Levels Of Functional Diversity Research Articles

The multifaceted diversification of the sagitta otolith across the fish tree of life

Abstract Otoliths of actinopterygians are calcified structures playing a key role in hearing and equilibrium functions. To understand their morphological diversification, we quantified the shape of otoliths in both lateral and dorsal view from 697 and 323 species, respectively, using geometric morphometrics. We then combined form (i.e. size and shape) information with ecological data and phylogenetically informed comparative methods to test our hypotheses. Initially, the exploration of morphospaces revealed that the main variations are related to sulcus acusticus shape, elongation and lateral curvature. We also found strong integration between otolith and sulcus shape, suggesting that they are closely mirroring each other, reinforcing a shape-dependent mechanism crucial for otolith motion relative to its epithelium and validating the functional significance of otolith morphology in auditory and vestibular processes. After revealing that otolith shape and size retained a low phylogenetic signal, we showed that the disparity of otolith size and shape is decoupled from order age and from the level of functional diversity across clades. Finally, some traits in otolith disparity are correlated with their morphological evolutionary rate and the order speciation rate. Overall, we observed that the pattern of diversification of otoliths across the fish tree of life is highly complex and likely to be multifactorial.

Dominant species establishment may influence invasion resistance more than phylogenetic or functional diversity

Abstract Phylogenetic and functional diversity are theorised to increase invasion resistance. Experimentally testing whether plant communities higher in these components of diversity are less invasible is an important step for guiding restoration designs. To investigate how phylogenetic and functional diversity of vegetation affect invasion resistance in a restoration setting, we used experimental prairie restoration plots. The experiment crossed three levels of phylogenetic diversity with two levels of functional diversity while species richness was held constant. We allowed invaders to colonise plots; these included native species from neighbouring plots and non‐native invasive species from a surrounding old field. We tested if invader biomass was influenced by phylogenetic and functional diversity, and phylogenetic and hierarchical trait distances between invaders and planted species. We binned each invader into three categories: native species from neighbouring experimental plots (site‐specific invaders), native species not part of the experimental species pool (native invaders) or non‐native species (non‐native invaders). Counter to expectation, both non‐native and native invaders became more abundant in more phylogenetically diverse plots. However, plots with higher abundance of planted Asteraceae, a dominant family of the tallgrass prairie, had lower invader biomass for both native and non‐native invaders. We also found that hierarchical trait differences shaped invasion. The species that became most abundant were non‐native invaders that were taller, and native invaders with low specific leaf area relative to planted species. Site‐specific invaders were not influenced by any plot‐level diversity metrics tested. Synthesis and application: Our results suggest that greater phylogenetic diversity may lower resistance to invasion. This effect may be due to more even but sparser niche packing in high‐diversity plots, associated with greater availability of unsaturated niche space for colonisation. However, trait composition fostered invasion resistance in two ways in our study. First, establishment of native species with strongly dominant traits may confer invasion resistance. Second, species mixes that optimise trait differences between planted vegetation and likely invaders may enhance invasion‐resistance.

Functional diversity increases the resistance of a tritrophic food web to environmental changes

In the light of global climate change and biodiversity loss, understanding the role of functional diversity in the response of food webs to environmental change is growing ever more important. Using a tritrophic food web model, with a variable degree of functional diversity at each trophic level, we studied the role of functional diversity on the resistance of a system against press perturbations. Perturbations affected either nutrient availability or the mortality of the species, which can be interpreted as effects of eutrophication and warming, respectively. We compared food webs with different levels of functional diversity by investigating the species trait and biomass dynamics, the overall changes in the species’ standing biomass as measured by the warping distance, and the duration of the system transients after the onset of a press perturbation (transition time). We found that higher functional diversity increased resistance since it buffered trophic cascading effects and delayed the onset of oscillatory behaviour caused by either bottom-up forcing via perturbations to nutrient concentration or top-down forcing via perturbations to mortality rate. This increased resistance emerged from a higher top-down control of the intermediate species on the basal species. Functional diversity also promoted a higher top biomass, in particular via a higher proportion of top selective species undergoing high mortality rates. Additionally, functional diversity had context-dependent effects on warping distances, and increased transition times. Overall, this study encourages accounting for functional diversity in future investigations about the response of multitrophic systems to global change and in management strategies.

