The evolutionary origins of ritualized acoustic signals in caterpillars.
Animal communication signals can be highly elaborate, and researchers have long sought explanations for their evolutionary origins. For example, how did signals such as the tail-fan display of a peacock, a firefly flash or a wolf howl evolve? Animal communication theory holds that many signals evolved from non-signalling behaviours through the process of ritualization. Empirical evidence for ritualization is limited, as it is necessary to examine living relatives with varying degrees of signal evolution within a phylogenetic framework. We examine the origins of vibratory territorial signals in caterpillars using comparative and molecular phylogenetic methods. We show that a highly ritualized vibratory signal--anal scraping--originated from a locomotory behaviour--walking. Furthermore, comparative behavioural analysis supports the hypothesis that ritualized vibratory signals derive from physical fighting behaviours. Thus, contestants signal their opponents to avoid the cost of fighting. Our study provides experimental evidence for the origins of a complex communication signal, through the process of ritualization.
Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, Canada K1S 5B6.
Jaclyn L
JL
Scott
Akito Y
AY
Kawahara
Jeffrey H
JH
Skevington
Shen-Horn
SH
Yen
Abeer
A
Sami
Myron L
ML
Smith
Jayne E
JE
Yack
D000162:Acoustics; D000819:Animal Communication; D000818:Animals; D005075:Biological Evolution; D007915:Lepidoptera / Q000502:physiology*; D008969:Molecular Sequence Data; D010802:Phylogeny