Biodiversity is essential to human survival in many ways, including medical research, the on-going health of our food supplies and the health of our environment. For its preservation, the maintenance of habitats should be given priority over saving individual species. The alternative of a zoo approach will only preserve individual species, not the biodiversity itself.
Notes
An example is the massive re-establishment of natural woodland habitats that is desperately needed if we are to save our native bird species, and this requires a clear plan, world-class research and significant ongoing funding. David Paton has done some work on this. This clearly extends beyond the common strategy of simply saving examples of species.