Megabat evolved early in the lineage of chiropterans. Although echolocation was later lost in family Pteropodidae, bats in the genus "Rousettus" are capable of primitive echolocation through clicking their tongues, and some species have been shown to create clicks similar to those of echolocating bats using their wings. Both echolocation and flight are energetically expensive processes. The nature of the flight and echolocation mechanism of bats allows for creation of echolocation pulses with minimal energy use. Energetic coupling of these two processes is thought to have allowed for both energetically expensive processes to evolve in bats. The loss of echolocation may
Evolutionary arms race on the amount of evolutionary time and whether or not the moth species has developed secondary uses for hearing. Some bats are known to use clicks at frequencies above or below moths' hearing ranges. This is known as the allotonic frequency hypothesis. It argues that the auditory systems in moths have driven their bat predators to use higher or lower frequency echolocation to circumvent the moth hearing.Barbastelle bats have evolved to use a quieter mode of echolocation, calling at a reduced volume and further reducing the volume of their clicks as they close in on prey moths. The lower volume