. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Subitaneous 100 50 12 18 Hours of light FIGURE 1. Subitaneous, diapause, and non-viable egg production (percent) by females reared under 8L:16D, 12L:12D, and 18L:6D at °°C (white), °°C (black), and °°C (dots). At °°C and 18L:6D only Subitaneous egg production was Smallman, 1971; Beck, 1980). For each temperature regimen tested, the proportion of diapause eggs produced by the laboratory-reared L. aestiva was greatest at 8L:16D and declined as the period of experimental daylengt
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Subitaneous 100 50 12 18 Hours of light FIGURE 1. Subitaneous, diapause, and non-viable egg production (percent) by females reared under 8L:16D, 12L:12D, and 18L:6D at °°C (white), °°C (black), and °°C (dots). At °°C and 18L:6D only Subitaneous egg production was Smallman, 1971; Beck, 1980). For each temperature regimen tested, the proportion of diapause eggs produced by the laboratory-reared L. aestiva was greatest at 8L:16D and declined as the period of experimental daylength was increased. This response was balanced by a reverse trend for Subitaneous egg production. The percentages of Subitaneous and diapause eggs produced was most affected by photo- period, and the values are comparable to values reported for animals collected from Vineyard Sound at times of the year with correspondingly equivalent daylength periods (Marcus, 1979, 1980). Subitaneous egg production is maximal under long daylength conditions which prevail during the summer, whereas diapause egg pro- duction is greatest under periods of short daylength during the fall. Although photoperiod is the primary factor controlling diapause and subitaneous egg pro- duction, temperature may modify this influence. Within the range of temperature (°°C) usually encountered in Vineyard Sound during September and October, the proportion of subitaneous eggs produced by laboratory-reared cope- pods is similar for any given photoperiod. However, for short daylength periods (, less than 12L:12D), warm temperatures (, °C) induce a greater pro- portion of subitaneous eggs (Table I; Figure 1). These photoperiods prevail in Vineyard Sound after mid-September until the vernal equinox. If water temper- atures were unseasonably warm one fall, then the usual decline in subitaneous egg production should be postponed or more gradual. This would enable the population to take adva
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
