Incredible work
@Zoofan15 putting this together as a major resource, seriously impressive.
Looking into the population's shared ancestry with many founders represented in most of the tigers ancestry multiple times over apparently forms something called loop contributions that increases the inbreeding coefficiency (i.c) % according to Sewell Wright's
Coefficients of inbreeding and relationship (1922), often referred to by genetecists as 'Wright’s Coefficient of Inbreeding', the current captive population of Sumatran tigers (except for the few first and second generation born to wild founders in Sumatra in Indonesian zoos and some sent overseas like Kaithlyn etc in Australia). Have considerably high-levels of i.c F% and some may even have genetic diversity percentages of less than 50% which is considerable to say the least.
But the founder base appears to have been very fortunate in having been a seemingly genetically 'robust' founder base and as you point out
@Zoofan15, the 20 wild caught founders whom Australasia's current population descend from on different levels (funnily enough none of those 20 Sumatran tigers ever lived in Australasia hey); it does underline the much needed new founders in the population if any future individuals born in Australasia (or the rest of the captive population too who descend from the Berlin Zoo and Rotterdam Zoo lines pedigrees too, some other lines too) are to be considered for being part of a rewilding program, or as an insurance population that can be expected to continue to survive multiple generations in the wild with managing to evade genetic health issues and stressors that generally arent issues for captive living tigers. In short apparently something known as founder effects or crypto founder effects when the current population is many generations removed from most of the initial founders, when those same founders appear multiple times in both the sire's and dam's lines, it increases the likelihood of their alleles becoming homozygous, especially over generations of linebreeding (can be decreased if one parent carries less of, but generally the way to lower the overall i.c% is to breed with a completely unrelated tiger who themselves has little to no inbreeding coefficiency's present in their genetic makeup and therefore lowers the offsprings by half and so on.
But each individual will always inherit on average half the i.c % of one parent (in addition to any new inbreeding caused by their parents being related which is what the Wright i.c calculation method helped work out and is what causes the i.c F% increase);and in linebreeding which is how the captive Sumatran tiger population has been sustained for most of the last ≈70 to ≈80 years (inbreeding really seemed to start to occur more in the 1970s onwards and was initially rarer of course), it has actually risen to concerning levels with what believe to be the majority of living captive Sumatran tigers currently.
It's difficult though as removing anymore of the ≈300 to ≈350 or less surviving wild Sumatran tigers from the wild is in itself detrimental to their wild population. So increasing genetic diversity in the population over the next few generations won’t be easy. Though am optimistic there will be ways to do and will be some more new founders albeit probably not too many given their (sub)species serious predicament in the wild. Wright's theory of inbreeding coefficiency percentage averages is considered the most reliable in terms of determining modern population genetics calculations.
Just as two examples: Kali, Shiva, Jambi, Sinta, Usha, Lunka, Mandau, Musara and all the other offspring of Meta and Nico were estimated as having an estimated genetic diversity percentage of ≈78.125% based on the Wright's i.c method of calculation (due to Meta and Nico's relation to one another, aswell as Meta's own i.c F% which her offspring all inherited part of). *And in comparison Selatan and Calang the offspring of Poetry and Frank had an estimated genetic diversity percentage of ≈96.875 (which is quite similar to what some wild Sumatran tigers are believed to have, although of course, higher the better for odds of genetic health. Believe many wild Sumatran tigers have about 98% or higher geneticly diverse dna). In Poetry and Franks case using the human relationship terms - they were half-first cousins, having shared a grand-dam in common: Lissy.
*As pretty much all of us know, cheetahs have a population bottleneck issue with very low genetic diversity though that has been a natural occurance in the wild, and other examples like Floridian pumas {wild} and Southern Chinese tigers {captivity from six 2.4 founders/probably extinct in wild} and others, but using fellow felid examples. Left Mohan descendant & 'Orissa line' descendant 'white'-gene carrying captive Bengal tigers out of as that inbreeding/linebreeding has been done deliberately with the full intention for them to be display animals and not a wild insurance population.
