Taxonomic Distinctness Indices Research Articles

Микобиота пелагиали Одесского региона северо-западной части Чёрного моря

Mycobiota of the marine area of Odessa region was studied (30°70′00′′-31°00′00′′N, 46°23′00′′-46°60′00′′E) (See Fig. 1). Hydrological and hydrochemical regimes of the marine area of Odessa region in the northwestern Black Sea are affected by the discharge of the Dnieper (93.4%) and the Southern Bug (5.7%) rivers, the permanent anthropogenic discharges of the cities of Odessa, Chernomorsk (Ilyichyovsk), Yuzhnyi and their ports, shipping, dredging, and the open sea. The aim of this work was to study the species composition, the number of colony forming units (CFU) and the dynamics of the spatiotemporal distribution of reared microfungi as a function of abiotic factors and the trophic level of seawater in this area. Water samples were taken in summer and autumn 2008-2012 in the surface (1 m depth) and bottom (7-24 m depth) layers. The samples were taken, at least, in three replicates. The results of processing 258 samples from 22 stations were analyzed. The effects of environmental factors (water temperature, salinity, dissolved oxygen, five-day biochemical oxygen demand, petroleum hydrocarbons, dissolved metals Cu, Zn, Ni, Cd and suspended particulate matter) were studied in 140 samples (See Table 1). Micromycetes were isolated on Czapek’s medium prepared in sea water. 1 ml of sample water was added to a Petri dish and filled with medium cooled to approximately 36-40 °C. To suppress the growth of bacteria, 0.03% chloramphenicol was added to the medium (by volume of the medium). Cultivation was carried out at a temperature of 18-20 °С for 2-8 weeks. Micromycetes were identified by morphological and cultural characteristics according to Vera Bilay and Eleonora Koval’ (1988) and GS De Hooh ea tl. (2000). Nomenclature, and taxonomy of fungi correspond to The Index Fungorum database. The ecological analysis of mycocomplexes was carried out according to: species composition, the number of species in complexes, frequency of occurrence of a species and the number of colony-forming units (CFU / L). In this research, 50 fungal species of 19 genera, 14 families, 9 orders, 4 classes of the division Ascomycota were revealed. Fungal taxa from Odessa region were grouped into families. The family Aspergillaceae included the genera Aspergillus, Penicillium and Talaromyces (27 species); the family Pleosporaceae included the genera Alternaria and Stemphylium (8); and there were 3 species of the genus Cladosporium from the family Cladosporiaceae. In total, 76.0% of species found were from the three families (See Table 2). Using Average Taxonomic Distinctness index, AvTD (Δ+), and Variation in Taxonomic Distinctness index, VarTD (Λ+), features of the taxonomic diversity of mycocomplexes were revealed. These indices were calculated from a matrix of micromycete species from the region under study combined with the fungi list (master list, 219 species) of the Black Sea pelagic zone. In the analysis, the taxonomy levels from Species to Kingdom were included. For the indices Δ+ and Λ+, 95% probability funnel graphs were plotted, and their mean expected values were calculated for mycobiota of the region under study and for mycocomplexes from each station. It was found out that the mean expected values of the index Δ+ for mycobiota of the marine area of Odessa region and the stations are considerably lower, and index Λ+ values are higher than those for the sea as a whole (See Fig. 2 and 3). According to literature sources, no significant seasonal and inter-annual changes in the trophic status of the region occurred in 1992-2010. It was transitional between mesotrophic and eutrophic. The long-term mean TRIX value was 5.3 (4-5: medium trophic level; 5-6: high trophic level and poor water quality). In the species composition and numerical structure of mycocomplexes of the mesotrophic and eutrophic zones, no significant differences were detected. Over the entire period of this research, a relatively uniform distribution of the mean abundance of fungi over the area and depth was noted (See Table 3). No significant correlation was found between abiotic parameters under study and micromycete abundance over the horizons, seasons, sampling dates, location of stations, as well as mesotrophic and eutrophic zones. In the region, 44% of fungi-indicators of different kinds of pollution were registered. In the areas of stormwater runoff and wastewater treatment plant discharges, the indicator value (IndVal) was the largest for melanin-containing fungi Cladosporium cladosporioides (28.3%), Alternaria alternata (17.5%), and Aspergillus niger (12.3%), which are resistant to several adverse environmental factors. In the eutrophic zone, large values of the indices were found in Aspergillus clavatus (21,2%), Penicillium expansum (17,7%), Penicillium citrinum (16,1%), Al. tenuissima (12,5%), and in A. fumigatus (60%), Al. alternata (40%) and A. niger (35,7%) in places of local oil pollution. It is established that in the entire marine area of Odessa region, the formed mycocomplexes have a high similarity in species and numerical structure, and therefore, they can be considered as a single community.

