pheromones, drumming and mating across species

I have recently observed a female A. avicularia drumming to a male A. versicolor in an enclosure next to hers (male molted mature that very day!), and a female B. vagans drumming madly to a mature male B. albopilosum (male drummed back). The female B. vagans, however, did not drum when placed next to a mature male G. rosea's enclosure.

So does this mean that their pheromones are recognizable across species within a certain genus? If this is so, and two species mate and do not produce viable offspring, it would seem to go against natural selection by wasting reproductive "time". Unless of course, these "species" are not true distinct species and are only normally geographically isolated from each other. This isolation would most likely eventually lead to a separate species based on genetic drift.

Anybody have thoughts, observations, or any facts to share? I find this topic very interesting.

I think there is a thread here regarding a hybrid vagansxalbopilosum if I recall correctly.
Apparently it does happen in nature to some extent.
I wish I could provide some answers, but I am totally in the dark, and it would all be guesswork.
I think there are others on here that may be able to provide more information, although alot of it is educated speculation!