ISSN 0022-0930, Journal of Evolutionary Biochemistry and Physiology, 2015, Vol. 51, No. 4, pp. 352—355. © Pleiades Publishing, Ltd., 2015. Original Russian Text © M.K. Zhemchuzhnikov, A.N. Knyazev, 2015, published in Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, 2015, Vol. 51, No. 4, pp. 307—310.
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Changes in the Calling Song Parameters of the Cricket Gryllus bimaculatus Deg. during Ontogenesis M. K. Zhemchuzhnikov and A. N. Knyazev Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russia E-mail:
[email protected],
[email protected] Received March 20, 2015
DOI: 10.1134/S0022093015040122 There is experimental evidence that in a number of animal species females make a sexual selection by preferring males of a specific age [1]. Females recognize a male’s age through the perception of male’s secondary sex characters, e.g. acoustic signals. Analysis of the of calling song structure in Gryllus crickets shows that while in some species a number of calling signal parameters change during ontogenesis [2, 3], in other species the signal structure remains intact [4–6]. Studies of calling signals in Gryllus bimaculatus Deg. yielded conflicting results: according to Simmons and Zuk [7], it is only the variation coefficient of pulse frequency that change with age, however, Verburgt et al. [8] asserted that most song parameters do change. Apparently, this discrepancy was due to the differences in the methods used (field or laboratory, respectively) and/or the use of different geographical populations of G. bimaculatus. The present study attempts to clarify this issue. The experiment was carried out on male G. bimaculatus crickets (n = 8) from the laboratory colony maintained at Sechenov Institute, RAS. This species is characterized by an enormous geographic range which includes Africa and Eurasia. For example, there are Mediterranean, South African, Central Asian and a few Far East-
ern populations of G. bimaculatus [9, 10]. Wild progenitors of the colony used in our experiments descend from the crickets caught in the environs of Dushanbe (Tajikistan). In the laboratory, the insects were reared at a temperature of 26°C and 12:12 h light:dark photoperiod [11]. Since the penultimate molt onwards, larvae were kept separately from each other. After the imaginal molt (adult developmental stage), acoustic signals were recorded in a sound-dampened anechoic chamber continuously for 7 h during the scotophase at the age of 10–15 days (young males) and 40–45 days (old males). Calling songs were recorded using a Sennheiser e614 microphone fed through a Focusrite Scarlett 2i2 audio interface to a Lenovo IdeaPad Z500 laptop. Acoustic signals were processed and analyzed using CoolEdit 2.0 software. The distance between the cricket and the microphone was 100–120 mm. The recording conditions met the keeping conditions. Crickets were permanently allowed of a free access to food (cabbage and water fleas) and water, including the time of recordings. To analyze the song components, the most stable (i.e. uninterrupted and lasted for no less than 1 min) phrase/sequence was chosen from each song. Three periods from each phrase were analyzed. Measurements were
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CHANGES IN THE CALLING SONG PARAMETERS OF THE CRICKET
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Changes in the calling song parameters of G. bimaculatus males during ontogenesis. Calling song oscillogram of a single cricket at the age of 14 days (corresponds to the spectrogram (g)) and 40 days after the final molt; SRP—series repetition period, SD—series duration, PRP—pulse repetition period, PD—pulse duration; (b)–(f) changes in the song parameters in young (10–15 days) versus old (40–45 days) crickets. Individual characteristics of each male cricket are denotes by the same line; (g) spectrogram of a section of calling song emitted by a young, 14-day-old, male.
JOURNAL OF EVOLUTIONARY BIOCHEMISTRY AND PHYSIOLOGY Vol. 51 No. 4 2015
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ZHEMCHUZHNIKOV, KNYAZEV
Calling song parameters in young and old males of the cricket Gryllus bimaculatus Song component Series duration, ms*
Male age, days 12.5 ± 1.5 (young)
41.0 ± 1.8 (old)
p
94.4 ± 9.5
94.6 ± 5.9
0.82
339.8 ± 78.8
453.8 ± 109.3
