scholarly journals Traditional functional groups capture limited variation in the trait space of macroalgae

2019 ◽  
Author(s):  
Alizée R. L. Mauffrey ◽  
Laura Cappelatti ◽  
John N. Griffin
Keyword(s):  
Space Use ◽  
Functional Ecology ◽  
List Type ◽  
Rocky Shores ◽  
Trait Variation ◽  
Individual Traits ◽  
Emergent Groups ◽  
Variation Explained ◽  
Ecosystem Changes ◽  
Post Hoc

ABSTRACTMacroalgal (seaweed) beds and forests fuel coastal ecosystems and are rapidly reorganising under global change, but quantifying their functional structure still relies on binning species into coarse groups on the assumption that they adequately capture relevant underlying traits.To interrogate this “group gambit”, we first measured 12 traits relating to competitive dominance and resource economics across 95 macroalgal species collected from UK rocky shores. We then assessed trait variation explained by traditional grouping approaches consisting of (i) two highly-cited schemes based on gross morphology and anatomy and (ii) two commonly-used categorisations of vertical space use. To identify the limitations of traditional grouping approaches and to reveal potential alternatives, we also assessed the ability of (iii) emergent groups created from post hoc clustering of our dataset to account for macroalgal trait variation.(i) Traditional groups explained about a third of multivariate trait expression with considerable group overlap. (ii) Classifications of vertical space use accounted for even less multivariate trait expression. Notwithstanding considerable overlap, the canopy vs. turf scheme explained significant differences in most individual traits, with turf species tending to display attributes of opportunistic forms. (iii) Emergent groups were substantially more parsimonious than all existing grouping approaches.Synthesis: Our analysis using a comprehensive dataset of directly measured functional traits failed to strongly support the group gambit in macroalgae. While existing grouping approaches may allow first order approximations, they risk considerable loss of information at the trait and, potentially, ecosystem levels. We call for further development of a trait-based approach to macroalgal functional ecology to capture unfolding community and ecosystem changes with greater accuracy and generality.

scholarly journals Intraspecific trait variability and community assembly in hawkmoths (Lepidoptera: Sphingidae) across an elevational gradient in the eastern Himalayas, India

2019 ◽  
Author(s):  
Mansi Mungee ◽  
Ramana Athreya
Keyword(s):  
Community Assembly ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Elevational Gradient ◽  
Functional Ecology ◽  
List Type ◽  
Environmental Response ◽  
Trait Variation ◽  
Eastern Himalayas ◽  
Response Traits

AbstractRecent progress in functional ecology has advanced our understanding of the role of intraspecific (ITV) and interspecific (STV) trait variation in community assembly across environmental gradients. Studies on plant communities have generally found STV as the main driver of community trait variation, whereas ITV plays an important role in determining species co-existence and community assembly. However, similar studies of faunal taxa, especially invertebrates, are very few in number.We investigated variation of hawkmoth (Lepidoptera: Sphingidae) traits along an environmental gradient spanning 2600 m in the eastern Himalayas and its role in community assembly, using the morpho-functional traits of body mass (BM), wing loading (WL) and wing aspect ratio (AR).We employ the recently proposed T-statistics to test for non-random assembly of hawkmoth communities and the relative importance of the two opposing forces for trait divergence (internal filters) and convergence (external filters).Community-wide trait-overlap decreased for all three traits with increasing environmental distance, suggesting the presence of elevation specific optimum morphology (i.e. functional response traits). Community weighted mean of BM and AR increased with elevation. Overall, the variation was dominated by species turnover but ITV accounted for 25%, 23% and <1% variability of BM, WL and AR, respectively. T-statistics, which incorporates ITV, revealed that elevational communities had a non-random trait distribution, and that community assembly was dominated by internal filtering throughout the gradient.This study was carried out using easily measurable morpho-traits obtained from calibrated field images of a large number (3301) of individuals. That these also happened to be important environmental response traits resulted in a significant signal in the metrics that we investigated. Such studies of abundant and hyperdiverse invertebrate groups across large environmental gradients should considerably improve our understanding of community assembly processes.

