Northward shift in faunal diversity is a general pattern of evolution of the phanerozoic marine biota

The analysis of two global databases on spatio-temporal distribution of fossil marine animal genera (Sepkoski's compendium and The Paleobiology Database) has revealed the presence of the latitudinal diversity gradient (LDG) in the marine realm throughout the Phanerozoic. Within each time interval, LDG is characterized by two parameters: the latitudinal position of peak diversity and the steepness of monotonous decline of diversity with increasing distance from the zone of the highest diversity. During the Phanerozoic, peak diversity has drifted gradually from the tropics and subtropics of the Southern hemisphere into northern midlatitudes. The shift in peak diversity is not likely to be an artifact of incompleteness of the fossil record or uneven sampling of different regions. The shift proceeded in a stepwise manner, with periods of relatively fast changes separated by longer periods of little or no change. The latitudinal shift in peak diversity was probably due to a combination of several causes: tectonic (northward shift in the latitudinal distribution of continental shelf area), climatic (as demonstrated by the fact that peak diversity tended to occur near equator during the cold epochs and in midlatitudes during the warm epochs), and historical ("evolutionary inertia" of local faunas).     

Convergent evolution masks extensive biodiversity among marine coccoid picoplankton

Coccoid picoplankters are minute unicellular algae that, when viewed with a light microscope, appear as little balls. They comprise an important component of open-ocean phytoplankton, and, except for colour differences (i.e. red, green, brown), many eukaryotic picoplankters are morphologically similar. To evaluate the biological diversity of the little brown ball subpopulation of little balls, we randomly selected nine undescribed algal strains and compared the nucleotide sequences of their nuclear 18S ribosomal RNA genes. The results indicate that little brown balls have evolved independently in three distinct eukaryotic lineages (heterokont algae, haptophyte algae, and green algae), and at least four taxonomic classes, and that, even within the four classes, considerable genetic diversity exists. These findings suggest that a tiny coccoid morphology confers some adaptive advantage in the open ocean, that repeated convergent evolution has occurred, and that molecular data may be necessary for taxonomic distinction of closely related coccoid picoplankters.     

Relationship between the alpha diversity of communities and the appearance rates of new genera in the evolution of phanerozoic marine biota

The influence of the alpha diversity of communities on the appearance rates of new species may be either positive (due to coevolution and niche construction) or negative (due to community saturation). The development of global paleontological databases allows the extrapolation of the analysis of these effects to past geological epochs. To assess the effect of alpha diversity on the rates of generic formation in the evolution of the Phanerozoic marine biota, the correlation of the parameters D (mean generic diversity of paleontological collections containing representatives of a large taxon) and B (relative rate of the appearance of new genera in the given large taxon) was analyzed. The majority of large taxa, and the Phanerozoic biota in general, characteristically show predominance of periods of positive correlation (synchronous changes) of B and D, separated by shorter periods of negative correlation (opposite phase changes). These can be interpreted as periods of positive and negative influence of alpha diversity on diversification, although positive correlation can be generated by other factors, including taphonomic ones. Apparently, in the evolution of the Phanerozoic marine biota, the coevolution and “niche construction” played a more significant role than the effect of “saturation” of communities.     

近5.4亿年以来生物多样性的变化

简要介绍了地质年代表的划分以及地球历史中的重要类群的起源时间;重点介绍了5.4亿年以来有关生物多样性变化的研究。生命发展史表明人类需要保护生物多样性来维持自己的生存。     

The origin and evolution of coral species richness in a marine biodiversity hotspot*

The Coral Triangle (CT) region of the Indo‐Pacific realm harbors an extraordinary number of species, with richness decreasing away from this biodiversity hotspot. Despite multiple competing hypotheses, the dynamics underlying this regional diversity pattern remain poorly understood. Here, we use a time‐calibrated evolutionary tree of living reef coral species, their current geographic ranges, and model‐based estimates of regional rates of speciation, extinction, and geographic range shifts to show that origination rates within the CT are lower than in surrounding regions, a result inconsistent with the long‐standing center of origin hypothesis. Furthermore, endemism of coral species in the CT is low, and the CT endemics are older than relatives found outside this region. Overall, our model results suggest that the high diversity of reef corals in the CT is largely due to range expansions into this region of species that evolved elsewhere. These findings strongly support the notion that geographic range shifts play a critical role in generating species diversity gradients. They also show that preserving the processes that gave rise to the striking diversity of corals in the CT requires protecting not just reefs within the hotspot, but also those in the surrounding areas.     