Responses of the macroinvertebrate taxonomic distinctness indices of lake fauna to human disturbances in the middle and lower reaches of the Yangtze river

Abstract In recent decades, floodplain lakes have been among the most endangered ecosystems in the world due to human activities, and they are experiencing severe degradation in ecological function and declines in biodiversity. Previous studies have mostly concentrated on the effects of human disturbances on the traditional taxonomic structure of aquatic communities, but little is known about the responses of other facets of biodiversity measures (e.g., phylogenetic relatedness) to anthropogenic impacts. Here, we examined the effectiveness of species richness and taxonomic distinctness (TD) indices (the average taxonomic distinctness, Δ+, and variation in taxonomic distinctness, Λ+) in determining anthropogenic effects based on four datasets of macroinvertebrate communities in 31 shallow lakes in the Yangtze floodplain. The species composition and number of entire taxa and three subsets (mollusk-, insect- and oligochaete-only taxa) were all significantly different among the five lake groups, with the highest species richness in the river-connected lakes, followed by the oxbow, macrophytic, macrophytic-algal transition and algal lakes. For the TD indices, only the Λ+ of entire taxa showed clear differences among lake groups, with the highest values in the algal lakes and the lowest values in the river-connected lakes. However, the TD indices based on the other three datasets showed no differences and did not clearly reveal the degree of anthropogenic disturbances as we expected. However, the spatial pattern of species richness was largely influenced by lake area rather than by water quality. In contrast, the TD indices were insensitive to lake area and responded more readily to water quality than species richness. We proposed that the TD indices provided a useful complement to traditional diversity indices (e.g., species richness) and could be considered as a potential bioassessment metric for detecting the environmental degradation level of freshwater lakes.

Application of taxonomic distinctness indices of fish assemblages for assessing effects of river-lake disconnection and eutrophication in floodplain lakes

Abstract The taxonomic distinctness (TD) indices have been recommended as robust measures for detecting human disturbances, due to their appealing properties such as independence of sampling settings and statistical framework for discriminating disturbed habitats by randomization test. Here we test the application of two widely-used TD indices, namely average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+), for assessing the effects of anthropogenic impacts (loss of river-lake connectivity and deterioration of water quality) based on the presence/absence data of fish assemblages from the floodplain lakes in the Yangtze River Basin, China. The river-disconnected lakes showed significantly lower Δ+ values than connected lakes, and the Δ+ values slightly decreased with increasing water eutrophication. Whereas no significant difference was detected for Λ+ values of fish assemblages among lake groups. The Δ+ funnel plot can relatively well discriminate anthropogenically disturbed lakes, identifying about half of the disconnected lakes as disturbed, and the percentage of lakes identified as disturbed increased with increasing deterioration of water quality. Furthermore, we found species richness was highly related to lake area but not to nutrient levels. On the contrary, the Δ+ was independent of lake area and responded significantly to water quality gradients, implying that the index is comparable among lakes with different surface area. In summary, the Δ+ index of fish assemblages showed advantages over species richness for assessing anthropogenic effects in the Yangtze floodplain lakes. Therefore, the Δ+ of fish assemblages could be considered as a potential metric for lake bioassessment and management in the studied region in particular and for other river floodplains in general.

