A meta‐analysis reveals a positive correlation between genetic diversity metrics and environmental status in the long‐lived seagrass<i><scp>P</scp>osidonia oceanica</i>

Jahnke, Marlene; Olsen, Jeanine L.; Procaccini, Gabriele

doi:10.1111/mec.13174

Cited by 55 publications

(44 citation statements)

References 71 publications

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“…However, recent studies indicated that temperature variation rather than mean value could be the main trigger of flowering (Diaz-Almela et al, 2007). Since the genetic diversity of some meadows in the biogeographic transition zone appears be higher compared to others meadows of the Mediterranean (Jahnke et al, 2015), future studies should investigate whether there is a relationship between the success of seed production in these meadows and their genetic diversity. Flowering had rarely been observed before 1984 along the coasts of Corsica and Livorno (Caye and Meinesz, 1984), but from 1994 onward this phenomenon occurred regularly (Balestri, 2004; Gobert et al, 2005), possibly due to moderate warming of the northwestern Mediterranean over the past decades (Lejeusne et al, 2010; Marbà et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Recruitment and Patch Establishment by Seed in the Seagrass Posidonia oceanica: Importance and Conservation Implications

2017

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Seagrasses are declining globally, and deeper understanding is needed on the recruitment potential and distribution of new populations for many threatened species to support conservation planning in the face of climate change. Recruitment of Posidonia oceanica, a threatened seagrass endemic to the Mediterranean, has long been considered rare due to infrequent flowering, but mounting evidence demonstrates that the species is responding to a changing climate through greater reproductive effort. Due to the fragmentary information on recruit occurrence and distribution, little is known about reproductive success in the species and its contribution to persistence. We assembled P. oceanica recruitment data from published and unpublished sources, including our own, to examine the frequency and extent of recruitment events (establishment of seedlings in a site), seedling growth potential and habitat characteristics at recruitment sites. Results show that at least one recruitment event has occurred about every 3 years, and 18 localities were colonized at least one time since the first seedling record in 1986. Notably, consistently high seedling inputs were observed in four localities of the Western Mediterranean. Seedlings established mainly on unoccupied substrate areas along the coasts of islands, in sheltered sites and at shallower depths (<3 m) than the upper limit of adjacent P. oceanica meadows. Seedling establishment occurred more frequently on rocky than on sandy substrate, and rarely on dead “matte” or meadows of the seagrass Cymodocea nodosa. The chance of colonization success on rock was two times higher than on sand. Our 11 years of observations have allowed for the first time the documentation of the formation and development of patches by P. oceanica seed. These findings contradict the historical assumption that sexual recruitment is rare and usually unsuccessful for P. oceanica, and highlight the potential importance of recruitment for the long-term persistence and adaptation of the species to sea level rise predicted in the next century in the Mediterranean. Unfortunately, management actions have mainly focused on established meadows, ignoring the presence of recruits in outside areas. Therefore, it will be useful to identify and consider regeneration sites in designing future management strategies to improve seagrass conservation effectiveness.

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Section: Discussionmentioning

confidence: 99%

Recruitment and Patch Establishment by Seed in the Seagrass Posidonia oceanica: Importance and Conservation Implications

2017

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“…Finally, whereas the genetic make‐up is a permanent characteristic of a plant, and patch genetic structure may require years to decades to change (see for instance Zupo et al . ; Jahnke, Olsen & Procaccini ), nutrient levels and the amount of herbivory may have changed between the time of flower induction and when ecological data were collected.…”

Section: Discussionmentioning

confidence: 99%

“…In fact, if those cues do not exist locally, populations in a given area may only subsist via asexual reproduction, with important implications for their future (Honnay & Jacquemyn ; Hughes & Stachowicz ; Oliva et al . ; Jahnke, Olsen & Procaccini ).…”

