Molecular phylogeny of the foraminiferal genus Uvigerina based on ribosomal DNA sequences

Uvigerina is a common genus of benthic foraminifera, often used as a proxy for paleoclimate and paleoenvironment reconstructions. Better understanding of the phylogeny of Uvigerina would improve its proxy value and would allow us to check whether its different morphospecies are real species or ecophenotypes only. Here, we used partial small-subunit ribosomal DNA (SSU rDNA) sequences to examine the phylogenetic relationships within Uvigerina and between this genus and other rotaliids. Our analyses show that the family Uvigerinidae forms a well supported clade branching as a sister group to Bolivinidae and Cassidulinidae. Studied individuals of Uvigerinidae include three species described as Uvigerina - U. mediterranea, U. elongatastriata and U. peregrina - as well as Rectuvigerina phlegeri and Trifarina earlandi. As U. peregrina is more closely related to R. phlegeri and T. earlandi than to the other two Uvigerina, the taxonomic status of these species needs to be revised. At the intraspecific level, we studied a morphologically highly variable population of U. peregrina from the Oslo Fjord. For the sequences obtained from this population of U. peregrina, we found almost no divergence inside the internal transcribed spacer (ITS), which is the most variable part of ribosomal DNA. This indicates a high morphological plasticity of Uvigerina species, which should be taken into consideration when using this genus as a proxy in paleoecological reconstructions.