Latent factors on the design and adoption of gamified apps in primary education

The main objective of this research is to determine the perception of teachers about the elements that increases the educational effectiveness of gamified apps in primary education. A methodology based on an importance-performance analysis was daeveloped, using a structural equations model to calcuate the degree of importance of each variable. The sample was formed of 212 Spanish teachers with experience using educational apps in the teaching–learning process. Six categories were identified as precursors of educational effectiveness: (1) curriculum connection, (2) feedback and operational experience, (3) assessment and learning analytics, (4) sustainability (Protection Personal data), (5) equal access and (6) flow. These six categories enhance the three traditional areas of gamification intervention: cognitive, emotional and social. In this sense, the design and adoption of an educational gamified app should: (1) establish a clear link between the game and curricular content and competence development; (2) promote self-regulated learning through individual and collaborative activities; (3) offer adapted learning by integrating differentiated personalized learning pathways; (4) integrate learning analytics that can be consulted by teacher, student and family; (5) comply with data protection regulation and promote a safe, sustainable and ethical use of the information generated; (6) take into account different levels of functional diversity. When the gamified app design incorporates these attributes, primary education teachers perceive that such resources can be integrated effectively into the teaching–learning processes.

Functionally diverse cover crops support ecological weed management in orchard cropping systems

Abstract Diverse agricultural management practices are critical for agroecosystem sustainability, and cover crops provide opportunity for varied management and increased biodiversity. Understanding how cover crops fill open ecological niches underneath the trees, interact with weeds, and potentially provide ecosystem services to decrease pest pressure is essential for ecological agricultural management. The goal of this study was to test the weed suppression potential of two cover crop treatments with varied functional diversity compared to standard weed management practices in commercial almond orchards in California. Transect plant surveys were used to evaluate orchard plant communities under a functionally diverse seed mix including grasses, legumes, and brassicas, and a relatively uniform cover crop mix that included only brassica species. Winter annual orchard cover crops reduced bare ground from 39.3% of total land area to 15.9 or 11.4%, depending on treatment. Furthermore, winter cover crops displaced weeds with a negative correlation of 0.74. The presence of cover crops did not consistently affect weed community composition for low-richness weed communities found in California orchards. Diverse cover crop mixes more reliably resulted in increased ground cover across site years compared to uniform cover crop mixes, with coefficients of variation for ground cover at 49.6 and 91.5%, respectively. Cover crops with different levels of functional diversity can contribute to orchard weed management programs at commercial scales. Functional diversity supports cover crop establishment, abundance, and competitiveness across varied agroecological conditions, and cover crop mixes could be designed to address an assortment of orchard management concerns.

Diversified production systems in sandy soils of the Brazilian Cerrado: nutrient dynamics and soybean productivity

Increased functional diversity, given by the Integrated Crop-Livestock System (ICLS), is an alternative of quantitative and qualitative technical evolution for soybean (Glycine max) cropping in sandy soils. The objective of the present research was to investigate production systems with different levels of functional diversity in sandy soils of the Brazilian Cerrado regarding their (a) soil microbiological activity, (b) macronutrient accumulation and release, and (c) soybean yield. The experimental design was randomized blocks with three replications and the treatments corresponded to different levels of functional diversity: very low (Fallow), low (Ruziziensis), medium (Ruziziensis, niger, radish and rattlepod), and high (Ruziziensis, niger, radish and rattlepod with animal entrance). The plants were desiccated and the phytomass contained within a frame was collected at ground level. The evaluation of phytomass decomposition and nutrient release was performed at 0, 15, 30, 60, 90 and 120 days after desiccation (DAD) of the plants. Functional diversity levels increase the carbon content of the microbial biomass in the sandy soil, with an emphasis on systems with high plant diversity and the presence of animals. High functional diversity with the presence of the animal results in higher rates of phytomass decomposition and nutrient release with a shorter half-life (t 1/2=85 DAD), mainly with respect to potassium. This functional diversity increases soybean yield by up to 25% in the high diversity system compared to a system with very low diversity. The high functional diversity in ICLS enriches soil microbiological quality and increases soybean productivity in the sandy soil in the short term.

