High connectivity across environmental gradients and implications for phenotypic plasticity in a marine plant

Bricker, Eric; Waycott, Michelle; Calladine, Ainsley; Zieman, Joseph C.

doi:10.3354/meps08962

Cited by 37 publications

(43 citation statements)

References 49 publications

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“…2006, 2008), very little comparable information is available of aquatic species. The specific conditions of aquatic environments may contribute to the development of metapopulations with a high connectivity among subpopulations, as discovered in the present study on mosses, and also, for instance, in the seagrass Thalassia testudinum , which has been found to possess a metapopulation structure instead of spatially segregated and genetically distinguishable subpopulations (Bricker et al. 2011).…”

Section: Discussionsupporting

confidence: 56%

Spatial genetic structure of aquatic bryophytes in a connected lake system

et al. 2012

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Using genetic markers, we investigated the genetic structure of three clonal aquatic moss species, Calliergon megalophyllum Mikut., Fontinalis antipyretica Hedw. and F. hypnoides Hartm. on two scales: among populations in a connected lake system (large-scale spatial genetic structure) and among individuals within populations (fine-scale spatial genetic structure). Mean genetic diversities per population were 0.138, 0.247 and 0.271, respectively, and total diversities equalled 0.223, 0.385 and 0.421, respectively. Relative differentiation levels (FST values of 0.173, 0.280 and 0.142, respectively) were significant but showed that there is a moderate amount of gene flow taking place within the lake system connected with narrow streams. Bayesian STRUCTURE analysis provided some indication that the direction of water flow influences population genetic structuring in the studied aquatic mosses. We propose that dispersal leading to gene flow in C. megalophyllum, F. antipyretica and F. hypnoides takes place both along water via connecting streams and by animal vectors, such as waterfowl. Nevertheless, the slight genetic structuring pattern along the direction of water flow suggests that dispersal of shoots or their fragments along water is a means of dispersal in these mosses. The absence of sexual reproduction and spores may have caused the observed spatial genetic structure within populations, including aggregations of similar genotypes (clones or closely related genotypes) at short distances in populations otherwise showing an isolation by distance effect. Regardless of the results pointing to the dominance of vegetative propagation, it is impossible to completely rule out the potential role of rare long-distance spore dispersal from areas where the species are fertile.

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Section: Discussionsupporting

confidence: 56%

Spatial genetic structure of aquatic bryophytes in a connected lake system

et al. 2012

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“…This shows that sexual reproduction plays an important role in Ruppia meadows. In seagrass species, which usually occur in less variable or temporary habitats, the relative contribution of sexual versus clonal reproduction can be extremely variable between populations, as shown for Zostera noltei Diekmann et al, 2005), Zostera marina , Cymodocea nodosa (Alberto et al, 2008), Posidonia oceanica (Arnaud-Haond et al, 2007), and Thalassia testudinum (Bricker et al, 2011). The highest contribution of asexual reproduction was detected in the hybrid ('R.…”

Section: Discussionmentioning

confidence: 99%

Multilocus genetic analyses provide insight into speciation and hybridization in aquatic grasses, genusRuppia

Martínez-Garrido

Serrão

Engelen

et al. 2015

Biol. J. Linn. Soc.

