation of particles (usually lipids) in an emulsion. Coacervates containing self-replicating ribozymes are believed to be the precursors to cellular life.

Cyanobacteria

The 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.

Endosymbiont

An organism that lives within the body or cells of another organism.

Endosymbiosis

The process by which organisms are incorporated into eukaryotic cells producing organelles such as mitochondria and chloroplasts.

Extant Taxa

Organisms listed on a phylogentic tree, also known as "leaves" on the tree.

Extremophile

An 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.

Genotype

The genetic sequence of an organism that leads to a certain physical characteristic, or phenotype.

Gradualism

The theory of evolution that major phenotypic changes occur as an accumulation of minor phenotypic changes over several generations.

Half-life

The 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.

Isotope

Variant of a chemical element that has the same number of protons, but different numbers of neutrons.

Local Extinction

Extinction of a species in a certain location, while the species as a whole continues to survive in other locations.

Mass Number

The number of protons and neutrons in an isotope of a chemical element.

Microsphere

Small spherical particles, like a coacervate, which may have formed the earliest precursors to cellular life.

Node

A point in evolution where a hypothetical ancestor diverged into multiple taxa.

Non-synonymous Mutation

A mutation in a codon of DNA that affects the amino acid sequence.

Outgroup

A reference organism (or group of organisms) that serves to determine the evolutionary relationship of other organisms.

Ozone

A 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.

Panspermia

The theory that life originated from an extraterrestrial source. It still doesn't explain where THAT life originated from.

Phenotype

A 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.

Phylogenetics

A 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.

Phylogenomics

A process to measure the relationships between genomic structures of different organisms.

Polytomy

A point where the evolutionary ancestor of related species cannot be easily resolved. Not to be confused with the star of the film Biodome.

Radioactive Dating

The 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 Decay

The 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 Isotope

A form of an element that will spontaneously decay particles until it is in the natural elemental state.

Ribozyme

An 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).

Saltation

The theory that evolution occurs in major leaps, with morphological features evolving in single generations.

Selection

The force of evolution that lets individuals with "advantageous" mutations survive in a population.

Sexual Selection

The 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 Mutation

A mutation in a codon of DNA that doesn't affect the amino acid sequence.

Spontaneous Generation

An 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).

Taxonomy

The process of classifying organisms based upon shared characteristics and naming these groups.

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