Chi Haojun, Sha Zhongli, He Lin, Hui Min
Laboratory of Marine Organism Taxonomy and Phylogeny, Qingdao Key Laboratory of Marine Biodiversity and Conservation Institute of Oceanology, Chinese Academy of Sciences Qingdao China.
University of Chinese Academy of Sciences Beijing China.
Ecol Evol. 2025 Aug 8;15(8):e71965. doi: 10.1002/ece3.71965. eCollection 2025 Aug.
Various hypotheses have been proposed to explain the origin of the high biodiversity in the Indo-Malay Archipelago (IMA), such as the center of origin, overlap zone, and accumulation center; yet these theories remain subjects of ongoing debate. The small giant clams, , are iconic inhabitants of coral reefs and are widely distributed in the Indo-West Pacific. However, due to overexploitation and climate change, wild populations of most giant clam species worldwide have been severely impacted and are now endangered. In this study, () gene sequences of 35 individuals from two populations in the South China Sea (SCS) were amplified and sequenced. These data were integrated with published sequences of from other studies. A total of 610 individuals in 34 locations across the Indian Ocean to the Central Pacific were included in the population genetic analysis based on a 417 bp fragment of . The genetic differentiation index = 0.856 ( = 0.000) shows a significantly differentiated genetic structure, which can be categorized into six distinct groups from west to east, as previously suggested. The populations in the SCS exhibited strong connectivity with the IMA populations, forming a single group. Gene-flow analysis revealed a pattern of migration from the Seas of Southeastern Asia (SEA) towards both the eastern and western directions, supporting the center of origin hypothesis for the high biodiversity of IMA. Historical population dynamics analysis indicated that most groups experienced expansion, primarily associated with the late Pleistocene glaciations. Moreover, the Species Distribution Model (SDM) predicted that climate change might lead to a significant reduction in suitable habitats for and a slight shift towards higher latitudes. These results are expected to provide insights into the origin of the biodiversity in the IMA and baseline data for the conservation of giant clams.
人们提出了各种假说，以解释印度 - 马来群岛（IMA）高生物多样性的起源，例如起源中心、重叠区和聚集中心；然而，这些理论仍是持续争论的主题。小型巨蛤是珊瑚礁的标志性生物，广泛分布于印度 - 西太平洋地区。然而，由于过度开发和气候变化，全球大多数巨蛤物种的野生种群受到了严重影响，现已濒临灭绝。在本研究中，对来自中国南海（SCS）两个种群的35个个体的（）基因序列进行了扩增和测序。这些数据与其他研究中已发表的来自的序列相结合。基于的417 bp片段，对印度洋至中太平洋34个地点的总共610个个体进行了群体遗传分析。遗传分化指数= 0.856（= 0.000）显示出显著分化的遗传结构，如先前所示，可从西到东分为六个不同的组。中国南海的种群与IMA种群表现出很强的连通性，形成了一个单一的群体。基因流分析揭示了从东南亚海域（SEA）向东西两个方向迁移的模式，支持了IMA高生物多样性的起源中心假说。历史种群动态分析表明，大多数群体经历了扩张，主要与晚更新世冰川作用有关。此外，物种分布模型（SDM）预测，气候变化可能导致适合的栖息地显著减少，并略微向高纬度地区转移。这些结果有望为IMA生物多样性的起源提供见解，并为巨蛤的保护提供基线数据。
