变异轴孔珊瑚(Acropora valida)对酸化高温胁迫的转录组水平反应及恢复潜力分析

采用RNAseq测序技术对比变异轴孔珊瑚(Acropora valida)在酸化高温胁迫及去胁迫条件下的mRNA转录组。构建了12个cDNA文库,共获得451789689个双端片段。通过拼接共得到1 056 727个转录本,其中86.5%匹配到珊瑚序列。转录本的差异表达分析显示,胁迫条件下共6 328个转录本发生了显著变化,主要涉及热休克蛋白、物质转运蛋白、凋亡调节和钙化四个方面。其中98.1%的差异表达转录本在胁迫去除后都能恢复到对照组水平;结果表明,尽管变异轴孔珊瑚在酸化高温胁迫时受到很大影响,但其转录本表达在胁迫去除后能恢复到原来的水平。首次探究酸化高温双胁迫去除后变异轴孔珊瑚转录本表达水平的恢复潜力,对研究珊瑚如何应对全球气候变化有一定指导意义。     

Genetic seascape of the threatened Caribbean elkhorn coral,Acropora palmata,on the Puerto Rico Shelf

It has been proposed that the elkhorn coral Acropora palmata is genetically separated into two distinct provinces in the Caribbean, an eastern and a western population admixing in Western Puerto Rico and around the Mona Passage. In this study, the genetic structure of A. palmata sampled at 11 Puerto Rican localities and localities from Curaçao, the Bahamas and Guadeloupe were examined. Analyses using five microsatellite markers showed that 75% of sampled colonies had unique genotypes, the rest being clone mates. Genetic diversity among genets was high (H_E = 0.761) and consistent across localities (0.685–0.844). F_ST ranged from ?0.011 to 0.047, supporting low but significant genetic differentiation between localities within the previously reported eastern and western genetic provinces. Plots of genetic per geographic distances and significant Mantel tests supported isolation‐by‐distance (IBD) within Puerto Rico. Analysis with the software STRUCTURE favored a scenario with weak differentiation between two populations, assigning Eastern Puerto Rican locations (Fajardo and Culebra), Guadeloupe and Curaçao to the Caribbean eastern population and Western Puerto Rican locations (west of Vega Baja and Ponce), Mona and the Bahamas to the Caribbean western population. Vieques and San Juan area harbored admixed profiles. Standardized F_ST per 1000 km unit further supported higher differentiation between localities belonging to different STRUCTURE populations, with IBD being stronger within Puerto Rico than on larger regional scales. This stronger genetic transition seems to separate localities between putative eastern and western provinces in the Eastern Puerto Rican region, but not around the Mona Passage.     

海水升温对壮实鹿角珊瑚幼虫存活和附着的影响

研究海水升温对石珊瑚幼虫存活及附着的影响有助于理解和预测海洋暖化背景下幼虫的扩散和种群补充动态.探究了海水升温(+3℃)对壮实鹿角珊瑚(Acropora robusta)幼虫存活和附着的影响.两个温度下孵育7d后幼虫的存活率均大于90%,升温对珊瑚幼虫的存活并无明显的影响;在孔水石藻(Hydrolithon onkodes)诱导下,3℃的升温使珊瑚幼虫的附着率提高了75%,同时升温改变了珊瑚幼虫的附着选择:30℃下孵育7d的幼虫中附着在塑料六孔板表面的比例是27℃条件下孵育的幼虫的13倍,然而二者中附着于珊瑚藻表面和侧面骨骼的幼虫比例相近.研究表明环境温度3℃以上7d的升温处理并不影响壮实鹿角珊瑚幼虫的存活,但会促进幼虫的附着进而缩短幼虫的浮游期,升温会限制珊瑚幼虫的扩散并对排卵型珊瑚种群间的遗传连通性产生潜在影响.     

Reproductive synchrony in a diverse Acropora assemblage,Vamizi Island,Mozambique

Multi‐specific synchronous spawning has never been documented for East Africa, but coral spawn‐slicks are observed annually around Vamizi Island, Northern Mozambique. We monitored gamete development in Acropora species from July 2012 to October 2013 and from August to September 2014 to describe patterns of reproductive seasonality and synchrony within and amongst species of Acropora. Gamete maturation was highly synchronized within and amongst Acropora species and culminated in multi‐specific spawning events lasting 1–3 nights in each year of the study, in late August or September. In 2013 and 2014, 50% or more of the colonies of over 50% of the species sampled prior to the spawning events had mature gametes. In all years, 91–99% colonies sampled after the spawning events had no visible gametes. The percentage of colonies with mature gametes was up to 100% for some species. In other species, the absence of mature gametes throughout the study period indicates that they might not spawn in certain years. The analysis of a 8‐year record of observations of spawn‐slicks showed that spawning generally occurred once a year for a few consecutive days between September and December, during periods of rising sea surface temperature and low wind speed and rainfall. This study is the first to quantitatively document coral reproduction in Mozambique and multi‐specific synchronous spawning off the coast of Africa. These findings contrast with the asynchronous breeding reported for Kenyan reefs and support the absence of breakdown in coral reproductive synchrony towards low latitudes.