The influence of Pleistocene dynamics on the South African salt marsh species Sarcocornia pillansii (Moss) A. J. Scott (Amaranthaceae): Inferences from phylogeography and species distribution modelling
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Abstract
Glacial–interglacial climate oscillations during the Pleistocene played a significant role in shifting species distributions. During this period (26 500 - 19 000 years ago) the sea level was 120 m lower than it is currently with large areas of the Southern African continental shelf being exposed. This formed a barrier to cold-water dispersal of various aquatic organisms between the west and east coast. This study explores the influence of past climatic conditions on the salt marsh species Sarcocornia pillansii (Moss) A. J. Scott using species distribution modelling and multi-locus phylogeography. The area under curve (AUC) values were considered ‘good’ (> 0.80), indicating that the models had high specificity and sensitivity. The AUC was greater for the Maxent model (AUC = 0.881) compared to the Bioclim model (AUC = 0.837) under current conditions. Climate simulation of the Last Glacial Maximum (LGM) indicated greatest habitat suitability in estuaries along the west (Orange River Estuary to Langebaan) and east (Algoa Bay to Keiskamma) coast of South Africa. This pattern is reflected in the phylogeographic analysis where a greater number of haplotypes were found in estuaries west and east of the greater continental shelf. The nuclear DNA dataset that included 97 sequences eight ribotypes whereas the chloroplast DNA for 94 sequences that were resolved into four haplotypes. The results suggest that species survived in these estuaries (as refugia) during Pleistocene climate cycles. Post-LGM increases in sea level along the south coast allowed confluence between isolated river systems, offering opportunities for dispersal among populations.
Cite this as
2018. The influence of Pleistocene dynamics on the South African salt marsh species Sarcocornia pillansii (Moss) A. J. Scott (Amaranthaceae): Inferences from phylogeography and species distribution modelling. PeerJ Preprints 6:e26927v1 https://doi.org/10.7287/peerj.preprints.26927v1Author comment
This is a submission to PeerJ for review.
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Supplemental Information
trnQ-5’-rps16 Sequences of Sarcocornia pillansii
Additional Information
Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Dimitri A Veldkornet conceived and designed the experiments, performed the experiments, analyzed the data, prepared figures and/or tables, authored or reviewed drafts of the paper, approved the final draft.
Anusha Rajkaran contributed reagents/materials/analysis tools, authored or reviewed drafts of the paper, approved the final draft.
Janine B Adams authored or reviewed drafts of the paper, approved the final draft.
DNA Deposition
The following information was supplied regarding the deposition of DNA sequences:
Sequences are provided in supplemental files.
Data Deposition
The following information was supplied regarding data availability:
Raw data is submitted as supplementary material
Funding
This study was funded by the National Research Foundation (Thuthuka Grant), University of the Western Cape Early Career Fellowship and SANCOR. DAV is a NRF-Sancor postdoctoral fellow. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.