Haplotype Network Analysis and Genetic Diversity
Although there is no strong documentation about the mechanisms ofH. leucisculus introduction to Iran, it has been guessed that theH. leucisculus could be accidentally introduced with other cyprinid species with higher commercial values (Abdoli et al., 2022).
The haplotype network of H. leucisculus indicated that all Iranian specimens except for two were positioned with samples in china (Fig. 3). Due to the identification of haplogroups for all 98 specimens studied in different regions, out of the 14 individuals studied in this research, two individuals (op 11, op 12) from the Karun River formed two separate haplogroups. It can indicate the potential of increasing population diversity of H. leucisculus compared to its native distribution area and it may constitute separate haplotypes specific to Iran in the future. Based on haplotype network, almost there is one haplotype for every two individuals sampled and if the number of sampling areas and the number of samples increases, the number of haplotypes will probably increase. Moy et al. (2022) for non-native species resulted that high natural diffusion and human translocation could facilitate gene flow and high genetic diversity between river basins, which may help maintain the invasive potential. based on the observed results of the haplotype network, especially for Karun and the existence of separate haplogroups for this population, guessed according to being the long karun river, this river longest and the highest discharge river in Iran, H. leucisculus easily expands all over Karun River. As with expention of H. leucisculus in Karun River, it can constitute separate haplotypes specific in the future.
It highlighted, the molecular diversity indices, the haplotype and genetic diversity within the species were high ( Table. 1). Also according to table 1, the π of H. leucisculus in the Iranian population was low (0.00337) whereas, in the Chinese population was high (0.01792). The reason may have been affected by the founder effect during the invasion of the Iranian population, resulting in lower genetic diversity than in the Chinese population (Yangtze River basin). This result was like Xu et al. (2001) that believed having genetic diversity for non-native species will help to adapt to new habitats and maintain new population sizes.
Kolbe et al. (2004) mentioned one of the most important features affecting the success of invasive species is haplotype diversity. The haplotype result showed that by removing one haplotype from the population of H. leucisculus in Iran, other haplotypes have replaced it, and this proves that it has had invasive success in Iran’s inland freshwaters.
Johnston et al (2009) founfed one of the important factors in the genetic diversity of invasive species probably is that Propagule Pressure (PP). In fact, PP is the result of the combination of the number of individuals participating in reproduction at any time the invasive species is introduced and the number of introductions. In the other words, an increase of individuals participating in reproduction probably has a direct effect on genetic diversity and releasing large numbers of individuals into the new environment significantly increases the probability will be maintained the genetic diversity of the introduced source population. In some cases, multiple introductions can lead to more high genetic diversity compared to the native distribution area of the invasive population and basically, the reason for this phenomenon is equivalent to the increase in the number of people participating in reproduction (fertilization). New genotypes can adapt to the features of the new environment in a different way from the initially introduced populations and respond to environmental selection pressures. The combination of newly created genotypes with the original invader population can increase the success capacity of these species.