BIOL214 Vocab

DNA

A molecule that stores hereditary information in code form

Gene

Segments of DNA that contain the information that molecular machines use to make a product—an RNA or protein—that functions in the organism

Mutation

Any change in DNA. Mutations create new alleles

Allele

Versions of a gene. For example, if the product of a certain human gene affects hair color, one allele may lead to redder hair while another allele leads to browner hair. Different alleles have different variations of the coded information in the gene

Genotype

A listing of the alleles present in an individual

Phenotype

What an individual looks or acts like

Fitness

The ability to produce viable offspring

Natural Selection

The process that changes allele frequencies when certain heritable traits are associated with different levels of reproductive success.

Evolution

A change in allele frequencies.

Directional Selection

Natural selection that favors an extreme phenotype.

Stabilizing Selection

Natural selection that favors the average phenotype in the population and acts against extreme phenotypes.

Adaptation

A heritable trait that increases fitness in a particular environment.

Theory

An explanation or set of hypotheses that attempt to explain a large and pervasive phenomenon, meaning they that tie together a large suite of observations about how the natural world works.

Phylogenetic tree

A graphical depiction of evolutionary history, or phylogeny.

Homologous traits

Any characteristic, ranging from a single nucleotide in DNA to body parts, that is observed in multiple species and inherited from the same common ancestor.

Root (of a phylogenetic tree)

The base of a tree, indicating the common ancestor of all the taxa indicated at the tips.

Node (of a phylogenetic tree)

A split where a speciation event occurs, so one species splits into two. Also represents the last common ancestor before a speciation event.

Branch (of a phylogenetic tree)

A species or other group changing through time.

Tip (of a phylogenetic tree)

The end of a branch, representing a taxon

Taxon

A named group of organisms (plural is taxa)

Monophyletic group

An ancestor and all of its descendants.

Synapomorphy

A trait that one group has that no one else does. Synapomorphies define monophyletic groups.

Homoplasy

Similarity in traits that is not due to common ancestry but due to independent evolution.

Outgroup

Any lineage that is not part of the monophyletic group that is the focus of a phylogenetic tree.

Parsimony

A criterion in logic that states that the simplest explanation is the most likely to be correct.