Pleistocene adaptive radiation in Globorotalia truncatulinoides: genetic, morphologic, and environmental evidence
By C. de Vargas, S. Renaud, H. Hilbrecht, J. Pawłowski. Paleobiology, 2001
203 citations recorded by the source corpus.
Abstract Globorotalia truncatulinoides is an extant species of planktic foraminiferans commonly used for stratigraphic and paleoenvironmental analyses. It originated ∼2.8 m.y. ago in subtropical areas of the South Pacific, spread to all subtropical and temperate regions of the world ocean, and expanded its range to southern subantarctic waters between 500 and 200 Ka. The wide geographic distribution of G. truncatulinoides is associated with a latitudinal morphological variability considered as an ecophenotypic variation within a single species. Here, we present the first molecular, morphological, and ecological evidence that G. truncatulinoides corresponds to a complex of four genetic species adapted to particular hydrographic conditions. The different species are separated by significant genetic distances in several ribosomal genes (SSU, ITS-1, 5.8S, ITS-2). Species 1 and species 2 characterize subtropical waters, species 3 is abundant exclusively in the Subantarctic Convergence, while species 4 inhabits subantarctic waters. By using an absolute molecular clock, we deduce the time of divergence between the subtropical and frontal/subantarctic species at ∼300 Ka, which is in agreement with stratigraphic data and suggests an adaptive radiation of the species allowing it to colonize the nutrient-rich and cold subantarctic waters. This genetic dichotomy is associated with a morphological differentiation identified using outline analysis. Species of the same regions are more similar in test shape but can be distinguished by coiling direction. The evolutionary patterns recognized here by combining DNA and morphological analyses from plankton-tow specimens mirror and allow a new interpretation of the data available from Recent sediments. They highlight the importance of adaptation and heterochronic processes, leading to cryptic speciation, in planktic foraminifera.
Subfields: Atmospheric Science, Ecology, Oceanography
View Paper: https://www.semanticscholar.org/paper/df9da52ec214a8fd42802a62584f28477d1f84f1
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Citations in the corpus
- A molecular approach to biodiversity and biogeography in the planktonic foraminifer Globigerinella siphonifera (d’Orbigny) (2002, methodology): “Even in this relatively young genetic isolation , a signi¢cant morphometric di¡erentiation was detected in the outlines of the tests of the southern populations using Fourier analyses (Healy Williams et al., 1985; De Vargas et al., 2001).”
- Seasonal distribution of genetic types of planktonic foraminifer morphospecies in the Santa Barbara Channel and its paleoceanographic implications (2003, background): “However, the distinct genetic types recognized within a morphospecies have been shown to exhibit different environmental preferences [Huber et al., 1997; Darling et al., 1999, 2000; de Vargas et al., 1999, 2001].”
- The cryptic and the apparent reversed: lack of genetic differentiation within the morphologically diverse plexus of the planktonic foraminifer Globigerinoides sacculifer (2013, background): “The reason for obtaining sequences of the ITS-1 region was the observation from species of non-spinose planktonic foraminifera in which this region showed higher rate of substitution and thus allowed finer differentiation (de Vargas et al. 2001; Morard et al. 2011).”