Uncovering sibling species in Radiolaria: Evidence for ecological partitioning in a marine planktonic protist

Ishitani, Yoshiyuki; Ujiie, Yasushige; Takishita, Kiyotaka

doi:10.1016/j.ympev.2014.05.021

Cited by 23 publications

(18 citation statements)

References 38 publications

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“…In the present study, we analyzed the symbionts from two specimens of each of the radiolarian species of A. vinculata and E. elegans , and we detected that they all harbored G. radiolariae as a symbiont; moreover, the sequences of the dinoflagellate symbionts in the two specimens of radiolarian S. glacialis reported by Ishitani et al. () from the Pacific Ocean were also the same. This suggests that the symbiotic interactions of polycystine radiolarians are probably not random, but rather selective, in contrast to the case of the acantharian radiolarians reported by Decelle et al.…”

Section: Discussionsupporting

confidence: 58%

“…As mentioned in the Introduction , Gymnodinium ‐like symbionts in radiolarians have been reported by Hollande and Enjumet (), Hollande and Carré (), and Ishitani et al. (). In the report of Ishitani et al.…”

Section: Discussionmentioning

confidence: 72%

“…In the report of Ishitani et al. (), a molecular phylogenetic analysis was used to identify Gymnodinium sp. obtained from radiolarian S. glacialis .…”

Section: Discussionmentioning

confidence: 99%

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Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians

Yuasa

Horiguchi

Mayama

et al. 2016

Journal of Phycology

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The symbiotic dinoflagellate Gymnoxanthella radiolariae T. Yuasa et T. Horiguchi gen. et sp. nov. isolated from polycystine radiolarians is described herein based on light, scanning and transmission electron microscopy as well as molecular phylogenetic analyses of SSU and LSU rDNA sequences. Motile cells of G. radiolariae were obtained in culture, and appeared to be unarmored. The cells were 9.1-11.4 μm long and 5.7-9.4 μm wide, and oval to elongate oval in the ventral view. They possessed an counterclockwise horseshoe-shaped apical groove, a nuclear envelope with vesicular chambers, cingulum displacement with one cingulum width, and the nuclear fibrous connective; all of these are characteristics of Gymnodinium sensu stricto (Gymnodinium s.s.). Molecular phylogenetic analyses also indicated that G. radiolariae belongs to the clade of Gymnodinium s.s. However, in our molecular phylogenetic trees, G. radiolariae was distantly related to Gymnodinium fuscum, the type species of Gymnodinium. Based on the consistent morphological, genetic, and ecological divergence of our species with the other genera and species of Gymnodinium s.s., we considered it justified to erect a new, separate genus and species G. radiolariae gen. et sp. nov. As for the peridinioid symbiont of radiolarians, Brandtodinium has been erected as a new genus instead of Zooxanthella, but the name Zooxanthella is still valid. Brandtodinium is a junior synonym of Zooxanthella. Our results suggest that at least two dinoflagellate symbiont species, peridinioid Zooxanthella nutricula and gymnodinioid G. radiolariae, exist in radiolarians, and that they may have been mixed and reported as "Z. nutricula" since the 19th century.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 72%

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Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians

Yuasa

Horiguchi

Mayama

et al. 2016

Journal of Phycology

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“…Because most other microfossils are unicellular organisms and thus have a simpler body plan and structure compared to metazoan ostracodes, their morphological characters may be less informative. However, recent studies have shown that detailed morphological analyses of unicellular microfossils allow identification of molecular types and sibling species (Hayward et al, 2004;Aurahs et al, 2011;Ishitani, Ujiié & Takishita, 2014).…”

Section: Affinity Between Macroecology and Palaeoecologymentioning

confidence: 99%

Combining marine macroecology and palaeoecology in understanding biodiversity: microfossils as a model

et al. 2015

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There is growing interest in the integration of macroecology and palaeoecology towards a better understanding of past, present, and anticipated future biodiversity dynamics. However, the empirical basis for this integration has thus far been limited. Here we review prospects for a macroecology-palaeoecology integration in biodiversity analyses with a focus on marine microfossils [i.e. small (or small parts of) organisms with high fossilization potential, such as foraminifera, ostracodes, diatoms, radiolaria, coccolithophores, dinoflagellates, and ichthyoliths]. Marine microfossils represent a useful model system for such integrative research because of their high abundance, large spatiotemporal coverage, and good taxonomic and temporal resolution. The microfossil record allows for quantitative cross-scale research designs, which help in answering fundamental questions about marine biodiversity, including the causes behind similarities in patterns of latitudinal and longitudinal variation across taxa, the degree of constancy of observed gradients over time, and the relative importance of hypothesized drivers that may explain past or present biodiversity patterns. The inclusion of a deep-time perspective based on high-resolution microfossil records may be an important step for the further maturation of macroecology. An improved integration of macroecology and palaeoecology would aid in our understanding of the balance of ecological and evolutionary mechanisms that have shaped the biosphere we inhabit today and affect how it may change in the future.

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“…Nevertheless, biogeographical patterns based on morphospecies may be obscured by cryptic and polymorphic species, given that conserved, convergent or plastic morphologies can mask major molecular, biological, physiological and ecological differences (Dolan, 2015). The increasing combination of morphological and DNA sequence analyses in single specimens has revealed, for instance, cryptic species with different distributions and likely dissimilar ecology in marine plankton (Weiner et al, 2012;Ishitani et al, 2014;Santoferrara et al, 2015). Furthermore, the characterization of natural communities by high-throughput sequencing (HTS) is now offering the potential to reveal new distribution patterns based on the detection of rare species and the discovery of novel, atypical taxa that may not be recognized by microscopy, even in some groups with a long tradition of morphological description (Lecroq et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Patterns and processes in microbial biogeography: do molecules and morphologies give the same answers?

et al. 2016

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Our knowledge on microbial biogeography depends on the way we define and study diversity. In contrast to most microbes, some protist lineages have conspicuous structures that allow comparisons of diversity concepts and measures-those based on molecules and those based on morphology. We analyzed a group of shell-bearing planktonic ciliates, the tintinnids, in a coast-to-ocean gradient using highthroughput sequencing and microscopy. First, we compared molecular operational taxonomic units (OTUs) and morphospecies in terms of assemblage composition, distribution and relationships with the environment. OTUs revealed potentially novel and rare taxa, while morphospecies showed clearer correlations with environmental factors, and both approaches coincided in supporting a coastal versus oceanic pattern. Second, we explored which processes influence assembly across the environmental gradient examined. Assemblage fluctuations were associated with significant distance-decay and changes in morphospecies size and prey proxies, thus suggesting niche partitioning as a key structuring mechanism. Our conclusion is that molecules and morphologies generally agreed, but they provided complementary data, the first revealing hidden diversity, and the latter making better connections between distribution patterns and ecological processes. This highlights the importance of linking genotypes and phenotypes (using multidisciplinary analyses and/or reliable databases of barcoded species), to understand the diversity, biogeography and ecological roles of microbes.

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Uncovering sibling species in Radiolaria: Evidence for ecological partitioning in a marine planktonic protist

Cited by 23 publications

References 38 publications

Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians

Gymnoxanthella radiolariae gen. et sp. nov. (Dinophyceae), a dinoflagellate symbiont from solitary polycystine radiolarians

Combining marine macroecology and palaeoecology in understanding biodiversity: microfossils as a model

Patterns and processes in microbial biogeography: do molecules and morphologies give the same answers?

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