What Wildbook should this feature be in? Flukebook, perhaps others also.
What would you like to see? the ability to specify and match within a certain population (i.e. in a similar way to how you can match within a location).
How would this functionality help you? Sometimes the population for an occurrence is known, and it would be more efficient to match within that population while excluding other populations that exist in the same location (e.g. northern resident killer whales and southern resident killer whales in British Columbia).