Data from: Changes in Bivalve functional and assemblage ecology in response to environmental change in the Caribbean Neogene

We documented changes in the relative abundance of bivalve genera and functional groups in the southwest Caribbean over the past 11 Myr to determine their response to oceanographic changes associated with the closure of the Central American Seaway ca. 3.5 Ma. Quantitative bulk samples from 29 localities yielded 106,000 specimens in 145 genera. All genera were assigned to functional groups based on diet, relationship to the substrate, and mobility. Ordinations of assemblages based on quantitative data for functional groups demonstrated strong shifts in community structure, with a stark contrast between assemblages older than 5 Ma and those younger than 3.5 Ma. These changes are primarily due to an increase in the abundance of attached epifaunal bivalves (e.g., Chama, Arcopsis, and Barbatia) and a decrease in infaunal bivalves (e.g., Varicorbula and Caryocorbula). Taxa associated with seagrasses, including deposit-feeding and chemosymbiotic bivalves (e.g., Lucina), also increased in relative abundance compared to suspension feeders. The composition of bivalve assemblages is correlated with the carbonate content of sediments and the percentage of skeletal biomass that is coral. Our results strongly support the hypothesis that increases in the extent of coral reefs and Thalassia communities were important drivers of biologic turnover in Neogene Caribbean benthic communities.本研究记录了过去11百万年间加勒比海西南部双壳类属（bivalve genera）及其功能群（functional groups）的相对丰度变化，旨在探究类群对约350万年前中美洲海道（Central American Seaway）关闭所引发的海洋学变化的响应。研究团队对29个采样点获取的定量混合样品进行分析，共得到145个属的106000件标本。所有属级类群均根据其食性、与底质的关联模式以及运动能力被划分为不同功能群。基于功能群定量数据的生物组合排序分析显示，群落结构发生了显著转变：早于5百万年的生物组合与晚于3.5百万年的生物组合之间存在鲜明差异。这类转变主要表现为附着型表栖双壳类（epifaunal bivalves，如Chama、Arcopsis及Barbatia）的丰度上升，以及内栖双壳类（infaunal bivalves，如Varicorbula与Caryocorbula）的丰度下降。与海草生境相关的类群——包括沉积食性（deposit-feeding）与化能共生（chemosymbiotic）双壳类（如Lucina）——相较于悬浮食性类群（suspension feeders），其相对丰度亦有所提升。双壳类生物组合的组成与沉积物碳酸盐含量以及珊瑚骨骼生物量占比显著相关。本研究结果有力支持了下述假说：珊瑚礁与泰来藻（Thalassia）群落分布范围的扩张，是新近纪（Neogene）加勒比海底栖生物群落发生生物更替的重要驱动因素。