Paleobiology of the Polycystine Radiolaria

David Lazarus, Noritoshi Suzuki, Yoshiyuki Ishitani, Kozo Takahashi

• Publisher: Wiley-Blackwell
• Year: 2020
• ISBN:
  9781119697466
• Edition: 1
• Topic: Sciences physiques
• Subtopic: Géologie et sciences de la Terre

Polycystineradiolariaare exclusively marineprotistsand are found in all ocean waters, from polar regions to the tropics, and at all water depths. There are approximately 600 distinct described living species and several thousand fossil species ofpolycystines. Radiolarians in general, andpolycystinesinparticular, have recently been shown to be a majorcomponent of the living planktonand important to the oceanic carboncycle. As fossilsradiolarians arealsofairly common, and often occur in sediments where other types of fossils are absent. This has made them very valuable for certain types of geologic research, particularly estimating the geologic age of the sediments containing them, and as guides to past oceanic water conditions. Asour current understanding of the biology, and even taxonomy of the living fauna is still very incomplete, evolutionary studies based on livingpolycystinesare still rare. However, the common occurrence of numerous specimens for many species, and in a wide variety of oceanic environments, provides an excellent opportunity to studythe processes ofbiologic evolution in the fossil record.

Paleobiology of the PolycystineRadiolaria is the first major book on radiolarians to appear in the western literature since 2001.?Focusing on living and fossil siliceous shelled radiolarians, it is notable for its emphasis not upon morphologic or taxonomic detail but on concepts and applications. The book attempts to provide a balanced, critical review of what is known of the biology, ecology, and fossil record of the group, as well as their use in evolutionary, biostratigraphicandpaleoceanographicresearch. Full chapters on the history of study, and molecular biology, are the first ever in book form.

Written foran audience of advanced undergraduate to doctoral students, as well as for a broad range of professionals in the biological and Earth sciences, Paleobiology of thePolycystineRadiolaria summarizes current understanding of the marine planktonic protist grouppolycystineradiolaria, both in living and fossil form.

1
History

Introduction

The history of radiolarian research begins in the mid-nineteenth century, with research activity continuing with widely varying intensity and focus up to the present day. Unlike large primary divisions of science which have their own internal dynamics, radiolarian studies have always been carried out by relatively small numbers of individuals. Their work has been very strongly shaped by the development of the larger scientific subjects within which radiolarian research has been embedded. It is thus not possible to understand the historical development of the field without also understanding something of the history of these larger fields within which radiolarian studies have been carried out. These include biology, both in general, and specifically protistan biology and marine biology (particularly plankton); and earth sciences: paleontology, stratigraphy, and paleoenvironmental studies – e.g. paleoclimatology and paleoceanography. All of these disciplines have significantly affected the type and intensity of radiolarian research. This chapter thus covers not only radiolarian research but, to the degree appropriate, developments in these other disciplines as they affected the development of radiolarian research.

Bibliographic summaries of radiolarian research provide an overview of activity in the field. Because different bibliographies, each with different degrees of completeness and detail, are available, it is best to look at data from multiple sources (Figures 1.1, 1.2). Species descriptions (Figure 1.1a) provide one measure of research activity as taxonomic work is a foundation for other types of research. After a modest degree of publication in initial period of study from ca. 1840–1870, there is a huge spike (due to Haeckel's Challenger monograph, described in “E. Haeckel and his disciples”) in the late 1880s, followed by a period of moderate activity up to ca. 1910 or so, after which taxonomic research on radiolarians dropped to very low values until the late 1950s, other than a couple of “spikes” due to some monographic papers in the late 1920s and mid-1940s. Taxonomic work on radiolarians then, from ca. 1960 or so, increased gradually to levels higher than seen in earlier times, followed by a decline in annual species numbers from around 1980 on. Interestingly, a rather parallel pattern of initial interest up to the beginning of the twentieth century, then a period of decline until ca. the 1950s, is also seen in the history of diatom research (Stoermer and Smol, 2010).

If, instead of using numbers of species, one plots numbers of papers (Figures 1.1b, 1.2), a rather different picture emerges. Although there are still two peaks in publication activity, one in the late nineteenth century, and the other in the 1980s, the relative sizes of the peaks are now dramatically different, with many more papers being published in the twentieth, vs. nineteenth century. More papers with time reflects a general pattern in the history of science, where scientific activity and numbers of publications increase rapidly in the twentieth century – indeed, for academic publishing as a whole, the trend has been more or less one of continuous geometric increase with doubling times of 15–24 years since the early nineteenth century, measured either by publications (Larsen and von Ins, 2010) or numbers of journals (Jinha, 2010). Several aspects of the radiolarian publication history however differ from the general pattern of scientific publication.