scholarly journals Does the punishment fit the crime? Consequences and diagnosis of misspecified detection functions in Bayesian spatial capture-recapture modelling

2021 ◽  
Author(s):  
Soumen Dey ◽  
Richard Bischof ◽  
Pierre P. A. Dupont ◽  
Cyril Milleret
Keyword(s):  
Home Range ◽  
Space Use ◽  
Relative Bias ◽  
Diagnostic Tools ◽  
List Type ◽  
Detection Function ◽  
Density Estimates ◽  
Use Patterns ◽  
Wide Range ◽  
Capture Recapture

AbstractSpatial capture-recapture (SCR) is now used widely to estimate wildlife densities. At the core of SCR models lies the detection function, linking individual detection probability to the distance from its latent activity center. The most common function (half-normal) assumes a bivariate normal space use and consequently detection pattern. This is likely an oversimplification and misrepresentation of real-life animal space use patterns, but studies have reported that density estimates are relatively robust to misspecified detection functions. However, information about consequences of such misspecification on space use parameters (e.g. home range area), as well as diagnostic tools to reveal it are lacking.We simulated SCR data under six different detection functions, including the half-normal, to represent a wide range of space use patterns. We then fit three different SCR models, with the three simplest detection functions (half-normal, exponential and half-normal plateau) to each simulated data set. We evaluated the consequences of misspecification in terms of bias, precision and coverage probability of density and home range area estimates. We also calculated Bayesian p-values with respect to different discrepancy metrics to assess whether these can help identify misspecifications of the detection function.We corroborate previous findings that density estimates are robust to misspecifications of the detection function. However, estimates of home range area are prone to bias when the detection function is misspecified. When fitted with the half-normal model, average relative bias of 95% kernel home range area estimates ranged between −25% and 26% depending on the misspecification. In contrast, the half-normal plateau model (an extension of the half-normal) returned average relative bias that ranged between −26% and −4%. Additionally, we found useful heuristic patterns in Bayesian p-values to diagnose the misspecification in detection function.Our analytical framework and diagnostic tools may help users select a detection function when analyzing empirical data, especially when space use parameters (such as home range area) are of interest. We urge development of additional custom goodness of fit diagnostics for Bayesian SCR models to help practitioners identify a wider range of model misspecifications.

Synchronous changes in length at maturity across four species of Lake Erie fish with different harvest histories

2021 ◽  
Author(s):  
Davíð Gíslason ◽  
Robert L. McLaughlin ◽  
Beren W Robinson
Keyword(s):  
Yellow Perch ◽  
Lake Erie ◽  
Large Scale ◽  
White Perch ◽  
Water Levels ◽  
White Bass ◽  
Morone Chrysops ◽  
Harvest Intensity ◽  
Ecosystem Changes ◽  
Post Hoc

Decreases in size at maturation in harvested fish populations can reduce productivity and resilience. Delineating the causes for these changes in maturation is challenging. We assessed harvest and large-scale ecosystem variability as causes for changes in maturation in four Lake Erie fishes. Regulated harvests of Yellow Perch (Perca flavescens) and Walleye (Sander vitreus) are greater than unregulated harvests of White Perch (Morone americana) and White Bass (Morone chrysops). Our assessment considered cohort data from 1991-2012 for each species. We used a conceptual model of harvest-induced plasticity to show that changes in female length at 50% maturity (L50) were unrelated to harvest intensity in all species. We then demonstrated that changes in female L50 among cohorts were synchronous across species. Post-hoc analysis of variables capturing year-to-year variation in climatic and lake conditions suggested L50 was larger when water levels were near the norm for the study period and smaller at low and high levels. We conclude that changes in L50 were most strongly related to ecosystem changes unrelated to harvest intensity.

scholarly journals Decomposing leaf mass into photosynthetic and structural components explains divergent patterns of trait variation within and among plant species

2017 ◽  
Author(s):  
Masatoshi Katabuchi ◽  
Kaoru Kitajima ◽  
S. Joseph Wright ◽  
Sunshine A. Van Bael ◽  
Jeanne L. D. Osnas ◽  
...  
Keyword(s):  
Plant Species ◽  
List Type ◽  
Metabolic Rates ◽  
Leaf Lifespan ◽  
Trait Variation ◽  
Leaf Toughness ◽  
Leaf Trait ◽  
Metabolic Traits ◽  
Leaf Mass ◽  
Mass Dependent

