Expansion of the mangrove species Rhizophora mucronata in the Western Indian Ocean launched contrasting genetic patterns

AbstractEstimates of population structure and gene flow allow exploring the historical and contemporary processes that determine a species’ biogeographic pattern. In mangroves, large-scale genetic studies to estimate gene flow have been conducted predominantly in the Indo-Pacific and Atlantic region. Here we examine the genetic diversity and connectivity of Rhizophora mucronata across a > 3,000 km coastal stretch in the Western Indian Ocean (WIO) including WIO islands. Based on 359 trees from 13 populations and using 17 polymorphic microsatellite loci we detected genetic breaks between populations of the (1) East African coastline, (2) Mozambique Channel Area (3) granitic Seychelles, and (4) Aldabra and northern Madagascar. Genetic structure, diversity levels, and patterns of inferred connectivity, aligned with the directionality of major ocean currents, driven by bifurcation of the South Equatorial Current, northward into the East African Coastal Current and southward into the Mozambique Channel Area. A secondary genetic break between nearby populations in the Delagoa Bight coincided with high inbreeding levels and fixed loci. Results illustrate how oceanographic processes can connect and separate mangrove populations regardless of geographic distance.

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Speciation with gene flow via cycles of isolation and migration: Insights from multiple mangrove taxa

10.1101/335166 ◽

2018 ◽

Author(s):

Ziwen He ◽

Xinnian Li ◽

Ming Yang ◽

Xinfeng Wang ◽

Cairong Zhong ◽

...

Keyword(s):

Gene Flow ◽

Indian Ocean ◽

Large Scale ◽

Marine Species ◽

Allopatric Speciation ◽

Unified Framework ◽

Geographical Isolation ◽

Mangrove Species ◽

Geographical Barrier ◽

Time Required

AbstractAllopatric speciation requiring an unbroken period of geographical isolation has been the standard model of neo-Darwinism. While doubts have been repeatedly raised, strict allopatry without any gene flow remains a plausible mechanism in most cases. To rigorously reject strict allopatry, genomic sequences superimposed on the geological records of a well-delineated geographical barrier will be necessary. The Strait of Malacca, narrowly connecting the Pacific and Indian Ocean coasts, serves at different times either as a geographical barrier or a conduit of gene flow for coastal/marine species. We surveyed 1,700 plants from 29 populations of five common mangrove species by large scale DNA sequencing and added several whole-genome assemblies. Speciation between the two oceans is driven by cycles of isolation and gene flow due to the fluctuations in sea level leading to the opening/closing of the Strait to ocean currents. Because the time required for speciation in mangroves is longer than the isolation phases, speciation in these mangroves has proceeded through many cycles of mixing-isolation-mixing, or MIM cycles. The MIM mechanism, by relaxing the condition of no gene flow, can promote speciation in many more geographical features than strict allopatry can. Finally, the MIM mechanism of speciation is also efficient, potentially yielding mn (m>1) species after n cycles.Significance statementMechanisms of species formation have always been a conundrum. Speciation between populations that are fully geographically isolated, or allopatric speciation, has been the standard solution in the last 50 years. Complete geographical isolation with no possibility of gene flow, however, is often untenable and is inefficient in generating the enormous biodiversity. By studying mangroves on the Indo-Malayan coasts, a global hotspot of coastal biodiversity, we were able to combine genomic data with geographical records on the Indo-Pacific barrier that separates Pacific and Indian Ocean coasts. We discovered a novel mechanism of speciation, that we call mixing-isolation-mixing (MIM) cycles. By permitting intermittent gene flow during speciation, MIM can potentially generate species at an exponential rate, thus combining speciation and biodiversity in a unified framework.

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Author Correction: Large-scale mass wasting in the western Indian Ocean constrains onset of East African rifting

Nature Communications ◽

10.1038/s41467-020-18395-8 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Vittorio Maselli ◽

David Iacopini ◽

Cynthia J. Ebinger ◽

Sugandha Tewari ◽

Henk de Haas ◽

...

Keyword(s):

Indian Ocean ◽

Large Scale ◽

Western Indian Ocean ◽

Mass Wasting ◽

East African

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Large-scale mass wasting in the western Indian Ocean constrains onset of East African rifting

Nature Communications ◽

10.1038/s41467-020-17267-5 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Vittorio Maselli ◽

David Iacopini ◽

Cynthia J. Ebinger ◽

Sugandha Tewari ◽

Henk de Haas ◽

...

