Synirr
"No one is a failure unless you try"
Even then the offspring would carry genes from both subspecies and still wouldn't be 100% endlers. The only way for a species/subspecies to mate with another species/subspecies and still produce offspring that are 100% pure would be like with Amazon mollies where it's really a case of parthenogenesis, but it's impossible for this to happen with the offspring being the father's species because an egg is required (and thus the genetic code from that egg.)
But only slightly 
. I would assume that, because the offspring are genetic clones of their mothers, their environment must be relatively stable. Sexual reproduction involving genes from both parents allows for quicker evolution/adaptation, but it also produces more offspring less suited to their environment than clones of a well-adapted specimen would be. In other words, their method of reproduction works because they have no need to change. If their environment changes much it would be more detrimental to the mollies than to other fishes because the mollies would be less able to quickly adapt.
