Linking functional diversity to ecological indicators: A tool to predict the anthropogenic effects on ecosystem functioning

Functional diversity is related to the maintenance of processes and functions in ecosystems. However, there is a lack of a conceptual framework that highlights the application of functional diversity as an ecological indicator. Therefore, we present a new initiative for motivating the development of ecological indicators based on functional diversity. We are interested in showing the challenges and solutions associated with these indicators. We integrated species assemblage theories and literature reviews. We considered plant traits related to ecosystem processes and functions (specific leaf area, leaf dry matter content, wood density, phenology, and seed mass) to show the application of a selection of functional diversity metrics that can be used as ecological indicators (i.e., Community Weighted-Mean, Functional Divergence, Functional Richness and Functional Evenness). We caution that functional diversity as an ecological indicator can be misinterpreted if species composition is unknown. Functional diversity values can be overrepresented by weed species (species established in disturbed sites) and do not maintain original processes and functions in ecosystems. Therefore, we searched for evidence to demonstrate that weed species are ecological indicators of functional diversity changes. We found support for two hypotheses that explain the effect of weed species on ecosystem function: functional homogenization and functional transformation. Likewise, we showed the application of some tools that can help study the anthropogenic effect on functional indicators. This review shows that the paradigm of addressing the effects of disturbances on ecosystem processes by using functional diversity as an ecological indicator can improve environmental evaluation, particularly in areas affected by human activities.

Patterns and Predictors of Small Mammal Phylogenetic and Functional Diversity in Contrasting Elevational Gradients in Kenya

Mountains of the Afrotropics are global biodiversity hotspots and centers of speciation and endemism; however, very few studies have focused on the phylogenetic and functional dimensions of Afromontane small mammals. We investigated the patterns and mechanisms of small mammal phylogenetic and functional diversity and assembly along elevational gradients in Mount Kenya, the second highest mountain in Africa, and a contrasting low mountain range, Chyulu Hills. We sampled 24 200-m interval transects in both sites; 18 in Mt. Kenya (9 each in the windward side, Chogoria, and the leeward side, Sirimon) and 6 in Chyulu. We extracted the mitochondrial Cytochrome b gene to reconstruct a time-calibrated species tree for estimating phylogenetic diversity indices [phylogenetic richness (PD), mean nearest taxon distance (PDMNTD), and nearest taxon index (PDNTI)]. A functional trait data set was compiled from the field-recorded measurements and published data sets for estimating functional diversity indices [functional richness (FD), mean nearest taxon distance (FDMNTD), and nearest taxon index (FDNTI)]. Several environmental variables representing water-energy availability, primary habitat productivity, and topographic heterogeneity were used to estimate the predictive power of abiotic conditions on diversity variances using generalized linear and generalized additive regression models. The PD and FD peaked around mid-elevations in Mt. Kenya, unimodally increased or decreased in Chogoria and Sirimon, and monotonically increased in Chyulu. The divergence and community structure indices—PDMNTD, FDMNTD, and PDNTI and FDNTI—were relatively weakly associated with elevation. Overall, the tendency of assemblages to be phylogenetically and functionally closely related than expected by chance decreased with elevation in Mt. Kenya but increased in Chyulu. Across the indices, the annual precipitation and topographic ruggedness were the strongest predictors in Mt. Kenya, evapotranspiration and temperature seasonality were the strongest predictors in Chyulu, while temperature seasonality and terrain ruggedness overlapped as the strongest predictors in Chogoria and Sirimon in addition to annual precipitation in the latter and normalized difference vegetation index in the former. The observed contrasting trends in diversity distribution and the strongest predictors between elevational gradients are integral to the sustainable management of the high faunal biodiversity in tropical Afromontane ecosystems.

Responses of functional traits in cavity-nesting birds to logging in subtropical and temperate forests of the Americas

Logging causes changes in habitat structure, which can potentially lead to variations in taxonomic and functional richness of biodiversity. Studies on how functional traits in birds are affected by logging operations can provide an important element for the understanding of ecosystem processes. In this paper, we examined how logging in subtropical Andean forests influenced taxonomic and functional diversity of cavity-nesting birds. We used these results to compare how logging affected ecosystem functions in temperate and subtropical forests of the Americas. We used point-counts to examine the effects of logging on taxonomic and functional traits in avian communities (Functional Richness, Functional evenness, Functional Divergence, and Community-weighted mean). We found that logging changed bird richness and abundance, although it had no effect on the functional response to the measured traits. The comparison of our results with those of temperate forests of Canada and Chile reveals differences in the functional richness of birds in these habitats, with a lower impact of logging on functional traits. We highlight the importance of including functional traits in the analyses, since the reduction in the species richness and abundance may not be translated into functional changes within the ecosystem.

