A phylogeographic break in a South African coastal saltmarsh macrophyte, Juncus kraussii

Potts, Alastair J.; Veldkornet, D.A.; Adams, Janine B.

doi:10.1016/j.sajb.2016.08.006

Cited by 5 publications

(4 citation statements)

References 25 publications

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“…A refugial area on the south-western coast may explain the presence of both clusters in Langebaan Lagoon. Notably, this split between the clusters roughly coincides with the split between described temperate and sub-tropical bioregions (Sink et al 2012) along which phylogeographic breaks have been recorded for marine coastal species (von der Heyden 2009;Teske et al 2011), including one other saltmarsh plant (Potts et al 2016). Given lack of gene flow and apparent high levels of clonality in Z. capensis, the structure detected through outlier loci most likely reflects ancestral adaptation during conditions more conducive to gene flow or incomplete lineage sorting during post-LGM expansion.…”

Section: Shared Adaptive Divergence Across Two Genomic Clusters Shapesupporting

confidence: 65%

Shared genomic outliers across two divergent population clusters of a highly threatened seagrass

Phair

Toonen

Knapp

et al. 2019

Preprint

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The seagrass, Zostera capensis, occurs across a broad stretch of coastline and wide environmental gradients in estuaries and sheltered bays in southern and eastern Africa. Throughout its distribution, habitats are highly threatened and poorly protected, increasing the urgency of assessing the genomic variability of this keystone species. A pooled genomic approach was employed to obtain SNP data and examine neutral genomic variation and to identify potential outlier loci to assess differentiation across 12 populations across the ~9600km distribution of Z. capensis. Results indicate high clonality and low genomic diversity within meadows, which combined with poor protection throughout its range, increases the vulnerability of this seagrass to further declines or local extinction. Shared variation at outlier loci potentially indicates local adaptation to temperature and precipitation gradients, with Isolation-by-Environment significantly contributing towards shaping spatial variation in Z. capensis. Our results indicate the presence of two population clusters, broadly corresponding to populations on the west and east coasts, with the two lineages shaped only by frequency differences of outlier loci. Notably, ensemble modelling of suitable seagrass habitat provides evidence that the clusters are linked to historical climate refugia around the Last Glacial Maxi-mum. Our work suggests a complex evolutionary history of Z. capensis in southern and eastern Africa that will require more effective protection in order to safeguard this important ecosystem engineer into the future.

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Section: Shared Adaptive Divergence Across Two Genomic Clusters Shapesupporting

confidence: 65%

Shared genomic outliers across two divergent population clusters of a highly threatened seagrass

Phair

Toonen

Knapp

et al. 2019

Preprint

View full text Add to dashboard Cite

show abstract

“…Results from this study is similar to that of Potts et al, (2016) for Juncus kraussii Hochst. They suggest that a break shoreline along the south coast may have been driven by the rapid shifts in response to Pleistocene climate cycles.…”

Section: Discussionsupporting

confidence: 85%

“…Recently Potts et al, (2016) explored the phylogeographic pattern of the upper intertidal salt marsh plant species, Juncus kraussii Hochst., along the west, south and east coast of South Africa. A phylogeographic break was found along the south coast within the warm temperate coastal biogeographic zone.…”

Section: Introductionmentioning

confidence: 99%

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Supplemental Information 3: trnQ-5’-rps16 Sequences of Sarcocornia Pillansii

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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.

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“…The wide distribution of Poales can be attributed to several traits such as wind pollination and seed dispersal, rapid, clonal, and high reproductive output, and tolerance to stressful and disturbed environments [81,82]. It was also found that coastal species in Poales have high haplotype diversity compared to their terrestrial conspecifics suggesting a genetic adaptation for along a climatic diverse coastline [81][82][83]. Similar to Poales, Alismatales exhibit long-distance dispersal traits (e.g., [18], for seagrasses).…”

Section: Discussionmentioning

confidence: 99%

The Influence of Macroclimatic Drivers on the Macrophyte Phylogenetic Diversity in South African Estuaries

Veldkornet

2023

Diversity

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The geographical distribution of plants is influenced by macroclimate and dispersal limitations, which have led to lineage isolation and subsequent diversification within and across various environmental gradients. Macroclimatic variables in coastal wetlands influence plant species and lineages across biogeographical boundaries. This study aimed to determine the influence of macroclimatic variables on species and phylogenetic richness in South African estuaries. Open-source chloroplast DNA barcoding sequences, species distribution and climatic data layers were used to determine the relationship between species richness, MPD, MNTD and each bioclimatic variable individually. Temperate species richness and phylogenetic diversity were positively correlated with temperature bioclimatic variables whereas subtropical and tropical species were associated with increases in precipitation. Phylogenetic niche conservatism is evident in malvids and rosids which are restricted to tropical and subtropical regions due to their physiological adaptations to tropical climates. Caryophylales was mostly associated with temperate regions. Poales and Alismatales showed wide distributions that is likely attributed to traits related to wind pollination and hydrochory, rapid, clonal, and high reproductive output, tolerance to stressful conditions, and intraspecific genetic diversity. The findings highlight the importance of considering macroclimate and phylogenetic factors in understanding the distribution and diversity of coastal wetland plants.

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A phylogeographic break in a South African coastal saltmarsh macrophyte, Juncus kraussii

Cited by 5 publications

References 25 publications

Shared genomic outliers across two divergent population clusters of a highly threatened seagrass

Shared genomic outliers across two divergent population clusters of a highly threatened seagrass

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The Influence of Macroclimatic Drivers on the Macrophyte Phylogenetic Diversity in South African Estuaries

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