Proximate sources of marine biodiversity

When temperature and other kinds of barrier divide formerly continuous populations and confine them to more restricted geographical areas, there is an evolutionary reaction that will, over time, result in the formation of endemic species. In such cases, an allopatric speciation process is considered to have taken place because reproductive isolation was caused by physical means instead of by natural selection. In contrast, when populations exist in a very high-diversity area and remain undivided by physical events, they exhibit a tendency to speciate by means of sympatry (or parapatry). This process, sometimes called competitive or ecological speciation, does involve reproductive isolation by means of natural selection. Populations that exist in geographical provinces bounded by physical barriers add to the overall diversity through the production of endemic species. This increase by species packing is relatively slow due to the very gradual tempo of the allopatric speciation process. Populations existing in centres of origin add to the general diversity through the production of species that are dominant in terms of their ability to spread over large parts of the world. It is proposed that such species are usually formed by sympatric speciation, a process that can be c. 20 times faster than species formation by allopatry. It is not suggested that sympatry is exclusive to centres of origin, nor that allopatry is confined to peripheral provinces. Both processes are widespread, but there do appear to be distinctive geographical concentrations. Considering that numbers of widespread species produced by centres of origin may eventually become subdivided by barriers, and thus give rise to descendants by allopatry, it is difficult to say how much of our present species diversity has come from one source or the other. Both speciation by sympatry from centres of origin and speciation by allopatry in peripheral provinces appear to be important sources of marine biodiversity.     

Ecology and evolution of mammalian biodiversity

Mammals have incredible biological diversity, showing extreme flexibility in eco-morphology, physiology, life history and behaviour across their evolutionary history. Undoubtedly, mammals play an important role in ecosystems by providing essential services such as regulating insect populations, seed dispersal and pollination and act as indicators of general ecosystem health. However, the macroecological and macroevolutionary processes underpinning past and present biodiversity patterns are only beginning to be explored on a global scale. It is also particularly important, in the face of the global extinction crisis, to understand these processes in order to be able to use this knowledge to prevent future biodiversity loss and loss of ecosystem services. Unfortunately, efforts to understand mammalian biodiversity have been hampered by a lack of data. New data compilations on current species' distributions, ecologies and evolutionary histories now allow an integrated approach to understand this biodiversity. We review and synthesize these new studies, exploring the past and present ecology and evolution of mammalian biodiversity, and use these findings to speculate about the mammals of our future.     

生物多样性起源与进化研究进展

生物多样性的起源与进化是生命科学领域最重要的科学问题之一。多组学数据的积累和相关分析技术的发展, 极大地推动了人们对生物多样性起源与进化的理解和研究, 使得阐明生物进化事件发生的过程与机制成为可能。值此《生物多样性》创刊30周年之际, 本文简要回顾生物多样性起源与进化相关研究在近年来取得的重要研究进展, 以期帮助读者了解该研究方向的发展现状。过去10年中, 生物多样性起源与进化相关研究在生命之树重建、生物多样性时空分布格局、物种概念、物种形成与适应性进化以及新性状起源与多样化等方面取得了许多重要进展, 并在此基础上厘清了许多分类单元间的系统发育关系、揭示了生物多样性分布格局的部分历史成因、提出了新的物种概念和物种形成模型、阐明了新性状和新功能发生的部分分子机制。我们认为, 更精准地重建生命之树、深入挖掘基因组数据以及多学科交叉融合将是今后生物多样性研究的主要趋势。     

Digest: Floral evolution through the lens of the community context*

How do emergent properties of natural plant communities affect floral evolution? In this issue, Eisen et al. explored this question by studying selection on floral traits in natural communities of Clarkia species. They found that two community properties, namely congeneric species richness and floral density (of conspecifics and heterospecifics), influenced the patterns of selection, although not through the expected means of pollinator-mediated selection. Instead, the authors suggest that additional factors like competition and facilitation between plants are responsible. The results support the hypothesis that, beside pollinators, other factors of the community context can also determine floral evolution.     

Antarctic marine biodiversity and deep-sea hydrothermal vents

The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented from many sites across the globe, associated with the thermally and chemically variable habitats found around these, typically high temperature, streams that are rich in reduced compounds and polymetallic sulphides. The animal communities of the East Scotia Ridge vent ecosystems are very different to those elsewhere, though the microbiota, which form the basis of vent food webs, show less differentiation. Much of the biological significance of deep-sea hydrothermal vents lies in their biodiversity, the diverse biochemistry of their bacteria, the remarkable symbioses among many of the marine animals and these bacteria, and the prospects that investigations of these systems hold for understanding the conditions that may have led to the first appearance of life. The discovery of diverse and unusual Antarctic hydrothermal vent ecosystems provides opportunities for new understanding in these fields. Moreover, the Antarctic vents south of 60°S benefit from automatic conservation under the Convention on the Conservation of Antarctic Marine Living Resources and the Antarctic Treaty. Other deep-sea hydrothermal vents located in international waters are not protected and may be threatened by growing interests in deep-sea mining.     

