 Now, expand your image to encompass all the butterflies of this species in a particular meadow over several generations. A pedigree for this population might look something like the one in Figure 1C. Note that each individual in the figure has two parents, but each gives rise to a variable number of offspring in the next generation. Next, imagine taking your pedigree and getting rid of the organisms, thus keeping only the descent relationships, which are the glue that holds the population together (Figure 1D inset box). Then zoom out even farther to include many more individuals (say, from multiple meadows in the same region) and more generations. For example, the whole of Figure 1D is derived from a similar diagram as the inset box, but it now includes more individuals and many generations. As you can see, if one were to try to represent a typical population of several thousand individuals that persists for hundreds or thousands of generations, all one would see would be a fuzzy line. Individual populations may be fairly isolated for some period of time. However, on an evolutionary timescale, migration will occur among the discrete populations that make up a typical species. This gene flow between populations has the effect of "braiding" the population lineages into a single species lineage, which might be thought of as resembling Figure 1E. Moreover, during evolution, lineages often split. This occurs when populations or groups of populations become genetically isolated from one another. Lineages most commonly split because of the migration of a few individuals to a new, isolated region (e.g., an island). This is sometimes called a founder event. Alternatively, a formerly contiguous range can be broken up by geological or climatic events (e.g., the creation of mountains, rivers, or patches of inhospitable terrain). This phenomenon is called vicariance. No matter whether populations split due to founder events or vicariance, if the isolated populations remain separate, they will start evolving differences from one another (Figure 1F). After all, a mutation that arises in one population will have no way to get to the other population. Thus, even a mutation that would be selectively favored in both populations will become fixed in only one of the groups. As a consequence of this genetic isolation, the lineages will evolve separately, becoming more and more different over time. If they remain apart for long periods, enough physiological and behavioral differences may evolve to result in reproductive isolation, such that it will be impossible for individuals from the two lineages to reproduce even in the case that they do come back into contact. Because of this, it is a useful simplification to assume that once lineages diverge, the two sets of descendants will remain distinct. Figure 2B shows what we might see if we followed the fate of a single ancestral lineage (Figure 2A) long enough that it gave rise to four descendant lineages (species). This example includes three lineages that were established but became extinct before the end of the observation period. This diagram is an example of a simple phylogenetic tree. In most cases, researchers draw phylogenetic trees in such a way as to record only those events that are relevant to a set of living taxa. Most commonly, these taxa are species. For example, Figure 2C shows the basic tree we could draw to represent the history of the four "tip" species, A through D. This tree shows that species A and B share a more recent common ancestor with each other than with either species C or species D. Likewise, species C and D share a more recent common ancestor with each other than with either species A or species B. This example illustrates the fact that a phylogeny is, at its most basic level, a history of descent from common ancestry. Phylogenetic trees are fractal in the sense that the same pattern is found whether we consider recently diverged lineages or deep splits in the tree of life. Indeed, the most basic postulate of evolutionary theory is that the same general phenomenon of descent from common ancestry applies to both the most diverse branches of the tree of life and the most similar. As a result, the tree structure is extremely helpful in tracking biological diversity at all levels.
Genus n., plural: genera [ˈdʒiːnəs] Definition: a taxonomic rank consisting of species with common attributes A genus is a taxonomic category ranking used in biological classification that is below family and above species. Species exhibiting similar characteristics comprise a genus. An estimate of the number of published genus names was at about 510,000 as of 2016. (1) In 2018, the Catalogue of Life quoted 173,363 accepted genus names for both extant and extinct species. Also included in their report are genus names with no species for certain groups. (2) In binomial nomenclature, the genus is used as the first word of a scientific name in which the first letter is capitalized. Together with the specific epithet, they are italicized, e.g., Homo sapiens, or underlined if handwritten, e.g., Homo sapiens. Biology definition:
The classification of organisms is the systematic grouping of living things based on characteristics, hierarchical, or phylogenetic relationships. It is one of the major aspects of taxonomy. Organisms are investigated in terms of their morphology, anatomy, physiology, evolution, behavior, development, and genetics in order to find out relationships between and among them. They are then classified into taxonomic groups and into a taxonomic hierarchy. The common taxonomic levels are domain, kingdom, phyla, class, order, family, genus, and species. Genus taxonomy is a rank generally above the species level and below the family level. One of the most prominent contributors to a systematized classification of organisms is the Swedish botanist Carl Linnaeus. The classification system where organisms are categorized into taxa is called Linnaean, which was named after him. He also proposed the binomial nomenclature. In the Linnaean system, organisms are grouped based on the presumed homologies, i.e. similarities in anatomical, morphological, and physiological features. The more homologous structures shared between organisms, the more they are likely evolutionary related. In binomial nomenclature, the genus is used as the first word of a scientific name. The genus name is always capitalized and italicized. For example, the binomial name of the lion is Panthera leo. The first part, Panthera, is the genus name whereas the second part, leo, is the specific epithet. A taxonomist (experts in taxonomy) assigns a scientific name for a particular species. In order for a genus to be descriptively useful, it must have monophyly, reasonable compactness, and distinctness. Willi Hennig, a German biologist, defined monophyly as groups based on shared derived characteristics or traits that distinguish the group from other groups of organisms. As for reasonable compactness, it means that the genus needs not be expanded unnecessarily. The genus name must also show distinctness with respect to evolutionarily relevant criteria such as ecology, morphology, or biogeography. In genus classification and naming, the Nomenclature Codes provide an archetypal standard. The binomial name is different from the common or vernacular name. The latter is non-standardized and varies by location as opposed to the former that is standardized and usage is globally accepted. Genus vs. SpeciesA species is regarded as the most basic unit or category in the biological system of classification. To be considered into a species rank, the group must have at least two of its members capable of reproducing fertile offspring (such as by sexual reproduction). Organisms from different species, although they belong under the same genus, generally cannot interbreed as their offspring would likely be infertile. The species of a particular group of organisms would, therefore, pertain to those that can reproduce and sire fertile offspring of the same kind. Thus, they would have the same set of DNA, similar physical and morphological attributes, and demonstrate communal behavior. The species is located below the genus rank. Thus, a genus is more encompassing and relatively wider in scope than a species. Nevertheless, the genus lies below the taxonomic family and therefore it would be less inclusive than a family since the latter serves as the collective umbrella of related genera. Certain species can still be further subdivided into subgroups (called subspecies), such as varieties, formae, etc. The genus-species format is essential in naming an organism. The genus is the generic name whereas the species is the specific name in a binomial nomenclature. For example, Allium cepa (commonly known as onion). The Allium is the generic name whereas the cepa is the specific name.
