This definition encompasses everything from small-scale evolution (for example, changes in the frequency of different gene versions in a population from one generation to the next) to large-scale …

This in-depth, multi-part course takes you through evolutionary theory and mechanisms, from definitions to details, natural selection to genetic drift, mutations to punctuated equilibrium.

Each of these four processes is a basic mechanism of evolutionary change and is illustrated with an example of gene frequency change in a beetle population with brown and green individuals.

Evolution occurs when there is a change in the heritable information passed from one generation to the next. Typically, we think of biological evolution as changes in gene frequency within a population …

Natural selection is one of the basic mechanisms of evolution, along with mutation, migration, and genetic drift. Darwin’s grand idea of evolution by natural selection is relatively simple but often …

Changes in the genes controlling development can have major effects on the morphology of the adult organism. Because these effects are so significant, scientists suspect that changes in developmental …

Read about speciation in plants and how speciation factored into the history of evolutionary thought. Or explore different modes of speciation, including: Allopatric speciation Peripatric speciation Parapatric …

Nov 29, 2025 · Activity: Plant on a Rampage! Plant on a Rampage: Evolutionary scientists to the rescue!

Scientists think that geographic isolation is a common way for the process of speciation to begin: rivers change course, mountains rise, continents drift, organisms migrate, and what was once a continuous …

So fish with better sight no longer out-competed fish with worse sight. Today, these fish still have eyes — but they are not functional and are not an adaptation; they are just the by-products of the fishes’ …