Difference Between Taxonomy and Ontology

Main Difference – Taxonomy vs Ontology

Taxonomy and ontology are very similar phenomena used in biology to describe and classify organisms. The main difference between taxonomy and ontology is that taxonomy is only based on hierarchy whereas ontology is based on both hierarchy and other complex variations. Taxonomy produces the hierarchical arrangement of different classes that represent entities. These classes are the different taxonomic ranks known as species, genus, family, order, class, phylum, kingdom, and domain. During ontology, the nature of the being, its existence or reality is studied along with the hierarchy of the being.

Key Areas Covered

1. What is Taxonomy
      – Definition, Criteria, Facts
2. What is Ontology
      – Definition, Criteria, Facts
3. What are the Similarities Between Taxonomy and Ontology
     – Outline of Common Features
4. What is the Difference Between Taxonomy and Ontology
    – Comparison of Key Differences

Key Terms: Arbitrary Complex Relations, Binomial Nomenclature, Classification, Hierarchy, Ontology, Philosophy, Systematics, Taxonomy

What is Taxonomy

Taxonomy refers to a branch of science in which the organisms are defined and named based on their shared characteristics. In taxonomy, morphological, genetic, behavioral, and biochemical observations are used to describe organisms. Taxonomy, along with the systematic, creates a hierarchy of organisms known as biological classification. Systematics uses evolutionary relationships to describe the organisms. Based on the above-mentioned characteristics, organisms are classified into different taxonomic ranks starting from species, genus, family, order, class, phylum, kingdom, and domain. The taxonomic ranks used to describe a red fox is shown in figure 1.

Figure 1: Taxonomic Ranks of Red Fox

The fundamental level of biological classification of an organism is the species. In taxonomy, a unique name is assigned to each species for the universal identification of organism worldwide. The criteria used for naming of a species are known as binomial nomenclature. The first part of the name consists of the name of the genus and the second part of the name consists of the name of the species. Taxonomists have named around 1.78 million species of animals, plants, and microorganisms over the past 250 years based on taxonomy and systematics.

What is Ontology

Ontology refers to a branch of science that studies the nature of being, existence or reality as well as the hierarchy of the being. The main concept of ontology is to group existing entities in a hierarchy. Then the groups are subdivided based on the similarities and differences within the group. The two main criteria used in ontology are the hierarchy and the arbitrary complex relations. Thus, ontology is a more complex phenomenon than taxonomy. The ontological relationship between fruit fly tibia and human tibia is shown in figure 2.

Figure 2: Ontological Relationship between Fruit Fly Tibia and Human Tibia

Ontology generates more intricate ways of categorization. Thus, ontological relationship can be considered as a web, linking several categories together. In this web, everything is interrelated.

Similarities Between Taxonomy and Ontology

• Both taxonomy and ontology are types of phenomena used in biology to describe organisms while classifying them.
• Both taxonomy and ontology use hierarchy to describe organisms.

Difference Between Taxonomy and Ontology

Definition

Taxonomy: Taxonomy refers to a branch of science in which the organisms are defined and named based on their shared characteristics.

Ontology: Ontology refers to a branch of science that studies the nature of being, its existence or reality as well as the hierarchy of the being.

Significance

Taxonomy: Taxonomy is a type of anatomical, physiological and evolutionary study of organisms.

Ontology: Ontology is a type of philosophical study about organisms.

Criteria

Taxonomy: Taxonomy uses the hierarchy of the organisms to describe and classify organisms.

Ontology: Ontology uses more complex variations such as the nature of the being, its reality.

Role

Taxonomy: Taxonomy is involved in the naming, defining, and classifying organisms.

Ontology: Ontology is involved in the classification of organisms using a complex and sophisticated model where everything is interconnected.

Complexity

Taxonomy: Taxonomy is a comparatively simple phenomenon.

Ontology: Ontology is more complex than taxonomy.

Appearance

Taxonomy: Taxonomy produces a tree with branches like relationships.

Ontology: Ontology produces a web-like relationship where everything is interconnected.

Conclusion

Taxonomy and ontology are two types of phenomena used to describe and classify organisms in biology. Taxonomy uses biological and evolutionary relationships to arrange organisms in a hierarchy. However, ontology uses philosophical characteristics as well in describing organisms. Therefore, the main difference between taxonomy and ontology is the type of criteria used by each phenomenon to classify organisms.  

Reference:

1. “What is Taxonomy?” Convention on Biological Diversity, Available here.
2. Bard, Jonathan B. L., and Seung Y. Rhee. “ONTOLOGIES IN BIOLOGY: DESIGN, APPLICATIONS AND FUTURE CHALLENGES.” Nature News, Nature Publishing Group, Available here.

Image Courtesy:

1. “Taxonomic Rank Graph” By Annina Breen – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Uberon-an-integrative-multi-species-anatomy-ontology-gb-2012-13-1-r5-4” By Mungall C, Torniai C, Gkoutos G, Lewis S, Haendel M – Image file from Mungall C, Torniai C, Gkoutos G, Lewis S, Haendel M (2012). “Uberon, an integrative multi-species anatomy ontology”. Genome Biology. DOI:10.1186/gb-2012-13-1-r5. PMID 22293552. PMC: 3334586 (CC BY 2.0) via Commons Wikimedia

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