Genus and FamilyA taxonomic family is a group of one or more genera. The genera under a particular family share a common attribute. Thus, a family would usually be more inclusive and consists of a greater number of organisms. The genera of a particular family evolve from the same ancestors for having relatively common characteristics. In the taxonomic rank, a family is above the genus level and below the order. Type ConceptIn modern biological classification, the type genus serves as the representative of a taxonomic family. Thus, one or more genera in a family would define the latter. In zoology, the International Code of Zoological Nomenclature provides the fundamental standards. Accordingly, the family-group name would be based upon the type genus. For example, the genus Cricetus (Leske, 1779) is the type genus of the family Cricetidae. Another example is the mallard Anas platyrhynchos. Anas is the type genus for the family Anatidae. Canis lupus (dogs and wolves) belongs to the family Canidae. The family name is derived from the generic name Canis. The genus could serve as the root and the family name as the stem, with a name often ending in –idae. There are also instances wherein the next major taxonomic rank, particularly order, is based as well on the type genus. In dogs and wolves, for instance, belong to the order Carnivora. A family name should have a type genus just as a type genus has a type species. If a specimen turns out to be of another genus, then the generic name becomes a junior synonym. UsageIn zoology, a genus may be available or unavailable. The available names are genus names that are published based upon the standards of the International Code of Zoological Nomenclature (ICZN), as well as by the International Commission on Zoological Nomenclature. The unavailable names were those that were not published because of nonconformity to the ICZN Code. Other possible reasons are incorrect spellings and lack of type species. In botany, an available name is a validly published name whereas an unavailable name is an invalid name. A genus name that is invalid is given a label, nomen invalidum (nom. Inval.). A valid name in botany is labeled as the correct name or current name. The genus name could change over time and be replaced with another. This happens when new information comes along. The formerly accepted name, as a result, becomes a synonym. For example, Physeter (Linnaeus, 1758) has the following synonyms: Catodon (Linnaeus, 1761), Cetus (Billberg, 1828), Meganeuron (Gray, 1865), Megistosaurus (Harlan, 1828), Phiseter (Bonnaterre, 1789), Physalus (Lacépède, 1804), Physeterus (Duméril, 1806), and Tursio (Fleming, 1822).(2) A homonym in biological classification is a name that is associated with two different taxa. For example, the ambrosia beetle and the platypus had been given the generic name Platypus. Nevertheless, the ambrosia beetle was the first to get a generic name Platypus and thus the platypus eventually was given a new generic name Ornithorhynchus. The two cannot share the same generic name since they are both from Kingdom Animalia. However, the use of the same genera for specimens from different kingdoms is still discouraged. There are thousands of cases wherein species from different kingdoms share with the same genera. For example, Aoutus is the generic name for the night monkeys and also for the golden peas. ExamplesHomo (from Latin that literally means “man”) is a genus of humans that belong to the tribe Hominini of the family Hominidae, order Primates, class Mammalia. The fundamental features of the human species in the genus Homo are bipedalism, opposable thumb, possession of a notochord that is eventually replaced by a vertebral column, live birth, and mammary glands producing breast milk in women to nourish the newly born. In this genus example, several species are included. However, only one species remain extant, i.e. H. sapiens sapiens (modern). Below is the genus list of human species (genus Homo).
These species possess a highly developed brain and advanced skills, particularly in abstract reasoning, problem-solving, self-awareness, and articulate communication. They walk on two legs, with an erect carriage. They have relatively smaller teeth than other primates. These features set them apart from other genera, such as Australopithecus. The genus Australopithecus also belongs to the tribe Hominini. Their brains were smaller, about 35% of the brain size of modern humans. They generally had smaller built than humans and were shorter (about 3’11 to 4’7). They were more morphologically similar to chimpanzees and bonobos than to humans since their bodies are fully covered with hair. Astralopithecus, though, play a part in human evolution. The genus Homo is presumed to originate from one of the species of this genus million years ago.(4) Ardipithecus is another genus belonging to family Hominidae. Members of this genus were already extinct. They diverged from the chimpanzees. They have a grasping hallux or big toe that enabled them to move from one tree to another with relative ease. This genus as the earliest human ancestor is a matter of debate though since they likely behave more like a chimpanzee than humans. Sahelanthropus is a genus comprised of extinct species from the Miocene epoch, particularly during the time close to that when chimpanzees and humans diverged. Try to answer the quiz below to check what you have learned so far about genus. Further Reading
References
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In order for two organisms to belong to the same species individuals of their species must
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