• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.992-996
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• 1997

Study on sexual dimorphism in Littorphism in Littorina brevicula should be interesting to examine that how the species prevent niche-overlap between the sexes? and how the species act differently in the reproductive roles of the sexes? Sexual dimorphism on the shell of L. brevicula was examined with 211 periwinkles larger than 5 mm shell length in Pusan, Korea. Sexual dimorphism was detected in the aperture length only. Aperture length of the female was longer than that of the male. A difference in the sexual role in the reproduction seems to be a probable explanation for the sexual dimorphism in the aperture length. The reproductive role of the male is to choose the best female and to transfer the sperm successfully by copulation, and the role of the female is to spawn their fertilised eggs into the seawater successfully. Perhaps females migrate to lower elevations on the shore than the males, so that they are submerged when they spawn. Because wave action at the lower area of the shore is stranger than that at the higher area on the shore, the females might need larger aperture size than the males to avoid dislodgement.

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.186.2-187
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• 2003

A sexual dimorphism in terbufos (S-t-butylthiomethyl-O,O-diethyl phosphorodithioate: TBF) toxicity was not reported and remains unclear. Previously. we reported that TBF treatment showed sexual dimorphic effects on acetylcholinesterase (AchE) activity. We further investigated that sexual dimorphism of TBF was affected to age and brain-regional selectivity, and whether ovary plays an important role in the effect. (omitted)

• Korean Journal of Ichthyology
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• v.29 no.3
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• pp.176-189
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• 2017

Age estimation and sexual dimorphism of Coreoleuciscus splendidus were estimated using otolith, length-frequency distribution and 23 morphological measurements, from 245 individuals collected from September 2016, February and April 2017 in the Gapyeong stream, Han River, Korea. Result of age estimation of C. splendidus, we most examined were 2, 3 and 4-age, and the maximum observed ages were 5-age. Nine out of twenty-three morphometric measurements were significantly different between the genders. Anal fin have showing major sexual dimorphism in particular between adult individuals. This sexual dimorphism was based on extension of anal fin soft rays of male individuals. Therefore anal fin of males is always longer and wider than females. During spawning season male individuals possess nuptial tubercles on anal fin rays. However, another measurements and morphological characters does not exhibit sexual dimorphism in the between male and female individuals. The sexual dimorphism was observed to only over 2-years old individuals with sexual maturity. But juvenile and 1-years old individuals do not have sexual dimorphism with sexual maturity. Peak season of spawning was April to May and they start first spawning at 2-age. The ages at major spawning groups were most 3-age, and they maximum GSI index was 14.91 (female), 8.96 (male) at 5-age, respectively.

• The Korean Journal of Zoology
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• v.33 no.3
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• pp.260-265
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• 1990

Pungitius sinensis specimens were collected from the Namdae River and Chusu River drained into Sea of Japan, and their morphological characters were investigated to determine if this species shows sexual dimorphism. The ratio of the head length to the body length revealed marked sexual difference; the head length in males was longer than in females. The snout length and body depth at anus showed a tendency to be larger in males than in females. This dimorphism seems to be related to breeding habits. The ethological significance of the larger head of males was discussed.

• Interdisciplinary Bio Central
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• v.6 no.4
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• pp.2.1-2.7
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• 2014

Sexual dimorphism in intelligence suggests that this phenotype is a sexually selected trait. This view is supported by an overrepresentation (compared to the autosomal genome) of genes affecting cognition on the X chromosome. The aim of this study is to test the hypothesis that sexual selection can explain sex and country-level differences in performance on tests of fluid intelligence. Nationally representative samples from N = 44 countries were obtained from the Programme for International Student Assessment (PISA) Creative Problem Solving (CPS), which evaluates the core of intelligence, that is novel problem solving ability. Sexual selection has the double effect of increasing the prevalence of a favored phenotype and reducing genetic variation in sexually selected traits. Matching these predictions from evolutionary theory, the average country fluid intelligence is positively correlated to sexual dimorphism after partialling out per capita GDP and the latter in turn is inversely correlated to variance in intelligence scores within populations. Males have a higher variance than females but there is a negative correlation between male-female difference in variance and sexual dimorphism in intelligence, suggesting that selection reduces variance more in the selected sex. Average country male height is negatively correlated to sexual dimorphism in intelligence, a fact that supports the notion of a trade-off between physical and intellectual competition in the context of access to females. The results of this study, if replicated, imply that genome-wide association studies of cognition may benefit from a focus on sex chromosomes, which so far have been neglected. Another implication of this study is that intelligence has continued to evolve after different human populations migrated out of Africa and possibly up to the 19th century, as suggested by the substantial variability in sex differences even between neighbouring countries.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.515-520
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• 2017

