Species

specificspecific epithetspecific namespp.phylogenetic species conceptbiological speciesanimal speciesmorphospeciesOther speciessp.
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.wikipedia
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Taxonomic rank

superfamilysuperfamiliesrank
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.
Examples of taxonomic ranks are species, genus, family, order, class, phylum, kingdom, domain, etc.

Biodiversity

diversitybiological diversitybiodiverse
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.
Biodiversity is typically a measure of variation at the genetic, species, and ecosystem level.

Biology

biologicalBiological Sciencesbiologist
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity.
Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species.

Karyotype

karyotypingkaryogramFN
Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche.
The term is also used for the complete set of chromosomes in a species or in an individual organism and for a test that detects this complement or measures the number.

Binomial nomenclature

scientific namebinomial namebinomial authority
All species (except viruses) are given a two-part name, a "binomial".
Binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, although they can be based on words from other languages.

Chronospecies

paleosubspeciesPaleospeciesfaunal turnover
In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. In palaeontology, with only comparative anatomy (morphology) from fossils as evidence, the concept of a chronospecies can be applied.
A chronospecies is a species derived from a sequential development pattern which involves continual and uniform changes from an extinct ancestral form on an evolutionary scale.

Reproduction

reproductiveprocreationreproduce
A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.
Sexual reproduction typically requires the sexual interaction of two specialized organisms, called gametes, which contain half the number of chromosomes of normal cells and are created by meiosis, with typically a male fertilizing a female of the same species to create a fertilized zygote.

Organism

organismsflora and faunaliving organisms
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.
Estimates on the number of Earth's current species range from 2 million to 1 trillion, of which over 1.7 million have been documented.

Conservation biology

conservationAnimal conservationconservationist
Though none of these are entirely satisfactory definitions, scientists and conservationists need a species definition which allows them to work, regardless of the theoretical difficulties.
Conservation biology is the management of nature and of Earth's biodiversity with the aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the erosion of biotic interactions.

Specific name (zoology)

specific namespecific epithetspecies name
The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes in zoological nomenclature).
In zoological nomenclature, the specific name (also specific epithet or species epithet) is the second part (the second name) within the scientific name of a species (a binomen).

Evolution

evolvedtheory of evolutionevolutionary
If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change continually, and to grade into one another.
It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms and molecules.

Speciation

divergedspeciatedspeciate
Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection.
Speciation is the evolutionary process by which populations evolve to become distinct species.

Boa (genus)

Boaboa constrictorboas
For example, Boa constrictor is one of four species of the genus Boa.
Two species are currently recognized.

Ecology

ecologicalecologistecologically
That understanding was greatly extended in the 20th century through genetics and population ecology.
Topics of interest include the biodiversity, distribution, biomass, and populations of organisms, as well as cooperation and competition within and between species.

Natural selection

selectionselectiveselected
Charles Darwin's 1859 book The Origin of Species explained how species could arise by natural selection.
The environment of a genome includes the molecular biology in the cell, other cells, other individuals, populations, species, as well as the abiotic environment.

Extinction

extinctspecies extinction
Genes can sometimes be exchanged between species by horizontal gene transfer; new species can arise rapidly through hybridisation and polyploidy; and species may become extinct for a variety of reasons.
In biology, extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species.

Sexual reproduction

sexuallysexualreproduce sexually
A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction.
Sexual dimorphism is where the basic phenotypic traits vary between males and females of the same species.

Mutation

mutationsgenetic mutationmutated
Genetic variability arises from mutations and recombination, while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures.
One study on genetic variations between different species of Drosophila suggests that, if a mutation changes a protein produced by a gene, the result is likely to be harmful, with an estimated 70 percent of amino acid polymorphisms that have damaging effects, and the remainder being either neutral or marginally beneficial.

Ernst Mayr

MayrErnst W. MayrErnst Walter Mayr
Ernst Mayr emphasised reproductive isolation, but this, like other species concepts, is hard or even impossible to test.
His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.

Ring species

Rassenkreisring distribution
For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species.
Ring species also present an interesting case of the species problem for those seeking to divide the living world into discrete species.

DNA barcoding

DNA barcodebarcodingbarcoded
DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use.
These "barcodes" are sometimes used in an effort to identify unknown species, parts of an organism, or simply to catalog as many taxa as possible, or to compare with traditional taxonomy in an effort to determine species boundaries.

Fossil

fossilsfossil recordfossilized
In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. In palaeontology, with only comparative anatomy (morphology) from fossils as evidence, the concept of a chronospecies can be applied.
They work on the premise that, although different sediments may look different depending on the conditions under which they were deposited, they may include the remains of the same species of fossil.

Gene pool

genepoolgenetic poolallelic diversity
Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridize successfully, they are still distinct cohesion species if the amount of hybridization is insufficient to completely mix their respective gene pools.
The gene pool is the set of all genes, or genetic information, in any population, usually of a particular species.

DNA

deoxyribonucleic aciddouble-stranded DNAdsDNA
Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche.
In many species, only a small fraction of the total sequence of the genome encodes protein.

Comparative anatomy

comparative anatomistmorphologicalcomparative morphology
In palaeontology, with only comparative anatomy (morphology) from fossils as evidence, the concept of a chronospecies can be applied.
Comparative anatomy is the study of similarities and differences in the anatomy of different species.