How does evolution produce new and complex features?: Week 1

How does evolution produce new and complex features?

    New and complex features are adaptive and occur through intermediate forms. Such intermediate forms can either be advantageous for the organism or involved in co-opting. Advantageous intermediates give organisms abilities that they did not have previously that allowed them to gain whatever new trait to eventually become fully functional. An example of advantageous intermediates is the development of light-sensing eyespots in flatworms. The light-sensing eyespots were advantageous compared to no eyespot and would go on to evolve into complex eyes. Co-opting occurs when the intermediate form has a different function or purpose than the complex feature. An example of co-opted features is the evolution of feathers. Dinosaurs evolved feathers prior to birds. However, these feathers were not used for flight, rather, they were likely used for insulation. Although new and complex features can be produced through different routes during the evolutionary process, both advantageous intermediates and co-opted intermediates do present functional features that an organism used prior to evolving into the most recent feature.