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Globigerinella siphonifera is one of the most abundant planktonic foraminifera species in the subtropical ocean. As symbiont bearing species, it dwells only in the euphotic zone and two phenotypically divergent types of G. siphonifera have been described based on differences in symbiont density and coloration. Three sister species are assigned to G. siphonifera: Globigerinella calida as its direct sister species, Beella digitata, and Globigerinella adamsi. Molecular genetic research of the last decade found multiple genetic types in G. siphonifera, using the ribosomal small subunit DNA (SSU rDNA), and also produced contradictory hypothesis on the genetic identity of G. calida as a genotype of G. siphonifera. Using data from various surveys around the globe, we investigate the genetic diversity within G. siphonifera. We find a high diversity of subtypes belonging to the already described four genotypes. The sequence variability within these genotypes ranges from only two subtypes in Type I to up to seven subtypes in Type IIa. Whereas some genotypes seem to be restricted to either the Atlantic or the Pacific, genotype IIa was found at all the regions sampled having not only the widest distribution, but also the highest sequence diversity. In addition, we used morphometric measurements to address the question whether the morphological characteristics of Globigerinella calida can be assigned to a single specific genotype of G. siphonifera or if the description of the morphotaxon is in fact referring to an ecophenotypic variation that can be found in several genotypes. This has potential implications for the application of G. calida in the fossil record. Moreover, we present the first sequence data of Beella digitata and use these for a reevaluation of the phylogenetic relationships between G. siphonifera and its sister species as they are hypothesized from their fossil record.
|Title of host publication||TMS Foraminifera and Nannofossil Groups Joint Meeting Edinburgh 2012|
|Subtitle of host publication||Interdisciplinary advances in foraminiferal and nannofossil research|
|Number of pages||1|
|Publication status||Published - 2012|
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- 1 Finished
1/05/06 → 30/09/10