Collaborative research: Is hybridization among threatened Caribbean coral species the key to their survival or the harbinger of their extinction?

合作研究：受威胁的加勒比珊瑚物种之间的杂交是它们生存的关键还是它们灭绝的预兆？

• 批准号: 1537959
• 负责人: Iliana Baums
• 金额: $ 69.97万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-10-01 至 2020-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1537959&HistoricalAwards=false
• 关键词: Collaborative; research; hybridization; among; threatened

Reef-building acroporid corals form the foundation of shallow tropical coral communities throughout the Caribbean. Yet, the once dominant staghorn coral (Acropora cervicornis) and the elkhorn coral (A. palmata) have decreased by more than 90% since the 1980s, primarily from disease. Their continuing decline jeopardizes the ability of coral reefs to provide numerous societal and ecological benefits, including economic revenue from seafood harvesting and tourism and shoreline protection from extreme wave events caused by storms and hurricanes. Despite their protection under the U.S. Endangered Species Act since 2006, threats to the survival of reef-building acroporid corals remain pervasive and include disease and warming ocean temperatures that may lead to further large-scale mortality. However, hybridization among these closely related species is increasing and may provide an avenue for adaptation to a changing environment. While hybrids were rare in the past, they are now thriving in shallow habitats with extreme temperatures and irradiance and are expanding into the parental species habitats. Additional evidence suggests that the hybrid is more disease resistant than at least one of the parental species. Hybridization may therefore have the potential to rescue the threatened parental species from extinction through the transfer of adapted genes via hybrids mating with both parental species, but extensive gene flow may alter the evolutionary trajectory of the parental species and drive one or both to extinction. This collaborative project is to collect genetic and ecological data in order to understand the mechanisms underlying increasing hybrid abundance. The knowledge gained from this research will help facilitate more strategic management of coral populations under current and emerging threats to their survival. This project includes integrated research and educational opportunities for high school, undergraduate and graduate students, and a postdoctoral researcher. Students in the United States Virgin Islands will take part in coral spawning research and resource managers will receive training on acroporid reproduction to apply to coral restoration techniques. Current models predict the demise of reefs in the next 200 years due to increasing sea surface temperatures and ocean acidification. It is thus essential to identify habitats, taxa and evolutionary mechanisms that will allow some coral species to maintain their role as foundation fauna. Hybridization can provide an avenue for adaptation to changing conditions. Corals hybridize with some frequency and results may range from the introduction of a few alleles into existing parent species via introgression, to the birth of a new, perhaps better adapted genetic lineage. The only widely accepted coral hybrid system consists of the once dominant but now threatened Caribbean species, Acropora cervicornis and A. palmata. In the past, hybrid colonies originating from natural crosses between elkhorn and staghorn corals were rare, and evidence of hybrid reproduction was limited to infrequent matings with the staghorn coral. Recent field observations suggest that the hybrid is increasing and its ecological role is changing throughout the Caribbean. These hybrids appear to be less affected by the disease that led to the mass mortality of their parental species in recent decades. Hybrids are also found thriving in shallow habitats with high temperatures and irradiance suggesting they may be less susceptible to future warming scenarios. At the same time, they are expanding into the deeper parental species habitats. Preliminary genetic data indicate that hybrids are now mating with each other, demonstrating the potential for the formation of a new species. Further, hybrids appear to be capable of mating with both staghorn and elkhorn coral, perhaps leading to gene flow between the parent species via the hybrid. Research is proposed to address how the increase in hybridization and perhaps subsequent introgression will affect the current ecological role and the future evolutionary trajectory of Caribbean acroporids. Specifically, this collaborative project aims to answer the following questions: 1) What is the historic rate, direction, and degree of introgression across species ranges and genomes? Linkage block analysis based on genome-wide SNP genotyping across three replicate hybrid zones will answer this question. 2) What is the current extent and future potential of later generation hybrid formation? Morphometric and genetic analyses combined with in vitro fertilization assays will be used. 3) What mechanisms allow hybrids to thrive in hot, shallow waters? A series of manipulative in situ and ex situ experiments will determine whether biotic or abiotic factors favor hybrid survival in shallow waters. 4) Are hybrids more disease resistant than the parentals species? Disease transmission assays in reciprocal transplant experiments and histological analysis to determine the extent of disease will be conducted. A multidisciplinary approach will be taken that combines traditional and cutting edge technology to provide a detailed analysis of the evolutionary ecology of Caribbean corals.

