Adaptive Evolution In Life-History Strategies Of Invasive Fishes In Lake Fuxian

In the present study, life-history strategies of the invasive populations (in Lake Fuxian) and the original populations (in Lake Chao and Lake Dongting) of three species, Abbottina rivularis, Pseudorasbora parva and Rhinogobius giurinus, were analyzed, with their adaptive evolutionary responses to the environmental conditions in Lake Fuxian discussed. It was found that there had been some marked changes in these fishes' life-history strategies after they were introduced to Lake Fuxian. First, for the invasive populations, the maximum breeding age of A. rivularis increased, as well as the percentage of old individuals of P. parva, which meant the decrease of old individuals' mortality. Annuli of pre-matured A. rivularis and matured P. parva were formed in winter in their original habitats; however, it was in March, April and May in the invaded habitat. Second, the growth rate of A. rivularis increased in the invaded habitat, with larger body size and growth index than those in the original habitats. However, with smaller body size and growth index, the growth rate of P. parva decreased in the invaded habitat. Third, in the invaded habitat, A. rivularis, P. parva and R. giurinus all had prolongation in their breeding durations, with the same initiation time but the delayed termination time of breeding activities. A. rivularis and P. parva began to mature at the age of 1+ years both in the invaded and original habitats. But the body sizes at maturity increased significantly in the invaded habitat. Additionally, the individual fecundity of A. rivularis increased significantly, but those of P. parva and R. giurinus decreased significantly. These results showed that the three fishes experienced some similar changes in their life-history strategies, such as the breeding time, the annuli formation time, the mortality of old individuals, etc. All these changes were adaptive evolutionary response to the environmental conditions in Lake Fuxian, including water temperature, nutrition, fishing stress, and native fishes compositions. These results also showed some different changes in their life-history traits for these fishes, such as fecundity and growth rate, which was due to the difference in their genetic traits and spatial distribution.