Sexual dimorphism of the mouthpart, antenna and mandible of the Cyllorhynchites ursulus in South Korea was studied with linear measurements. The mouthpart and antenna measurements were conducted with a stereoscopic microscope using 122 specimens (72 males and 50 females). Microscopic observation of the mandible were conducted with a Field Emission Scanning Electron Microscope (FE-SEM) using 103 specimens (73 males and 30 females). Results showed that the size difference between males and females was significant in the size of the mouthpart and antenna. On the other hand, we could not detect sexual size dimorphism in the microstructure of the mandible. The bivariate plots made by the result of Principal Component Analysis (PCA) and Discriminant Analysis (DA) showed a size dimorphism in the size of the mouthpart and the antenna between males and females. Based on our study, sexual dimorphism in the mouthpart and antenna exists in C. ursulus from the South Korean population, and this difference seems to be related to the behavioral differences between males and females.

• Korean Journal of Ichthyology
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• v.8 no.1
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• pp.14-21
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• 1996

The sexual dimorphism of river sculpin (Cottus poecilopus Heckel) was investigated samples were collected from the Chiak stream from January 1993 to April 1994. Sexual dimorphism in body size and some morphological characteristics were observed in this species ; males were larger in size and had a larger mouth, anal fin, ventral fin and pevic fin than females. Males have a genital papilla and nuptial color, but females do not. Females may mate preferentially with large males. Larger males could be superior in nest defense and fanning of eggs to smaller ones, thus resulting in higher survival of eggs. Similary, the larger mouth in males could be advantageous in acquiring and defending their nests. Such sexual dimorphism in this species may reflect to outcome of sexual selection.

• Journal of Ecology and Environment
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• v.31 no.2
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• pp.107-113
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• 2008

We measured a set of 37 morphological characteristics in 97 specimens of adult Korean chub, Zacco koreanus, trapped in the Milyang River, Korea, in May and October of 2005. Twelve out of thirty-seven morphometric measurements were significantly different between the sexes. In particular, both the pectoral fin length and the direct distance between the insertion of the dorsal fin and the insertion of the anal fin were highly significant (p < 0.001). This sexual dimorphism may reflect the outcome of sexual selection in this species.

• Journal of Fisheries and Marine Sciences Education
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• v.29 no.2
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• pp.447-452
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• 2017

A closely associated set of characteristics was analyzed using both classical and truss dimensions to discriminate sexual dimorphism between spawning season and non spawning season in grass puffer, Takifugu niphobles. In non-spawning season, $1{\times}10/Ls$ of classical dimension was significantly different between male and female (P<0.05). In spawning season, $1{\times}9/Ls$ and $1{\times}10/Ls$ of classical dimension, $3{\times}8/Ls$, $3{\times}9/Ls$, $3{\times}10/Ls$, $4{\times}8/Ls$, $4{\times}9/Ls$ and $8{\times}9/Ls$ of truss dimension and $7{\times}9/HL$ of head part dimension were significantly different between male and female (P<0.05). The results of this study may be useful as basic information of other fish species to compare the change of sexual dimorphism between spawning season and non spawning season.

• Journal of Environmental Science International
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• v.32 no.4
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• pp.277-284
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• 2023

Seventy Pipistrellus abramus samples were caught to analyze their sexual dimorphism and mophological characteristics. The mean HB and FA were 50.86 mm and 34.93 mm, respectively, based on external measurements and skull shape. The length of the TL, Hfcu, and Tra were approximately 70%, 55.6%, and 38% of the HB, Tib, and E, respectively. Both the lambdoid crest and the sagittal crest were well developed and the H.BC was approximately 84% of the W.BC. P2 was inside the toothrow and metacone of canine was clearly visible. According to the analysis of sexual dimorphism, the following characteristics were different in between males and females: WS, C-M³, C-C, M³-M³, LOM, LUC, and i-m³. The WS, C-M³, C-C, M³-M³, LOM, and i-m³ were bigger in females than males, whereas the LUC was bigger in males.