Discriminating the effects of local stressors from climatic factors and dispersal processes on multiple biodiversity dimensions of macroinvertebrate communities across subtropical drainage basins

Metacommunity ecology emphasizes that community structure and diversity are not only determined by local environmental conditions through environmental filtering, but also by dispersal-related processes, such as mass effects, dispersal limitation and patch dynamics. However, the roles of dispersal processes are typically ignored in bioassessment approaches. Here, we simultaneously explored the potential influences of four groups of factors: local stressors, climatic factors, within-basin spatial factors and basin identity in explaining variation in diversity indices of macroinvertebrate assemblages from seven subtropical tributary rivers. A total of 12 biodiversity indices based on species identities, functional traits and taxonomic relatedness were calculated and used in the subsequent statistical analysis. Our results showed that, although differing in their relative importance, the four explanatory factor groups all played important roles in explaining variation in biodiversity indices. Of the pure fractions, index variation was best explained by local environmental stressors, whereas the other three explanatory factor groups appeared less influential. Furthermore, diversity indices from species, functional and taxonomic dimensions responded distinctly to the focal ecological factors, and differed in their abilities to portray the effects of human disturbances on macroinvertebrate communities. Taxonomic distinctness indices performed best, with the highest amount of variation associated to local stressors and hardly any variation explained by other factors, implying that these indices are robust in portraying human disturbances in streams. However, species diversity and functional diversity indices were also affected by spatial processes and climatic factors, suggesting that these indices should be used with caution in bioassessment. We hence conclude that environmental assessment of riverine ecosystems should not rely entirely on the perspective of species sorting. In contrast, both roles of spatial processes and environmental variables related to human disturbances and climatic variation should be incorporated in management and conservation of riverine ecosystems.

Assessment of benthic diatoms taxonomic diversity at coastal biotopes with different anthropogenic impact (Crimea, the Black Sea)

An analysis of the taxonomic diversity of benthic diatoms was carried out for near-shore biotopes of Crimea with different content of trace metals and organic pollutants (PCBs, PAHs, DDTs). Taxonomic distinctness indices such as average taxonomic distinctness, AvTD (Δ+) and variation in taxonomic distinctness, VarTD (Λ+) were used for evaluation of the hierarchical structure of diatom taxocenes of two intact sites (Dvuyakornaya Bay and Cape Fiolent) and two heavily polluted water areas (Sevastopol Bay and Balaklava Bay). The highest similarity of species was revealed between healthy biotopes, in spite of their differences in hydrological and hydrochemical conditions. AvTD values for Dvuyakornaya Bay and Cape Fiolent (Δ+ = 79.0 and 76.7, respectively) were lower in comparison with expected average levels (Δ+ = 82.2) evaluated for the flora of benthic Bacillariophyta (1094 species) registered for the Northern part of the Black Sea (NPBS). As established, the taxonomic trees of the diatom taxocenes at pristine water areas are characterized by a moderate degree of vertical evenness and high variability of distances between neighboring clusters of species; they are mainly formed by polyspecific branches close on the genus level. The AvTD values for diatom taxocenes of the heavily polluted Sevastopol Bay (Δ+ = 83.6) and Balaklava Bay (Δ+ = 84.1) were significantly higher than the corresponding indices for undisturbed biotopes and exceeded the expected average level for the entire list of Bacillariophyta for NPBS. The upward trend of AvTD along the increasing technogenic impact can be caused by the disappearance of taxonomically close species with low tolerance from the same genus and prevalence of oligo- and monospecies branches in architectonics of the hierarchical tree. The present study shows that the application of TaxD indices can be considered an additional appropriate indicator tool for quantifying changes in the hierarchical structure of diatom taxocenes under persistent anthropogenic stress.