Economic growth and biodiversity

I argue that there is no fundamental conflict between economic growth and biodiversity. Humans can maintain and produce biological diversity just as we can maintain and produce other goods. Efforts to preserve and enhance biodiversity add to the size and growth of the economy. We are losing biodiversity because of human preferences and human inefficiencies, not because of economic growth. Inefficiency occurs when our actions do not reflect our real preferences, and is mainly due to failures of social coordination. To alleviate the problem of biodiversity loss we should address these failures.     

海洋生物多样性损害与沿海地区经济增长关系实证研究

海洋生物多样性是海洋生态系统服务的基础,保护海洋生物多样性不仅对维持地球生态系统的功能至关重要,也与人类福祉密切相关。基于沿海11个省区生态系统亚健康程度指标和物种多样性损害指标,运用面板回归模型对中国沿海地区经济增长与海洋生物多样性损害的关系进行实证考察。研究结果表明：(1)海洋生态系统亚健康程度与沿海地区经济增长之间存在显著的线性关系,随着经济增长,典型海洋生态系统亚健康状态占比呈现出持续上升趋势。此外,实施排污费制度和建立海洋自然保护区有利于抑制海洋生态系统的恶化。(2)海洋物种多样性损害与沿海地区经济增长之间存在显著“倒U”型关系,随着经济增长,海洋物种多样性损害呈现先上升后下降的态势,转折点为人均GDP 45145元,目前海南省、广西壮族自治区、河北省未跨过转折点。此外,排污费制度有利于抑制海洋物种多样性损害,而沿海地区目前的产业结构加重了海洋物种多样性损害。根据实证分析结果,海洋生态系统健康尚未出现拐点,沿海地区经济增长如果建立在对生态环境破坏的基础上,则势必会造成生物多样性的损害。因此从规范海域利用方式,完善海岸生态保护红线划定,加强生态系统的监测与管理,保持绿色可持续的...     

Highly diverse, poorly studied and uniquely threatened by climate change: an assessment of marine biodiversity on South Georgia's continental shelf

We attempt to quantify how significant the polar archipelago of South Georgia is as a source of regional and global marine biodiversity. We evaluate numbers of rare, endemic and range-edge species and how the faunal structure of South Georgia may respond to some of the fastest warming waters on the planet. Biodiversity data was collated from a comprehensive review of reports, papers and databases, collectively representing over 125 years of polar exploration. Classification of each specimen was recorded to species level and fully geo-referenced by depth, latitude and longitude. This information was integrated with physical data layers (e.g. temperature, salinity and flow) providing a visualisation of South Georgia's biogeography across spatial, temporal and taxonomic scales, placing it in the wider context of the Southern Hemisphere. This study marks the first attempt to map the biogeography of an archipelago south of the Polar Front. Through it we identify the South Georgian shelf as the most speciose region of the Southern Ocean recorded to date. Marine biodiversity was recorded as rich across taxonomic levels with 17,732 records yielding 1,445 species from 436 families, 51 classes and 22 phyla. Most species recorded were rare, with 35% recorded only once and 86% recorded <10 times. Its marine fauna is marked by the cumulative dominance of endemic and range-edge species, potentially at their thermal tolerance limits. Consequently, our data suggests the ecological implications of environmental change to the South Georgian marine ecosystem could be severe. If sea temperatures continue to rise, we suggest that changes will include depth profile shifts of some fauna towards cooler Antarctic Winter Water (90-150 m), the loss of some range-edge species from regional waters, and the wholesale extinction at a global scale of some of South Georgia's endemic species.     

Contrasting patterns in species boundaries and evolution of anemonefishes (Amphiprioninae, Pomacentridae) in the centre of marine biodiversity

Many species of coral reef fishes are distinguished by their colour patterns, but genetic studies have shown these are not always good predictors of genetic isolation and species boundaries. The genus Amphiprion comprises several species that have very similar colouration. Additionally, morphological characters are so variable, that sibling species can show a considerable overlap, making it difficult to differentiate them. In this study, we investigated the species boundaries between the sibling species pair A. ocellaris and A. percula (Subgenus Actinicola) and three closely related species of the subgenus Phalerebus (A. akallopisos, A. perideraion, A. sandaracinos) by phylogenetic analysis of mitochondrial cytochrome b and control region sequences. These two subgenera show strong differences in their patterns of species boundaries. Within the A. ocellaris/A. percula complex, five clades were found representing different geographic regions. Two major divergences both with genetic distances of 4-7% in cty b and 17-19% in the d-loop region indicate the presence of three instead of two deep evolutionary lineages. The species of the subgenus Phalerebus show three monophyletic clades, independent of the geographical location of origin, but concordant to the morphological species classification. The genetic distances between the Phalerebus species were 2-5% in cty b and 10-12% in the control region.     

