Macroevolution studies how taxonomic groups above the level of species change. Its evidence draws frequently from the fossil record and DNA comparisons to reconstruct how various organisms may be related.

Organisms belong to the same species if they can interbreed to produce fertile offspring. Species are separated by prezygotic and postzygotic barriers, preventing mating or producing fertile offspring.

There Are Six Important Patterns of Macroevolution:

• Mass Extinctions.
• Adaptive Radiation.
• Convergent Evolution.
• Coevolution.
• Punctuated Equilibrium.
• Developmental Gene Changes.

Occurs at the level of the species or above. Such changes often span long periods of time (but can also happen rapidly). Examples of macroevolution include: the origin of eukaryotic life forms; the origin of humans; the origin of eukaryotic cells; and extinction of the dinosaurs.

In contrast, macroevolution describes patterns on the tree of life at a grand scale across vast time periods. Example of macroevolutionary patterns as they would appear in a phylogenetic tree, including extinctions, adaptive radiations, and stasis.

Macroevolutionary hypotheses can be tested by using them to generate predictions then asking whether observations from the biological world match those predictions.

An example of macroevolution is the evolution of a new species. One mechanism that drives evolution is natural selection, which is a process that increases the frequency of advantageous alleles in a population. Natural selection results in organisms that are more likely to survive and reproduce.

about one million years

Speciation is the process by which one or more species1 arises from a common ancestor, and “macroevolution” refers to patterns and processes at and above the species level – or, transitions in higher taxa, such as new families, phyla, or genera.

Speciation, the process by which one group of interbreeding populations or individuals diverges into two or more reproductively isolated groups, is responsible for much of the diversity of life on Earth.

Species selection is the process responsible for the proliferation of species that have lower extinction and higher speciation rates. Species selection is a reason why macroevolution and microevolution may be uncoupled.

To Mayr, the key to identifying species is determining whether there is shared reproduction within a population of organisms and whether there are barriers to reproduction with other organism. Mayr called this idea of defining species on the basis of reproduction the Biological Species Concept, or BSC.

For example, a phylogenetic species as defined by Cracraft (10) constitutes “the smallest diagnosable cluster of individual organisms within which there is a parental pattern of ancestry and descent,” with diagnosis based strictly on one or more synapomorphic (shared–derived) characters that identify a monophyletic …

The Biological Species Concept defines a species taxon as a group of organisms that can successfully interbreed and produce fertile offspring. According to that concept, a species’ integrity is maintained by interbreeding within a species as well as by reproductive barriers between organisms in different species.

evolutionary species concept

Mayr proposed that a biological species is comprised of groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups (57). Although Mayr developed this definition specifically for eukaryotes, it can be modified to apply to bacteria.

Allopatric speciation, also known as geographic speciation, is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration.

Such a definition is called a species concept; there are at least 26 recognized species concepts. A species concept that works well for sexually reproducing organisms such as birds may be useless for species that reproduce asexually, such as bacteria.

In his landmark 1942 book, Mayr proposed that Darwin’s theory of natural selection could explain all of evolution, including why genes evolve at the molecular level. The traits that evolve during the period of isolation are called “isolating mechanisms,” and they discourage the two populations from interbreeding.