High Levels Of Functional Diversity Research Articles

The rise and fall of shark functional diversity over the last 66 million years

AbstractAimModern sharks are a diverse and highly threatened group playing important roles in ecosystems. They have an abundant fossil record spanning at least 250 million years (Myr), consisting primarily of isolated teeth. Throughout their evolutionary history, sharks have faced multiple environmental changes and extinction events. Here, we aim to use dental characters to quantify how shark functional diversity has changed during the last 66 Myr.LocationGlobal.Time periodCenozoic era (66–0 million years ago; Ma).Major taxa studiedSharks (Selachii).MethodsWe complied a dataset of over 9000 shark teeth belonging to 537 taxa from museum collections and scientific literature and measured six dental characters strongly linked with functional traits. We then quantified different functional diversity metrics across Cenozoic time bins, compared them against null expectations and identified the most important taxa contributing to maintaining functional diversity.ResultsSharks displayed relatively high functional diversity during the Cenozoic, with 66%–87% of the functional space being occupied for ~60 Myr (Palaeocene to Miocene). High levels of functional redundancy during this time resulted in larger‐than‐expected functional richness; but a large decline (−45%) in redundancy in the Oligocene (~30 Ma) left shark functional diversity highly vulnerable to further loss. Shark functional diversity declined from the late Miocene (~10 Ma) onwards, losing 44% of functional richness by the Recent. Extinct sharks disproportionally contributed to the Cenozoic functional diversity and spanned a wider range of functional space than extant sharks, with the loss of mid‐sized suction feeders and large‐bodied predators driving functional declines.Main conclusionsAfter maintaining high levels of functional diversity for most of the Cenozoic, sharks lost nearly half of their functional diversity in the last ~10 Myr. Current anthropogenic pressures are therefore likely eroding an already diminished shark functional diversity, leaving future communities ecologically deprived compared with their thriving geological past.

Effects of increasing drip irrigation at different maize growth stages on soil microorganisms.

To investigate the effects of different drip irrigation periods on soil microbial communities and functions. Increasing drip irrigation amount at the seedling (S), jointing (J), bell (B), tasseling (T) and grain filling (G) stages of maize were studied using no increase in irrigation amount as control (CK). Principal component analysis was conducted to comprehensively evaluate soil microbial quality following the different drip irrigation treatments. In addition, the characteristics of the community structure and the potential functional composition of soil bacteria and fungi were comparatively analyzed by combining amplicon sequencing and functional prediction methods. The results indicated that MBNT15 was the most important genus for the classification of soil bacterial samples, Saitozyma was the most important genus for the classification of soil fungal samples, and fungi were more important than bacteria for the classification of soil microbial samples. Compared with fungal communities, bacterial communities exhibited high levels of functional diversity. The proportion of metabolism was the highest in the prediction of bacterial primary functions, and carbohydrate metabolism and amino acid metabolism were important functions in the prediction of bacterial secondary functions. BugBase phenotype prediction results showed that soil bacteria under B treatment had a higher number of aerobic bacteria and greater resistance to disease and stress. The J treatment had the highest number of bacteria with biofilm forms, and the J, S, and G treatments contained more potentially pathogenic bacteria but fewer stress-tolerant bacteria compared with the CK treatment. The number of Saprotroph was the largest and the number of Symbiotroph was the least. The relative abundances of Saprotroph, Pathotroph and Symbiotroph were 68.60%~74.33%, 15.76%~20.60% and 9.16%~11.13%, respectively. The findings provide a reference for conserving water resources, improving maize yield, and predicting soil microbial metabolic potential and function by reflecting the richness of the soil microbial community structure in maize fields.

