Microevolution: Variations within the same species e.g. different kinds of dogs, black and white human beings, etc. This is a fact.
Macroevolution: Variations among different species e.g. Humans coming from Apes. This is highly disputed.
Many Muslim evolutionists have written that al-Jahiz speculated about macroevolution which is absolutely wrong. Frank N. Egerton in his ‘Roots to Ecology’ clears this out. But al-Jahiz has most clearly written about microevolution which is complete brilliance.
Al-Jahiz writes in his Kitab al-Hayawan vol. 4, p: 68 “Lice are black on the head of a young man with black hair, light on that of a hoary old man (with white hair)’ this is the clearest example of microevolution which al-Jahiz expounded in the 9th century.
Besides this, al-Jahiz also talks about survival of the fittest, saw food nets and webs and understood the ecosystem. This is totally striking.