珊瑚礁建筑acroporid珊瑚形成整个加勒比海的浅热带珊瑚群落的基础。然而，曾经占主导地位的鹿角珊瑚（鹿角珊瑚）和埃尔克霍恩珊瑚（A.自20世纪80年代以来，palmata）的发病率下降了90%以上，主要是由于疾病。珊瑚礁的持续减少危及珊瑚礁提供众多社会和生态效益的能力，包括海产品捕捞和旅游业带来的经济收入，以及保护海岸线免受风暴和飓风造成的极端海浪事件的影响。尽管自2006年以来受到美国《濒危物种法》的保护，但对造礁顶孔珊瑚生存的威胁仍然普遍存在，包括疾病和可能导致进一步大规模死亡的海洋温度变暖。然而，这些密切相关的物种之间的杂交正在增加，并可能为适应不断变化的环境提供一条途径。虽然杂交种在过去很少见，但它们现在在极端温度和辐射的浅水栖息地中蓬勃发展，并正在扩展到亲种栖息地。其他证据表明，杂交种比至少一个亲本物种更抗病。因此，杂交可能有可能通过与两个亲本物种交配的杂交种转移适应基因来拯救受威胁的亲本物种免于灭绝，但广泛的基因流动可能会改变亲本物种的进化轨迹，并将一个或两个物种推向灭绝。该合作项目旨在收集遗传和生态数据，以了解杂交丰度增加的机制。从这项研究中获得的知识将有助于促进对珊瑚种群在当前和新出现的生存威胁下进行更具战略性的管理。该项目包括高中，本科和研究生的综合研究和教育机会，以及博士后研究员。美属维尔京群岛的学生将参加珊瑚产卵研究，资源管理人员将接受关于顶孔珊瑚繁殖的培训，以应用于珊瑚恢复技术。目前的模型预测，由于海洋表面温度上升和海洋酸化，珊瑚礁将在未来200年内消亡。因此，必须确定生境、分类群和进化机制，使某些珊瑚物种能够保持其作为基础动物的作用。杂交可以为适应不断变化的条件提供一条途径。珊瑚以一定的频率杂交，结果可能从通过基因渗入将一些等位基因引入现有的亲本物种，到一个新的，也许是更好的适应遗传谱系的诞生。唯一被广泛接受的珊瑚杂交系统包括曾经占主导地位但现在受到威胁的加勒比物种，鹿角鹿角珊瑚和A。掌形的过去，源自埃尔克霍恩和鹿角珊瑚之间自然杂交的杂交群体是罕见的，杂交繁殖的证据仅限于与鹿角珊瑚的罕见交配。最近的实地观察表明，在整个加勒比地区，这种混合体正在增加，其生态作用正在发生变化。近几十年来，这些杂交种似乎较少受到导致其亲本物种大规模死亡的疾病的影响。杂交种也被发现在高温和辐照的浅水栖息地蓬勃发展，这表明它们可能不太容易受到未来变暖的影响。与此同时，它们正在向更深的亲本物种栖息地扩张。初步的遗传数据表明，杂交种现在正在相互交配，表明有可能形成一个新物种。此外，杂种似乎能够与鹿角珊瑚和埃尔克霍恩珊瑚交配，这可能导致亲本物种之间通过杂种的基因流动。研究提出，以解决如何增加杂交，也许随后的基因渗入将影响目前的生态作用和未来的进化轨迹的加勒比acroporids。具体来说，这个合作项目旨在回答以下问题：1）在物种范围和基因组之间，基因渗入的历史速率、方向和程度是什么？基于三个重复杂交区的全基因组SNP基因分型的连锁区组分析将回答这个问题。2)下一代杂种形成的目前程度和未来潜力是什么？将使用形态测量和遗传分析结合体外受精试验。3)是什么机制让杂交种在炎热的浅水沃茨中茁壮成长？一系列的原位和非原位实验将确定生物或非生物因素是否有利于杂交在浅水沃茨中的生存。4)杂交种比亲本种更抗病吗？将进行相互移植实验中的疾病传播试验和组织学分析，以确定疾病的程度。将采取多学科方法，结合传统和尖端技术，对加勒比珊瑚的进化生态进行详细分析。

项目成果

STAGdb: a 30K SNP genotyping array and Science Gateway for Acropora corals and their dinoflagellate symbionts

• DOI: 10.1038/s41598-020-69101-z
• 发表时间: 2020-07-27
• 期刊: SCIENTIFIC REPORTS
• 影响因子: 4.6
• 作者: Kitchen, S. A.;Von Kuster, G.;Baums, I. B.
• 通讯作者: Baums, I. B.

Age and intraspecific diversity of resilient Acropora communities in Belize

伯利兹有复原力的鹿角珊瑚群落的年龄和种内多样性

• DOI: 10.1007/s00338-017-1602-9
• 发表时间: 2017
• 期刊: Coral Reefs
• 影响因子: 3.5
• 作者: Irwin, Adele;Greer, Lisa;Humston, Robert;Devlin-Durante, Meghann;Cabe, Paul;Lescinsky, Halard;Wirth, Karl;Allen Curran, H.;Baums, Iliana B.
• 通讯作者: Baums, Iliana B.

Genomic Variants Among Threatened Acropora Corals

• DOI: 10.1534/g3.119.400125
• 发表时间: 2019-05-01
• 期刊: G3-GENES GENOMES GENETICS
• 影响因子: 2.6
• 作者: Kitchen, Sheila. A.;Ratan, Aakrosh;Baums, Iliana B.
• 通讯作者: Baums, Iliana B.

Deep-sea corals provide new insight into the ecology, evolution, and the role of plastids in widespread apicomplexan symbionts of anthozoans

深海珊瑚为生态学、进化以及质体在广泛的珊瑚虫顶端复合体共生体中的作用提供了新的见解

• DOI: 10.1186/s40168-020-00798-w
• 发表时间: 2020
• 期刊: Microbiome
• 影响因子: 15.5
• 作者: Vohsen, Samuel A.;Anderson, Kaitlin E.;Gade, Andrea M.;Gruber-Vodicka, Harald R.;Dannenberg, Richard P.;Osman, Eslam O.;Dubilier, Nicole;Fisher, Charles R.;Baums, Iliana B.
• 通讯作者: Baums, Iliana B.

How old are you? Genet age estimates in a clonal animal

• DOI: 10.1111/mec.13865
• 发表时间: 2016-11-01
• 期刊: MOLECULAR ECOLOGY
• 影响因子: 4.9
• 作者: Devlin-Durante, M. K.;Miller, M. W.;Baums, I. B.
• 通讯作者: Baums, I. B.