Genes related to senses and their variation across animals
There are two notions I could think of


There might have a trade-offs about where to spend ressources (energy and nutrients). If an organism spend a lot of ressources in, say, vision (incl. the part of the brain that deal with interpreting the input), then there won't be much left for other things.
When a sensory system is well enough developed that the other sensory systems would bring up only marginal benefits, it is better to just not spend unecceesary ressources on building these other sensory systems.


Please note that 


The above two hypotheses are just guess work from me and I did not support any of what I said with an actual evidence.
I assumed that there is a negative correlation between the "quality of the different sensory systems" (whichever way that would be defined) but I don't know whether this is true or not.