Runaway fathers? Limited pollen dispersal and mating system in Rhizophora racemosa populations of a disturbed mangrove estuary

Ngeve, Magdalene N.; Koedam, Nico; Triest, Ludwig

doi:10.1016/j.aquabot.2020.103241

Cited by 2 publications

(6 citation statements)

References 71 publications

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“…Inbreeding within nearly each R. mucronata site is most likely the result of geitonogamy as in R. racemosa 60 . This can blur the determination of a genetic structure at the population level because occasional fixation of private alleles might lead to enforced clusters of gene pools.…”

Section: Discussionmentioning

confidence: 99%

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

Triest

Stocken

Ryck

et al. 2021

Sci Rep

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Estimates 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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Section: Discussionmentioning

confidence: 99%

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

Triest

Stocken

Ryck

et al. 2021

Sci Rep

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“…For comparative purposes, we included materials and microsatellite genotypes from Ngeve et al (2016Ngeve et al ( , 2017a; Ngeve et al (2020) (details below) and Figure 1 shows in detail all sites within all estuaries from which we had samples: from Ekondo Titi (EKO), Mbongo (MBO), Bekumu (BEK) in the Rio del Rey Estuary in the north; Mabeta (MAB), Tiko (TIK), Douala-Bonamoussadi (SADI), Douala-Akwa-Nord (AKN), Douala-Bonaberi (BERI), Mouanko at the Douala-Edea National Park (RSVM) in the central Cameroon Estuary complex; Kribi in the Lokoundje Estuary; and Campo in the Ntem Estuary. Hereafter, the Rio Del Rey samples are all referred to as RDR, the Cameroon Estuary complex samples as CEC, the Lokoundje Estuary as Kribi, and the Ntem Estuary as Campo, while the cohort of drift propagules are referred to as Drift.…”

Section: Study Species and Study Areamentioning

confidence: 99%

“…Selfing rates were estimated based on standardized identity disequilibrium which assumes a mixed mating model, and computed standard error estimates by jackknifing over loci (as described in Hardy, 2016). Assuming mixed mating system is appropriate based on previous studies in R. racemosa (Ngeve et al, 2020). For all SPAGeDi analyses, we estimated significance based on 10,000 permutations, and reference allele frequencies used for computing pairwise statistics were from all three sites-Kribi, Campo, and Drift.…”

Section: Relatedness and Population Structurementioning

confidence: 99%

“…Before performing actual assignment tests, we first explored the resolution of our markers for this purpose by using progeny arrays originally genotyped for the same loci (Ngeve et al, 2020), to assess the power of the markers to validate known origin of progenies, similar to Kennedy et al (2020). Secondly, we used the population assignment option in GenAlex to explore our actual data with drift propagules, to see where they plot with samples from closest mangrove areas (Kribi and Campo) as well as others in RDR and CEC.…”

Section: Assignment Tests and Species Identificationmentioning

confidence: 99%

“…The spatial scale over which pollen dispersal occurs in many mangrove species is usually shorter than seedling (propagule) dispersal (e.g., Wee et al, 2015;Ngeve et al, 2020). As a result, mangrove species mainly depend on propagule dispersal for connectivity among populations, both close by and remote.…”

Section: Introductionmentioning

confidence: 99%

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Genotypes of Rhizophora Propagules From a Non-mangrove Beach Provide Evidence of Recent Long-Distance Dispersal

Ngeve

Koedam

Triest

2021

Front. Conserv. Sci.

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Dispersal plays a crucial role in the connectivity of established mangrove populations and in species range dynamics. As species ranges shift in response to climate change, range expansions can occur from incremental short-distance dispersal events and from stochastic long-distance dispersal events. Most population genetic research dealt with historically accumulated events though evidence of actual propagule dispersal allows to estimate genotypic features and origin of founders. In this study, we aim to disentangle a contemporary dispersal event. Using microsatellite markers, we genotyped 60 Rhizophora racemosa drift propagules obtained on a bare unforested coastal area in southern Cameroon, estimated their relationship to 109 adult trees from most proximate sites (which were 3–85 km away), and assessed their relative difference with 873 trees of major mangrove areas (> 300 km) along the Cameroonian coastline. Proximate mangrove populations were considered as potential source populations in assignment tests. However, drift propagules could not be assigned to any of the Cameroonian mangrove sites and were genetically isolated from Cameroonian populations. Drift propagules showed higher levels of genetic diversity and private alleles giving a higher relatedness to each other than to any putative source population. Chloroplast sequences were used to confirm the identity of drift propagules as R. racemosa. We postulate that a complex interaction of ocean currents, estuarine geomorphology, and tidal patterns explain drift propagule dispersal to an area. Most likely the investigated cohort of propagules originated from more southern mangrove areas of the West African range beyond the Cameroonian border. This study unraveled the allelic, genetic, and genotypic features of stranded propagules following a stochastic long-distance dispersal. Transboundary dispersal of these propagules highlights the need for intergovernmental efforts in the management of biodiversity.

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Runaway fathers? Limited pollen dispersal and mating system in Rhizophora racemosa populations of a disturbed mangrove estuary

Cited by 2 publications

References 71 publications

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

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

Genotypes of Rhizophora Propagules From a Non-mangrove Beach Provide Evidence of Recent Long-Distance Dispersal

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