AbstractAcross the global flora, photosynthetic and metabolic rates depend more strongly on leaf area than leaf mass. In contrast, intraspecific variation in these rates is strongly mass-dependent. These contrasting patterns suggest that the causes of variation in leaf mass per area (LMA) may be fundamentally different within vs. among species.We used statistical methods to decompose LMA into two conceptual components – ‘photosynthetic’ LMAp (which determines photosynthetic capacity and metabolic rates, and also affects optimal leaf lifespan) and ‘structural’ LMAs (which determines leaf toughness and potential leaf lifespan) using leaf trait data from tropical forest sites in Panama and a global leaf-trait database.Statistically decomposing LMA into LMAp and LMAs provides improved predictions of trait variation (photosynthesis, respiration, and lifespan) across the global flora, and within and among tropical plant species in Panama. Our analysis shows that most interspecific LMA variation is due to LMAs (which explains why photosynthetic and metabolic traits are area-dependent across species) and that intraspecific LMA variation is due to changes in both LMAp and LMAs (which explains why photosynthetic and metabolic traits are mass-dependent within species).Our results suggest that leaf trait variation is multi-dimensional and is not well-represented by the one-dimensional leaf economics spectrum.

scholarly journals Weak spatiotemporal response of prey to predation risk in a freely interacting system

2017 ◽  
Author(s):  
Jeremy J. Cusack ◽  
Michel T. Kohl ◽  
Matthew C. Metz ◽  
Tim Coulson ◽  
Daniel R. Stahler ◽  
...  
Keyword(s):  
Predation Risk ◽  
Cervus Elaphus ◽  
Null Model ◽  
Space Use ◽  
Home Ranges ◽  
List Type ◽  
Predator Prey ◽  
Risk Of Predation ◽  
Spatiotemporal Scales ◽  
Spatiotemporal Response

AbstractThe extent to which prey space use actively minimises predation risk continues to ignite controversy. Methodological reasons that have hindered consensus include inconsistent measurements of predation risk, biased spatiotemporal scales at which responses are measured, and lack of robust null expectations.We addressed all three challenges in a comprehensive analysis of the spatiotemporal responses of adult female elk (Cervus elaphus) to the risk of predation by grey wolves (Canis lupus) during winter in northern Yellowstone, USA.We quantified spatial overlap between the winter home ranges of GPS-collared elk and three measures of predation risk: the intensity of wolf space use, the distribution of wolf-killed elk and vegetation openness. We also assessed whether elk varied their use of areas characterised by more or less predation risk across hours of the day, and estimated encounter rates between simultaneous elk and wolf pack trajectories. We determined whether observed values were significantly lower than expected if elk movements were random with reference to predation risk using a null model approach.Although a small proportion of elk did show a tendency to minimise use of open vegetation at specific times of the day, overall we highlight a notable absence of spatiotemporal response by female elk to the risk of predation posed by wolves in northern Yellowstone.Our results suggest that predator-prey interactions may not always result in strong spatiotemporal patterns of avoidance.

scholarly journals Leaf nitrogen from first principles: field evidence for adaptive variation with climate

2016 ◽  
Author(s):  
Ning Dong ◽  
Iain Colin Prentice ◽  
Bradley J. Evans ◽  
Stefan Caddy-Retalic ◽  
Andrew J. Lowe ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Species Turnover ◽  
Leaf Nitrogen ◽  
Functional Ecology ◽  
Leaf Mass Per Area ◽  
Mean Annual Temperature ◽  
Rubisco Activity ◽  
Trait Variation ◽  
Leaf Trait ◽  
Field Evidence

