Evolution Terms

Adaptation

A trait, or integrated suite of traits, that increases the FITNESS of its possessor. Such a trait is ADAPTIVE.

Recurrent Laryngeal Nerve

The recurrent laryngeal nerve is a branch of the vagus nerve that supplies all the intrinsic muscles of the larynx, with the exception of the cricothyroid muscles.

Left Recurrent Laryngeal Nerve

One of two recurrent laryngeal nerves, the left nerve loops under the aortic arch on its recurrent path to the larynx.

Hypothesis

A proposed, but testable, explanation for a phenomenon that may be based on limited scientific data.

Scientific Theory

Collection of hypotheses that have withstood rigorous scrutiny and are a comprehensive form of scientific knowledge.

Descent with Modification

Evolutionary change in traits that are passed from parent to offspring.

Historical Constraint

A limitation imposed on the path of evolutionary change due to the nature of the preceding forms

Aristotle

Greek philosopher whose classification of animals served as a basis for the ladder of life (scala naturae or great chain of being).

Carolus Linneaus

Natural theologian credited with promoting the binomial system of nomenclature

William Paley

English author of "Natural Theology" in which he presents the 'watch on the heath' analogy in support of a design inference for living organisms.

David Hume

English philosopher and mathematician who presented arguments against a teleological (i.e., purpose and design) assessment of biological origins.

James Hutton

English lawyer and geologist who is often credited with laying the foundation for the concept of uniformitarianism.

Jean Lamarck

French natural historian who framed one of the first evolutionary hypotheses.

Spontaneous Generation

The notion that life arises from non-life and served as one of the key features of Lamarck's evolutionary framework

Thomas Malthus

English clergyman whose treatise on the relationship between human population growth and the growth of resources needed to sustain that population greatly influenced Charles Darwin's thoughts about evolution.

Charles Lyell

English geologist (and contemporary of Charles Darwin) who clarified the concept of uniformitarianism and advocated in favor of the notion of "deep time".

Uniformitarianism

The assumption that the physical processes that operate today were also in operation in the distant past (unless compelling contrary data can be cited).

Charles Darwin

English natural historian credited with developing the concept of natural selection as a mechanism for descent with modification (aka transmutation or evolution).

Gregor Mendel

Austrian monk whose studies of inheritance using the pea plant confirmed the concept of particulate inheritance (vs. blending inheritance).

Alfred Russel Wallace

English natural historian whose studies of asian biota allowed him to conceive of a mechanism for evolutionary change that was parallel to the concept of natural selection developed by Charles Darwin.

Paradigm

A distinct set of concepts or thought patterns, including theories, as applied in science and philosophy.

Scala Naturae

Latin version for the ladder of life (or Great Chain of Being) that formed the basis of biological classification for natural theologians.

Great Chain of Being

Another name for the ladder of life (or Scala Naturae) that formed the basis of biological classification for natural theologians.

Thomas (of) Aquinas

Italian priest who is one of the earliest and most influential proponents of natural theology.

Natural Theology

Arguments for the existence of God based on reason and the experience of nature.

Teleology

Description of a thing based on its purpose, use or goal.

Argument from Design (AFD)

An argument for the existence of God (or some creative intelligence) based on perceived evidence of deliberate design in the natural or physical world.

Empirical

Evidence obtained by observation or experimentation.

HMS Beagle

British warship that served as Charles Darwin's base of scientific operations during a nearly 5 year survey expedition (1831-1836) that was spent primarily in South America.

Fleeming Jenkin

English civil engineer who argued that natural selection had no power to produce stable changes since novel traits that arise in one parent would inevitably be diluted in any offspring when blended with wild-type (normal) traits in the other parent.

James Ussher

Catholic theologian whose careful evaluation of biblical lineages was used to identify the date of creation (October 22, 4004 BCE) and, thus, the age of the earth.

William Thomson (Lord Kelvin)

English engineer whose expertise in thermodynamics (heat transfer in particular) led to proposals that the earth was likely no older than 20 million years

Deep Time

The concept (derived largely from the work of geologists) that the earth is much older (at least 500,000,000 years) than suggested by the Ussherian timeline (ca. 6000 years).

Henri Becquerel

French physicist who is credited with the discovery of radioactivity.

Marie Curie

Polish physicist who expanded our understanding of radioactivity and is credited with the discovery of Polonium and Radium

Natural Selection

The preservation of favorable genetic traits as a consequence of action by the environment.

Differential Reproductive Success

The outcome of natural selection.

Artificial Selection

The preservation of favorable genetic traits as a consequence of action by humans (e.g., as in domestication).

Brassica olearacea

Cabbage, Broccoli, Cauliflower, Brussel Sprouts, Kale and Kohlrabi.

Ernst Mayr

American evolutionary biologist who influenced our understanding of speciation and provided a synopsis of "On the Origin of Species" by Charles Darwin.

