Microevolution

 

 

Microevolution is the change in inherited traits of a population from one generation to the other. This prediction from the idea of descent with modification leads to an accumulation of changes and ultimately a transformation of a species over a period of time. The definition comes from the book "Primer to Evolution” that we have access to in our evolution class. When I think of the idea of descent with modification, I immediately think of the prediction that a species changes over time. It is still fresh in my mind from a previous assignment discussing beak size in a bird population. I think it is my favorite because it makes the most sense to me. The change from one generation to the next is usually subtle but when natural selection is a strong factor at play, we can observe the evolutionary changes in relatively short periods of time.

The idea of evolution itself can be overwhelming and confusing as you aren’t sure what can fall under that theory as our understanding is changing over the years. The example that our book gives us covering the Three-spine Stickleback fish is a great one to read. It explains the differences seen between generations and even covers a 1964 experiment showing how quick the stickleback fish could evolve.

 

A stickleback fish is one characterized for their “armor plates” along their body. Evidence has shown over time that these fish have a reduction in their armor plates and in some cases even a complete lack of pelvic spines. This species adapts to its environment; whether it be streams, lakes or pelagic and benthic habitats. The fish’s body shape and coloration and diet are all different depending on their environment. The 1964 Great Alaska Earthquake that changed the region and quite literally lifted islands further out of the ocean created a phenomenon that showed us just how quickly the Stickleback fish could evolve. According the the book, the stickleback fish that colonized the new freshwater pounds evolved to form similar characteristics of the stickleback found in continental freshwaters in just 50 years! While this seems like close to a lifetime for us, this period of evolution happened in just a blink of an eye for life on earth.

I found microevolution so interesting because not only does it make sense, but it is the first thing that we were taught about evolution in middle school biology. It is an idea that sort of wraps a neat little bow around this aspect of evolution. It can get a little confusing when you add genetics into the mix, but overall it is a prediction that is based off of so much evidence scientists have uncovered throughout the years. Microevolution will continue to happen throughout our lifetime and long after we are gone.

Book: Primer to Evolution

https://www.k-state.edu/biology/p2e/index.html