. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EXTENDED MALE PHASE IN A HERMAPHRODITIC SHRIMP 351 then placed in aquaria of the suboptimal treatment to in- crease water temperature to that of the optimal treatment, and photoperiod was changed to 14-h light: 10-h dark, simulating a change from fall/winter to spring/summer con- ditions. The experiment then continued for another 8 weeks. The shrimps were maintained and checked for molts as in the previous experiment. Male-phase individuals that changed to FP (brood of embryos observed) were removed from the experiment and p
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EXTENDED MALE PHASE IN A HERMAPHRODITIC SHRIMP 351 then placed in aquaria of the suboptimal treatment to in- crease water temperature to that of the optimal treatment, and photoperiod was changed to 14-h light: 10-h dark, simulating a change from fall/winter to spring/summer con- ditions. The experiment then continued for another 8 weeks. The shrimps were maintained and checked for molts as in the previous experiment. Male-phase individuals that changed to FP (brood of embryos observed) were removed from the experiment and preserved. When only one MP remained in an aquarium, it was removed when it reached the late transitional stage (mature vitellogenic ovotestes), with the assumption that it would have transformed to FP at the next molt. This was done because it could not have produced a brood of embryos (visible evidence of sex change) upon molting to FP without a mating partner. Results Occurrence of large MPs Large MPs. denned as MPs > mm CL. composed to 100% of the MP population (Fig. 1). with higher proportions of large MPs in the fall through early spring 100 -, large MPs Jun 99 - May 00 22. 5 Jun Jul Aug Sept Oct Nov Dec Jan Feb Mar Apr May Jun 00 - Jun 01 100 -, I1 9S 68 80 - \ j 60 - 210 26° j n - \ 226 40 - 20 1 ii \ ' , if -1 fa Jun Aug Oct Dec Mar Apr Jun Month Figure 1. Temporal variation in percent frequency of large and very large male-phase (MPl individuals, and of female-phase (FP) individuals. Frequency (converted to percent) for large MPs = (# large MPs)/(# total MPs); very large MPs = (# very large MPs)/(# large MPs); FPs = (# FPs (/(total # individuals in population sample). Percent total MPs = 100 - % FPs. Months in which sampling occurred are listed on the abscissa. The number of individuals in population samples is given above the histogram bars for each month. 100 -| ^ 2 » Jun 99 - May 00 « • Jun 00 -May 01 ^ 3 14 A Jun 01 80 - 0 c CD 3 o- 60 - £ •*
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
