Dimorphism Fish Freshwater Sexual

Ichthyological Research. The population structure of the Japanese fluvial sculpin, Cottus pollux large egg type , in the upper reaches of the Inabe River, Mie Prefecture, central Japan, was investigated by a mark-and-recapture method from July to January Breeding of the species occurred from mid February to early May, peaking from mid February to late March. The mean size of mature males observed in March was significantly larger than that of females, showing apparent sexual size dimorphism. Data analysis of the growth of marked individuals revealed that the species matured at 2 years of age in both sexes. Whereas 1 year old males reached ca.
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New species of fish displays striking color difference between males and females

Use the link below to share a full-text version of this article with your friends and colleagues. Learn more. Abstract — The different reproductive roles of the sexes can predict the direction and magnitude of sexual dimorphism of external and internal morphology. Males should have enlarged structures that enhance the acquisition of mating opportunities, whereas females are predicted to have enlarged organs that are associated with the production of eggs. We tested these predictions in male and female lake whitefish, a species in which both sexes have similar overall body size and shape.

Sexual dimorphism

Sexual dimorphism is the condition where the two sexes of the same species exhibit different characteristics beyond the differences in their sexual organs. The condition occurs in many animals and some plants. Differences may include secondary sex characteristics , size, weight, color, markings, and may also include behavioral and cognitive differences. These differences may be subtle or exaggerated, and may be subjected to sexual selection.
Sexual size dimorphism is an interesting phenomenon occurred in many fish species. Wildtype zebrafish exhibits a significant sexual dimorphism in body size at the adult stage. Previous studies indicated that sexual size dimorphism was eliminated in stat5b -mutated zebrafish. Herein, the comparative transcriptome analysis was conducted to observe the genes and pathways involved in sexual size dimorphism. The number of male-biased and female-biased genes was much less in the liver of stat5b mutant zebrafish than in wildtype.
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