Multi-dimensional diversity patterns of the subalpine meadow on Heyeping peak, Luya Mountain, Shanxi province, China

Plant community diversity is a major research focus in community ecology. The relationship between diversity patterns and different diversity indices is important for developing and improving biodiversity protection. In order to fully understand multi-dimensional diversity patterns of the subalpine meadow on Heyeping peak of Luya Mountain, we used a systematic sampling method and set 150 1 m × 1 m plots in June of 2018. Based on an analysis of the subalpine meadow community on Heyeping peak, we measured multiple diversity indices, carried out a correlation analysis between diversity and environmental factors, and compared correlations among different diversity indices. The goal was to clarify the ecological mechanisms and variation among various diversity indices and environmental factors. The main results were as follows: (1) The species diversity distribution was uniform, the taxonomic level was narrow, functional differences were small, and different pedigree structures were present in each plot. (2) A stable correlation between pedigree diversity index (PD) and species diversity index indicated niche conservativism; the net relatedness index (NRI) of community lineage structure was significantly correlated with the nearest species taxon index (NTI), species richness, and evenness index, indicating that plant community composition in the study area is mainly affected by habitat filtration. (3) The average taxonomic distinctness index (Λ+) and the average taxonomic distinctness index (Λ+) had a stable correlation; only the functional richness index (FRic) and Patrick species richness index were closely related. (4) Among the selected environmental factors, only the forest line had a stable correlation with species diversity index and PD and showed a negative correlation change, indicating an “edge effect” distribution of species diversity in the study area. In summary, the forest line was the key factor affecting the distribution of species diversity in the study area and the species relationships within the community. This work was supported by the National Natural Science Foundation of China (31400358).

Diversity and space-time dynamics of fish assemblages in a coastal lagoon, western Atlantic

The knowledge of the temporal and spatial dynamics in the composition of fish fauna makes it possible to identify patterns of occupation of ecosystems, providing a basis for evaluation and preservation of the local biodiversity. Monthly samplings were carried out at seven sites in a coastal lagoon, using a casting net, dip net and beach seine. A total of 4,110 individuals were collected, distributed in 23 families and 49 taxa of fish, with a predominance of Mugilliza, M.curema, Atherinellabrasiliensis, Micropogoniasfurnieri and Eucinostomusargenteus, corresponding to more than 80% total weight of all individuals caught. Regarding seasonality, greater abundances were recorded in fall, influenced by the high abundance of A.brasiliensis in this period. In addition to fall, this species was also abundant in summer. However, this pattern of dominance was different for the families Mugilidae and Gerreidae, with higher abundances in spring and summer, respectively. The highest abundances were found in the southern section of the lagoon, which are related to the high abundance of A.brasiliensis, M.liza and M.curema. In relation to the indices of average taxonomic distinctness and variation in the taxonomic distinctness, no significant differences were detected between the seasons of the year. Thus, the patterns of distribution and occurrence of fish in the lagoon were consistent with the patterns observed in Brazilian coastal lagoons and estuaries, as well as to the coastal shallow areas of the southeastern and southern regions.

Phylogenetic diversity of larval Chironomidae (Diptera) in lowland rivers as a potential tool in assessment of environmental quality

Different components of biological diversity of larval Chironomidae, typically the most abundant and the most diverse of all lotic zoo-benthos, were assessed to determine their suitability in prediction of the environmental quality. Animals were collected as 73 samples at 62 riverine sites on the territory of Poland and identified morphologically. The analysis of nonlinear regression was used to compare the suitability of the seven indices of diversity. Traditional indices of taxonomic diversity (taxonomic richness, Margalef and Shannon indices) and indices of taxonomic distinctness were found to be unsuitable for this purpose because of the unimodal type of response of their values along with the gradient of the environmental quality. Contrary to them, values of two measures of phylogenetic diversity monotonically increased along with the values of environmental quality measured by official index MMI (Multimetric Macroinvertebrate Index) and were considered highly useful. The best fitted functions estimating relationships between MMI and both indices of phylogenetic diversity (total phylogenetic distance and quadratic entropy) were statistically highly significant and have high values of the fit-accuracy parameters. Original index of phylogenetic diversity ChiPDi based on total phylogenetic diversity, quadratic entropy and taxonomic richness has been presented as well as the proposal of related procedure using barcoding methods.

