International Journal of Marine Science, 2025, Vol.15, No.2, 53-64 http://www.aquapublisher.com/index.php/ijms 59 formation of species and rapid changes in the genome (Cao et al., 2022). Although groupers generally have little karyotype differentiation, reproductive isolation has gradually increased over time. This suggests that reproductive biology plays an important role in hindering gene flow (Amorim et al., 2024). 7.2 Site fidelity, spawning aggregation, and larval dispersal Groupers have strong site fidelity and spawning aggregation behaviors, which limit gene flow between populations and promote genetic differentiation. The study found that populations within the region have strong self-replenishment capabilities, while inter-regional migration is very rare, indicating that the dispersal of juveniles is limited and local spawning behavior helps maintain unique genetic populations and promotes regional diversification. These behaviors are very important for understanding the spatial distribution and evolution of grouper populations. 7.3 Trophic niche partitioning and ecological speciation Differences in living environment, especially "different food", are the key to the emergence of new species of groupers. For example, closely related groupers live in different areas and eat different foods, so even if they live in the same sea area (such as those in Southeast Asia with many coral reefs), they will gradually become different species. Scientists have found that this change in lifestyle will prompt groupers to evolve into new species-just like they each occupy different "territories" in coral reefs (Stryjewski et al., 2017). Recent genetic studies have also shown that genes that control eating habits and survival skills are particularly susceptible to natural selection when animals differentiate. It is very likely that groupers differentiate into different species in this way (Roycroft et al., 2021; Allio et al., 2021). 7.4 Habitat specialization (e.g., coral reefs vs. rocky reefs) Habitat specialization is a key ecological factor in grouper diversification. Studies have found that groupers originating from marginal areas with less coral resources contribute significantly to species diversity. In large coral reef biodiversity hotspots, coral reefs are the center of survival and a large number of species are concentrated (Stryjewski and Sorenson, 2017). Groupers can adapt to different reef types (such as coral reefs and rocky reefs), which is related to their genetic adaptations in immunity, growth, and reproduction, allowing them to thrive in complex environments (Cao et al., 2022). Geological and climatic events create new ecological opportunities and barriers, further promoting this diversification driven by habitat specialization. 8 Implications of Genomics for Conservation and Fishery Management 8.1 Assessment of genetic diversity and population structure Scientists now use genetic technology to study groupers. Common methods include RAD-seq, SNP analysis, and whole genome sequencing. These technologies can help us understand the genetic differences between different grouper populations and the relationships between them. Studies have found (Jackson, 2014; Sherman team, 2020; Weng team, 2021) that the genetic differences between Nassau grouper and red grouper are mainly affected by two factors: one is the geographical barriers in the sea (such as deep trenches), and the other is their spawning habits. These findings are particularly important for formulating conservation measures. For example, Sherman's team used more precise SNP markers in 2020 to find that the relationship between the various populations of Nassau grouper is more complicated than previously thought. If the old method is used, these details will not be discovered at all. Recently, Begossi's team (2022) also used a similar method to study comb groupers. Not only did they figure out the relationship between this fish and other species, but these findings can also be directly used in artificial breeding and conservation work. For example, farms can now select healthier fry based on genetic information. 8.2 Identification of evolutionarily significant units (ESUs) Genomic data are crucial in identifying ESUs in grouper populations. The clear regional genetic differentiation between Nassau grouper and leopard grouper means that different grouper subpopulations require different management strategies. These studies also suggest that international cooperation and standardized management
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