. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 108 H. J. BROOK AT AL. m Q O DM O m 100 - 60 - 40 - 20 - 0 ^ w - - - - - Q - O 4.!. A TT TTT T TUJft* B 50 100 150 200 TIME (days) Figure 8. Changes in the external morphology of mature female Gnorimosphaeroma oregnnenxe that survived 200 days in the laboratory or that molted to the terminal mature male stage. (A) Percentage of isopods (n = 14) at each reproductive stage; (B) mean body length (±SE) of these individuals, for each observation interval. males are not necessarily nearing the reproductive
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 108 H. J. BROOK AT AL. m Q O DM O m 100 - 60 - 40 - 20 - 0 ^ w - - - - - Q - O 4.!. A TT TTT T TUJft* B 50 100 150 200 TIME (days) Figure 8. Changes in the external morphology of mature female Gnorimosphaeroma oregnnenxe that survived 200 days in the laboratory or that molted to the terminal mature male stage. (A) Percentage of isopods (n = 14) at each reproductive stage; (B) mean body length (±SE) of these individuals, for each observation interval. males are not necessarily nearing the reproductive molt. The operational sex ratio may thus be skewed towards males, further increasing male-male competition for fe- males that are nearing the reproductive molt, as well as selection for larger male size. Active precopulatory guarding has not been observed in protandrous isopods. Precopulatory behavior may in- volve the passive attachment of the dwarf male onto the larger female, as seen in the parasitic epicarids (Wilson, 1991). There is no evidence, however, that this excludes other males from mating with females in these species. In the protandrous hippolytid shrimp Thor manning! (Bauer. 1986), available evidence suggests that male reproductive success may be independent of size. Although larger males are more frequently paired with females in the partially protandrous shrimp Athanas kominatoensis (Nakashima. 1987), some small males do successfully mate with fe- males. Female fecundity increases with body size, and thus a small male will increase its reproductive output. In both protandrous and protogynous crustaceans, female fecundity is usually positively correlated with body size (Charnov, 1979; Bauer, 1986; Nakashima, 1987; Bamber, 1985; Buss and Iverson. 1981: Kneib, 1992; this study). It appears, therefore, that the advantage gained by larger males in the protogynous crustacean mating system over- rides the selective force of increased female fecundity with increased f
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