The hump-shaped effect of plant functional diversity on the biological control of a multi-species pest community

Plant taxonomic and functional diversity promotes interactions at higher trophic levels, but the contribution of functional diversity effects to multitrophic interactions and ecosystem functioning remains unclear. We investigated this relationship in a factorial field experiment comparing the effect of contrasting plant communities on parasitism rates in five herbivore species. We used a mechanistic trait-matching approach between plant and parasitoids to determine the amount of nectar available and accessible to parasitoids. This trait-matching approach best explained the rates of parasitism of each herbivorous species, confirming the predominant role of mass-ratio effects. We found evidence for an effect of functional diversity only in analyses considering the ability of plant communities to support the parasitism of all herbivores simultaneously. Multi-species parasitism was maximal at intermediate levels of functional diversity. Plant specific richness had a negligible influence relative to functional metrics. Plant communities providing large amounts of accessible nectar and with intermediate levels of functional diversity were found to be the most likely to enhance the conservation biological control of diverse crop herbivores.

Adaptive genetic diversity and evidence of population genetic structure in the endangered Sierra Madre Sparrow (Xenospiza baileyi)

The magnitude and distribution of genetic diversity through space and time can provide useful information relating to evolutionary potential and conservation status in threatened species. In assessing genetic diversity in species that are of conservation concern, several studies have focused on the use of Toll-like receptors (TLRs). TLRs are innate immune genes related to pathogen resistance, and polymorphisms may reflect not only levels of functional diversity, but may also be used to assess genetic diversity within and among populations. Here, we combined four potentially adaptive markers (TLRs) with one mitochondrial (COI) marker to evaluate genetic variation in the endangered Sierra Madre Sparrow (Xenospiza baileyi). This species offers an ideal model to investigate population and evolutionary genetic processes that may be occurring in a habitat restricted endangered species with disjunct populations (Mexico City and Durango), the census sizes of which differ by an order of magnitude. TLRs diversity in the Sierra Madre Sparrow was relatively high, which was not expected given its two small, geographically isolated populations. Genetic diversity was different (but not significantly so) between the two populations, with less diversity seen in the smaller Durango population. Population genetic structure between populations was due to isolation and different selective forces acting on different TLRs; population structure was also evident in COI. Reduction of genetic diversity in COI was observed over 20 years in the Durango population, a result likely caused by habitat loss, a factor which may be the main cause of diversity decline generally. Our results provide information related to the ways in which adaptive variation can be altered by demographic changes due to human-mediated habitat alterations. Furthermore, our findings may help to guide conservation schemes for both populations and their restricted habitat.

Effects of functional diversity and salinization on zooplankton productivity: an experimental approach

Quantifying the interactions between functional diversity and environmental change is important for understanding the effects of biodiversity on ecosystem processes. This study aims to evaluate zooplankton secondary production and biomass in an experiment with different levels of functional diversity and environmental stress in the form of increased salinity. It is expected that communities that are more functionally diverse will present higher secondary production and biomass, even under conditions of environmental stress. To test this hypothesis, a mesocosm experiment with two factors was performed: low and high diversity and with and without salt totaling four possible combinations of treatments over the duration of 4 weeks. The high functional diversity treatments showed higher zooplankton secondary production and biomass than those of the low diversity treatments, even under salt addition. The salinity decreased zooplankton production and functional diversity, but its effects were more pronounced in the low than in the high diversity communities. However, in the low diversity treatments the zooplankton biomass and production were maintained due to the dominance of species with certain traits. In summary, our study contributed to understanding the role of zooplankton functional diversity on ecosystem processes in the face of environmental changes promoted by increased salinity.

