What is the difference between microevolution and macroevolution?

Answer

Micro- and macro-evolution is about the same mechanism of evolution, but over a different time span as viewed by biologists.

Micro-evolution is about relatively short periods of time, for example decades. Here, biologists study evolutionary changes within a population of a particular species. A recent example: in England, measurements of the bill length of great tits over the last 100 years have shown that their bill length has increased. This extension is not seen in the Netherlands, where the bill of great tits is on average 0.3 cm shorter than that of English great tits. The researchers attribute this to the fact that in England for over a hundred years much attention has been paid to birds in the garden and to feeding them by humans, which has only become a habit much more recently in the Netherlands (and the rest of Europe). In England the great tits have adapted to the feed silos where a longer bill offers advantages. This is an example of what biologists call microevolution.

In the longer term, a population of birds with a longer bill could in the future “split off” from the ancestral species and evolve into a new bird species, which could be called, for example, the “long-billed tit”. This is then macro evolution. In macroevolution, biologists study evolutionary changes that take place over very long periods of time – on the order of millions of years. For example, the evolution of the whale from a hippo-like land mammal. Or the human from a kind of anthropoid.

In fact, there is no sharp boundary between micro and macro evolution. It is about the time span in which the evolution process takes place and is studied.