Abstract. Nitrogen content per unit leaf area (Narea) is a key variable in plant functional ecology and biogeochemistry. Narea comprises a structural component, which scales with leaf mass per area (LMA), and a metabolic component, which scales with Rubisco capacity. The co-ordination hypothesis, as implemented in LPJ and related global vegetation models, predicts that Rubisco capacity should be directly proportional to irradiance but should decrease with ci:ca and temperature because the amount of Rubisco required to achieve a given assimilation rate declines with both. We tested these predictions using LMA, leaf δ13C and leaf N measurements on complete species assemblages sampled at sites on a North-South transect from tropical to temperate Australia. Partial effects of mean canopy irradiance, mean annual temperature and ci:ca (from δ13C) on Narea were all significant and their directions and magnitudes were in line with predictions. Over 80 % of the variance in community-mean (ln) Narea was accounted for by these predictors plus LMA. Moreover, Narea could be decomposed into two components, one proportional to LMA (slightly steeper in N-fixers), the other to predicted Rubisco activity. Trait gradient analysis revealed ci:ca to be perfectly plastic, while species turnover contributed about half the variation in LMA and Narea. Interest has surged in methods to predict continuous leaf-trait variation from environmental factors, in order to improve ecosystem models. Our results indicate that Narea has a useful degree of predictability, from a combination of LMA and ci:ca – themselves in part environmentally determined – with Rubisco activity, as predicted from local growing conditions. This is consistent with a 'plant-centred' approach to modelling, emphasizing the adaptive regulation of traits. Models that account for biodiversity will also need to partition community-level trait variation into components due to phenotypic plasticity and/or genotypic differentiation within species, versus progressive species replacement, along environmental gradients. Our analysis suggests that variation in Narea is about evenly split between these two modes.

scholarly journals Airborne point counts: a method for estimating songbird abundance with drones

2020 ◽  
Author(s):  
McKenzie D. Somers ◽  
Darren B. Glass ◽  
Marisa A. Immordino ◽  
Precious S. Ozoh ◽  
Lauren B. Sherman ◽  
...  
Keyword(s):  
Bird Species ◽  
Field Tests ◽  
List Type ◽  
Similar Data ◽  
Northern Cardinal ◽  
Point Counts ◽  
Survey Techniques ◽  
The Mean ◽  
Difficult Terrain ◽  
Post Hoc

AbstractUsing drones to conduct airborne bioacoustic surveys is a potentially useful new way to estimate the abundance of vocal bird species. Here we show that by using two recording devices suspended from a quadcopter drone it is possible to estimate distances to birds with precision. In an experimental test, the mean error of our estimated distances to a broadcast song across 11 points between 0 and 100 m away was just 3.47 m. In field tests we compared 1-minute airborne counts with 5-minute terrestrial counts at 34 count locations. We found that the airborne counts yielded similar data to the terrestrial point counts for most of the 10 the songbirds included in our analysis, and that the effective detection radii were also similar. However, airborne counts significantly under-detected the Northern Cardinal (χ29 = 22.8, post-hoc test P = 0.007), which we attribute to a behavioral response to the drone. Airborne counts work best for species that vocalize close to the ground and have high frequency-range songs. Under those circumstances, airborne bioacoustics could have several advantages over ground-based surveys, including increased precision, increased repeatability, and easier access in difficult terrain. Further, we show that it is possible to do rapid surveys using airborne techniques, which could lead to the development of much more efficient survey protocols than are possible using traditional survey techniques.Lay SummaryWe show that it is possible to estimate the distance of singing birds from a drone, which then allows bird counts to be converted to true abundance or population densities.Using drones to count birds allows researchers to survey areas that may be difficult or dangerous to access on foot.Airborne counts are potentially a highly efficient and highly repeatable way to estimate populations of vocal bird species.

scholarly journals Expression of substance P, calcitonin gene-related peptide and vascular endothelial growth factor in human dental pulp under different clinical stimuli

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Javier Caviedes-Bucheli ◽  
Luis Fernando Lopez-Moncayo ◽  
Hernan Dario Muñoz-Alvear ◽  
Jose Francisco Gomez-Sosa ◽  
Luis Eduardo Diaz-Barrera ◽  
...  
Keyword(s):  
Dental Pulp ◽  
Defense Mechanism ◽  
Initial Step ◽  
Control Group ◽  
List Type ◽  
Registration Number ◽  
Human Dental Pulp ◽  
Orthodontic Forces ◽  
Post Hoc ◽  
Endothelial Growth Factor

