Numeruous scientific sites state that hybrids (like mules) are infertile. On the other hand, ligers are known to mate with both tigers and lions and still have viable offspring.
So my question is: if the hybrid is fertile in the first generation, does further mating with either of the parents' species somehow affect its offsping's fertility?
For example: if liger mates with tiger let the odds to produce viable offsping be 50%. If this offsping further mates with tiger, are odds the same or are they lower / higher?