Belyaev's Foxes

Wild animals (with valuable fur) that were bred for reduced flight initiation distance, but acquired traits that were extraordinarily dog-like (without the valuable fur!).

Flight Initiation Distance

The distance between an animal and a human at which the animal flees.

Melanin

Skin pigmentation

Domestication

A kind of artificial selection of animals or plants that leads to greater utility for humans.

Homology

In biology, similarity by descent.

Analogy

In biology, similarity that cannot be attributed to shared ancestry.

Pharyngeal pouches (slits)

Feature found in all chordate embryos, but that have different developmental fates (e.g., they become gills in some chordates, but not in others).

Notocord

Feature found in all chordate embryos, but that has different developmental fates (e.g., it is transformed into vertebrae in some chordates, but not in others).

Post-anal Tail

Feature found in all chordate embryos, but that has different developmental fates (e.g., it is lost in some chordates as they mature).

Dorsal Hollow Nerve Cord

Feature found in all chordate embryos, but that has different developmental fates (e.g., it is transformed into part of the central nervous system in some chordates, but not in others).

Law of Succession

A concept developed by Clift and (later) Darwin that acknowledges the biogeographic bias that may exist for organisms and their fossil antecedents (e.g., the armadillo and the glyptodont).

Convergence

In biology, the concept that organisms with distinct evolutionary histories may exhibit analogous features as a consequence of a shared environment.

Biogeography

The study of the distribution of organisms in space and in time.

Transitional Fossil

A fossil organism that exhibits traits that place it in an intermediate position on a phylogenetic tree.

Pakicetus

An extinct genus of cetacean regarded as one of the most ancient members of the group.

Cetacea

The whales, dolphins and porpoises.

Limb Buds

The terms used to describe early embryological development of arms or legs in tetrapods.

Vestigial

A trait that generally exists in a reduced form and that has either lost it's original function or has an alternative function.

Pangenesis

A theory of inheritance that the physical components of heritability are ultimately derived from the features or traits themselves

Allele

A variant form of a gene.

Locus (Loci)

A synonym for gene

Genotype

The genetic makeup of an organisms that ultimately produces the phenotype.

Phenotype

The physical manifestation of the genotype.

Gametes

Cells (haploid) that are involved in the process of fusion or fertilization.

Chromosome

Molecule of DNA that contains a specified set of genes.

Recombination

In biology, the consequences of crossing over during meiosis (or mitosis in rarer instances).

Dominant

In genetics, a trait that is expressed even with paired with a recessive form.

Recessive

In genetics, a trait that is only expressed in the homozygous condition.

Homozygote

Comprised of only one type of allele.

Heterozygotes

Comprised of two (or more) different alleles.

Hardy-Weinberg Theorem

Mathematical model that allows one to test for changes in allele frequency.

Genetic drift

Change in allele frequency due to stochastic phenomena (i.e., sampling error as a consequence of small sample [population] size).

Founder Effect

Change in allele frequency due to a small portion of a population (i.e., Genetic Drift) that has moved to a new location.

Bottleneck Effect

Change in allele frequency due to a small portion of a population (i.e., Genetic Drift) that has survived some form of catastrophe.

Assortative Mating

A form of non-random mating.

Panmixis

Random mating

Inbreeding

A form of non-random mating that involves close relatives.

Gene Flow

In biology, another term for the genetic consequences of migration.

Immigration

Individuals of one population join another population

Emigration

Individuals of one population leave that population to join another.

Mutation

In biology, the general term for a change in the DNA.

Point Mutation

In biology, the specific term for a change in a single nucleotide

Insertion

In biology, the specific term for a change in the DNA that involves that gain of one or more nucleotides.

Deletion

In biology, the specific term for a change in the DNA that involves that loss of one or more nucleotides.

DNA

Deoxyribonucleic Acid.

RNA

Ribonucleic Acid.

Nucleotides

Guanine, Cytosine, Adenine and Thymine (or Uracil)

DNA Replication

A process that enzymatically copies the nucleic acid.

Protein

A polymer of amino acids that may function structurally or as a catalyst.

Amino Acid

The monomer unit that comprises protein

Gene Duplication

In biology, the specific term for a change in the DNA that involves the acquisition of a gene (1 or more) copy.

Polyploidy

In biology, the specific term for a change in the DNA that involves the acquisition of an entire genome copy.

Haploid

Description of a nucleus (or cell that contains the nucleus) that has a single set of chromosomes.

Diploid

Description of a nucleus (or cell that contains the nucleus) that has a two sets of chromosomes.

Stabilizing Selection

A mode of selection that acts against both phenotypic extremes.

Directional Selection

A mode of selection that acts against one of the phenotypic extremes.

Disruptive (Diversifying) Selection

A mode of selection that acts against the mean phenotype.

Sexual Selection

A type of natural selection involving mate choice that appears to be driven by parental asymmetries in the investment in offspring.

Reverse Transcriptase

Enzyme that creates a DNA copy from a RNA template.

Reproductive Cohesion

The ability to mate with other organisms.