The key difference between species and strain is that species is the largest group of organisms in which any two individuals of appropriate sexes can produce fertile offspring through sexual reproduction, while strain is a sub-type of a genetic variant of biological species.
The classification of living organisms is based on the taxonomic units. In biology, classification is the scientific study of naming, defining, and classifying biological groups of organisms based on their shared characteristics. The organisms usually group into taxa, and these groups are given a taxonomic rank. The principal ranks that use in modern classification are class, order, family, genus, and species. Strain is a sub rank.
What is a Species
Species is defined as the largest group of organisms in which any two individuals of appropriate sexes can produce fertile offspring through sexual reproduction. Species refer to organisms that are closely related. The other ways of defining species include their DNA sequence, morphology, karyotype, behavior, ecological niche, or sequential development pattern. Often they can interbreed with each other to produce fertile offspring.
Species is also a fundamental unit of classification. Species have similar characteristics such as similar DNA sequences, morphological features, and ecological features. Scientists consider “natural selection” as the origin of species. Most importantly, the species that are originating from a common ancestor tend to live in the same habitat. However, some have different breeds with great variation. The total number of estimated species is between 8 to 8.7 million. However, only 14% of these had been described till 2011. All species are given a two-part name (binomial). The first name indicates the genus to which the species belongs. The second name is the specific name or specific epithet. Furthermore, species were observed from the time of Aristotle. Charles Darwin explained species could arise from natural selection, and species may become extinct for a variety of reasons.
What is a Strain?
Strain is defined as a sub-type or a genetic variant of biological species. Sometimes, it is called a culture of biological species. In microorganisms, strains tend to originate from a single cell colony of microorganisms. It is often considered an inherently artificial concept because it describes a specific intent such as genetic isolation. Strains are commonly found in virology, botany, insects, and experimental rodents.
For example, Influenza comprises four species: Influenza A, B, C, and D. These species further divide into subtypes (strains) based on the viral proteins such as haemagglutinin (H) and neuraminidase (N). The familiar subtypes (strains) of Influenza A and Influenza B viral species are Influenza A (HINI), Influenza A (H3N2), Influenza B (Victoria), Influenza B (Yamagata). Genetic mutations tend to bring out the genetic variation in a strain. This process normally occurs during sexual reproduction. Moreover, the other significant causes of genetic variation in a strain are gene flow, crossing over between homologues chromosomes, random fertilization, and random mating.
What are the Similarities Between Species and Strain?
- Species and strain are two taxonomic rank and sub rank.
- They are both classified based on their usage.
- Both groups contain organisms that show similar genetic, morphological, behavioral characteristics.
- These groups are influenced by natural selection.
- Both groups contain organisms that can breed to produce fertile offspring.
What is the Difference Between Species and Strain?
Species is defined as the largest group of organisms in which any two individuals of appropriate sexes can produce fertile offspring through sexual reproduction. On the other hand, strain is defined as a sub-type or a genetic variant of biological species. Thus, this is the key difference between species and strain. Moreover, species is the basic taxonomic unit of classification, while strain is a sub-type of species.
The following infographic lists the differences between species and strain in tabular form for side by side comparison.
Summary – Species vs Strain
Biodiversity is the total number and variety of species in a given area. Taxonomists classify species using a hierarchy of taxa. Species is the basic taxonomic unit of classification which have individuals that can produce fertile offspring through sexual reproduction. In contrast, strain is a sub-type or a genetic variant of biological species. Thus, this is the summary of the difference between species and strain.
1. Rossum, Thea Van, et al. “Diversity within Species: Interpreting Strains in Microbiomes.” Nature News, Nature Publishing Group.