Explain the genetic mechanisms of micro and macro evolution

Microevolutionary mechanisms

• Mutation supplies new alleles. Most are neutral or harmful; a few are useful, as in lactase persistence.
• Natural selection changes frequencies by differential survival and fertility. Sickle-cell and malaria is the human classroom case.
• Genetic drift, including founder effect and bottleneck, is strong in small groups. Andaman and other island isolates illustrate drift and founder sampling.
• Gene flow mixes populations. Migration prevents full local fixation.
• Non-random mating, including inbreeding and assortative mating, changes genotype frequencies and can raise homozygosity.

To the macro scale

• Speciation is the hinge. Allopatric isolation, then reproductive barriers, turns micro change into new species. Hominin fossils show this as splitting lineages, not one file.
• Macroevolution adds origin of bauplans, mass extinction, and adaptive radiation. Gould and Eldredge argued punctuated equilibrium: long stasis, then geologically rapid change, still built from genetic processes.
• Chromosomal rearrangements and regulatory (Hox) shifts can produce larger morphological jumps than a single point mutation. They remain genetic mechanisms.

Unity and caution

• The Modern Synthesis treated macro as accumulated micro. Palaeontology adds time, extinction, and development. Anthropology uses both for fossils and living variation.