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Aquatic plants of the genus Ruppia inhabit some of the most threatened habitats in the world, such as coastal lagoons and inland saline to brackish waters where their meadows play several key roles. The evolutionary history of this genus has been affected by the processes of hybridization, polyploidization, and vicariance, which have resulted in uncertainty regarding the number of species. In the present study, we apply microsatellite markers for the identification, genetic characterization, and detection of hybridization events among populations of putative Ruppia species found in the southern Iberian Peninsula, with the exception of a clearly distinct species, the diploid Ruppia maritima. Microsatellite markers group the populations into genetically distinct entities that are not coincident with geographical location and contain unique diagnostic alleles. These results support the interpretation of these entities as distinct species: designated here as (1) Ruppia drepanensis, (2) Ruppia cf. maritima, and (3) Ruppia cirrhosa. A fourth distinct genetic entity was identified as a putative hybrid between R. cf. maritima and R. cirrhosa because it contained a mixture of microsatellite alleles that are otherwise unique to these putative species. Hence, our analyses were able to discriminate among different genetic entities of Ruppia and, by adding multilocus nuclear markers, we confirm hybridization as an important process of speciation within the genus. In addition, careful taxonomic curation of the samples enabled us to determine the genotypic and genetic diversity and differentiation among populations of each putative Ruppia species. This will be important for identifying diversity hotspots and evaluating patterns of population """genetic connectivity.

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“…Interestingly, seagrasses with intermediate AG : BG (HOM) showed few negative responses to shading and actually increased leaf length and leaf area shoot 21 . Other research has shown that seagrasses sometimes increase allocation to leaf tissue in low light conditions, presumably benefiting from garnering more light through leaves that reach higher in the water column or have more photosynthetic area (Bulthuis 1983;Lee and Dunton 1997;Olesen et al 2002;Maxwell et al 2014). Our work suggests that this response might be advantageous only to seagrasses that have a relatively balanced AG : BG, which provides them with adequate carbohydrate reserves to support leaf metabolism and adequate leaf tissue to support belowground respiration.…”

Section: Discussionmentioning

confidence: 53%

“…The seemingly paradoxical role of roots and rhizomes may arise from the fact that many shading studies do not account for morphological plasticity of seagrasses, which is extensive for T. testudinum (Lee and Dunton b ; Hackney and Durako ; Bricker et al ; Barry et al ). In addition, many studies do not place results in the context of long‐term variations in water quality or the light environment experienced by seagrasses.…”

Section: Mean ± Sd For Total Water Column Phosphorus (Tp) T Testudimentioning

confidence: 99%

Resilience to shading influenced by differential allocation of biomass inThalassia testudinum

Barry

Jacoby

Frazer

2018

Limnology & Oceanography

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Seagrasses are marine plants with fully developed leaves, roots, and rhizomes and a high degree of phenotypic plasticity. In the shallow waters along Florida's central Gulf of Mexico coast, leaf morphology of the dominant seagrass, Thalassia testudinum, varies along a spatial gradient in concentrations of total phosphorus (TP) in the water column. We examined ratios of aboveground to belowground biomass (AG : BG) for T. testudinum along this gradient to determine if they varied consistently with TP. Ratios were positively correlated with TP, indicating T. testudinum allocated more carbon to leaf biomass relative to belowground biomass as TP increased. To determine if this variation in AG : BG influenced resilience to shading, we carried out an 8-week, comparative shading experiment in three T. testudinum meadows that spanned the range of recorded ratios. The experiment showed that seagrasses employing a range of AG : BG strategies persisted for 5 weeks with ambient light reduced by 93%. Thalassia testudinum with intermediate AG : BG exhibited the least severe impacts and strongest recovery when compared to T. testudinum with either high or low AG : BG. Seagrasses with high AG : BG ratios showed the most severe responses and weakest recovery. These results suggest T. testudinum allocates biomass such that growth and survival are maximized under the local, long-term nutrient regime, which affects the direction and magnitude of a response to a short-term reduction in light availability. In addition, we suggest that AG : BG is an important metric to monitor in T. testudinum meadows because of its potential to identify areas of high and low resilience.

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High connectivity across environmental gradients and implications for phenotypic plasticity in a marine plant

Cited by 37 publications

References 49 publications

Spatial genetic structure of aquatic bryophytes in a connected lake system

Spatial genetic structure of aquatic bryophytes in a connected lake system

Multilocus genetic analyses provide insight into speciation and hybridization in aquatic grasses, genusRuppia

Resilience to shading influenced by differential allocation of biomass inThalassia testudinum

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