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Satsumasendai, Japan

Miyagi Gakuin Women's University is a private university in Aoba-ku, Sendai, Miyagi, Japan. Wikipedia.

Watari Y.,Ashiya University | Tanaka K.,Miyagi Gakuin Womens University
Journal of Insect Physiology

Daily light and temperature cycles entrain adult eclosion rhythms in many insect species, but little is known about their interaction. We studied this problem in the onion fly, Delia antiqua. Pupae were subjected to various combinations of a photoperiod of 12L:12D and thermoperiods. The thermoperiods consisted of 12. h warm phase (W) and 12. h cool phase (C), giving a mean temperature of 25°C with different temperature steps of 8, 4 and 1°C. As the phase relation of the two Zeitgebers was varied, the phase of eclosion rhythm was shifted, depending on the phase angle with the light cycle and the amplitude of the temperature cycle. When the temperature step in the thermoperiod was 8°C (WC 29:21°C), the eclosion rhythm was entrained mainly to thermoperiod rather than photoperiod. In the regime with a 4°C temperature step (WC 27:23°C), both thermoperiod and photoperiod affected eclosion rhythm, and a phase jump of the eclosion rhythm occurred when the warm phase of thermoperiod was delayed 15-18. h from light-on. In regimes with a 1°C temperature step (WC 25.5:24.5°C), the eclosion rhythm was completely entrained to photoperiod. The observed interacting effect of light and temperature cycle on the eclosion rhythm in D. antiqua can be explained by the two-oscillator model proposed by Pittendrigh and Bruce (1959). © 2010 Elsevier Ltd. Source

Tanaka K.,Miyagi Gakuin Womens University | Watari Y.,Ashiya University

To confirm whether the amplitude of diel temperature cycles causes a phase shift of adult eclosion rhythm of the onion fly, Delia antiqua, the peak time (∅ E) of adult eclosion was determined under various thermoperiods with a fixed temperature either in the warm or cool phase and temperature differences ranging from 1°C to 4°C between the two phases. Irrespective of the temperature level during the warm or cool phase, ∅ E occurred earlier with decreasing amplitude of the temperature cycle. The results strongly support the previous conclusion of Tanaka and Watari (Naturwissenschaften 90:76-79, 2003) that D. antiqua responds to the amplitude of temperature cycle as a cue for the circadian adult eclosion timing. The phase advance was larger in thermoperiods with a fixed warm-phase temperature than in those with a fixed cool-phase temperature. This might be ascribed to the interaction between the amplitude and level of temperature in the thermoperiodic regimes. © 2011 Springer-Verlag. Source

Tanaka K.,Miyagi Gakuin Womens University | Kimura Y.,Agriculture Research Institute | Watari Y.,Ashiya University
Biological Rhythm Research

Adult eclosion rhythm of the cabbage moth, Mamestra brassicae, pupating in the soil, was recorded in darkness under two thermoperiods, 24°C (12 h):16°C (12 h) and 20.5°C (12 h):19.5°C (12 h), with different amplitude and the same average temperature. Clear daily rhythms of eclosion were observed in both conditions. However, moths eclosed about 2 h before the temperature drop in 20.5°C:19.5°C, but 4 h later in 24°C:16°C. This response to the amplitude of temperature cycle, together with similar previous observations of adult eclosion rhythms in dipterous insects, might suggest a widespread means of adaptation among insects pupating in the soil to compensate for the depth-dependent phase delay of the temperature cycle, which is the only time cue available in the soil. Copyright © 2013 Taylor & Francis. Source

Watari Y.,Ashiya University | Tanaka K.,Miyagi Gakuin Womens University
Entomological Science

To elucidate the effects of light on thermoperiodic regulation of adult eclosion rhythm in the onion fly, Delia antiqua, the responses to two thermoperiods, 29°C (12h):21°C (12h) and 25.5°C (12h):24.5°C (12h), with different amplitude and same average temperature, were examined in continuous darkness (DD) and continuous light (LL). Irrespective of the temperature step between warm phase (W) and cool phase (C), temperature cycles effectively entrained the adult eclosion rhythm in both DD and LL. Eclosion peaks, however, varied with light conditions and temperature step between W and C. It advanced by approximately 2-3h in DD than in LL and at smaller temperature step. Background light conditions and temperature step also affect the amplitude of eclosion rhythm. It became lower in LL than in DD and at smaller temperature steps. On transfer to constant temperature (25°C), eclosion rhythm was elicited earliest in the pupae at 8°C temperature step in DD and latest in those at 1°C temperature step in LL. Pupae at 1°C temperature step in DD and at 8°C temperature step in LL demonstrated intermediate responses, but the eclosion rhythm was elicited 1day earlier in the former than in the latter. This might be ascribed to the interaction between background light and temperature step under thermoperiodic conditions. The results suggest that continuous light and a smaller temperature step weaken the coupling strength between eclosion rhythm and thermoperiod, but the light effect is stronger than the temperature step effect. © 2013 The Entomological Society of Japan. Source

Krehenwinkel H.,University of California at Berkeley | Graze M.,University of Greifswald | Tanaka K.,Miyagi Gakuin Womens University | Baba Y.G.,Japan National Institute for Agro - Environmental Sciences | And 2 more authors.
Journal of Biogeography

Aim: The phylogeographical history of wide-ranging Palaearctic species is not well understood. Here, we present a range-wide phylogeographical study of the wasp spider, Argiope bruennichi (Scopoli, 1772), a highly dispersive and widely distributed Palaearctic species. We aim to identify glacial refugia and patterns of interglacial gene flow across the Palaearctic. Location: Palaearctic region, including the Azores, Madeira, Europe, North Africa and Asia. Methods: We conduct a range-wide phylogeographical survey. Our study is based on nuclear and mitochondrial DNA markers, as well as morphological characters. We use species distribution models to predict the species' current range as well as its historical distribution during and shortly after the Last Glacial Maximum (LGM). Results: All analysed genetic markers and morphological characters support the divergence of a lineage in eastern Asia from the remainder of the Palaearctic. Within the Western Palaearctic, a less pronounced divergence into an Azorean and a European clade is found. Species distribution models predict a pronounced loss of suitable habitat for Western Palaearctic lineages during the LGM, whereas the range of East Asian populations remained largely unaffected. Main conclusions: Our results highlight the existence of non-European glacial refugia for Palaearctic species, particularly in East Asia. The current genetic structure is best explained by the recent recolonization of the Western Palaearctic from eastern Asia, or repeated interglacial contact of populations. © 2016 John Wiley & Sons Ltd. Source

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