Seasonal changes of locomotor activity patterns in the desert isopod Hemilepistus reaumuri |
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Authors: | Karima Nasri-Ammar Raja Jelassi Anas Ayari Elfed Morgan |
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Institution: | 1. Faculté des Sciences de Tunis, Unité de Bio-écologie et Systématique évolutive, Université de Tunis El Manar, 2092 Manar II, Tunis, Tunisia;2. School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK |
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Abstract: | The locomotor activity rhythm of the desert woodlouse Hemilepistus reaumurii was monitored as individuals over the four seasons, under entraining and constant darkness conditions. Results indicated that individuals exhibited an endogenous rhythm of locomotor activity with a circadian period longer in spring than the other seasons whatever the regimen. Due to the important inter-individual variability, no significant difference in period was found between seasons as well as between regimens. Periodogram analysis revealed also an ultradian period around 12 h. Activity was mostly confined to the hours of the photophase or to those of subjective day. The activity pattern showed two main peaks. This bimodal circadian rhythm persisted for as long as the experiments were run, and was clearer in summer and autumn than in winter. The most clearly defined rhythms were found in spring and summer recordings, respectively, under entraining and free running conditions. The variation of activity patterns according to the seasons will be discussed. |
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Keywords: | Oniscidea circadian component entraining conditions seasons arid zones |
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