What is the current genetic tree?
https://en.wikipedia.org/wiki/Phylogenetic_tree
The idea of a "tree of life" arose from ancient notions of a ladder-like progression from lower into higher forms of life (such as in the Great Chain of Being). Early representations of "branching" phylogenetic trees include a "paleontological chart" showing the geological relationships among plants and animals in the book Elementary Geology, by Edward Hitchcock (first edition: 1840).
Charles Darwin (1859) also produced one of the first illustrations and crucially popularized the notion of an evolutionary "tree" in his seminal book The Origin of Species. Over a century later, evolutionary biologists still use tree diagrams to depict evolution because such diagrams effectively convey the concept that speciation occurs through the adaptive and semirandom splitting of lineages. Over time, species classification has become less static and more dynamic.
The term phylogenetic, or phylogeny, derives from the two ancient greek words φῦλον (phûlon), meaning "race, lineage", and γένεσις (génesis), meaning "origin, source"
https://www.nature.com/scitable/topicpage/trait-evolution-on-a-phylogenetic-tree-relatedness-41936
In biology, the concept of relatedness is defined in terms of recency to a common ancestor. As a result, the question "Is species A more closely related to species B or to species C?" can be answered by asking whether species A shares a more recent common ancestor with species B or with species C. To help clarify this logic, think about the relationships within human families. The most recent common ancestors of both you and your siblings are your parents; the most recent common ancestors of you and your first cousins are your grandparents; and the most recent common ancestors of you and your second cousins are your great-grandparents. Note that your parents are situated one generation ago, your grandparents are situated two generations ago, and your great-grandparents are situated three generations ago. This arrangement of ancestors explains why you are more closely related to your siblings than your cousins, and why you are more closely related to your first cousins than your second cousins.
https://en.wikipedia.org/wiki/Evolution#Speciation
Speciation is the process where a species diverges into two or more descendant species.[234]
There are multiple ways to define the concept of "species." The choice of definition is dependent on the particularities of the species concerned.[235] For example, some species concepts apply more readily toward sexually reproducing organisms while others lend themselves better toward asexual organisms. Despite the diversity of various species concepts, these various concepts can be placed into one of three broad philosophical approaches: interbreeding, ecological and phylogenetic.[236] The Biological Species Concept (BSC) is a classic example of the interbreeding approach. Defined by evolutionary biologist Ernst Mayr in 1942, the BSC states that "species are groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups."[237] Despite its wide and long-term use, the BSC like others is not without controversy, for example because these concepts cannot be applied to prokaryotes,[238] and this is called the species problem.[235] Some researchers have attempted a unifying monistic definition of species, while others adopt a pluralistic approach and suggest that there may be different ways to logically interpret the definition of a species.[235][236]
Barriers to reproduction between two diverging sexual populations are required for the populations to become new species. Gene flow may slow this process by spreading the new genetic variants also to the other populations. Depending on how far two species have diverged since their most recent common ancestor, it may still be possible for them to produce offspring, as with horses and donkeys mating to produce mules.[239] Such hybrids are generally infertile. In this case, closely related species may regularly interbreed, but hybrids will be selected against and the species will remain distinct. However, viable hybrids are occasionally formed and these new species can either have properties intermediate between their parent species, or possess a totally new phenotype.[240] The importance of hybridisation in producing new species of animals is unclear, although cases have been seen in many types of animals,[241] with the gray tree frog being a particularly well-studied example
ring species:
) Cat-serval hybrids are usually infertile, especially males.
