Animal echolocation in the external ear. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in the Yangochiroptera and once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus "Rousettus". Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by
Food waste that is lost during any of the four stages of the food supply chain: (1) producers, (2) processors, (3) retailers, and (4) consumers. Precise definitions are contentious, often defined on a situational basis (as is the case more generally with definitions of waste). Professional bodies, including international organizations, state governments and secretariats may use their own definitions. Definitions of food waste vary, among other things, in what food waste consists of, how it is produced, and where or what it is discarded from or generated by. Definitions also vary because certain groups do not consider (or have traditionally not considered)