Abstract
Global climate change and anthropogenic disturbance have significantly degraded biodiversity in coral reef ecosystems. The genetic potential and adaptability of corals are key factors used to predict the fate of global coral reefs under climate change. In this study, we used eight microsatellite loci to study the patterns of reproduction, genetic diversity, and genetic structure of 302 Porites lutea samples across 13° latitudes in the South China Sea (8.8644°N–22.6117°N). The results indicated that P. lutea reproduces largely via sexual reproduction on scales of 5 m and greater and has abundant gene diversity. Additionally, the tropical populations harbored high genetic diversity (based on alleles, effective number of alleles, gene diversity, and heterozygosity). In contrast, genetic diversity was lower in subtropical coral populations. Genetic variation values and pairwise FST revealed that tropical and subtropical populations had significantly different genetic structures. Finally, the Mantel tests showed that the genetic differentiation and genetic variation of P. lutea were strongly correlated with sea surface temperature and slightly correlated with geographical distance. These results indicated that tropical P. lutea populations have high genetic potential and adaptability because of their sexual reproduction and genetic diversity, giving them a greater capacity to cope with climate change. Subtropical coral populations showed lower genetic diversity and, thus, relatively poor genetic resilience in response to low average sea surface temperature and human activities. Our study provides a theoretical basis for the protection and restoration of coral reefs.
Highlights
Global warming has greatly decreased biodiversity and poses a critical threat to the health of coral reef ecosystems (Hughes et al, 2017; Thomas et al, 2017)
We focused on (1) the relationship between genetic potential and reproduction patterns and genetic diversity, (2) how genetic structure varies across latitudes, (3) the relationship between P. lutea genetic structure and sea surface temperature (SST) in the South China Sea (SCS), and (4) the genetic potential and adaptability of P. lutea populations in tropical areas
Our findings suggest that sexual reproduction and rich genetic diversity will benefit the adaptability of P. lutea in tropical areas
Summary
Global warming has greatly decreased biodiversity and poses a critical threat to the health of coral reef ecosystems (Hughes et al, 2017; Thomas et al, 2017). An important factor in coral recovery from environmental stress is its genetic potential (Williams et al, 2014), or the ability of a population to evolve under changing selection pressures (Meyers et al, 2005). With increases in environmental stressors such as eutrophication, habitat fragmentation, and climate change, the genetic diversity of keystone species may become increasingly important (Hughes and Stachowicz, 2004). The sea surface temperature, ocean currents, breeding patterns, and geographical distances were the most reported factors affecting genetic characteristics of corals in some coral reefs (Knittweis et al, 2009; Tye et al, 2013; Mclachlan et al, 2020). The corals in high latitudes were more vulnerable than corals in tropical areas to cope with global climate change (Ayre and Hughes, 2004; Miller and Ayre, 2010; Thomas et al, 2017). Genetic diversity is considered to enhance the sustainability of populations over evolutionary time scales by furnishing sufficient alleles for future environment changes (Ayre and Hughes, 2004; Williams et al, 2014)
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