Functional diversity along disturbance and environmental gradients in Ethiopian moist Afromontane forest

Considering multiple measures to fully capture functional diversity is important. However, the effects of disturbance gradients on diversity have been controversial, as species diversity alone may not fully capture these effects. This study aimed to evaluate trait-based diversity across disturbance gradients in the moist Afromontane forest of Ethiopia, Yayu Coffee Forest Biosphere Reserve (YCFBR). Vegetation data and relevant traits related to plant-life strategies, competition, and responses to disturbances were collected. A multiple regression model was used to test the response of functional diversity to disturbances and environmental gradients. The results revealed functional diversity in plant communities, including dendrogram-based functional diversity for plot-based (FDp), functional richness (FRic), functional evenness (FEve), functional divergence (FDiv), functional dispersions (FDis), and community-weighted mean of maximum tree height (CWM.Hmax), showed decreasing patterns with increasing disturbance intensity in the YCFBR. Additionally, the findings highlighted that FDis and Hmax are the most vulnerable functional traits to anthropogenic factors and are less tolerant in disturbed ecosystem environments. Therefore, reducing disturbances is crucial to maintaining higher levels of these functional diversities. For example, the results showed that the CWM.Hmax declined from 27.25 m to 15 m, indicating a shift towards shorter plant species. In contrast, the community-weighted mean of woody density (CWM.WD), the community-weighted mean of specific leaf area (CWM.SLA), and the community-weighted mean of seed mass (CWM.SM) increased significantly with an increase in disturbance intensity. For instance, CWM.SM and CWM.SLA changed from 5 to 14.25 (g) and 90 to 130 (cm2/g), respectively. These indices may serve as indicators of ecosystem resilience at disturbed forest ecosystem sites. Furthermore, the regression results indicated that FDp, FRic, FEve, FDiv, FDis, CWM.WD, and CWM.Hmax showed increasing patterns with increasing species richness, which suggests that protecting and promoting species diversity can contribute to maintaining high levels of functional diversity. The mixed effects model revealed that anthropogenic disturbance and elevational gradients had significant effects on functional diversity in the YCFBR. Therefore, when managing and conserving biodiversity in heterogeneous environments, both anthropogenic factors and environmental variables need to be considered. Species with low SLA and SM are recommended for the restoration of disturbed ecosystems. Overall, this study demonstrates that trait-based functional diversity is useful for predicting the adaptation potentials of species in heterogeneous environments and disturbance gradients.

Boosting the confidence of new product development teams: The role of team boundary spanning, team size and functional diversity

In today's highly interconnected, uncertain and dynamic business environment, team boundary spanning has become an important determinant of the performance of new product development (NPD) projects. Despite the positive evidence supporting the use of boundary spanning activities by NPD teams, little is still known about how boundary spanning teams become high‐performance teams. The current study advances research on this subject by examining the mediating effect of team potency on the relationship between team boundary spanning and new product performance, as well as the moderating effects of team size and functional diversity on the relationship between team boundary spanning and team potency. Data from a time‐lagged survey study of 140 NPD projects found that team boundary spanning can promote team potency that, in turn, results in greater new product quality and new product creativity. The positive effect of team boundary spanning on team potency was found to be more pronounced for NPD teams of medium size and high levels of functional diversity.

Effects of different types of land-use on taxonomic and functional diversity of benthic macroinvertebrates in a subtropical river network.

Expansion of agricultural and urban areas and intensification of catchment land-use increasingly affect different facets of biodiversity in aquatic communities. However, understanding the responses of taxonomic and functional diversity to specific conversion from natural forest to agriculture and urban land-use remains limited, especially in subtropical streams where biomonitoring programs and using functional traits are still under development. Here, we conducted research in a subtropical stream network to examine the responses of macroinvertebrate taxonomic and functional diversity to different types of land-use in central China. Our results showed that medium body size, univoltine, gill respiration, and slow seasonal development were much higher in natural forest sites, while certain traits related to strong resilience and resistance (e.g., small body size, fast seasonal development, bi-or multivoltine, abundant occurrence in drift, sprawler) dominated in high-intensity agriculture and urbanization sites. We further found that land-use compromised water quality (e.g., increases in total phosphate, conductivity and water temperature) and habitat conditions (e.g., high proportion of sand and silt, gravel, and channel width) accounted for the changes in trait composition based on a combination of RLQ and fourth-corner analysis. Moreover, natural forest sites presented relatively high values of functional richness than other land-use, demonstrating the importance of natural forest maintenance to promote high levels of functional diversity. However, taxonomic diversity indexes showed higher sensitivity to distinguish different types of land-use compared to functional diversity measures. Even so, given that certain trait categories showed significant relationships with specific local environmental stressors, trait-based approaches can provide reliable evidence to diagnose the cause of impairment and complement the results of the taxonomic-based approaches. Our findings support the idea that taxonomic and functional approaches should be integrated in river restoration and land-use management.

