. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 154 W. E. BRADSHAW AND C. M. HOLZAPFEL TTH == 6 + (£) (TAt + 2TAt_i).. with no decrease in the coefficient of multiple cor- relation (R == ) (Fig. 5A). Therefore, at least during the month of May and June, tree-hole temperature was closely correlated with air temperature. DISCUSSION Prior to chilling, larval diapause in T. rutilus is maintained primarily by photoperiod (Figs. 1A and 2; Bradshaw7 and Holzapfel, 1975; McCrary, 1965). The critical photoperiod of this response varies as little as plus or minus minutes ov
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 154 W. E. BRADSHAW AND C. M. HOLZAPFEL TTH == 6 + (£) (TAt + 2TAt_i).. with no decrease in the coefficient of multiple cor- relation (R == ) (Fig. 5A). Therefore, at least during the month of May and June, tree-hole temperature was closely correlated with air temperature. DISCUSSION Prior to chilling, larval diapause in T. rutilus is maintained primarily by photoperiod (Figs. 1A and 2; Bradshaw7 and Holzapfel, 1975; McCrary, 1965). The critical photoperiod of this response varies as little as plus or minus minutes over the range of ° to 25° C (Fig. 1A). Moreover, the slopes of the lines between threshold and saturation do not appear to differ over these temperatures. The photoperiodic mechanism is thus highly temperature-compensated, maintaining a given set-point (critical photoperiod) and inherent accuracy (slope of the response curve) between ° and 25° C. Although the photoperiodic clock imposes an all-or-none response on each individual over a wide range of tempera- tures, both temperature and photoperiod affect the rate of ensuing development (Fig. IB). These differences in rates of development at various temperatures and photoperiods could be due to either variation in the rate of termination of dia- pause, per sc, or in the completion of post-diapause morphogenesis. Regardless of the 36-1 30- '24- a v_ O S3 a. F. •3 o 18- 12- 6- Chilling Time at 7°C 6 0 Days O 45 Days a 90 Days • 135 Days 180 Days. 100 140 180 220 260 Days on Experirrvental Conditions 300 340 FIGURE 4. Mortality of larvae at 21° C (all photoperiods combined) after various chilling times. Days on experimental conditions refer to days since the start of the initial chilling and do not include rearing times up to the fourth Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustratio
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
