The evolution, which results in the production of new adaptive types through a process of population fragmentation and genetic divergence, is known as macro evolution. It operates above the species level and results in the splitting of the population of a species into several subgroups, each of which exhibits changes in a definite adaptive direction. These changes are known as adaptive trends and the phenomenon as the adaptive radiation or macro evolution. It means macro evolution is actually adaptive radiation.
Features of Macro Evolution:
- Macro Evolution occurs on account of mutations.
- Macro Evolution occurs in those populations, which have entered or acquired a new adaptive zone.
- Macro Evolution results in evolutionary divergence i.e. the pre-existing populations divide into several diverging descendant populations by acquiring special adaptations.
- Macro Evolution produces groups of parallel special adaptations among divergent stocks.
- Macro Evolution leads to specialization in a particular direction. This very often leads to over-specialization and finally to the extinction because over specialized forms are unable to modify when they enter a new adaptive zone.
Examples of Macro Evolution:
Evolution of reptiles and horse represents the best-documented examples of macro evolution in the fossil records. Class Reptilia first appeared in the fossil records in Pennysalvanian period. Adaptive Radiation in the group occurred between the Permian and cretaceous periods. The divergent evolution or adaptive evolution of different reptilian or amphibian groups from initial reptiles and amphibian ancestors of macro evolution.