scholarly journals Intraspecific variation shapes community-level behavioural responses to urbanisation in spiders: from traits to function

2016 ◽  
Author(s):  
Maxime Dahirel ◽  
Jasper Dierick ◽  
Maarten De Cock ◽  
Bonte Dries
Keyword(s):  
Ecosystem Functioning ◽  
Urban Areas ◽  
Environmental Changes ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Community Level ◽  
List Type ◽  
Trait Variation ◽  
Behavioural Responses ◽  
Intraspecific Trait Variation

SummaryApproaches based on functional traits have proven especially valuable to understand how communities respond to environmental gradients. Until recently, they have, however, often ignored the potential consequences of intraspecific trait variation (ITV). This position becomes potentially more problematic when studying animals and behavioural traits, as behaviours can be altered very flexibly at the individual level to track environmental changes.Urban areas are an extreme example of human-changed environments, exposing organisms to multiple, strong, yet relatively standardized, selection pressures. Adaptive behavioural responses are thought to play a major role in animals’ success or failure in these new environments. The consequences of such behavioural changes for ecosystem processes remain understudied.Using 62 sites of varying urbanisation level, we investigated how species turnover and ITV influenced community-level behavioural responses to urbanisation, using orb web spiders and their webs as models of foraging behaviour.ITV explained around 30% of the total trait variation observed among communities. Spiders altered their web-building behaviour in cities in ways that increase the capture efficiency of webs. These traits shifts were partly mediated by species turnover, but ITV increased their magnitude. The importance of ITV varied depending on traits and on the spatial scale at which urbanisation was considered. Available prey biomass decreased with urbanisation; the corresponding decrease in prey interception by spiders was less important when ITV in web traits was accounted for.By facilitating trait-environment matching despite urbanisation, ITV thus helps communities to buffer the effects of environmental changes on ecosystem functioning. Despite being often neglected from community-level analyses, our results highlight the importance of accounting for intraspecific trait variation to fully understand trait responses to (human-induced) environmental changes and their impact on ecosystem functioning.

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 Intraspecific trait variation and species functional turnover in successional tropical forests: assessing gap-filling for community weighted means

2021 ◽  
Author(s):  
J. Aaron Hogan ◽  
Han Xu ◽  
Christopher Baraloto
Keyword(s):  
Secondary Forest ◽  
Species Turnover ◽  
Specific Root Length ◽  
Plant Ecology ◽  
Primary Forest ◽  
Forest Age ◽  
Gap Filling ◽  
Trait Variation ◽  
Intraspecific Trait Variation ◽  
Age Related

Abstract Accounting for intraspecific trait variation (ITV) is central to plant ecology and crucial for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with community data from 164 small plots comprising 582 species to evaluate the contribution of ITV to CWMs, comparing unlogged, primary forest to selectively-logged and clear-cut secondary forest. We examine the effect of gap-filling missing trait values via phylogenetic generalized linear modeling (PhyloPars) on CWMs. For six of seven traits, ITV negatively covaried with species turnover to generate larger CWM differences than observed if ITV was not integrated. For example, plot average CWM specific leaf area was 10.7 and 10.4 m2 kg− 1 for primary and secondary forest, not accounting for ITV, but shifted to 9.8 and 11.1 m2 kg− 1 after doing so. Specific root length showed a similar trend. Our results from 72-species assemblages were supported by the results from the gap-filled analysis using the entire community, where the contribution of ITV to CWMs ranged from 25 to 75%, with nearly all trait variation due to forest type attributable to ITV. Therefore, CWM trait estimates became more-conservative with forest age, whereas ITV for many traits showed an acquisitive shift, and because of negative covariation between ITV and species turnover, forest age-related CWM differences increased. Differences were unaffected, if not strengthened, by gap-filling incomplete functional trait matrices.

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 Leaf trait variation in species-rich tropical Andean forests

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jürgen Homeier ◽  
Tabea Seeler ◽  
Kerstin Pierick ◽  
Christoph Leuschner
Keyword(s):  
Environmental Gradients ◽  
Elevation Gradient ◽  
Environmental Filtering ◽  
Leaf Thickness ◽  
Community Level ◽  
Plant Performance ◽  
Small Scale ◽  
Trait Variation ◽  
Leaf Trait ◽  
Foliar N

