Glossary of "The Cell (5th ed.)" by Alberts et al. (2008)
- One of several alternative forms of a gene. In a diploid cell each gene will typically have two alleles, occupying the corresponding position (locus) on homologous chromosomes.
Glossary of "Ecology (6th ed.)" by Krebs (2009)
- one of a pair of characters that are alternative to each other in inheritance, being governed by genes situated at the same locus in homologous chromosomes.
Glossary of "Evolution of Plants (2nd ed.)" by Willis & McElwain (2014)
- One of two or more forms of a gene.
Glossary of "Plant Biology (1st ed.)" by Graham et al. (2003)
- One of two or more different forms of a gene.
Glossary of "Evolution (3rd ed.)" by Futuyma (2013)
- One of several forms of the same gene, presumably differing by mutation of the DNA sequence. Alleles are usually recognized by their phenotypic effects; DNA sequence variants, which may differ at several or many sites, are usually called haplotypes.
- Alberts, B., Johnson, A., Lewis, J. Raff, M., Roberts, K. & Walter P. 2008. Molecular Biology of the Cell, 5th ed. -xxxiv + 1616 pp. Garland Science, New York.
- Futuyma, D. J. 2013. Evolution, 3rd ed. -xviii + 656 + 14 + 37 + 2 + 36 pp. Sinauer Associates, Inc., Sunderland.
- Graham, L. E., Graham, J. M. & Wilcox, L. W. 2003. Plant Biology. -xxxv + 497 pp. Pearson Education, Inc., Upper Saddle River.
- Krebs, C. J. 2009. Ecology, 6th ed. -xvi + 655 pp. Pearson Benjamin Cummings, San Francisco.
- Willis, K. J. & McElwain, J. C. 2014. The Evolution of Plants, 2nd ed. -ix + 398 pp. Oxford University Press, Oxford.