Outline Communication Animal Communication Bioacoustics Katydids – Natural History Katydid Calling song: Katydid communication – Calling song A case study My research on Conocephalus brevipennis Female responses to song Male responses to song Patrick A. Guerra Male responses to song Div. of Life Sciences, UTSC The Agora Effect Communication Bioacoustics The cooperative transfer of The study of sound in animals information from a signaler to a Animal communication and receiver associated behaviour Information contained within the Sound production anatomy and message neurophysiology of animals Multimodal signals Auditory capacities and auditory Multicomponent signals mechanisms of animals 1 Katydid – Natural History Katydids – Natural History Habitat: grassland areas and forests Life cycle: Diet: Leaves, stems, flowers, and fruits of ¾ Have incomplete metamorphosis (egg- plants; some are carnivorous (e.g. nymph-adult) subfamily Listroscelidiae) ¾ Lay eggs in many places (e.g. soil, in Predators: Bats, birds, snakes, shrews, and monkeys; important in the food web stems of plants, and in bark of trees) chain ¾ Nymphs are very similar to adults, but are A key feature: They have antennae, which smaller and lack fully developed wings. can be 2-3 times as long as their body ¾ The nymph goes through several molts Diversity: some 4,000 species of katydids (generally five), gradually developing into in the world; e.g. Amazon rain forests = an adult. about 2,000 katydid species Katydids – Natural History Katydids – Natural history Panacanthus cuspidatus showing anti-predator A Leaf Mimic Lichen-colored An Airplane response Subfamily: Pseudophyllinae katydid. A highly katydid. The camouflaged widely-spread rear insect. legs resemble the wings on a plane. A wasp-like katydid. Notice the Orchelimum grasshopper-like legs which vulgare, a meadow give it away. It is a type of bush Neoconocephalus katydid katydid or Phaneropterinae. nebrascensis, a Pterophylla camellifolia, a coneheaded katydid true katydid Photos: Dr. James Castner Photos: Glenn K. Morris and Thomas J. Walker 2 Katydid Communication: Calling Katydid Calling song: Stridulatory Song apparatus Functions Intersexual: e.g., Song production: mate attraction, Wing structure of C.brevipennis sound created by call-reply systems male rubbing a scraper Intrasexual: e.g., on one forewing male-male against a file on competition the other front Aggregate wing (stridulation) behaviour: e.g., habitat selection Conocephalus brevipennis Katydid Calling song: Hearing The Short-winged meadow katydid Male Hearing: the hearing organ, an "ear" (tympanum- covered auditory structure), is found Female Ear at the base of each Conocephalus brevipennis Ear front leg’s second segment (tibia) Ovipositor 3 Sympatric and syntopic C. brevipennis Calling song Conocephalus nigropleurum Comparison Buzz-tick-gap AM pattern Continuous buzz AM pattern Experiments Problems faced in nature by C. brevipennis Present signals to animals that may be relevant to them in the field No choice phonotaxis trials: Species recognition • The song of an individual conspecific male (C. brevipennis) • The song of a single sympatric and syntopic heterospecific (C. nigopleurum) Localization of sound source nigopleurum) • The song of a single sympatric heterospecific (Conocephalus attenuatus) Evaluation of a singer • Simulated aggregate song Signal interference Two choice phonotaxis trials: • The choice between an individual and a group 4 Methods: Phonotactic bioassays Results: No choice Hanging 1. Individual singer 2. Simulated aggregate song H G F 50 cm E 70 cm 90 cm FM FM Females (p < 0.0005) Females (p < 0.05) and and males (p < 0.025) males (p < 0.01) both D approach conspecific AB approach simulated C song aggregate song Results: Two choice Female responses to song Simulated aggregate song Individual singer No choice results VS. • Group song = evaluate males • Conspecific song = choose appropriate mates 70 dB 58 dB • Species-specific features of calling song aid approaching appropriate mates F M Two choice results M • Choose signals that facilitate finding an appropriate mate Females approach a single singer (p < 0.005) while males approach a group if it is more quiet than the individual singer (p < 0.02) 5 Aggregate song response and the Male responses to song Agora effect No choice results C. brevipennis and C. nigropleurum approach • Attracted to group song and conspecific aggregate signals song Males benefit by joining forces with other • Aggregative behaviour favoured by conspecific females males, regardless of species Two choice results Produce a stronger signal and attract more • Space themselves within groups in order females to be perceived by females Just a lottery as to which species a female • Calling song: a mediating factor for inter- belongs to male spacing within groups A problem? Future Research How do ♂s form 1. Intermingled aggregations appropriate groups? Determine actual distributions of signalling males in aggregations 2. Contiguous aggregations 6 Summary • C. brevipennis aggregative behaviour • Females choose signals aiding mate choice • Males choose signals aiding aggregate formation & proper inter-male spacing within groups • Context-dependent functions of C. brevipennis calling song 7.