Glossary of genetics and evolutionary biology

Glossary of Genetics and Evolutionary Biology

The field of genetics and evolutionary biology encompasses a wide range of terms and concepts that are essential for understanding the mechanisms of heredity and the processes that drive the diversity of life on Earth. This glossary provides definitions and explanations for key terms used in these disciplines.

A

• Allele: An allele is a variant form of a gene. Different alleles can result in different traits, such as eye color or blood type.

• Adaptation: An adaptation is a trait that increases the fitness of an organism, allowing it to survive and reproduce in its environment.

B

• Bottleneck Effect: The bottleneck effect is a sharp reduction in the size of a population due to environmental events or human activities, leading to a loss of genetic diversity.

• Biogeography: Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time.

C

• Chromosome: A chromosome is a long DNA molecule with part or all of the genetic material of an organism. Chromosomes are located in the cell nucleus.

• Cladistics: Cladistics is a method of classifying species based on common ancestry and evolutionary relationships.

D

• DNA (Deoxyribonucleic Acid): DNA is the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses.

• Darwinian Fitness: Darwinian fitness refers to the ability of an organism to survive and reproduce, thereby passing on its genes to the next generation.

E

• Evolution: Evolution is the change in the heritable characteristics of biological populations over successive generations.

• Epigenetics: Epigenetics involves changes in gene expression that do not involve alterations to the underlying DNA sequence.

F

• Founder Effect: The founder effect occurs when a new population is established by a very small number of individuals from a larger population, leading to a reduction in genetic variation.

• Fitness: In evolutionary biology, fitness refers to an organism's ability to survive and reproduce in its environment.

G

• Gene: A gene is a sequence of DNA that contains the necessary information to produce a functional product, typically a protein.

• Genotype: The genotype is the genetic makeup of an individual organism, often in reference to a specific trait.

H

• Homozygous: An individual is homozygous for a gene if they have two identical alleles for that gene.

• Heterozygous: An individual is heterozygous for a gene if they have two different alleles for that gene.

I

• Inheritance: Inheritance is the process by which genetic information is passed from parents to offspring.

• Inbreeding: Inbreeding is the breeding of closely related individuals, which can increase the chance of offspring being affected by recessive or deleterious traits.

J

• Junk DNA: Junk DNA refers to regions of DNA that do not encode proteins and were once thought to have no function, though some may have regulatory roles.

K

• Karyotype: A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell.

L

• Locus: A locus is the specific physical location of a gene or other significant sequence on a chromosome.

• Linkage: Linkage refers to the tendency of genes located close to each other on a chromosome to be inherited together.

M

• Mutation: A mutation is a change in the DNA sequence that can lead to changes in phenotype and potentially affect an organism's fitness.

• Mendelian Inheritance: Mendelian inheritance refers to the patterns of inheritance for traits that follow the laws proposed by Gregor Mendel.

N

• Natural Selection: Natural selection is the process by which organisms better adapted to their environment tend to survive and produce more offspring.

• Nucleotide: A nucleotide is the basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

O

• Organism: An organism is any individual living entity that can react to stimuli, reproduce, grow, and maintain homeostasis.

P

• Phenotype: The phenotype is the set of observable characteristics or traits of an organism, resulting from the interaction of its genotype with the environment.

• Polygenic Trait: A polygenic trait is a trait that is influenced by multiple genes, often resulting in a continuous distribution of phenotypes.

Q

• Quantitative Trait Loci (QTL): Quantitative trait loci are regions of the genome that are associated with a particular quantitative trait.

R

• Recessive Allele: A recessive allele is an allele that produces its characteristic phenotype only when its paired allele is identical.

• Recombination: Recombination is the process by which genetic material is physically mixed during the formation of gametes, leading to new combinations of alleles.

S

• Speciation: Speciation is the evolutionary process by which populations evolve to become distinct species.

• Selective Pressure: Selective pressure is any phenomena which alters the behavior and fitness of living organisms within a given environment.

T

• Trait: A trait is a specific characteristic of an organism, which can be physical, behavioral, or physiological.

• Transcription: Transcription is the process of copying a segment of DNA into RNA.

U

• Unlinked Genes: Unlinked genes are genes that are located on different chromosomes or far apart on the same chromosome and assort independently.

V

• Variation: Variation refers to the differences in DNA sequences among individuals within a population.

• Vestigial Structure: A vestigial structure is a structure in an organism that has lost all or most of its original function in the course of evolution.

W

• Wild Type: The wild type is the typical form of a species as it occurs in nature.

X

• X-linked Trait: An X-linked trait is a trait that is determined by a gene located on the X chromosome.

Y

• Y Chromosome: The Y chromosome is one of the two sex chromosomes in mammals, including humans, and is typically associated with male characteristics.

Z

• Zygote: A zygote is the initial cell formed when two gamete cells are joined by means of sexual reproduction.

See Also

• Genetic drift
• Molecular biology
• Population genetics
• Phylogenetics

References

• Hartl, D. L., & Clark, A. G. (2007). Principles of Population Genetics. Sinauer Associates.
• Futuyma, D. J. (2013). Evolution. Sinauer Associates.