. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 8 12 18 8 10 12 18 8 12 18 ° ° ° PHOTOPERIOD/ TEMPERATURE. PHOTOPERIOD/TEMPERATURE SUBITANEOUS DIAPAUSE NON-VIABLE SUBITANEOUS DIAPAUSE NON-VIABLE FIGURE 2. Subitaneous, diapause, and non-viable egg production (percent) by females reared under 8L-16D, 10L-14D, 12L-12D, or 18L-6D at °C, °C, or °C (±°C). a) Vineyard Sound and Delaware Bay, b) Beaufort and Fort Pierce. Data for Vineyard Sound from Marcus (1980a, 1982b). consistently produced by these females. Females that were collected from the field
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 8 12 18 8 10 12 18 8 12 18 ° ° ° PHOTOPERIOD/ TEMPERATURE. PHOTOPERIOD/TEMPERATURE SUBITANEOUS DIAPAUSE NON-VIABLE SUBITANEOUS DIAPAUSE NON-VIABLE FIGURE 2. Subitaneous, diapause, and non-viable egg production (percent) by females reared under 8L-16D, 10L-14D, 12L-12D, or 18L-6D at °C, °C, or °C (±°C). a) Vineyard Sound and Delaware Bay, b) Beaufort and Fort Pierce. Data for Vineyard Sound from Marcus (1980a, 1982b). consistently produced by these females. Females that were collected from the field in July did not produce diapause eggs. For Delaware Bay animals reared in the laboratory, short day lengths were most effective in the induction of diapause egg production. Although a 12L-12D photoperiod at 18°C did not result in a marked decline of subitaneous egg production compared to 18L-6D, a decline in subitaneous and an increase in diapause egg production was obtained by rearing the animals at 10L-14D at this temperature. The percentage of non-viable eggs produced ranged from to for the entire study, but most values were less than DISCUSSION The results of this study demonstrate that L. aestiva is not genetically homogeneous throughout its range, but rather is composed of distinct populations genetically adapted to local environmental conditions. Within each region the critical photoperiod for diapause induction expressed by the population has been adjusted by natural selection to maximize growth of the species. Due to latitudinal variation in climatic (, temperature, Bumpus, 1957) and day length conditions (U. S. Dept. of Commerce, 1983), disruptive selection has promoted differentiation of populations along the north-south gradient. This divergence has occurred despite the potential for gene flow via transport of planktonic stages in ocean Please note that these images are extracted from scanned page images that may have been
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