Functional diversity of Himalayan bat communities declines at high elevation without the loss of phylogenetic diversity

Species richness exhibits well-known patterns across elevational gradients in various taxa, but represents only one aspect of quantifying biodiversity patterns. Functional and phylogenetic diversity have received much less attention, particularly for vertebrate taxa. There is still a limited understanding of how functional, phylogenetic and taxonomic diversity change in concert across large gradients of elevation. Here, we focused on the Himalaya—representing the largest elevational gradients in the world—to investigate the patterns of taxonomic, functional and phylogenetic diversity in a bat assemblage. Combining field data on species occurrence, relative abundance, and functional traits with measures of phylogenetic diversity, we found that bat species richness and functional diversity declined at high elevation but phylogenetic diversity remained unchanged. At the lowest elevation, we observed low functional dispersion despite high species and functional richness, suggesting a niche packing mechanism. The decline in functional richness, dispersion, and divergence at the highest elevation is consistent with patterns observed due to environmental filtering. These patterns are driven by the absence of rhinolophid bats, four congeners with extreme trait values. Our data, some of the first on mammals from the Himalayan region, suggest that in bat assemblages with relatively high species diversity, phylogenetic diversity may not be a substitute to measure functional diversity.

Grammatical-pragmatic aspects of teaching verb forms to non-Georgian speakers

For non-Georgian speakers, in the process of teaching the Georgian language, it is crucial to overcome the problems that accompany the understanding, comprehension and mastering of verb forms. The complexity and diversity that is characteristic to the Georgian verb is conditioned not only by polypersonalism or even by the large number and functional richness of the prepositions, but also by the variety of lexical means. The Georgian language has inexhaustible means to produce new verb forms, in order to give the speaker (speaking individual) opportunity to express the new semantics more accurately, to specify the utterance and to add more clarity to the meaning. For example, if a language learner expresses a desire to perform an action, then it is better to first get him/her used to the infinitive constructions of the verbs including მინდა (მსურს) minda (msurs) I want (I would like), for example, I want (I would like) წაკითხვა tsakitkhva – to read (მუშაობა mushaoba – work... წასვლა tsasvla – go, დადგომა dadgoma – stand... თქმა tqma – say, ჩაცმა chatsma – dress...). In the next level of language learning, we can also introduce verb constructions expressing the desired action: I want (I would like) წავიკითხო tsavikitkho – to read (ვიმუშაო vimushao – to work... წავიდე tsavide – to go, დავდგე davdge – to stand... ვთქვა vtqva – to say, ჩავიცვა chavitsva – to put on)... This will also prepare the ground for the language learner to express the obligation with the help of a particle უნდა unda (I must): unda tsavikitkho – I must read (vimushao – work... tsavide – go, davdge – stand... vtqva – say, chavitsva – put on)... He/she could easily build relatively extensive constructions: qartuli ena kargad unda vistsavlo – "I must learn Georgian well"; dghes bevri unda vimushao – "I must work a lot today"; khval universitetshi unda tsavide – "I must go to university tomorrow"; dilit adre unda avdge – "I must get up early in the morning"; es teqsti zepirad unda vtqva? – "Should I say this text orally?"; Tbilad unda chavitsva – "I must dress warmly". The report will provide extensive material to demonstrate the grammatical and lexical means that will make the learning / teaching process of verb forms easier for non-Georgian speakers.

Taxonomically and Functionally Distinct Ciliophora Assemblages Inhabiting Baltic Sea Ice

Ciliophora is a phylum of unicellular eukaryotes that are common and have pivotal roles in aquatic environments. Sea ice is a marine habitat, which is composed of a matrix of solid ice and pockets of saline water in which Ciliophora thrive. Here, we used phylogenetic placement to identify Ciliophora 18S ribosomal RNA reads obtained from wintertime water and sea ice, and assigned functions to the reads based on this taxonomic information. Based on our results, sea-ice Ciliophora assemblages are poorer in taxonomic and functional richness than under-ice water and water-column assemblages. Ciliophora diversity stayed stable throughout the ice-covered season both in sea ice and in water, although the assemblages changed during the course of our sampling. Under-ice water and the water column were distinctly predominated by planktonic orders Choreotrichida and Oligotrichida, which led to significantly lower taxonomic and functional evenness in water than in sea ice. In addition to planktonic Ciliophora, assemblages in sea ice included a set of moderately abundant surface-oriented species. Omnivory (feeding on bacteria and unicellular eukaryotes) was the most common feeding type but was not as predominant in sea ice as in water. Sea ice included cytotrophic (feeding on unicellular eukaryotes), bacterivorous and parasitic Ciliophora in addition to the predominant omnivorous Ciliophora. Potentially mixotrophic Ciliophora predominated the water column and heterotrophic Ciliophora sea ice. Our results highlight sea ice as an environment that creates a set of variable habitats, which may be threatened by the diminishing extent of sea ice due to changing climate.