Section: Introductionmentioning

confidence: 99%

Should we sync? Seascape‐level genetic and ecological factors determine seagrass flowering patterns

et al. 2015

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Summary Spatial and temporal heterogeneity in flowering occur in many plant species with abiotic pollination and may confer fitness advantages through mechanisms such as predator satiation or pollination efficiency. Environmental factors such as light quality or quantity and temperature play an important role in inducing synchronization on wide geographic scales. On a smaller geographic scale, external factors such as resource availability and herbivory are theorized to trigger flowering, while genetic factors may also play an important role. In this study, we assessed the importance of ecological and genetic factors in shaping seascape‐level spatial heterogeneity in flowering of the seagrass Posidonia oceanica. By investigating spatially close sites (<20 km) with similar seascape configurations and depth, we assume that major environmental drivers (temperature and light) were equivalent. We assessed four ecological factors (productivity, leaf nitrogen and carbon content and herbivory) and three genetic factors (heterozygosity, relatedness and clonality) to assess three hypotheses for synchronized flowering in P. oceanica: (i) clone synchronization (internal clock hypothesis), (ii) variation in nutrient availability, potentially caused by spatial heterogeneity in herbivory rates or nutrient translocation via clonal integration (resource budget hypothesis) or (iii) kin selection and sibling synchronization. Internal relatedness and heterozygosity had a significant positive effect on the abundance of flowers. Moreover, productivity and genotypic richness (clonality) were negatively associated with flower density, although at a lower level of significance. In addition, we found that clones were almost exclusively shared among mass‐flowering patches and patches without mass‐flowering, respectively. Synthesis. The results shed new light on seagrass flowering patterns and on the mechanisms of flower synchronization at the patch level within a wider spatial scale. We found support for the kin selection hypothesis and indirect evidence for the resource budget hypothesis. Thus, a combination of mainly genetic but also ecological factors causes the observed heterogeneous flowering patterns in Posidonia oceanica seascapes. In addition, we found a strong positive relationship between the number of flowers and heterozygosity, adding evidence to the controversial association between heterozygosity and fitness when a limited number of loci are used. To our knowledge, this study is the first to link both ecological and genetic factors with flower abundance in a species with a presumed masting strategy.

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“…In seagrasses this is a critical life stage since, in some species, sexual reproduction is very variable in space and time and in general, there is a very low rate of seedling establishment12. Although some seagrass species rely mainly on clonal reproduction, sexual reproduction provides genetic diversity which could make seagrass populations more resilient and resistant to future changes13. Furthermore, seeds and seedlings provide a key opportunity to colonize new habitats14, and under the current scenarios of anthropogenic threats, this strategy may be particularly relevant for allowing the establishment of seagrass into more suitable environments.…”

mentioning

confidence: 99%

Seagrass (Posidonia oceanica) seedlings in a high-CO2 world: from physiology to herbivory

Hernán

Ramajo

Basso

et al. 2016

Sci Rep

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Under future increased CO2 concentrations, seagrasses are predicted to perform better as a result of increased photosynthesis, but the effects in carbon balance and growth are unclear and remain unexplored for early life stages such as seedlings, which allow plant dispersal and provide the potential for adaptation under changing environmental conditions. Furthermore, the outcome of the concomitant biochemical changes in plant-herbivore interactions has been poorly studied, yet may have important implications in plant communities. In this study we determined the effects of experimental exposure to current and future predicted CO2 concentrations on the physiology, size and defense strategies against herbivory in the earliest life stage of the Mediterranean seagrass Posidonia oceanica. The photosynthetic performance of seedlings, assessed by fluorescence, improved under increased pCO2 conditions after 60 days, although these differences disappeared after 90 days. Furthermore, these plants exhibited bigger seeds and higher carbon storage in belowground tissues, having thus more resources to tolerate and recover from stressors. Of the several herbivory resistance traits measured, plants under high pCO2 conditions had a lower leaf N content but higher sucrose. These seedlings were preferred by herbivorous sea urchins in feeding trials, which could potentially counteract some of the positive effects observed.

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A meta‐analysis reveals a positive correlation between genetic diversity metrics and environmental status in the long‐lived seagrassPosidonia oceanica

Cited by 55 publications

References 71 publications

Recruitment and Patch Establishment by Seed in the Seagrass Posidonia oceanica: Importance and Conservation Implications

Recruitment and Patch Establishment by Seed in the Seagrass Posidonia oceanica: Importance and Conservation Implications

Should we sync? Seascape‐level genetic and ecological factors determine seagrass flowering patterns

Seagrass (Posidonia oceanica) seedlings in a high-CO2 world: from physiology to herbivory

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