Abstract Background The aim of this study was to measure the dental pulp inflammatory response through neuropeptides (SP and CGRP) as a response to occlusal trauma, orthodontic movements and a combination of both, as well as the angiogenic defense mechanism through VEGF expression, which could be the initial step to mineralized tissue formation. Methods Forty human dental pulp samples were collected from healthy first premolars with extraction indicated due to orthodontic reasons from a sample of 20 patients. Patients were divided into four groups with 10 premolars each (1 mandibular and 1 maxillary premolar from each patient): healthy pulp control group, occlusal trauma group, moderate orthodontic forces group; and occlusal trauma plus moderate orthodontic forces group. Stimuli were applied for 24 h before tooth extraction in all experimental groups. All samples were processed, and SP, CGRP, and VEGF were measured by radioimmunoassay. The Kruskal–Wallis test was performed to assess significant differences among groups and Mann–Whitney’s U post hoc pairwise comparisons were also performed. Results The highest increase in SP, CGRP, and VEGF expressions was found in the occlusal trauma plus orthodontic forces group, followed by the moderate orthodontic forces, the occlusal trauma and the control groups, with statistically significant differences between all groups for each of the 3 peptides analyzed (Kruskal–Wallis p < 0.001). All possible pairwise post-hoc comparisons were also significant for each peptide analyzed (Mann–Whitney’s U p < 0.001). Conclusion SP, CGRP, and VEGF expressions significantly increase in human dental pulps when stimulated by occlusal trauma combined with moderate orthodontic forces, as compared with these two stimuli applied independently. Name of the registry: Importance of Neurogenic Inflammation in the Angiogenic Response of the Dental Pulp as a Defensive Response. Trial registration number: NCT03804034. Date of registration: 01/15/2019 Retrospectively registered. URL of trial registry record: https://clinicaltrials.gov/ct2/show/NCT03804034?term=NCT03804034&draw=2&rank=1.

scholarly journals Intraspecific root and leaf trait variation with tropical forest successional status: consequences for community-weighted patterns

2019 ◽  
Author(s):  
J. Aaron Hogan ◽  
Oscar J. Valverde-Barrantes ◽  
Qiong Ding ◽  
Han Xu ◽  
Christopher Baraloto
Keyword(s):  
Soil Fertility ◽  
Tropical Forest ◽  
Leaf Area ◽  
Specific Root Length ◽  
Functional Trait ◽  
Primary Forest ◽  
List Type ◽  
Forest Age ◽  
Trait Variation ◽  
Trade Offs

SummaryQuantifying the dimensions and magnitude of intraspecific root trait variation is key to understanding the functional trade-offs in the belowground plant strategies of tropical forest trees. Additionally, accurately measuring how belowground functional trait variation relates to soil environment and forest age is crucial to tropical forest modeling efforts.We sampled leaf and root morphologies from 423 juvenile trees of 72 species from 14 Angiosperm families along a 6.6 km transect that corresponded to an environmental gradient in decreasing soil fertility and texture with increasing forest age.We observed within-lineage conservative functional trait-shifts in root and leaf morphological traits along the transect. From secondary to primary forest, average leaf area increased 7 cm2and average root system diameter increased 0.4 mm. Mean specific leaf area decreased by 0.8 m2kg−1, specific root length decreased by 3.5 m kg−1, and root branching intensity decreased by 0.3 tips cm−1. Leaf thickness and root tissue density showed no change.We coupled trait measurements to a network of 164 1/16th-ha plots across a Chinese tropical forest reserve, to scale individual trait measurements up to the community-level, accounting for forest age.For most traits, intraspecific trait variation negatively covaried with species compositional turnover between plots in younger versus older forest to compound and create greater community-weighted differences in trait values than would be observed if intraspecific variation in traits with forest age was not accounted for.SummaryRoot morphologies are variable with local scale variation in soil fertility and texture. Accurately understanding broader (i.e. forest)-scale patterns in root functional traits, requires attention to underlying environmental variation in soil resources, which interacts with environmental filtering of plant communities.

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