Preliminary investigation on the structural, taxonomic and functional diversities of benthic communities at different areas in the West Antarctic Peninsula

A study was carried out to determine the influence of latitudes on benthic community assemblages at different stations in the West Antarctic Peninsula in January 2016. Three replicate sediment samples were collected using a hand-made dredge from 3 stations with different latitudes. Benthic communities were compared in terms of their structure, taxonomy (i.e. Taxonomic Distinctness index, TD) and function (i.e. Functional Diversity index, FD). Results showed that in terms of abundance, Trinity Island (the lowest latitude station) recorded the highest number of individuals while the lowest abundance was recorded at higher latitude station, Paradise Bay. However, from a general observation, the benthic organisms in Paradise Bay were relatively larger than in the other two stations. The functional aspects of the communities were also different where the higher latitude station encompassed a less functionally diverse benthic community compared to the other two stations. This finding showed that the different latitudes not only affected the community structure, but such effect was also evident for the functional aspect of the Antarctic benthic communities.

Responses of different biodiversity indices to subsampling efforts in lotic macroinvertebrate assemblages

As a less time-consuming procedure, subsampling technology has been widely used in biological monitoring and assessment programs. It is clear that subsampling counts affect the value of traditional biodiversity indices, but its effect on taxonomic distinctness (TD) indices is less well studied. Here, we examined the responses of traditional (species richness, Shannon-Wiener diversity) and TD (average taxonomic distinctness: Delta(+), and variation in taxonomic distinctness: Lambda(+)) indices to subsample counts using a random subsampling procedure from 50 to 400 individuals, based on macroinvertebrate datasets from three different river systems in China. At regional scale, taxa richness asymptotically increased with fixed-count size; >= 250-300 individuals to express 95% information of the raw data. In contrast, 'ID indices were less sensitive to the subsampling procedure. At local scale, TD indices were more stable and had less deviation than species richness and Shannon-Wiener index, even at low subsample counts, with >= 100 individuals needed to estimate 95% of the information of the actual Delta(+) and Lambda(+) in the three river basins. We also found that abundance had a certain effect on diversity indices during the subsampling procedure, with different subsampling counts for species richness and TD indices varying by regions. Therefore, we suggest that TD indices are suitable for biodiversity assessment and environment monitoring. Meanwhile, pilot analyses are necessary when to determine the appropriate subsample counts for bioassessment in a new region or habitat tyPe.

Changes in multiple facets of macroinvertebrate alpha diversity are linked to afforestation in a subtropical riverine natural reserve.

Land use change is one of the major factors impacting freshwater biodiversity. Afforestation could convert new lands from agriculture or urban land uses to reduce erosion and lead to landscape alterations and biodiversity changes. Here, we examined the changes in the three facets of macroinvertebrate alpha diversity (i.e., taxonomic, functional, and phylogenetic diversity) and further explored possible mechanisms driving their variations before (2007) and after (2016) afforestation along the undammed Chishui River, the core of the National Nature Reserve of Rare and Endemic Fishes in the Upper Yangtze River. We found that taxonomic diversity measures (e.g., species richness, Shannon-Wiener index and Simpson index) increased but all measures of functional diversity (e.g., FRic, FEve, FDiv, and RaoQ) and phylogenetic diversity (e.g., indices of taxonomic distinctness) exhibited stability after the afforestation practice. We also found that only significant taxonomic diversity variation was detected and it showed a relationship to alterations of land use rather than local environmental condition changes across the 10-year afforestation practice. Moreover, hydrology and nutrients levels showed changes after afforestation, but these changes had no effect on the biodiversity changes based on multiple linear regression models. In each survey, the three facets of alpha diversity were significantly explained by natural physical factors and showed inconsistent responses to these underlying environmental variables. In addition, the biodiversity-environment relationships remained stable before and after afforestation, indicating that the inherent mechanisms that drive macroinvertebrate community variation have not changed. Our findings highlight that different alpha diversity measures of lotic macroinvertebrates provide different information about biodiversity and respond differently to various environmental variables. Thus, it is necessary to integrate them into one framework when applying routine monitoring, assessment, and conservation procedures based on lotic macroinvertebrates.

