Effect of Warming on Personality of Mosquitofish (Gambusia affinis) and Medaka Fish (Oryzias latipes)

Temperature is a pervasive environmental factor influencing animal behavior, yet its effects on the personalities of invasive and native species remain largely unexplored. In this study, we simulated temperature increases from climate change in our lab, i.e., constant temperature treatment (control group) and warming treatment (warming group); the control group temperature was kept at 20 degrees C, the warming group treatment temperatures were 20 degrees C, 25 degrees C, and 30 degrees C. We reared mosquitofish and medaka fish under different treatments and measured personality (sociability, exploration, novelty, and boldness) in various temperature environments. The results showed that individuals of both species exhibited repeatable variation along the four behavioral axes across all temperature conditions. Sociability was significantly positively correlated with exploration, novelty, and boldness in both species, suggesting the presence of behavioral syndromes. Compared to medaka fish, mosquitofish exhibited higher dispersal ability and greater exploration in elevated temperature environments. These findings indicate that temperature is a crucial factor influencing animal personality and that the dispersal of mosquitofish may pose a potential threat to the survival of native species such as medaka fish. Global warming may accelerate the process of biological invasions, and invasive species that can quickly adapt to new environments will have a negative impact on native species. Animal personalities have significant implications for ecology and evolution. However, few studies have simultaneously examined the combined effects of climate warming and biological invasions on native species. In this study, we hypothesized that temperature was positively correlated with personality, and invasive species had stronger personalities than native species. Accordingly, we established control (20 degrees C) and warming groups (20 degrees C, 25 degrees C, and 30 degrees C) to rear mosquitofish and medaka fish, individuals acclimatized to rearing temperatures for 7 days, then measured their personalities (sociability, exploration, novelty, and boldness). The results showed that individuals exhibited repeatable variation along the four behavioral axes across all temperature conditions, providing evidence for the presence of personalities. Significant positive correlations were found between each pair of behaviors, indicating the presence of behavioral syndrome. Sociability and exploration were most affected by temperature, showing increasing trends in sociability, exploration, and novelty in both invasive and native species with rising temperatures. Compared to medaka fish, mosquitofish exhibited higher exploration and lower sociability at elevated temperatures, while showing little change in boldness. Our results provide evidence that increased temperatures may promote biological invasions and pose a potential threat to the survival of native species. These findings are significant for understanding the complex impacts of climate change on ecosystems and for formulating effective biodiversity preservation strategies.