Restoring dryland old fields with native shrubs and grasses: Does facilitation and seed source matter?

Restoration of agricultural fields is challenging, especially in arid and semi-arid ecosystems. We conducted experiments in two fields in the Great Basin, USA, which differed in cultivation history and fertility. We tested the effects of different levels of functional diversity (planting grasses and shrubs together, vs. planting shrubs alone), seed source (cultivars, local or distant wild-collections), and irrigation regime (spring or fall and spring) on restoration outcomes. We sowed either: 1) grasses and shrubs in year one, 2) shrubs only, in year one, 3) grasses in year one with herbicide, shrubs in year two, or 4) shrubs alone in year two, after a year of herbicide. We irrigated for two years and monitored for three years. Shrub emergence was highest in the lower fertility field, where increasing functional diversity by seeding grasses had a neutral or facilitative effect on shrub emergence. In the higher fertility field, increasing functional diversity appeared to have a neutral to competitive effect. After declines in shrub densities after irrigation ceased, these effects did not persist. Grasses initially suppressed or had a neutral effect on weeds relative to an unseeded control, but had neutral or facilitative effects on weeds relative to shrub-only seeding. Initially, commercial grasses were either equivalent to or outperformed wild-collected grasses, but after irrigation ceased, commercial grasses were outperformed by wild-collected grasses in the higher fertility field. Local shrubs initially outperformed distant shrubs, but this effect did not persist. Fall and spring irrigation combined with local shrubs and wild-collected grasses was the most successful strategy in the higher fertility field, while in the lower fertility field, irrigation timing had fewer effects. Superior shrub emergence and higher grass persistence indicated that the use of wild and local seed sources is generally warranted, whereas the effects of functional diversity and irrigation regime were context-dependent. A bet-hedging approach that uses a variety of strategies may maximize the chances of restoration success.

Reaping the Rewards of Functional Diversity in Healthcare Teams: Why Team Processes Improve Performance

Functional diversity in healthcare teams—where members from different healthcare professions work together—is often advocated as the key to achieving quality patient outcomes. However, although functionally diverse teams promise much, they do not always deliver on that promise. Based on the informational diversity perspective, we argue that functional diversity increases role conflict and is an important factor that can help to explain why functional diversity does not always lead to effective team performance. We also argue that team processes play an important role in moderating the effect of functional diversity on role conflict and that depending on how functionally diverse healthcare teams are, certain team processes are more important than others for reducing role conflict thereby leading to improved team performance. We contrast two specific team processes (interpersonal conflict management and back up and helping) and argue for their relative importance depending on the level of functional diversity in healthcare teams. Data from 75 hospital teams support our differential predictions that interpersonal conflict management is a particularly important team process for reducing role conflict and improving team performance for teams with high functional diversity, whereas for teams with low functional diversity, back up and helping is a more important team process. These results have important implications for the management of functionally diverse healthcare teams. By identifying the relative importance of team processes, these results provide evidence for investing in team processes that enable healthcare teams to reap the rewards of functional diversity.

Increasing plant functional diversity is not the key for supporting pollinators in wildflower strips

Abstract Intensification of agriculture has been one of the major drivers for biodiversity loss in recent decades. Pollinators, which serve an important role in pollinating crops as well as wild plants, have shown a decline in species richness. Flower strips can be used to support pollinators in agro-ecosystems, however the question remains as to how their design can be optimized in order to best benefit pollinators. Increasing plant species diversity has been shown to be beneficial for pollinators, and it is often suggested that functional traits are driving this relationship. Therefore, increasing plant functional diversity could be a tool to support pollinator abundance and diversity. As experimental evidence on this relationship is scarce, we developed a field study with experimental sown flower strips with four functional diversity levels, based on multiple flower traits and with equal plant species richness. We monitored vegetation development, as well as the flower-visiting pollinator community and their interaction networks with flowers. We were able to create a functional diversity gradient while controlling for plant species richness and evenness. However, in contrast to our expectations, pollinator species richness and evenness were not influenced by functional diversity, and increasing functional diversity even resulted in lower flower visitation rates. Network stability metrics showed no effect or negative relationships with functional diversity. We conclude that increasing functional diversity was not the key for supporting pollinators in wildflower strips. Our results also suggest that, for a constant amount of flower resources, increasing plant functional diversity and thus decreasing redundancy of potential pollinator feeding niches, decreases the amount of flower resources present per feeding niche. As pollinator species tended to have less overlap in their feeding niches in flower strips with increased functional diversity, this may lead to a reduction of flower resources available for pollinator species with a more specialized feeding niche.

