Abstract
ABSTRACTTo explore the differences in the swimming ability and environmental adaptive abilities between male and female Gambusia affinis, we assessed the differences in burst swimming speeds (Uburst), critical swimming speeds (Ucrit) and their related fin areas, and consumption of energy substances after starvation at 0 (control group), 15, 30, 45, and 60 days, respectively. The results showed that the pectoral and caudal fin areas did not differ significantly between male and female G. affinis. However, the dry mass, condition factors, and absolute contents of glycogen, lipids, and proteins were significantly elevated in females in the control group (P<0.05), whereas Uburst and Ucrit were significantly low (P<0.05). After starvation of 60 days, the rate of consumption of lipids was significantly low in the females (P<0.05). Although Uburst and Ucrit decreased linearly with increased duration of starvation, the coefficient of linear equation between Ucrit and starvation time was significantly lower in females than males (P<0.05). These findings indicated that low body mass and condition factors reduce the relative bear load and moving resistance that causes high swimming performance in male G. affinis. High contents of energy substances and low rate of consumption of lipids result in stable Ucrit in females during hunger.
Highlights
Swimming performance is crucial for the survival of fish in aquatic environments and is considered a crucial determinant of the fitness of fish (Oufiero and Garland, 2009)
When the pectoral and caudal fin areas of G. affinis were considered together with dry mass, the ratio of the pectoral fin area to dry mass and the ratio of the caudal fin area to dry mass were both significantly higher in males than females at 0-15 days of starvation (P
Our previous study showed that the size of caudal and pectoral fins are related to the swimming ability as the large size of caudal and pectoral fins can accelerate vast amounts of water and facilitate propulsion during swimming (Li et al, 2016)
Summary
Swimming performance is crucial for the survival of fish in aquatic environments and is considered a crucial determinant of the fitness of fish (Oufiero and Garland, 2009). The speed of swimming of fish is primarily categorized into burst swimming speed (Uburst) and critical swimming speed (Ucrit) according to the levels of oxygen demand. Burst swimming is powered anaerobically by white muscle and is considered as the highest speed; it is used only for a short period (
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