Species

We explain what a species is, what its origin is and its relationship with the genus. Types of species, endangered species and examples.

What is a species?

In biology, a species is defined as a set of organisms capable of reproducing among themselves, obtaining fertile offspring and being reproductively isolated (that is, its members do not reproduce with members of other groups). This last feature is known as reproductive isolationand constitutes a fundamental element for the current definition of species.

On the other hand, The species constitutes the basic unit of classification of living beings. It is the lowest link in the taxonomic classification. Several species can be grouped within the same gender.

in his book The origin of species, Charles Darwin made numerous contributions to the relationships between species. It allowed us to better understand the evolutionary relationships that exist between current species and those of the past.

It is possible to classify species into native species (if they originated in a certain habitat) and exotic species (if they were introduced). On the other hand, invasive species and endangered species constitute environmental problems that often require government policy intervention.

• See also: Population in biology

Origin of species

The way in which species appeared and diversified is known thanks to the works of Charles Darwin. Your essay The origin of species (published in 1859) laid the foundations for what we know today as biological evolution.

In that work, Darwin explained that the species of living beings came from other previous species whose destinies had been determined by environmental pressure. Organisms had to compete to survive and reproduce in a certain environment. Darwin's theory called this process natural selection.

According to this theory, current species come from other past species, and all come from a single common ancestor. Darwin developed his theory from his exploratory trips through America and Oceania.

He observed how some species on the Galapagos Islands were similar, but at the same time different from those on the mainland. This suggested that the animals on the islands had adapted to their new environment and had followed a different evolutionary path than their counterparts on the mainland. Eventually, each variant differentiated into a distinct species.

• It may help you: Evolution of man

Species and genus

The biological classification gives each species its own name in Latin that contains two terms: first that of the genus and then that of the species.

For example: Homo sapiens
– Homo: gender
– Homo sapiens: species

This code for naming species is known as binomial nomenclature.

The classification system of living beings organizes all known species into categories, called taxa. The genus is a taxonomic category higher (more general, less specific) than the species, but lower (less general) than the family.

• Kingdom
• Edge
• Class
• Order
• Family
• Gender
• Species

So, genus is a set of species that, in some way, constitute variants.

Genres, in addition, are often divided into subgenres or infragens. These constitute a kind of genres within the genre. Also, they can be grouped into supergenres, an intermediate link between gender and family. Some genera contain, so far, a single species.

• See also: Taxonomy

Types of species

Known species can be grouped according to the taxonomic group to which the organisms they describe belong. According to official records from 2022, the total number of identified species is 2.16 million distributed as follows:

Cluster	Number of species
invertebrate animals	1,424,153
Vertebrate animals	74.42
Floors	424,335
Fungal and protist species	141,541
bacteria	10

It is assumed that these data could be overestimated due to the presence of “synonymous species”. This phenomenon happens when a new species is recorded that, in reality, already existed under another name. It tends to happen more frequently in rare, little-researched organisms.

Examples of species

Some examples of species are:

1. Homo neanderthalensis . It is an extinct species of the genus Homowhich coexisted with current humans about 230,000 years ago.
2. panthera tigris . It is one of the four species of tigers in the world, famous for its grated, orange leather. It is endemic to the Asian continent, where it is a large jungle predator.
3. Danaus plexippu yes. Known as the monarch butterfly, one of its variants makes large migrations from Canada to central Mexico.
4. Populus alba . Known as white poplar or common poplar, it is a leafy tree with green leaves with a white back, common in Europe and Asia, which grows up to 30 meters high.
5. Zea mays . Popularly called corn, it is a plant of Mexican origin, which belongs to the grass family. It arose due to artificial selection, from selective crops of the teosinte (primitive corn).
6. Agaricus bisporus . It is usually called the common mushroom and is considered the most cultivated mushroom in the world for its use in gastronomy. It is a species native to the forests of Europe and North America.
7. Penicillium candidum . It is a mold belonging to the genus Penicillum. It is used in the production of fermented cheeses to create the white rind of goat and sheep cheeses.
8. Helicobacter pylori . It is a species of bacteria that lives in the human stomach, and can develop infections in the gastric mucosa.
9. Escherichia coli . It is a bacteria that is part of the digestive system of many mammals, where it participates in the digestion of food. Some strains (such as enteropathogenic E.Coli) can cause disease.
10. Paramecium Caudatum. It is a single-celled organism with the surface covered with small hairs (cilia) that are used to move in the water. It is found in both marine and freshwater environments.

