T I is a reflex that is characterised by a catatonic state and total loss of muscle tone ...
Helpful to researchers and predatory orcas it may be, but the evolutionary benefit to those elasmobranchs exhibiting TI is less certain. It may serve as a defence strategy, but the advantage of sharks being able to “play dead” is not clear. An alternative theory suggests that TI may be related to mating, with males using it as a technique to temporarily immobilise the female.
Surely not every trait is selected for in isolation?
What if there are 2 traits - one beneficial and one not and both traits evolve together?