Actualy the programe for Asiatic lions started in 1994 with only 9 founders, and in November 2015, 3 additional (1.2) Asiatic lions were imported, not from Singapure
There have
also been imports of males from Singapore to Rotterdam and Aalborg in 2014. At about the same time the latter zoo took over as EEP manager (before that the program had stalled somewhat).
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A subspecies is no more artificial than the concept of species, or indeed any biological taxonomy. Any problem with subspecies definitions exists in species too, and vice versa.
Using the biological species concept, subspecies always:
1. Differ in appearances – even if it may be internal, e.g. cranial measurements.
2. Differ in genetics – but not enough to prevent complete hybridization events.
3. Differ in distribution – subspecies can never be sympatric. They can, however, be parapatric, but without an ecological border this will generally result in a cline (itself invalidating the subspecies).
If you remove *any* of these, the subspecies is invalid. There are obviously plenty of questionable subspecies (and species), but this is strictly because only a minority of species have had a modern, taxonomic review. None of these fully resolve the potential problems with clines, hybrid zones, ring species, genetic drift, polyphyletic/paraphyletic species (as exist under the biological species concept) and "super hybrid" groups (e.g., Anseriformes), but those present equal problems to species vs. subspecies.
In some fields, the phylogentic species concept is used with an increasing frequency and (in its strict form) this invalidates subspecies entirely. Any valid subspecies automatically becomes a species.
NB. Old habits die hard and I've not really managed to make the shift myself, but ICZN rules now stipulate that nominotypical should be used for the type subspecies.