Independent and interactive effects of two facilitators on their habitat‐providing host plant, Spartina alterniflora

2014

Journal of Ecology

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Summary1. Intraspecific diversity can have important effects on population, community and ecosystem processes, yet we have little understanding of the relative importance of genetic-versus trait-based measures of intraspecific diversity.2. I conducted a manipulative field experiment of plant (Spartina alterniflora) genotypic diversity and trait diversity to examine their independent and interactive effects on plant performance and community structure. I focused on variation within and among genotypes in plant stem height, a trait that varies substantially across environmental gradients and can be an important predictor of plant competition intensity.3. Trait and genotypic diversity interactively affected multiple metrics of plant performance. Both stem density and spatial spread increased with genotypic diversity in the low trait diversity combinations, yet there were negligible to weak negative effects in the high trait diversity treatments. Spartina alterniflora percentage cover also varied with genotypic and trait diversity, but not in a clear linear pattern.4. There were no effects of trait or genotypic diversity on associated macrofauna above-ground, yet they interactively affected below-ground measures. Infaunal abundance and sediment oxygen availability mirrored the idiosyncratic response of plant percentage cover. 5.Despite the interactive effects of genotypic and trait diversity, high trait diversity consistently increased plant performance in genotypic monoculture.6. Synthesis. The effects of intraspecific plant trait diversity on a range of plant and community responses in this study reinforce the premise that functional differences underlie ecological effects of genetic diversity and suggest that readily measured trait variance may serve as a valuable predictor of plant performance.

Section: Discussionmentioning

confidence: 99%

Genotypic diversity and trait variance interact to affect marsh plant performance

2014

Journal of Ecology

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“…Six different Spartina genotypes collected from natural marshes in July 2009 and propagated in the greenhouse at the FSUCML were also used (Hughes et al. 2014). …”

Section: Methodsmentioning

confidence: 99%

Consumer trait variation influences tritrophic interactions in salt marsh communities

Hanley

Orozco

et al. 2015

Ecology and Evolution

The importance of intraspecific variation has emerged as a key question in community ecology, helping to bridge the gap between ecology and evolution. Although much of this work has focused on plant species, recent syntheses have highlighted the prevalence and potential importance of morphological, behavioral, and life history variation within animals for ecological and evolutionary processes. Many small-bodied consumers live on the plant that they consume, often resulting in host plant-associated trait variation within and across consumer species. Given the central position of consumer species within tritrophic food webs, such consumer trait variation may play a particularly important role in mediating trophic dynamics, including trophic cascades. In this study, we used a series of field surveys and laboratory experiments to document intraspecific trait variation in a key consumer species, the marsh periwinkle Littoraria irrorata, based on its host plant species (Spartina alterniflora or Juncus roemerianus) in a mixed species assemblage. We then conducted a 12-week mesocosm experiment to examine the effects of Littoraria trait variation on plant community structure and dynamics in a tritrophic salt marsh food web. Littoraria from different host plant species varied across a suite of morphological and behavioral traits. These consumer trait differences interacted with plant community composition and predator presence to affect overall plant stem height, as well as differentially alter the density and biomass of the two key plant species in this system. Whether due to genetic differences or phenotypic plasticity, trait differences between consumer types had significant ecological consequences for the tritrophic marsh food web over seasonal time scales. By altering the cascading effects of the top predator on plant community structure and dynamics, consumer differences may generate a feedback over longer time scales, which in turn influences the degree of trait divergence in subsequent consumer populations.

“…For example, genetic identity, diversity, and relatedness within populations of seagrasses and marsh plants have clear benefits for plant production, resistance to disturbance, and community composition, abundance, and diversity (Hughes and Stachowicz , , Hughes et al. ). In addition, genetic diversity and relatedness within and between populations of marine invertebrates have strong effects on settlement and colonization success of early life‐history stages (Gamfeldt et al.…”

Section: Introductionmentioning

confidence: 99%

“…Experiments with natural populations of aquaculture species suggest that these changes in intraspecific variation within and across populations could have large effects on both production and resilience to environmental change. For example, genetic identity, diversity, and relatedness within populations of seagrasses and marsh plants have clear benefits for plant production, resistance to disturbance, and community composition, abundance, and diversity (Hughes and Stachowicz 2004, 2011, Hughes et al 2014). In addition, genetic diversity and relatedness within and between populations of marine invertebrates have strong effects on settlement and colonization success of early life-history stages (Gamfeldt et al 2005, Aguirre et al 2013, Smee et al 2013, Plough et al 2016.…”

Section: Introductionmentioning

confidence: 99%

Genetic diversity and phenotypic variation within hatchery‐produced oyster cohorts predict size and success in the field

Ecological Applications

Hanley

Byers

et al. 2019

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The rapid growth of the aquaculture industry to meet global seafood demand offers both risks and opportunities for resource management and conservation. In particular, hatcheries hold promise for stock enhancement and restoration, yet cultivation practices may lead to enhanced variation between populations at the expense of variation within populations, with uncertain implications for performance and resilience. To date, few studies have assessed how production techniques impact genetic diversity and population structure, as well as resultant trait variation in and performance of cultivated offspring. We collaborated with a commercial hatchery to produce multiple cohorts of the eastern oyster (Crassostrea virginica) from field‐collected broodstock using standard practices. We recorded key characteristics of the broodstock (male : female ratio, effective population size), quantified the genetic diversity of the resulting cohorts, and tested their trait variation and performance across multiple field sites and experimental conditions. Oyster cohorts produced under the same conditions in a single hatchery varied almost twofold in genetic diversity. In addition, cohort genetic diversity was a significant positive predictor of oyster performance traits, including initial size and survival in the field. Oyster cohorts produced in the hatchery had lower within‐cohort genetic variation and higher among‐cohort genetic structure than adults surveyed from the same source sites. These findings are consistent with “sweepstakes reproduction” in oysters, even when manually spawned. A readily measured characteristic of broodstock, the ratio of males to females, was positively correlated with within‐cohort genetic diversity of the resulting offspring. Thus, this metric may offer a tractable way both to meet short‐term production goals for seafood demand and to ensure the capacity of hatchery‐produced stock to achieve conservation objectives, such as the recovery of self‐sustaining wild populations.