Study Guide

Special Topics in Evolution Terms

Special Topics in Evolution Terms

Abiogenesis

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

Allele

The possible forms of a gene found at a specific locus.

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 engulfing of one small organism by a larger one that results in a mutually beneficial relationship. Mitochondria and chloroplasts evolved through embosymbiosis.

Extant Taxa

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

Extremophile

An extremophile is an organism that prefers to live in harsh environments. Examples of harsh environments include high and low temperate and high and low pH, like a hydrothermal vent in the ocean or the inside of a cow’s stomach.

Genotype

A genetic constitution of an organism. It can refer to a single trait or a set of traits.

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

This is a compound in the upper atmosphere that filters out ultraviolet (UV) radiation. In the lower atmosphere, ozone is a pollutant and causes health problems.

Panspermia

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

Phenotype

The physical, observable manifestation of genetic traits.

Phylogenetics

The analysis of DNA to study the evolutionary relationships between groups of organisms.

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 evolutionary process in which individuals that have desirable sexual characteristics are more successful at attracting mates.

Synonymous Mutation

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

Spontaneous Generation

This refers to an incorrect theory that life sprang from nowhere. For example, people believed that under the right conditions, mud would transform itself into earth worms.

Taxonomy

The classification of organisms into different levels of relatedness, such as phylum, family, or species.

Roots of Common Terms in Special Topics in Evolution

Roots

G = Greek, L = Latin

Abiogenesis

abios = without life (G), genesis = make (G)

Coacervate

coacervare = to heap up (L)

Extremophile

exterus = outward (L), philos = to like (G)

Isotope

isos = equal (G), topos = place (G)

Panspermia

pân = all (G), spérma = seed (G)

Phylogenetics

phylon = leaf (G)

Radioactive

radius = beam (L), activus = doing (L)

Saltation

saltare = leap (L)

Taxonomy

taxis = arrangement (G), nomia = method (G)