AbstractScreening species-rich communities for the variation in functional traits along environmental gradients may help understanding the abiotic drivers of plant performance in a mechanistic way. We investigated tree leaf trait variation along an elevation gradient (1000–3000 m) in highly diverse neotropical montane forests to test the hypothesis that elevational trait change reflects a trend toward more conservative resource use strategies at higher elevations, with interspecific trait variation decreasing and trait integration increasing due to environmental filtering. Analysis of trait variance partitioning across the 52 tree species revealed for most traits a dominant influence of phylogeny, except for SLA, leaf thickness and foliar Ca, where elevation was most influential. The community-level means of SLA, foliar N and Ca, and foliar N/P ratio decreased with elevation, while leaf thickness and toughness increased. The contribution of intraspecific variation was substantial at the community level in most traits, yet smaller than the interspecific component. Both within-species and between-species trait variation did not change systematically with elevation. High phylogenetic diversity, together with small-scale edaphic heterogeneity, cause large interspecific leaf trait variation in these hyper-diverse Andean forests. Trait network analysis revealed increasing leaf trait integration with elevation, suggesting stronger environmental filtering at colder and nutrient-poorer sites.

scholarly journals Intraspecific Trait Variation and Coordination: Root and Leaf Economics Spectra in Coffee across Environmental Gradients

2017 ◽  
Vol 8 ◽  
Author(s):  
Marney E. Isaac ◽  
Adam R. Martin ◽  
Elias de Melo Virginio Filho ◽  
Bruno Rapidel ◽  
Olivier Roupsard ◽  
...  
Keyword(s):  
Environmental Gradients ◽  
Trait Variation ◽  
Intraspecific Trait Variation ◽  
Leaf Economics

scholarly journals Urbanization-driven changes in web-building are decoupled from body size in an orb-web spider

2017 ◽  
Author(s):  
Maxime Dahirel ◽  
Maarten De Cock ◽  
Pieter Vantieghem ◽  
Dries Bonte
Keyword(s):  
Body Size ◽  
Environmental Changes ◽  
Spatial Scales ◽  
Local Scale ◽  
List Type ◽  
Behavioural Responses ◽  
Prey Biomass ◽  
Araneus Diadematus ◽  
Biomass Availability ◽  
Web Building

AbstractIn animals, behavioural responses may play an important role in determining population persistence in the face of environmental changes. Body size is a key trait central to many life history traits and behaviours. While behaviours are typically assumed to be highly plastic, size correlations may impose constraints on their adaptive value when size itself is subject to environmental changes.Urbanization is an important human-induced rapid environmental change that imposes multiple selection pressures on both body size and (size-constrained) behaviour. How these combine to shape behavioural responses of urban-dwelling species is unclear.Using web-building, an easily quantifiable behaviour linked to body size, and the garden spider Araneus diadematus as a model, we disentangle direct behavioural responses to urbanization and body size constraints across a network of 63 selected populations differing in urbanization intensity at two spatial scales.Spiders were smaller in highly urbanized sites (local scale only), in line with expectations based on reduced prey biomass availability and the Urban Heat Island effect. The use of multivariate mixed modelling reveals that although web traits and body size are correlated within populations, behavioural responses to urbanization do not appear to be constrained by size: there is no evidence of size-web correlations among populations or among landscapes. Spiders thus altered different components of their web-building behaviours independently in response to urbanization: mesh width and web surface decreased independently with urbanization at the local scale, while web surface also increased with urbanization at the landscape scale. These responses are expected to compensate, at least in part, for reduced prey biomass availability.Our results demonstrate that responses in typically size-dependent behaviours may be decoupled from size changes, thereby allowing fitness maximisation in novel environments. The spatial scale of the behavioural responses to urbanization suggest contributions of both genetic adaptation and plasticity. Although fecundity decreased with local-scale urbanization, Araneus diadematus abundances were remarkably similar across urbanization gradients; behavioural responses thus appear overall successful at the population level.

scholarly journals TURNOVER OR INTRASPECIFIC TRAIT VARIATION: EXPLAINING FUNCTIONAL VARIABILITY IN A NEOTROPICAL ANURAN METACOMMUNITY

2020 ◽  
Author(s):  
Diego Anderson Dalmolin ◽  
Alexandro Marques Tozetti ◽  
Maria João Ramos Pereira
Keyword(s):  
Body Mass ◽  
Intraspecific Variation ◽  
Environmental Gradients ◽  
Interspecific Variation ◽  
Limb Length ◽  
Head Shape ◽  
Trait Variation ◽  
Intraspecific Trait Variation ◽  
Relative Contribution ◽  
Eye Size

ABSTRACTTrait variation across environmental gradients results from two processes: intraspecific variation (ITV) and turnover. Tadpoles are known to exhibit phenotypic plasticity in several traits in response to the environment, resulting from intra or interspecific variation. Here we evaluate patterns of intraspecific variation in functional traits of adult anurans (head shape, eye size and position, limb length and body mass) and their relationship with environmental variables in an anuran metacommunity in southern Brazil. From anurans sampled from 33 ponds, we decomposed trait variation into ITV and turnover and modelled trait-environment relationships. We predict that the contribution of ITV and turnover to trait variation and trait-environment relationships should vary according to the preferred habitat of the species and the analysed traits. Intraspecific variation accumulated the highest rate of trait variation for arboreal species, while interspecific variation was greater for aquatic-terrestrial species and for the whole set of species. The contributions of turnover and ITV to shifts in community mean trait values were similar between traits, but differed between species sets. Depth, distance between ponds, area of Pinus surrounding the ponds, and types of pond vegetation and substrate strongly influenced trait variation, but their relative contribution depended on the analysed traits and species sets. The great contribution of ITV for head shape and eye size and position suggests the existence of intraspecific adaptations to microhabitats, while turnover dominance in the variation of body mass and limb length suggests differences in dispersal and trophic segregation between species.

