over 300 new species have been discovered at hydrothermal vents, many of them "sister species" to others in geographically separated vent areas. it has been proposed that before the north american plate overrode the mid-atlantic ridge, there was a single biogeographic vent region found in the eastern pacific. the subsequent barrier to travel began the evolutionary divergence of species in different locations. the examples of convergent evolution seen between distinct hydrothermal vents is seen as major support for the theory of natural selection and evolution as a whole.