Spatial plant resource acquisition traits explain plant community effects on soil microbial properties

Trait-based approaches have recently been employed to develop a more mechanistic understanding of plant community effects on the assembly and functioning of terrestrial ecosystems. Despite the broad consensus that soils provide essential ecosystem services, plant community effects on soil communities and functions have rarely been linked to aboveground and belowground plant traits. Here, we studied the effects of plant species richness, plant trait diversity, and single plant functional traits related to spatial and temporal resource acquisition on soil microbial properties over five years in a grassland biodiversity experiment. The main response variables were soil basal respiration and microbial biomass. Above- and belowground plant traits associated with spatial (plant height, leaf area, rooting depth, and root length density) and temporal resource acquisition (growth start, flowering start) were selected to design communities with different levels of functional diversity as well as to calculate realized community means weighted by plant species cover. Plant species richness and trait diversity effects on soil microbial properties were nonsignificant over the course of the five-year experiment. After four years, however, we found significantly higher soil basal respiration in plant communities with smaller leaves and both denser and shallower root systems than in plant communities with taller plants and sparse root systems. One year later, these effects were significant for both soil basal respiration and soil microbial biomass. Structural equation modeling revealed that plant community effects on soil microbial properties were mostly due to differences in rooting depth, although the explanatory power of our models was low. Our findings highlight the importance of incorporating plant traits, particularly root traits, in analyses of plant community effects on soil biota and functions. Selecting for particular plant traits in communities and considering interactive effects of specific plant traits may facilitate the targeted management of grasslands to maintain essential ecosystem services.

Plant community effects on CH4 fluxes, root surface area, and carbon storage in experimental wetlands

Wetland creation is a form of ecological engineering that often relies on establishing a plant community to increase ecosystem services. However, we still lack understanding about how species composition and diversity affect certain wetland ecosystem functions associated with these ecosystem services. Our objective was to investigate the link between plant community (diversity and composition) and plant carbon storage, root surface area and methane (CH4) emission. We hypothesized that more diverse mixtures would 1) store more carbon in above and belowground biomass and 2) emit less CH4 due to increased root surface area and aeration. Three plant groups that represented different growth forms (i.e., “functional groups”: ferns, reeds and tussocks) were planted in mesocosms to represent four levels of functional diversity and every combination of functional groups at each diversity level. Unplanted mesocosms served as the zero diversity treatment. At peak biomass in 2014 and 2015, we harvested aboveground biomass and took soil cores from each mesocosm at 0–10cm to determine the root biomass and surface area. Methane fluxes were measured in situ using a closed chamber system and a Picarro G2301 CRDS analyzer. Fluxes did not vary by functional group richness level or composition. Presence of the reed and tussock functional groups decreased fluxes; however, root surface area was not correlated with CH4 emission. Plant carbon storage was greater in all treatments containing tussocks (expect for the reed tussock mixture) compared with ferns grown alone. Functional group richness did not have a significant effect on plant carbon storage, however there was a positive trend. Root surface area increased 87% from the first to second year; however, there were no differences among functional group richness levels or mixtures. Our results indicate that planting reed and tussock functional groups in dense clumps during restoration could maintain a high level of carbon storage and relatively low CH4 emissions.