First, the ratio between numbers of new species and numbers of papers has changed dramatically over time, with nineteenth-century work being dominated by many new species descriptions in a small number of papers, while twentieth-century studies published, per paper, many fewer species, even if due to the larger total number of papers the total taxonomic output is similar. There is thus either a fundamental change in the style of taxonomic publishing, and/or a shift in publication to non-taxonomic research. Both are probably significant factors. It is possible even today for a student to encounter a nearly unknown radiolarian assemblage which needs to be sorted into species categories without the help of prior literature. This effort, vastly eased by modern imaging technology, can now be done for hundreds of species in a few months' work. However, without the need to reference prior literature, early workers could publish simple descriptions of large numbers of species relatively easily. There is of course also a shift toward applied work with radiolarians over time, so that, unlike in early years, more recent literature is dominated by papers that contain no new taxonomy.

Second, there is a substantial decline in outputs in both taxonomic description and general numbers of publications in the last ca. 20 years. Although this is in part due to incomplete recording in the last ca. 10 years, the similarity between different data sources, and in particular in the relatively comprehensive Paleotax data, suggests that the decline in output is real. This is not a general feature of science publication, which continues to grow rapidly (Larsen and von Ins, 2010; Jinha, 2010). Lastly, there are noticable differences in activity between subdisciplines. Subdisciplines in radiolarian research are, due to many differences in material and the research context that are linked to geologic age, conveniently expressed by the geologic time interval that individual studies examined (living; Cenozoic; Mesozoic; Paleozoic: Figure 1.2). Research on Cenozoic/living radiolarians dominates nineteenth-century studies, and increases relatively rapidly after WWII to a plateau by around 1970, before gradually declining in the 1990s to the present day. Mesozoic and Paleozoic studies by contrast begin to increase in the 1970s and 1980s, respectively, before declining in the beginning years of the twenty-first century. These differences create different time intervals of dominance, with Cenozoic/living being the dominant area of research up to ca. 1980, and Mesozoic research being the dominant activity after this time. The causes of these patterns will be described in our historical review.

These patterns suggest convenient time intervals in which to frame a review of radiolarian reseach: early studies up to around 1910, the low activity interval between 1910 and ca. 1950, the growth period of Cenozoic/living studies up to ca. 1970, and the “modern” phase of research beginning in the 1970s and continuing to the present day. The small (third) peak in publication seen in all data beginning in the late 2000s may represent a new phase of research, though this is more open to interpretation, and will be discussed together with “outlook – future developments” at the end of this chapter.

Within the field of radiolarian studies, the number of species descriptions by author (see Table 5.5) provides at least a rough guide to the importance of individual workers, particularly in earlier times when descriptive work dominated research activity.

Scientific Context

The first of the broader issues that influenced early studies of radiolarians are the basic framework ideas on the development of science itself, as early radiolarian research grew up during this period of general scientific development. Modern science, with its distinguishing characteristics of emphasis on non-metaphysical material mechanisms as the cause of the patterns and structure of the natural world, formal hypotheses, and testability, is generally agreed to have originally developed primarily in Europe over several centuries, but maturing in the eighteenth and nineteenth centuries (Wikipedia contributors, 21.6.2018). By the mid-1800s natural sciences were firmly established in western countries and divided into the major divisions we still use today, with numerous professional positions in universities, supported by professional societies and other coordinating organizations. Even the name was modern, with the term “scientist” (coined by W. Whewell in 1833) gradually replacing the earlier, less distinctive term “natural philosopher” (https://en.wikipedia.org/wiki/William_Whewell; accessed 3.9.2017). In other parts of the world descriptive and sometimes quite extensive studies of nature analogous to the descriptive studies of biodiversity in the western world were also developing, e.g. in Japan (Marcon, 2015). These activities were linked, as in western countries, to other interests (medicine, agriculture, hobby gardens, and others) but they were not systematically linked to developing formal paradigms of scientific hypotheses and testing as in the West. Nor, lacking widespread access to microscopes and other suitable technology, was the systematic study of microorganisms possible.

The development of science in Europe was gradual and not uniform between disciplines, with physical science developing more rapidly than biologic. At the beginning of the nineteenth century however, the transition in biology from a descriptive style to one where description was informed, and thus influenced by scientific theories of process, was already underway. Initial steps in this transformation included a re-examination of the “scala natura” description of the natural biologic world that had been inherited from antiquity (traceable back to Plato), and had been overlain with religious-metaphysical mechanisms (Mayr, 1982; https://en.wikipedia.org/wiki/Great_chain_of_being, accessed 21.6.2018). Observations of the diversity of life had been until then pressed into a description of a continuous chain of forms, from the simplest to the most complex, perfect forms (man, and above this the metaphysical beings of angels and god). The simplest forms at the base merged into and continuously arose from the inorganic world below via spontaneous generation – an idea which, although long under attack, was still present well into the early nineteenth century (https://en.wikipedia.org/wiki/Spont...

Table of contents

• Cover
• Table of Contents
• Title Page
• Copyright
• Preface
• Acknowledgements
• Chapter 1: History
• Chapter 2: Biology
• Chapter 3: Ecology
• Chapter 4: Genetics
• Chapter 5: Taxonomy and Fossil Record
• Chapter 6: Preservation and Methods
• Chapter 7: Paleoceanography
• Chapter 8: Radiolarian Biostratigraphy
• Chapter 9: Evolution
• References
• Index
• End User License Agreement