This is a phrase found in darwins origin of species? /

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?

Which zone within the open-ocean zone is home to the most organisms? deep zone surface zone intertidal zone transition zone

The image shows the evolution of a species of fish. a few fish from a population developed different social behaviors and evolved into different species. two fish according to the image, the fish underwent . the new species of fish had mating seasons that were different from that of the original fish. because of the differences in mating seasons, the fish underwent reproductive isolation. this mode of isolation would be .