High redox potential promotes oxidation of pyrite under neutral conditions: Implications for optimizing pyrite autotrophic denitrification

Pyrite autotrophic denitrification (PAD) represents an important natural attenuation process of nitrate pollution and plays a pivotal role in linking nitrogen, sulfur, and iron cycles in a variety of anoxic environments. However, there are knowledge gaps about the oxidation mechanism of pyrite under anaerobic neutral conditions. This study explored the performance of PAD in the presence of EDTA and revealed the mechanism of anaerobic pyrite oxidation and microbial mineral transformation. It was demonstrated that ~200 mV was the electrochemical threshold for converting pyrite into bioavailable forms in PAD conditions, and accelerated pyrite oxidation by Fe3+-EDTA complexes can improve the performance of PAD effectively. Furthermore, genus related to sulfur and nitrogen cycle (Sulfurimonas, Denitrobacter) were found at higher abundances in cultures containing EDTA. The analysis of metagenomic binning showed that the microbial community in PAD culture with EDTA addition exhibited higher levels of functional diversity and redundancy. These results will further the understanding of the oxidation mechanism of pyrite under anaerobic neutral conditions and the corresponding microbial activities, and provide insights into the practical application of PAD.

Peripheral Estates as Arrival Spaces? Conceptualising Research on Arrival Functions of New Immigrant Destinations

In recent years, the question of how urban spaces support the arrival of immigrants has found increased attention among scholars. The emerging discussion uses terms like arrival cities, arrival neighbourhoods, arrival spaces, arrival contexts, or arrival infrastructures to refer to local conditions which support immigrant inclusion. This discussion, however, tends to focus empirically and conceptually on neighbourhoods or cities with long-standing migration histories. Connected to this, arrival spaces are often conceptualised as spaces with strong migrant support networks and economies, as well as with high levels of functional diversity and a high fluctuation of residents. Less focus is placed on the question of if and how destinations that lack these characteristics support the arrival of new immigrants. This contribution focuses on this by discussing existent conceptualisations of arrival spaces and contrasting them with empirical illustrations of peripheral estate neighbourhoods in east German cities that have experienced a substantial population loss since the 1990s, resulting in the partial demolition of housing and infrastructure. Since the refugee migration to Germany starting in 2015, the population dynamic in these neighbourhoods has changed substantially. We contrast these developments with the literature on arrival contexts in order to reflect the strengths and weaknesses of the concept, specifically regarding the conditions in new destinations where migrant networks and economies are still emerging, functional diversity is low, and the role of residential fluctuation is unclear. While this article draws on empirical material, its major objective is to point out the blind spots in the current discussion around arrival spaces. It develops questions and offers a research agenda that introduces a wider and more varied set of neighbourhoods into the evolving research agenda on arrival spaces.

Drivers affecting mammal community structure and functional diversity under varied conservation efforts in a tropical rainforest in Cameroon

AbstractAs well as leading to a loss of biodiversity (i.e. species richness and abundance), human activities also affect ecosystem functioning. Documenting how the suite of ecological roles changes following disturbance provides a complementary source of information for conservation management. To this end, we measured mammal diversity in terms of community structure (i.e. abundance, composition and species richness) and functional diversity in three sites differing in conservation effort in a tropical rainforest in Cameroon. Results show that sites without primary or secondary conservation efforts had lower mammal abundances and an altered mammal composition but similar species richness compared to better‐protected areas. In terms of functional diversity, we found more variation of traits (i.e. FDis) in the site with primary conservation and higher abundances of functionally unique species (i.e. FOri) in sites with either primary or secondary conservation efforts. We found no overall difference in the abundance of specialist and generalist species between sites (i.e. FSpe). We identified several drivers affecting abundance, species richness and functional diversity of mammal communities, although there did not appear to be a common driver affecting all mammal diversity measures in a similar way. Our results suggest that, in addition to preserving mammal abundance and community composition, conservation efforts (both primary and secondary) are able to contribute to maintaining higher levels of functional diversity compared to areas devoid of conservation. We demonstrate that functional diversity metrics can provide valuable additional information about the status of mammal communities that can be used to better inform conservation management.