Advancing our understanding of the connectivity,evolution and management of marine lobsters through genetics

The genomic revolution has provided powerful insights into the biology and ecology of many non-model organisms. Genetic tools have been increasingly applied to marine lobster research in recent years and have improved our understanding of species delimitation and population connectivity. High resolution genomic markers are just beginning to be applied to lobsters and are now starting to revolutionise our understanding of fine spatial and temporal scales of population connectivity and adaptation to environmental conditions. Lobsters play an important role in the ecosystem and many species are commercially exploited but many aspects of their biology is still largely unknown. Genetics is a powerful tool that can further contribute to our understanding of their ecology and evolution and assist management. Here we illustrate how recent genetic advancements are (1) leading to a step change in our understanding of evolution and adaptation, (2) elucidating factors driving connectivity and recruitment, (3) revealing insights into ecological processes and can (4) potentially revolutionise management of this commercially important group. We discuss how improvements in sequencing technologies and statistical methods for genetic data analyses combined with increased sampling efforts and careful sampling design have transformed our understanding of lobsters biology in recent years. We also highlight possible future directions in the application of genomic tools to lobster research that can aid management, in particular, the close-kin-mark-recapture method. Finally, we identify gaps and challenges in lobster research, such as the lack of any reference genomes and predictions on how lobsters will respond to future environmental conditions.

     

海洋生物多样性保护优先区域的确定

为了有效利用资源和资金,合理保护海洋生物多样性,海洋生物多样性保护优先区域的确定成为目前保护生物学领域的热点之一.本文首先探讨了生物多样性保护优先区域的定义和内涵,认为海洋生物多样性保护优先区域是指生物多样性丰富、物种特有化程度高、珍稀濒危物种分布集中、具有重要生态功能和过程的海洋区域.其次对保护优先区域确定的内容和方法进行了总结,主要包括单元区划、指标体系的构建及保护优先区域评估3个方面.继而根据我国海洋生物多样性现状提出保护优先区域确定的基本思路,即在海洋生物地理分区的基础上,根据物种和生境的生物多样性指标确定保护优先区域.最后针对存在问题提出建议,包括运用生物地理学方法进行单元区划、基于物种和生态系统的方法构建生物学指标以及信息网络数据库的构建等.     

生物多样性的自组织、起源和演化

生命系统是典型的自组织系统,系统中的多样性和复杂性存在着涨落,巨涨落在生物多样性上表现为生物的大规模爆发和灭绝,微涨落则为常规发生和背景灭绝,不断增加多样性是生命系统的内在属性,而实际多样性由自然选择决定,低选择压有利于生物多样性的产生,系统中过于优势的单一成分抑制多样性,系统的复杂性相变存在临界点,临界点定,低选择压有利于生物多样性的产生,系统中过于优势的单一成分抑制多样性,系统的复杂性相变存在临界点,临界点之上可自发产生正反馈的繁荣,临界点之下会发生趋于简单性的相变。上述原理可应用在生物多样性研究和保护中,例如研究特定系统的相变临界点,以便在配置系统组分时使复杂性超过其相变临界点,促使多样性的维持和增长由“被组织”进入“自组织”的可持续发展。     

Predicted levels of future ocean acidification and temperature rise could alter community structure and biodiversity in marine benthic communities

A mesocosm experiment was conducted to quantify the effects of reduced pH and elevated temperature on an intact marine invertebrate community. Standardised faunal communities, collected from the extreme low intertidal zone using artificial substrate units, were exposed to one of eight nominal treatments (four pH levels: 8.0, 7.7, 7.3 and 6.7, crossed with two temperature levels: 12 and 16°C). After 60 days exposure communities showed significant changes in structure and lower diversity in response to reduced pH. The response to temperature was more complex. At higher pH levels (8.0 and 7.7) elevated temperature treatments contained higher species abundances and diversity than the lower temperature treatments. In contrast, at lower pH levels (7.3 and 6.7), elevated temperature treatments had lower species abundances and diversity than lower temperature treatments. The species losses responsible for these changes in community structure and diversity were not randomly distributed across the different phyla examined. Molluscs showed the greatest reduction in abundance and diversity in response to low pH and elevated temperature, whilst annelid abundance and diversity was mostly unaffected by low pH and was higher at the elevated temperature. The arthropod response was between these two extremes with moderately reduced abundance and diversity at low pH and elevated temperature. Nematode abundance increased in response to low pH and elevated temperature, probably due to the reduction of ecological constraints, such as predation and competition, caused by a decrease in macrofaunal abundance. This community‐based mesocosm study supports previous suggestions, based on observations of direct physiological impacts, that ocean acidification induced changes in marine biodiversity will be driven by differential vulnerability within and between different taxonomical groups. This study also illustrates the importance of considering indirect effects that occur within multispecies assemblages when attempting to predict the consequences of ocean acidification and global warming on marine communities.