Stickleback Evolution

Key Questions

  • Answer:

    An evolutionary trait that appears in two separate species with common ancestry


    This is a trait developing between two groups who are similar. They have a common ancestry, they descended from the same species. Let's say chickens and ducks came from the same ancestor. But for whatever reason they both evolve spots. Then dark stripes. Even though they split into separate species, their evolving in similar ways in response to the need for adaptation. Their phylogeny has them on separate branches, but still headed in the same direction, parallel.

    Don't this confuse this with convergent evolution. Fish became streamlined to fit ocean life, and so did dolphins but while they both did the same thing, they didn't come from the same place. They don't have a very recent ancestry together, ones a mammal ones a fish.

    Parallel applies to when their is a common ancestry the two species diverged from.

  • Answer:

    A great example of speciation that happen within short geological time peiod.


    Stickleback fish can undergo modifications to their genes and undergo evolution (through several generation) depending on the lake environment that is favorable for the evolved species.

    The genes in this case is PITX1 gene that is involved making armor plating (with spikes). The main environment that they live in contains different predator.

    One environment contains dragonfly larvae that can catch the fish by latching on to the spikes. Hence, the environment allows stickleback to evolve with no armor plating.

    Another environment contains big fish like trout that can consume stickleback with no armour plating. Hence, stickleback with no armor plating survive in this environment.