Temporal variability in taxonomic and trait compositions of invertebrate assemblages in two climatic regions with contrasting flow regimes

ContextUnderstanding natural temporal changes in Mediterranean rivers with contrasting flow regimes in relation to those of temperate rivers may prove helpful in predicting effects of climate change on aquatic biodiversity. GoalWe aimed to compare temporal variability in taxonomic and trait compositions of nearly natural rivers in two climatic regions with varying flow regimes to address the effects of future climate changes on aquatic biodiversity in reference conditions. MethodsWe analysed taxonomic and biological trait compositions using the Foucard multivariate method to compare within-site temporal variability levels and the evolution of within-date spatial variability patterns. In addition, we assessed the effects of temporal variability levels on taxonomic and functional diversity and on community specialization. ResultsOur results reveal (i) highly fluctuating environments of the Mediterranean region, particularly in intermittent rivers, which lead to higher levels of temporal variability in both taxonomic and trait compositions of benthic invertebrate assemblages, with marked synchrony in Mediterranean streams linked to contrasting flow characteristics; (ii) higher degrees of taxonomic richness associated with higher levels of functional diversity in Mediterranean rivers relative to temperate rivers, (iii) higher temporal stability for functional diversity and trait compositions of benthic invertebrate assemblages than for taxonomic richness and compositions; and (iv) a recovery of all diversity metrics following drying events in intermittent sites. ConclusionThis study offers insight into a rarely addressed question concerning the temporal variability of trait compositions in benthic invertebrate assemblages among rivers differing in terms of flow regimes. It suggests that temperate rivers will experience higher levels of temporal variability in terms of taxonomic and trait compositions under future climatic change scenarios, even in sites that will remain perennial, resulting in higher levels of taxonomic and functional diversity. This lack of temporal stability in least-disturbed situations should be taken into account when developing bioassessment tools based on reference conditions.

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.

Success factors for sourcing teams: How to foster sourcing team effectiveness

Cross-functional sourcing teams have become a popular coordination mechanism to organize company procurement activities. However, many of these teams fail to meet management’s long-term expectations. A lack of sourcing-specific team research obstructs a clear understanding of the factors that drive sourcing team performance. In the present study, we identified three major dimensions of sourcing team success. Apart from general overall team effectiveness and supply base management effectiveness, sourcing teams need to effectively cooperate with other stakeholders within the firm in order to secure purchasing cost savings and supplier contracts. Additionally, we identified factors that underlie sourcing team success, based upon extensive survey data taken from members, leaders, and managers of 59 (cross functional) sourcing teams in twelve large, multinational companies. Our study revealed that different success factors drive different sourcing team effectiveness dimensions. Also, we found a seemingly contradictory need for both autonomy and formalization to ensure sourcing team effectiveness on all three dimensions. The latter seemed particularly important for teams with high levels of functional diversity.

Diversity and social capital of nascent entrepreneurial teams in business plan competitions