Persistence of genetic diversity and phylogeographic structure of three New Zealand forest beetles under climate change

AbstractAimContemporary climate change is predicted to impact all levels of biodiversity, including intraspecific genetic diversity, the evolutionary basis for future adaptation. While numerous studies use species distribution models (SDMs) to predict species’ future distributions, relatively few investigate potential climatic impacts on the spatial structure of genetic diversity, and how it varies across species ranges. We revisited phylogeographic data for three New Zealand forest beetles to predict the effects of climate change on the geographic distributions, genetic diversity and phylogeographic structure for each species.LocationNew ZealandMethodsWe used ensemble SDMs to predict potential distributions for Agyrtodes labralis (Leiodidae), Brachynopus scutellaris (Staphylinidae) and Epistranus lawsoni (Zopheridae) in 2035, 2065 and 2100. To assess the impact of predicted range loss on genetic diversity and phylogeographic structure, we estimated haplotype and nucleotide diversity, ΦST, Average Taxonomic Distinctness (AvTax), Phylogenetic Diversity (PD) and Net Relatedness Index (NRI) under current and future climatic scenarios, excluding sequences from localities predicted to become unsuitable. We tested whether predicted population loss was spatially clustered and how losses were distributed across the phylogenies of each species.ResultsAgyrtodes labralis is predicted to lose parts of its current distribution by 2100, with the loss of 50% of unique haplotypes and a significant reduction in PD, while Brachynopus scutellaris and Epistranus lawsoni will likely experience an expansion in climatically suitable area and little change in genetic diversity. Brachynopus scutellaris populations are predicted to be more phylogenetically clustered than expected by 2100, but changes in AvTax were negligible for all species.Main conclusionsWe demonstrate that the loss of genetic diversity under climate change is significant; however, intraspecific lineages with deep genetic divergences are widely distributed, buffering against greater change in phylogeographic structure. For species with strong geographic clustering of genetic diversity, climate change impacts may be quite different.

Taphonomy and palaeoecology in the upper Barremian of the SW Iberian chain (Spain): A model to compare taxonomy and diversity of biotas from different coeval basins

A detailed study of the floral and faunal diversity of an upper Barremian lentic ecosystem was performed by examining 50,000microfossils. The study provides an assemblage of 41 species of charophytes, spermatophytes, ostracods, molluscs, and vertebrates (including eggshells). The main goal of this study is to reconstruct the palaeoecology of a fluvio-lacustrine and associated carbonate depositional system, by integrating the sedimentology, taphonomy, and diversity from twelve horizons cropping out in the Buenache de la Sierra and the Las Hoyas basins. The studied area corresponds to the lowermost succession of the Tragacete Formation (Serranía de Cuenca, Iberian chain). Four facies associations (polymictic alluvial; carbonate palustrine and lacustrine; eutrophic lacustrine; and calcarenitic drainage facies) were correlated to the composition of the fossil assemblages, which have yielded a set of taphofacies confirmed by the non-metric multidimensional scaling ordination test of all the horizons. The taphofacies are: (α) dominated by bones and plant leaves, (β) by charophytes-ostracods-bivalves and eggshells, and (γ) by coal-leaves and bones. The Tragacete depositional system consists of demic and mostly autochthonous (non-catastrophic) fossil associations. A mixture of aquatic and terrestrial plants, freshwater molluscs and ostracods coupled with aquatic and terrestrial vertebrate species fosters a biodiversity typical of depositional environments that are congruent with modern floodplain wetland systems. These floodplain wetlands are characterised by a combination of periodically inundated ponds, small lakes, and floodplain areas with terrestrial habitats. As such, they provide suitable environments for the diversification and colonisation of charophytes, ostracods, gastropods, fish, and an ample herpetofauna. The abundance and diversity of eggshells also suggest the development of nesting areas, whereas the occurrence of charred cheirolepidiacean conifer would indicate intermittent wild fires linked to drought events. The taxonomic breadth of this ecosystem is characterised by the taxonomic distinctness index, which, in turn, becomes a referential model to which other Lower Cretaceous microfossil sites may be compared.

