Macroevolution
evolution on a scale at or above the level of species / From Wikipedia, the free encyclopedia
Macroevolution refers to large-scale evolution. For some, this means the origin of species. For others, it means the large-scale changes seen in the fossil record.
- "Major changes in structure and ways of life over.. tens of millions of years". R.L. Carroll.[1]
- "A large evolutionary pattern... events that result in the origin of a new higher taxon". Dictionary of Genetics.[2]
- "All macroevolutionary processes take place in populations and in the genotypes of individuals, and are thus simultaneously microevolutionary processes". Mayr.[3]
- "A vague term for the evolution of great phenotypic changes, usually great enough to [put] the lineage into a distinct genus or higher taxon". Futuyma.[4]
- "Evolution on the grand scale". Ridley.[5]
It is a term of convenience: for most biologists it does not suggest any change in the process of evolution.[4][6] For a few palaeontologists, some things they see in the fossil record cannot be explained just by the gradualist evolutionary synthesis.[7] They are in the minority. There are some interesting discussions by other palaeontologists.[8]
Some biologists use the term for evolution in already separated gene pools.[9] For them, macroevolutionary studies focus on change that occurs at or above the level of species. Again, this is a minority position. Most biologist would not call evolution at the species level "macroevolution".
Microevolution,[10] on the other hand, refers to smaller evolutionary changes within species or populations. During microevolution changes in allele frequencies definitely do occur. Some biologists, Richard Dawkins in particular, have suggested that the gene is the object of selection.[11][12] This was always challenged by Ernst Mayr "The individual is the entity which survives or not, which reproduces or not, and which reproduces successfully or not".[13] Changes in gene frequency in populations is a by-product of what happens to individuals.