Keyword(s):

Indian Ocean ◽

Large Scale ◽

Western Indian Ocean ◽

Mass Wasting ◽

East African

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Variability in the Mozambique Channel Trough and Impacts on Southeast African Rainfall

Journal of Climate ◽

10.1175/jcli-d-19-0267.1 ◽

2020 ◽

Vol 33 (2) ◽

pp. 749-765 ◽

Cited By ~ 3

Author(s):

Rondrotiana Barimalala ◽

Ross C. Blamey ◽

Fabien Desbiolles ◽

Chris J. C. Reason

Keyword(s):

Indian Ocean ◽

Austral Summer ◽

Western Indian Ocean ◽

Strong Relationship ◽

Ocean Basin ◽

Moist Convection ◽

South Indian Ocean ◽

Mozambique Channel ◽

Mascarene High ◽

South Indian

AbstractThe Mozambique Channel trough (MCT) is a cyclonic region prominent in austral summer in the central and southern Mozambique Channel. It first becomes evident in December with a peak in strength in February when the Mozambique Channel is warmest and the Mascarene high (MH) is located farthest southeast in the Indian Ocean basin. The strength and the timing of the mean MCT are linked to that of the cross-equatorial northeasterly monsoon in the tropical western Indian Ocean, which curves as northwesterlies toward northern Madagascar. The interannual variability in the MCT is associated with moist convection over the Mozambique Channel and is modulated by the location of the warm sea surface temperatures in the south Indian Ocean. Variability of the MCT shows a strong relationship with the equatorial westerlies north of Madagascar and the latitudinal extension of the MH. Summers with strong MCT activity are characterized by a prominent cyclonic circulation over the Mozambique Channel, extending to the midlatitudes. These are favorable for the development of tropical–extratropical cloud bands over the southwestern Indian Ocean and trigger an increase in rainfall over the ocean but a decrease over the southern African mainland. Most years with a weak MCT are associated with strong positive south Indian Ocean subtropical dipole events, during which the subcontinent tends to receive more rainfall whereas Madagascar and northern Mozambique are anomalously dry.

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Akshay Sarathi (Ed.): Early Maritime Cultures in East African and the Western Indian Ocean

African Archaeological Review ◽

10.1007/s10437-020-09416-4 ◽

2020 ◽

Author(s):

Matthew Pawlowicz

Keyword(s):

Indian Ocean ◽

Western Indian Ocean ◽

East African

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Status of a Marginal Dugong (Dugong Dugon) Population in the Lagoon of Mayotte (Mozambique Channel), in the Western Indian Ocean

Western Indian Ocean Journal of Marine Science ◽

10.4314/wiojms.v6i1.48230 ◽

2009 ◽

Vol 6 (1) ◽

Author(s):

J Kiszka ◽

C Muir ◽

A Amon

Keyword(s):

Indian Ocean ◽

Western Indian Ocean ◽

Mozambique Channel

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Gene flow and demographic history of the mangrove crab Neosarmatium meinerti: A case study from the western Indian Ocean

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2009.11.002 ◽

2010 ◽

Vol 86 (2) ◽

pp. 179-188 ◽

Cited By ~ 30

Author(s):

Lapo Ragionieri ◽

Stefano Cannicci ◽

Christoph D. Schubart ◽

Sara Fratini

Keyword(s):

Gene Flow ◽

Indian Ocean ◽

Demographic History ◽

Western Indian Ocean ◽

Mangrove Crab ◽

History Of

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Genome Assembly of the Roundjaw Bonefish (Albula glossodonta), a Vulnerable Circumtropical Sportfish

10.1101/2021.09.10.458299 ◽

2021 ◽

Author(s):

Brandon D. Pickett ◽

Sheena Talma ◽

Jessica R. Glass ◽

Daniel Ence ◽

Paul D. Cowley ◽

...

Keyword(s):

Population Structure ◽

Gene Flow ◽

Indian Ocean ◽

Genome Assembly ◽

Anthropogenic Activities ◽

Western Indian Ocean ◽

Genetic Connectivity ◽

High Quality ◽

Widespread Species ◽

High Quality Genome

ABSTRACTBackgroundBonefishes are cryptic species indiscriminately targeted by subsistence and recreational fisheries worldwide. The roundjaw bonefish, Albula glossodonta is the most widespread bonefish species in the Indo-Pacific and is listed as vulnerable to extinction by the IUCN’s Red List due to anthropogenic activities. Whole-genome datasets allow for improved population and species delimitation, which – prior to this study – were lacking for Albula species.ResultsWe generated a high-quality genome assembly of an A. glossodonta individual from Hawai‘i, USA. The assembled contigs had an NG50 of 4.75 Mbp and a maximum length of 28.2 Mbp. Scaffolding yielded an NG50 of 14.49 Mbp, with the longest scaffold reaching 42.29 Mbp. Half the genome was contained in 20 scaffolds. The genome was annotated with 28.3 K protein-coding genes. We then analyzed 66 A. glossodonta individuals and 38,355 SNP loci to evaluate population genetic connectivity between six atolls in Seychelles and Mauritius in the Western Indian Ocean. We observed genetic homogeneity between atolls in Seychelles and evidence of reduced gene flow between Seychelles and Mauritius. The South Equatorial Current could be one mechanism limiting gene flow of A. glossodonta populations between Seychelles and Mauritius.ConclusionsQuantifying the spatial population structure of widespread fishery species such as bonefishes is necessary for effective transboundary management and conservation. This population genomic dataset mapped to a high-quality genome assembly allowed us to discern shallow population structure in a widespread species in the Western Indian Ocean. The genome assembly will be useful for addressing the taxonomic uncertainties of bonefishes globally.

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