PurposeThe purpose of this paper is to examine the influence of team member diversity and internal social capital on project performance within the context of business plan competitions (BPCs).Design/methodology/approachThe paper uses survey data on 95 nascent entrepreneurial teams enrolled in an open‐to‐the‐public BPCs. It assumes that higher levels of functional diversity as well as higher levels of internal social capital enhance the performance of nascent entrepreneurial teams in the crafting of their business plans (BPs).FindingsUnder this particular context, where the needs for information processing and decision‐making requirements are so high, teams having higher levels of functional diversity attained better performance. Inversely, teams with higher levels of internal social capital did not show a significant advantage in the development of the BP.Research limitations/implicationsLimitations are associated with the exclusion of external social capital measures and not considering demographic faultlines, which might have some impact on the results. Besides, this paper has the limitation of basing its analysis upon teams within a BP contest. Theoretical implications stress that under contexts maximizing the difference between potential upside gains and downside losses, team diversity is expected to play a larger role for BP effectiveness and success than team members' internal social capital.Practical implicationsRecognizing team prevalence and the impact of social dynamics amongst team members within entrepreneurial settings.Originality/valueThe paper contributes with the impact of social dynamic processes on nascent entrepreneurial teams.

Rapid Evolution by Positive Selection and Gene Gain and Loss: PLA2 Venom Genes in Closely Related Sistrurus Rattlesnakes with Divergent Diets

Rapid evolution of snake venom genes by positive selection has been reported previously but key features of this process such as the targets of selection, rates of gene turnover, and functional diversity of toxins generated remain unclear. This is especially true for closely related species with divergent diets. We describe the evolution of PLA(2) gene sequences isolated from genomic DNA from four taxa of Sistrurus rattlesnakes which feed on different prey. We identified four to seven distinct PLA(2 )sequences in each taxon and phylogenetic analyses suggest that these sequences represent a rapidly evolving gene family consisting of both paralogous and homologous loci with high rates of gene gain and loss. Strong positive selection was implicated as a driving force in the evolution of these protein coding sequences. Exons coding for amino acids that make up mature proteins have levels of variation two to three times greater than those of the surrounding noncoding intronic sequences. Maximum likelihood models of coding sequence evolution reveal that a high proportion (approximately 30%) of all codons in the mature protein fall into a class of codons with an estimated d(N)/d(S) (omega) ratio of at least 2.8. An analysis of selection on individual codons identified nine residues as being under strong (p < 0.01) positive selection, with a disproportionately high proportion of these residues found in two functional regions of the PLA(2) protein (surface residues and putative anticoagulant region). This is direct evidence that diversifying selection has led to high levels of functional diversity due to structural differences in proteins among these snakes. Overall, our results demonstrate that both gene gain and loss and protein sequence evolution via positive selection are important evolutionary forces driving adaptive divergence in venom proteins in closely related species of venomous snakes.

Homooligomeric and Heterooligomeric Associations between K+-Cl– Cotransporter Isoforms and between K+-Cl– and Na+-K+-Cl– Cotransporters

Little is known regarding the quaternary structure of cation-Cl- cotransporters (CCCs) except that the Na+-dependent CCCs can exist as homooligomeric units. Given that each of the CCCs exhibits unique functional properties and that several of these carriers coexist in various cell types, it would be of interest to determine whether the four K+-Cl- cotransporter (KCC) isoforms and their splice variants can also assemble into such units and, more importantly, whether they can form heterooligomers by interacting with each other or with the secretory Na+-K+-Cl- cotransporter (NKCC1). In the present work, we have addressed these questions by conducting two groups of analyses: 1) yeast two-hybrid and pull-down assays in which CCC-derived protein segments were used as both bait and prey and 2) coimmunoprecipitation and functional studies of intact CCCs coexpressed in Xenopus laevis oocytes. Through a combination of such analyses, we have found that KCC2 and KCC4 could adopt various oligomeric states (in the form of KCC2-KCC2, KCC4-KCC4, KCC2-KCC4, and even KCC4-NKCC1 complexes), that their carboxyl termini were probably involved in carrier assembly, and that the KCC4-NKCC1 oligomers, more specifically, could deploy unique functional features. Through additional coimmunoprecipitation studies, we have also found that KCC1 and KCC3 had the potential of assembling into various types of CCC-CCC oligomers as well, although the interactions uncovered were not characterized as extensively, and the protein segments involved were not identified in yeast two-hybrid assays. Taken together, these findings could change our views on how CCCs operate or are regulated in animal cells by suggesting, in particular, that cation-Cl- cotransport achieves higher levels of functional diversity than foreseen.