Biodiversity and ecosystem services−A case study for the assessment of multiple species and functional diversity levels in a cultural landscape

The expansion of large-scale plantations has a major impact on landscapes in the Tropics and Subtropics. Crops like soy bean, oil palm and rubber have led to drastic changes in land cover over the past decades, thereby altering ecosystem functions and services (ESS). Associated shifts in ESS such as climate regulation, erosion and water cycles, biodiversity as well as soil fertility or the provisioning of raw materials have been assessed through several models and software solutions (InVEST, ARIES, MIMES). However, suitable methods for the integration of a range of biodiversity assessments in agricultural landscapes are scarce.With this study, we introduce a methodology for incorporating multiple levels of species diversity into models to allow an integrated evaluation of ESS. We collected data sets from both published and unpublished sources on the distribution of vascular plants, selected pollinator groups, ground beetles, ungulates as well as amphibians, mammals, reptiles and birds in rubber-dominated landscapes, with a focus on our study sites in Southwest China and Thailand. Based on this information, we developed a common classification scheme that enables the integration of different facets of biodiversity (species diversity and functional diversity) to complement an interdisciplinary ESS assessment.Species diversity data were normalized against the most divers habitats reported (using habitat scores) to assess the impact of rubber cultivation on multiple levels of biodiversity. This resulted in a comparable matrix of different land use types and their suitability as habitat for the respective species groups allowing the aggregation of very diverse indicators. The findings were applied to two alternative land use scenarios in southern China to highlight the potential effects of land use and management decisions on species and functional diversity. Our results highlighted that the conservation oriented scenario did score higher for habitat suitability in both total species (+5%) as well as IUCN Red List species (+6%) assessments compared to the current state or business as usual scenarios (-2% and −3% compared to current state).The process presented here allows for an application within established ESS software programs, in our case InVEST, using aggregated indices while additionally providing enhanced opportunities for comparable, spatially explicit assessments of the expected impact of the analyzed scenarios on specific species groups.

Cuckoo as indicator of high functional diversity of bird communities: A new paradigm for biodiversity surrogacy

We tested the hypothesis that the cuckoo may serve as an effective surrogate for different aspects of biodiversity. Six different measures of biodiversity were estimated for these three bird communities: (a) taxonomic diversity, (b) host species richness, (c) functional richness, (d) functional evenness, (e) functional divergence, and (f) evolutionary distinctiveness. Mixed models were used for studying the patterns of occurrence of the cuckoo in relation to environmental variables and biodiversity measures.The presence of the cuckoo was positively correlated with high values of taxonomic diversity, functional richness and functional evenness, but not with functional divergence or evolutionary distinctiveness of bird communities. We demonstrate that host species represent different levels of functional diversity in bird communities, because they are broadly distributed and occupy many niches for breeding and feeding.The implications for conservation are many: Hotspots determined by the occurrence of the cuckoo are areas with higher functional richness and evenness, also indicating high potential resilience. If host species are functionally diversified, the bird community provides higher resilience to any eventual catastrophic events. Finally, we underline how the cuckoo is a charismatic species, easy to monitor and adequate for citizen science, providing new information on the paradigm of surrogacy in ecology.

Reducing the impacts of Neotropical oil palm development on functional diversity

Large-scale conversion of natural habitats to agriculture reduces species richness and functional diversity, with important implications for the provision of many ecosystem services. We investigated possible solutions to minimise loss of functional diversity: retaining forest fragments to enhance functional diversity within agricultural lands, and restricting future expansion of tropical crops to degraded lands or low-productivity farmlands to conserve functional diversity at a landscape level. We focused on birds, which play key functional roles and have well-known functional ecology, and oil palm, a rapidly expanding tropical crop. We did so in the Colombian Llanos, a region highlighted for the planting of sustainable oil palm, where plantations are currently replacing two main habitat types: forest remnants and improved cattle pasture. We found that levels of functional diversity (FD) and richness (FRic) were highest in remnant forests. Furthermore, levels of functional diversity and richness in oil palm and improved pasture were positively related to the proportion of forest in a 250m radius surrounding each sample point. Frugivorous and canopy foraging species were particularly associated with remnant forests, while aquatic and terrestrial foragers were associated with pasture. This suggests that retaining forest remnants in agricultural landscapes is important in preventing large losses of functional diversity, and might also play a role in maintaining avifaunal functional richness within farmland.

