Examining How and Why Scientific Names Change

Author: Marinda Vacanti, Collections Intern
Date: August 29, 2023

While interning in the Collections Department this summer, I became interested in how and why the scientific names of species evolve over time. Each individual species has a unique scientific name composed of two parts. The first part of the name indicates the genus the species belongs to while the second part of the name is specific and unique to the species. This naming system is called binomial nomenclature, meaning a two-term naming system. Scientific names provide important taxonomic information about a species as they indicate related groups of species. My interest in scientific names was sparked when I was working on labeling botany specimens. Each specimen must have a physical label on it before it can be integrated into our larger collection. These labels provide a summary of key information about the specimen, such as the scientific name, who identified it and when it was identified, the common name, who collected it and where and when it was collected. It is very important to have this essential information about a specimen captured in one place as it makes organization of our specimens much easier. To ensure labels are as accurate as possible, I check each specimen’s scientific name in the Integrated Taxonomic Information System, which is updated with the most accurate taxonomic information for plants in North America. If the taxonomy of a species has changed, I update the identification in Arctos, our online collections management database, and on the physical label to reflect the revised taxonomy.

Verbena canadensis specimen; the physical label and online identification had to be changed due to revised taxonomy (Chicago Academy of Sciences)

At first I was confused about why the name of a species would need to change. Was there something wrong with the original name? What would cause a scientific name to need to change? And what are the reasons behind a scientific name change?

Turns out that there are numerous reasons behind why scientific names change. Most name changes occur because of one of two reasons: either an earlier classification of the species is discovered or advances in our knowledge leads to reclassifications. The first reason is based on the rule of priority of publication, meaning that if a species has been named more than once, the first correctly published name is the one that must be used and any other later names effectively become synonyms instead (Mori). Therefore, long standing names of species can change if an earlier publication describing the same species is recognized and the older name must be adopted instead.

Secondly, and more common recently, advances in the field of study, such as botany, can lead to reclassifications. Taxonomy as a whole is based on hypotheses of how species are evolutionarily related and most of these hypotheses are formulated by comparing the phenotypes of species to try to determine visually if they may be closely related (Ritter). However, recently, DNA sequencing has given us an objective method to determine relatedness between species.

Now that genotype-based classification is possible, there have been some surprising discoveries. For example, in our botany collection we have several preserved specimens of the plant species Aliciella pinnatifida. This species is a member of the Polemoniaceae (phlox) family and has been reclassified from the genus of Gilia into the genus of Aliciella. The species was first collected by Thomas Nuttall along the Lewis River in the 1830s and he suggested the name of Gilia pinnatifida for the plant. When Nuttall first proposed the name of Gilia pinnatifida, the Gilia genus had become a catchall genus and was highly inclusive and variable. In 1905, the genus of Aliciella was created in an attempt to separate out those that seemed distinct from most of the others. However, it was abandoned soon after until genetic analyses in 1998 by J. Mark Porter showed that the genus should be revived (Southwest Colorado Wildflowers). Since then, several other species have been reclassified from the Gilia genus to other genera such as Ipomopsis, Allophyllum, Giliastrum, and Navarretia. There were several specimens in our collection whose identification had to be revised because of these new classifications.

Aliciella pinnatifida specimen with an updated label and updated identification in Arctos after being reclassified from the Gilia genus to the Aliciella genus (Chicago Academy of Sciences)

Ipomopsis multiflora specimen with an updated label and updated identification in Arctos after being reclassified from the Gilia genus to the Ipomopsis genus (Chicago Academy of Sciences)

Staying on top of a continuously evolving nomenclature can prove difficult for Collections staff. Physical labels can become out of date very quickly and are hard to continuously replace with updated ones. However, this challenge further proves the importance of digitizing collections. Even though physically changing labels can be a difficult and time consuming task, editing information on our online database proves much more manageable. Additionally, because a common reason for changing a species’ name is that the same species was described more than once by botanists, digitization of collections around the world becomes even more important so that taxonomists have access to as much information as possible to continue to establish connections between related plant species. Even though taxonomy can be confusing, complicated, and hard to stay on top of at times, updated collections continue to be a helpful tool to taxonomists as they provide digital as well as physical access to specimens that taxonomists might not have access to otherwise.

Sources

Kouduka, Mariko et al. “A Solution for Universal Classification of Species Based on Genomic DNA”. International Journal of Plant Genomics, 15 Feb. 2007, doi: 10.1155/2007/27894.

Mori, Scott. “The Shifting Science of Botanical Nomenclature – I”. New York Botanical Garden, 3 June 2013, www.nybg.org/blogs/plant-talk/2013/06/science/the-shifting-science-of-botanical-nomenclature-i/#:~:text=The%20most%20common%20reason%20for,been%20collected%20and%20formally%20described

Ritter, Matt. “Why Plant Names Change”. Pacific Horticulture, 2023, pacifichorticulture.org/articles/why-plant-names-change-2/

“The Story of Gilia and Aliciella”. Southwest Colorado Wildflowers, www.swcoloradowildflowers.com/Pink%20Enlarged%20Photo%20Pages/aliciella.htm