Geographical distribution of cryptic genetic types in the planktonic foraminifer Globigerinoides ruber |
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Authors: | RALF AURAHS GUIDO W GRIMM‡ VERA HEMLEBEN† CHRISTOPH HEMLEBEN MICHAL KUCERA |
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Institution: | Department of Micropalaeontology, Institute of Geosciences, Sigwartstrasse 10;, Department of General Genetics, Auf der Morgenstelle 28, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany,;Swedish Museum of Natural History, Department of Palaeobotany, Box 50007, 10405 Stockholm, Sweden |
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Abstract: | We present SSU rDNA data resolving the seasonal and geographical distribution of 'cryptic' genetic types of the planktonic foraminifer morphospecies Globigerinoides ruber in the eastern Atlantic Ocean and the Mediterranean Sea. Analysis of 262 sequences revealed the presence of five genetic types belonging to two distinct lineages. Although the morphospecies G. ruber occurs throughout the investigated region, its constituent 'cryptic' genetic types show a pattern of widespread exclusion, which is difficult to reconcile with the concept of ubiquitous dispersal. One of the newly discovered genetic types was exclusively found at stations in the Mediterranean Sea, possibly representing the smallest-scale example of endemism known in planktonic foraminifera. In general, our results suggest that the geographical scale of mutual exclusion between the genotypes is negatively correlated with their phylogenetic relatedness: the most similar and most recently diverged pair of siblings showed the strongest evidence for small-scale competitive exclusion. This pattern is consistent with the concept of niche partitioning, implying decreasing level of competition between genetic types with increasing degree of genetic divergence. |
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Keywords: | competition cryptic diversity niche partitioning phylogeography planktonic foraminifera SSU rDNA |
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