Clonal and genetic diversity of the threatened seagrass Halophila beccarii in a tropical lagoon: Resilience through short distance dispersal

Phan, Thi Thuy Hang; Raeymaeker, Marie De; Luong, Quang Doc; Triest, Ludwig

doi:10.1016/j.aquabot.2017.07.006

Cited by 20 publications

(22 citation statements)

References 68 publications

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“…The hypothesis proposed by Kendrick et al. (2012) may thus apply to some seagrass species, particularly short‐lived species producing a large number of seeds (Phan, De Raeymaeker, Luong, & Triest, 2017), especially if one also accounts for the dispersal of vegetative fragments (McMahon et al., 2014). However, the prevalence of clonality is associated with a decrease in the loss of diversity due to the influence of drift (Reichel et al., 2016), which may partly explain the elevated levels of genetic diversity observed in well‐established meadows.…”

Section: Discussionmentioning

confidence: 99%

New insights into the population genetics of partially clonal organisms: When seagrass data meet theoretical expectations

2020

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Seagrass meadows are among the most important coastal ecosystems in terms of both spatial extent and ecosystem services, but they are also declining worldwide. Understanding the drivers of seagrass meadow dynamics is essential for designing sound management, conservation and restoration strategies. However, poor knowledge of the effect of clonality on the population genetics of natural populations severely limits our understanding of the dynamics and connectivity of meadows. Recent modelling approaches have described the expected distributions of genotypic and genetic descriptors under increasing clonal rates, which may help us better understand and interpret population genetics data obtained for partial asexuals. Here, in the light of these recent theoretical developments, we revisited population genetics data for 165 meadows of four seagrass species. Contrasting shoot lifespan and rhizome turnover led to the prediction that the influence of asexual reproduction would increase along a gradient from Zostera noltii to Zostera marina, Cymodocea nodosa and Posidonia oceanica, with increasing departure from Hardy–Weinberg equilibrium (Fis), mostly towards heterozygote excess, and decreasing genotypic richness (R). This meta‐analysis provides a nested validation of this hypothesis at both the species and meadow scales through a significant relationship between Fis and R within each species. By empirically demonstrating the theoretical expectations derived from recent modelling approaches, this work calls for the use of Hardy–Weinberg equilibrium (Fis) rather than only the strongly sampling‐sensitive R to assess the importance of clonal reproduction (c), at least when the impact of selfing on Fis can be neglected. The results also emphasize the need to revise our appraisal of the extent of clonality and its influence on the dynamics, connectivity and evolutionary trajectory of partial asexuals in general, including in seagrass meadows, to develop the most accurate management strategies.

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Section: Discussionmentioning

confidence: 99%

New insights into the population genetics of partially clonal organisms: When seagrass data meet theoretical expectations

2020

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“…Our results of significant SGS both at ramet and genet levels, especially in short distance classes, indicate that gene dispersal was spatially restricted. The genet-level SGS of H. ovalis was similar to other seagrasses such as Posidonia oceanica (Diaz-Almela et al, 2007), Zostera marina (Becheler et al, 2010), Halophila beccarii (Phan et al, 2017), and Cymodocea nodosa in Italy (Ruggiero et al, 2005b), but weaker than that of Cymodocea nodosa in Spain (Alberto et al, 2005). The contribution of seed dispersal to SGS is likely to be higher in H. ovalis than other seagrasses, given that the rate of horizontal rhizome elongation is very high in H. ovalis (Marbà and Duarte, 1998).…”

Section: Spatial Genetic Structurementioning

confidence: 67%

Clone Configuration and Spatial Genetic Structure of Two Halophila ovalis Populations With Contrasting Internode Lengths

Jiang

Biswas

et al. 2019

Front. Ecol. Evol.

