. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. '14 A. M. WENNER AND C. FUSARO 100 (J4ff) 80 CD UJ 60 UJ o UJ CL 40 20 (/V--/9) o o o \ l° A. 4 56 78 9 10 II 12 13 14 15 16 17 18 SIZE CLASS (mm) FIGURE 5. A discrepancy between sex ratio curves (sex ratio as a function of size— Wenner, 1972). A sigmoid curve ("reversal pattern") was obtained in 1972 when approxi- mately 2000 animals were collected from six beaches on five different islets (A). A new pat- tern ("oscillation pattern") emerged when 4011 animals were removed from a single beach in the prese
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. '14 A. M. WENNER AND C. FUSARO 100 (J4ff) 80 CD UJ 60 UJ o UJ CL 40 20 (/V--/9) o o o \ l° A. 4 56 78 9 10 II 12 13 14 15 16 17 18 SIZE CLASS (mm) FIGURE 5. A discrepancy between sex ratio curves (sex ratio as a function of size— Wenner, 1972). A sigmoid curve ("reversal pattern") was obtained in 1972 when approxi- mately 2000 animals were collected from six beaches on five different islets (A). A new pat- tern ("oscillation pattern") emerged when 4011 animals were removed from a single beach in the present study (B). Out of several hundred small animals in 1972, only one was female (the first point in Fig. 1A). Data for initial samples in the current study yielded neither the Hawaii nor the earlier Enewetak sex ratio patterns; a sex ratio pattern existed which had not been found earlier (Fig. 5B). Instead, the percentage of males oscillated with increase in crab size. It is further evident that the number of oscillations cor- responded well with the basic number of modal size classes found for males and females in the comparable size ranges ( Fig. 2). The "oscillation" sex ratio pattern is what one might expect if the following conditions apply: first, the population consists of different cohorts which have arrived at different times from the plankton (three recent cohorts in this case), second, one sex grows faster than the other (females in this case—see Haley, 1979), and third, one sex reaches a maximum size, while the other sex continues growth beyond that size (females in this case). For the first three samples of the present study, the sex ratio curve formed by the data for all animals greater than 10-mm carapace length nearly exactly matched that same portion of the curve for the total number of animals collected, as seen in Figure 5B. For the 86 animals in the first three samples which were 10 mm and smaller, however, only 28% were males, a point wh
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