Characterization of the Multidimensional Functional Space of the Aquatic Macroinvertebrate Assemblages in a Biosphere Reserve (Central México)

The analysis of functional diversity has shown to be more sensitive to the effects of natural and anthropogenic disturbances on the assemblages of aquatic macroinvertebrates than the classical analyses of structural ecology. However, this ecological analysis perspective has not been fully explored in tropical environments of America. Protected Natural Areas (PNAs) such as biosphere reserves can be a benchmark regarding structural and functional distribution patterns worldwide, so the characterization of the functional space of biological assemblages in these sites is necessary to promote biodiversity conservation efforts. Our work characterized the multidimensional functional space of the macroinvertebrate assemblages from an ecosystemic approach by main currents, involving a total of 15 study sites encompassing different impact and human influence scenarios, which were monitored in two contrasting seasons. We calculated functional diversity indices (dispersion, richness, divergence, evenness, specialization, and originality) from biological and ecological traits of the macroinvertebrate assemblages and related these indices to the physicochemical characteristics of water and four environmental indices (Water Quality Index, habitat quality, Normalized Difference Vegetation Index, and vegetation cover and land use). Our results show that the indices of functional richness, evenness, and functional specialization were sensitive to disturbance caused by salinization, concentration of nutrients and organic matter, and even to the occurrence of a forest fire in the reserve during one of the sampling seasons. These findings support the conclusion that the changes and relationships between the functional diversity indices and the physicochemical parameters and environmental indices considered were suitable for evaluating the ecological conditions within the reserve.

Combined effects of bird extinctions and introductions in oceanic islands: decreased functional diversity despite increased species richness

Aim: We analyse the functional consequences of the changes in species composition resulting from extinctions and introductions on oceanic island bird assemblages. Specifically, we ask if introduced species have compensated the functional loss resulting from species extinctions. Location: Seventy-four oceanic islands (>100 km2) in the Atlantic, Pacific and Indian Oceans. Time period: Late Holocene. Major taxa studied: Terrestrial and freshwater bird species. Methods: We compiled a species list per island (extinct and extant, native and introduced), and then compiled traits per species. We used single-trait analyses to assess the effects of past species extinctions and introductions on functional composition. Then, we used probabilistic hypervolumes in trait space to calculate functional richness and evenness of original versus present avifaunas of each island (and net change), and to estimate functional originality of extinct and introduced species. Results: The net effects of extinctions and introductions were: an increase in average species richness per island (alpha diversity), yet a decline in diversity across all islands (gamma diversity); an average increase in the prevalence of most functional traits (23 out of 35) yet an average decline functional richness and evenness, associated with the fact that extinct species were functionally more original (when compared to extant natives) than introduced species. Main conclusions: Introduced species are on average offsetting (and even surpassing) the losses of extinct species per island in terms of species richness, and they are increasing the prevalence of most functional traits. However, they are not compensating the loss of functional richness due to extinctions. Current island bird assemblages are becoming functionally poorer, having lost original species and being composed of functionally more homogeneous species. This is likely to have cascading repercussions on the functioning of island ecosystems.

Temporal Variation in the Ecological Functioning of Benthic Communities After 20 Years in the Eastern Mediterranean

Marine benthic ecosystems face well-documented changes as a result of human activities. Describing these changes is important for predicting ecosystem functioning. In this context, long-term changes in soft-bottom macrofaunal communities after a quarter of a century were studied in the south Aegean Sea with the purpose of investigating whether temporal changes in taxa diversity are accompanied by changes in functional diversity, and secondly to determine the main mechanisms driving these changes (i.e., deterministic versus stochastic processes). To achieve this, a large data set that included species abundance data collected in 1990 and 2014 from several sampling sites along a transect line was used. A biological trait analysis (BTA) was conducted to determine the species functional roles. The results revealed a decline in taxonomic alpha and beta diversity metrics between 1990 and 2014, a difference that was also reflected in functional richness, partially in functional redundancy, but not in functional composition. The stability of functional composition indicated that replacements of functionally similar taxa may occur, ensuring the resilience of the ecosystem to provide goods and services. Finally, the comparison of co-occurrence and functional networks for 1990 indicated a non-differentiation with the null model and, it was not possible to determine if the benthic community was structured due to stochastic processes (e.g., dispersal, natural phenomena) or an overlap of deterministic processes (e.g., niche-filtering, competition). In contrast, the comparison of networks for 2014 pointed out that environmental conditions have acted as a major filter on species distribution.

Bird Functional Diversity in Agroecosystems and Secondary Forests of the Tropical Andes

Agricultural systems have increased in extension and intensity worldwide, altering vertebrate functional diversity, ecosystem functioning, and ecosystemic services. However, the effects of open monoculture crops on bird functional diversity remain little explored, particularly in highly biodiverse regions such as the tropical Andes. We aim to assess the functional diversity differences of bird guilds between monoculture crops (coffee, cocoa, and citrus) and secondary forests. We use four functional diversity indices (Rao Q, Functional Richness, Functional Evenness, and Functional Divergence) related to relevant morphological, life history, and behavioral traits. We find significant differences in functional diversity between agroecosystem and forest habitats. Particularly, bird functional diversity is quite homogeneous among crop types. Functional traits related to locomotion (body weight, wing-chord length, and tail length), nest type (closed), and foraging strata (canopy and understory) are dominant at the agroecosystems. The bird assemblages found at the agroecosystems are more homogeneous in terms of functional diversity than those found at the secondary forests, as a result of crop structure and management. We recommend promoting more diverse agroecosystems to enhance bird functional diversity and reduce their effects on biodiversity.