Bioscience Methods 2025, Vol.16, No.4, 173-182 http://bioscipublisher.com/index.php/bm 1 76 nocturnal foraging of snackshell fish (Lim et al., 2020). In addition, ammonia excretion is closely related to foraging activities and usually peaks in the early morning, indicating a high metabolic efficiency. Under different light cycles and foraging conditions, O. marmorata can maintain a relatively high metabolic rate, indicating that O. marmorata can effectively adapt to changes in environmental factors such as temperature, humidity and oxygen content, can adapt to different habitats such as rivers and reservoirs, and can cope with difficulties occurring in various natural and artificial environments. Figure 1 Histogam populasi O.marmorata di Waduk Sempor (Adopted from Lestari et al., 2019) 4.3 The Relationship between gene flow and habitat and its impact on species distribution Genetic analysis of mitochondrial DNA (COI gene) indicates that the genetic similarity between domesticated populations and wild populations in Indonesia is relatively high. Some individuals are very similar, while there are only minor genetic differences among others (Syaifudin et al., 2021). There is a continuous flow of genes among populations, which may be the result of the combined promotion of natural diffusion and aquaculture activities. This gene flow helps to form cross-regional genetic homogeneity, allowing O. marmorata to expand into new habitats. Understanding the relationship between gene flow and habitat can help us understand the distribution pattern of the marble goby. A higher gene flow can enhance the adaptability of O. marmorata, enabling them to establish populations in constantly changing environments. Excessive gene flow will reduce the occurrence of local genetic differentiation and slow down the adaptability of marble goby to specific environments. In the population of O. marmorata, the cross-regional genetic connectivity enables O. marmorata to successfully expand their growth area geographically and adapt to the ecology. 5 Molecular Evidence and Genetic Diversity 5.1 Application of molecular markers in the study of species genetic diversity Molecular markers have played an important role in evaluating the genetic diversity of O. marmorata. ISSR (simple sequence repetition) markers are used to analyze the genetic differences of populations from different geographical regions, such as Guangzhou and Sanya. Yao et al.'s (2012) study found that the proportion of polymorphic loci was relatively high (83.87%), and the Shannon information index was significant, indicating significant genetic diversity both within and outside the population. Most genetic differentiations result from variations within the population rather than genetic drift. The UPGMA tree does not show obvious population boundaries, indicating the existence of gene flow among different populations. O. marmorata has established an amplified fragment length polymorphism (AFLP) labeling system, providing high-resolution genetic material for the O. marmorata. These markers screened out 14 pairs of effective selective primers, which played an important role in the study of species genetic diversity and molecular-assisted selection, demonstrating the application value of molecular markers in wild and farmed populations (Zhu et al., 2012). The
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