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Fine-scale spatial genetic structure (SGS) is predominantly determined by gene flow. While sexually reproducing plants can disperse their genes through pollen and seed grains, clonal plants can additionally disperse genes through clonal growth. Plants' clonal reproduction strategy, however, often varies within and between species. Still, the effect of differential clonal reproduction strategy on fine-scale SGS remains somewhat unclear. Halophila ovalis is a fast-growing clonal seagrass, whose internode length (which defines a species' clonal reproduction strategy) varies among populations. Using eight polymorphic microsatellites, here we compare the genetic diversity, clonal structure and fine-scale SGS of two H. ovalis populations with contrasting internode lengths (Yingluo vs. Xialongwei populations). We found moderate to high genotypic and allelic richness and heterozygosities in both populations. Compared to Xialongwei population, genetic and genotypic diversity was significantly lower in Yingluo population. Although their internode length was relatively short, clones of Yingluo population spread farther than those of Xialongwei population. Sexual-to-vegetative dispersal variance ratios were 34.6 and 445.5 in Yingluo and Xialongwei populations, respectively. In both populations, clonal growth significantly intensified the SGS, especially in short distance classes. The SGS at small distance classes were weaker in Yingluo than Xialongwei, in part, due to more intermingled distribution of genets and more extensive clonal expansion in the former population. Our results indicate that vegetative dispersal variance/distance, rather than internode length, plays a crucial role in shaping the fine-scale genetic structure.

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“…A more detailed study covering the sampling of this species from the entire coast of India is necessary to understand the genetic variation of H. beccarii, as local environmental variables determine both phenotypic plasticity and genetic response of seagrass (Nguyen et al, 2015;King et al, 2018). Supporting this evidence is a recent study on karyomorphological properties of H. beccarii from the coast of Thailand, that revealed in difference of H. beccarii karyomorphological properties from India and China (Hang Phan et al, 2017).…”

Section: H Beccarii Geneticsmentioning

confidence: 99%

“…Except the Indian coast, they also have a wide distribution in South-East Asia (Short et al, 2011) including their presence from the coast of Sri Lanka (Udagedra et al, 2017), Bangladesh (Abu Hena and Short, 2009;Masum Billah et al, 2016), Malaysia (Zakaria et al, 2002;Fakhrulddin et al, 2013), Philippines (Liao andGeraldino., 2020), Thailand (Aye et al, 2014;Hiranphan et al, 2020) and Viet Nam (Hang Phan et al, 2017). H. beccarii acts as one of the pioneer species in the ecological succession process leading to mangrove formation of the Indian coast (Jagtap, 1985;Untawale and Jagtap, 1991;Parthasarathy et al, 1988Parthasarathy et al, , 1991.…”

Section: Introductionmentioning

confidence: 99%

The Current Status of <em>Halophila beccarii</em>: An Ecologically Significant, Yet Vulnerable Seagrass of India

Mishra

Apte

2020

Preprint

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We reviewed the current status of a Vulnerable seagrass, Halophila beccarii from the coast of India using the published data from 1977-2020. We found that the seagrass, H. beccarii has a pan India distribution on both east and west coast. It is abundant in the intertidal silty-muddy region on the west coast, while on the east coast it is found on sandy habitats, with few exceptions of muddy habitat. H. beccarii was found to be associated with mangroves or smaller seagrass species within a depth limit of 1.7m. Low salinity and high nitrate levels were observed for the H. beccarii meadows of the west coast due to its association with mangroves. The nutrient levels in H. beccarii meadows of India were comparatively lower than other seagrass meadows. Most of the research on H. beccarii has focoused on its morphometrics (41%), reproductive (33%) and distribution (29%) along the coast of India. Reproductive traits such as flowering and fruiting varying according to the seasons of each coast due to the influence of monsoon and its associated temperature, salinity and nutrient influx. H. beccarii has a great potential of various bioactive compounds, which needs further investigation. Habitat disturbance, anthropogenic pollution and coastal development are the major cause of declining H. beccarii ecosystems in India. Significant loss of the seagrass was observed from the west coast of India due to increased coastal development activities. There is a significant need in quantifying H. beccarii population trends, impact of climate and anthropogenic stressors, economic values of ecosystem services and the role of ecological connectivity for better conservation and management of H. beccarii seascapes across India. There is a need for integration of research outcomes in policy framing for preventing the decline and further loss of this vulnerable seagrass ecosystem.

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Clonal and genetic diversity of the threatened seagrass Halophila beccarii in a tropical lagoon: Resilience through short distance dispersal

Cited by 20 publications

References 68 publications

New insights into the population genetics of partially clonal organisms: When seagrass data meet theoretical expectations

New insights into the population genetics of partially clonal organisms: When seagrass data meet theoretical expectations

Clone Configuration and Spatial Genetic Structure of Two Halophila ovalis Populations With Contrasting Internode Lengths

The Current Status of <em>Halophila beccarii</em>: An Ecologically Significant, Yet Vulnerable Seagrass of India

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