Contemporary and future distribution patterns of fluvial vegetation under different climate change scenarios and implications for integrated water resource management

AbstractKnowledge of plant community structure and how it can confer resistance to climate change effects is required for the management of fluvial ecosystems. Findings from such studies can be applied in decision making processes to implement measures to maintain, conserve or improve fluvial quality. Floristic and environmental data from 100 sample stations located in three River Basin Districts in northern Portugal were gathered as part of the 2010 Water Framework Directive monitoring program carried out on mainland Portugal. Three habitat types were characterized based on the flow dynamic level: the wetted channel, the bankfull area and the riparian gallery. Hierarchical cluster analysis of environmental data revealed three distinct environmental groups of sites. Floristic data were organized by these environmental groups characterized by altitudinal, temperature and precipitation data variables. The combination of taxonomic diversity and species frequency reflect functional differences for these habitats, here explained by a resistance and resilience approach. More low‐frequency species and higher levels of functional diversity occurred at stations with more variable environmental conditions. Predictive modelling of the future distribution of the three environmental groups under two different climate scenarios supported the relevance of low‐frequency traits in conferring resistance to climatic change effects.

Resource partitioning along multiple niche axes drives functional diversity in parrotfishes on Caribbean coral reefs.

The recent loss of key consumers to exploitation and habitat degradation has significantly altered community dynamics and ecosystem function across many ecosystems worldwide. Predicting the impacts of consumer losses requires knowing the level of functional diversity that exists within a consumer assemblage. In this study, we document functional diversity among nine species of parrotfishes on Caribbean coral reefs. Parrotfishes are key herbivores that facilitate the maintenance and recovery of coral-dominated reefs by controlling algae and provisioning space for the recruitment of corals. We observed large functional differences among two genera of parrotfishes that were driven by differences in diet. Fishes in the genus Scarus targeted filamentous algal turf assemblages, crustose coralline algae, and endolithic algae and avoided macroalgae, while fishes in the genus Sparisoma preferentially targeted macroalgae. However, species with similar diets were dissimilar in other attributes, including the habitats they frequented, the types of substrate they fed from, and the spatial scale at which they foraged. These differences indicate that species that appear to be functionally redundant when looking at diet alone exhibit high levels of complementarity when we consider multiple functional traits. By identifying key functional differences among parrotfishes, we provide critical information needed to manage parrotfishes to enhance the resilience of coral-dominated reefs and reverse phase shifts on algal-dominated reefs throughout the wider Caribbean. Further, our study provides a framework for predicting the impacts of consumer losses in other species rich ecosystems.

Together but different: co-occurring dune plant species differ in their water- and nitrogen-use strategies

Stress factors may severely constrain the range of plant physiological responses in harsh environments. Convergence of traits is expected in coastal dunes because of environmental filtering imposed by severe abiotic factors. However, the wide range of morphological and phenological traits exhibited by coexisting dune species suggests considerable variation in functional traits. We hypothesized that the constraints imposed by structural traits ought to translate into physiological differences. Five dominant species with different morphological traits, but coexisting in a homogeneous dune area in Northwest Spain, were selected for study. Soil characteristics and leaf functional traits were measured in April, June and November 2008. Integrated water-use efficiency (assessed by C isotope discrimination) and N acquisition and use strategies (estimated by N isotope composition) varied significantly among species and the differences changed over time. Species differences in specific leaf area, relative water content, leaf N and C:N ratio, also varied over time. The species differed in stomatal density but not in soil characteristics, with the exception of pH. Species differences in functional traits related to the use of resources suggest species niche segregation. Species-specific temporal effects on the use of these resources support temporal niche differentiation. Somewhat in contrast to the findings of previous studies on harsh environments, this study revealed a considerable level of functional diversity and complexity, suggesting that dune plant species have evolved species-specific strategies to survive by partitioning growth-limiting resources.