scholarly journals The relative contribution of intraspecific variation and species turnover to the community-level foliar stoichiometric characteristics in different soil moisture and salinity habitats

PLoS ONE ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. e0246672
Author(s):  
Yelike Tusifujiang ◽  
Xueni Zhang ◽  
Lu Gong
Keyword(s):  
Soil Moisture ◽  
Drought Stress ◽  
Intraspecific Variation ◽  
Species Turnover ◽  
Community Level ◽  
Desert Plant ◽  
Trait Variation ◽  
Relative Contribution ◽  
Weighted Means

Background Trait-based approaches have been used to demonstrate the responses of plant functional traits to environmental change may manifest both among- and/or within-species. However, how community-level foliar stoichiometric characteristic variations respond to aridity and salinity is still not well-known. Methods We calculated community weighted means (CWMs) and non-weighted means (CMs) of foliar C, N, and P concentrations (and their ratios) in a dryland plant community respond to high (HSW) and low soil moisture and salinity (LSW). Based on a sum of squares decomposition method, we determined the relative contributions of intraspecific variation and species turnover in both HSW and LSW habitats. Results The CWMs of foliar C, C:N and C:P, and CM of N in the HSW habitat were significantly greater than those in the LSW habitat. The trait variations in two habitats were mainly driven by intraspecific variation, and its contribution to trait variation mostly declined with the decrease of soil moisture and salinity. The CWMs of foliar C-related stoichiometric characteristics were mainly dominated by species turnover in both habitats. Moreover, the contribution of species turnover to C and C:P variations showed an increasing trend in the LSW habitat. For CWMs, negative covariations between intraspecific variation and turnover occurred in HSW and positive covariations (except N:P) occurred in LSW; however, CMs were generally positively correlated in both habitats. Conclusions The intraspecific variation declined as drought stress intensified, which indicates that the adaptability of desert plants declined when the stress changed from salinity to aridity. The total variation of C-related traits in both habitats were mainly dominated by species turnover. These findings highlight the importance of intraspecific variation in driving desert plant response of community functional composition to salt stress, and the joint role of intraspecific variation and species turnover in resisting drought stress.

scholarly journals Parallel assemblage structures in Mediterranean marine amphipods revealed by beta diversity partitioning

2020 ◽  
Author(s):  
Bruno Bellisario ◽  
Federica Camisa ◽  
Chiara Abbattista ◽  
Roberta Cimmaruta
Keyword(s):  
Functional Diversity ◽  
Beta Diversity ◽  
Environmental Changes ◽  
Environmental Gradients ◽  
Species Turnover ◽  
Phylogenetic Signal ◽  
Ecological Communities ◽  
Diversity Partitioning ◽  
Distance Information

AbstractRelying on a purely taxonomic view of diversity may ignore the fact that ecological communities can be constituted of species having both distinct evolutionary histories and functional characteristics. Thus, considering how the multiple facets of diversity vary along environmental and geographic gradients may provide insights into the role of historic processes and current environmental changes in determining the divergence or convergence of lineages and functions, ultimately influencing the way species assemble across space. However, analyses can be somehow flawed by the choice of traits being analysed, as they should capture the whole functional variability of species in order to assess the relationship between phylogenetic and functional diversity along a gradient. When continuous measures of functional diversity based on a variety of different traits are absent, the use of functional traits known to show strong phylogenetic signal can help elucidating such relationship. By using distributional, traits and taxonomic-distance information, we explored how the taxon, functional and phylogenetic community composition (co)vary along spatial and environmental gradients in seagrass amphipod metacommunity within the Mediterranean Sea. We used beta diversity partitioning and null models to determine the role of deterministic and stochastic processes on the replacement and the net loss/gain of species, lineages and highly conserved β-niche traits. We showed that dispersal-based processes are the main determinants of the high taxonomic and phylogenetic beta diversity, while niche-based processes explain the low functional dissimilarity among assemblages. Moreover, phylogenetic and functional beta diversity showed contrasting patterns when controlling for the underlying taxonomic composition, with the former being not significantly different and the latter significantly lower than expected. Our results suggest the key role of historical and biogeographic processes in determining the present-day patterns of community assembly and species turnover, providing also evidence for parallel assemblage structures in Mediterranean seagrass amphipods.

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