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.