Native species

Native species are those that are native to the habitat in which they are found that is, they do not come from migrations, nor have they been artificially introduced.

Native species that preserve a limited geographic habitat are called endemic species. These species often receive special attention, as they are species vulnerable to extinction and are the target of environmental protection policies.

For example, the marine iguana of the Galapagos Islands (Amblyrhynchus cristatus) is native and endemic to the islands, since it is native there and is not found anywhere else in the world.

Instead, the Argentine ant (Linepithema humile) is a species native to South America which has been artificially introduced to almost all other continents, making it an exotic species there.

• Native species

exotic species

Exotic species, introduced species or foreign species are those that are not native to the place where they are found. These are organisms that were introduced into an ecosystem artificially or through migration, and found a comfortable place to live.

exotic species can be harmful to the habitat that receives them because they can alter the local ecological balance, by competing for resources with native species. An invasive species is an exotic species that, in competition for resources, manages to displace native species.

Human beings are responsible for many introductions of foreign species, voluntarily or involuntarily.

farm cows (Bos taurus) are an example of this. Cows are native species to Southeast Asia, but were introduced as an exotic species to other continents. In the case of plants, cereals such as wheat, corn and rice are examples of species introduced by humans.

• Exotic species

Invasive species

Invasive species are considered to be those exotic species that, once arrived in a new habitat, manage to establish and reproduce very quickly, and displace native species.

Invasive species generate an alteration in the ecosystem they reach, because they occupy ecological niches of native species and end up impoverishing the biodiversity of a region.

These species can represent a danger, not only at a biotic level but also at an economic and agricultural level, including public health.

An example of invasive species are common rabbits (Oryctolagus cuniculus) introduced in Australia. Rabbits came to Australia in the 19th century with the help of English settlers, for sport hunting. The initial few pairs found exceptional biological conditions to reproduce.

Australia is an isolated region of the continent, with very good pastures and free of natural predators. Due to the exponential growth of the exotic species, the Australian government had to take specific measures to try to control the rabbit plague.

Endangered species

Extinction is the death of a species, that is, the disappearance of all the individuals that make it up. According to the International Union for Conservation of Nature, a species is considered endangered when The number of individuals that currently exist is too low.

In these cases, all available information about the species is analyzed and, eventually, the species in question can be included in the Red List of threatened species (The IUCN Red List). Species that are part of the red list of endangered species often receive attention from government organizations to support conservation policies.

Although extinctions can occur for various reasons, there is currently an international consensus about the dangers that human activity entails.

• Endangered species

Controversies with the definition of species

The term species Its meaning has changed throughout history. Currently, the most accepted definition is called biological speciesand was proposed by Mayr in 1969. According to Mayr, a biological species is a population of organisms that have the ability to reproduce among themselves, leave fertile offspring and cannot reproduce with other groups (or at least they do not usually do so).

However, this species concept entails some difficulties, among which There is a problem in categorizing organisms that reproduce asexually. On the other hand, it also makes no mention of the evolutionary relationships between organisms. For these reasons, some scientists considered a broader species definition necessary.

In 1989, an alternative definition appeared among taxonomists, called phylogenetic species, which includes the evolutionary history of organisms. In 1989, Cracaft postulated that “a phylogenetic species is the smallest diagnosable grouping of individual organisms, within which there is a parental pattern of ancestry and descent.”

Currently, the debate continues regarding the definition of a species, although the definition of biological species remains the most recognized . Probably, if the concept of phylogenetic speciesthe number of species that we know would be greater than the current value.

References

• Bombara N., Godoy E., et al. BIOLOGY 2: Origin, evolution and continuity of biological systems. 1st edition. Santillana (2018)
• The IUCN Red List. https://www.iucnredlist.org/
• Hannah Ritchie (2022) – “How many species are there?” Published online at OurWorldInData.org. https://ourworldindata.org/