The best data design for applying the taxonomic distinctness index in lotic systems: A case study of the Southern Morava River basin

The taxonomic distinctness (Δ+) index has been recognized as a robust measure to assess human impacts on marine biodiversity. However, its applicability in freshwater ecosystems has still not been confirmed. We aimed to propose the most suitable data design for calculating the Δ+ index for application in assessing anthropogenically caused degradation in lotic environments. We calculated the values of Δ+ based on different taxa groups and taxa resolutions, in order to examine its utility as a potential metric in bioassessment programs. We found that the exclusion of non-insect taxa and selected insect orders significantly increased the index sensitivity. Thus, we believe that an appropriate data design for Δ+ calculation based on macroinvertebrate assemblages is the main prerequisite for the effective estimation of degradation in lotic environments. In addition, we argue that a decrease in taxonomic resolution up to genus level is completely acceptable, as it results in only minor information loss. Bearing this in mind would significantly facilitate its application in rapid bioassessment programs. Despite the observed correlation, the utility of Δ+ as a potential bioassessment metric is rather limited, since its fails to detect fine differences in environmental stress, and instead only roughly distinguishes between two basic classes of degradation level, unimpacted and impacted.

USING THE TAXONOMIC DISTINCTNESS AND DIVERSITY INDICES TO QUANTIFY CHANGE IN THE TAXA OF MEADOW PLANT COMMUNITIES RELYING ON DATA FROM LONG-TERM MONITORING

The results of the application of taxonomic distinctness and diversity indices for quantitative analysis of the dynamics of taxa in meadow communities using long-term monitoring data spanning 40 years from Zalidovskie meadows in the Kaluga Region are presented. It is shown that the magnitudes of the taxonomic distinctness and diversity indices changed following similar trends, i. e. having three intervals with values increasing in the second period while species richness decreased and falling in the third period while species richness increased. Additional analysis within the selected intervals and in their combinations using the Jaccard similarity index showed that after a critical change in the community structure during the second interval, the flora composition did not return to its original condition it used to have in the first period. These changes can be considered as characteristic of the succession in this site. We prove that indices of taxonomic distinctness and diversity can be used to analyze long-term dynamics of taxa of different ranks in meadow communities. They reveal the overall direction of change in the sward communities composition depending on the number of species and their positions in the taxonomic classification. The values of both indices increased when the number of related species decreased and vice versa.

Fish-based indicators of estuarine condition that do not require reference data

The species composition of fish communities in 15 microtidal estuaries in south-western Australia, ranging from permanently-open to normally-closed, is shown to be related to the geomorphological and hydrological regimes and not to environmental condition. This study then explored the effectiveness of using qualitative taxonomic distinctness and ABC curves for fish data as indicators of the environmental condition in nearshore, shallow waters of these estuaries and, in the case of taxonomic distinctness, also of their offshore, deeper waters. Neither of these indices require spatial or temporal reference data, which may be either prohibitively expensive and time-consuming to collect or unavailable. Taxonomic distinctness, in both nearshore and offshore waters, varied consistently among estuaries in relation to their recorded environmental status, and is thus a good indicator of overall estuarine condition. ABC analyses, however, did not prove a good measure of the environmental condition of the estuaries, because their results largely reflect differences in accessibility of the estuary to marine estuarine-opportunist species and especially those that grow to a larger size. It is concluded that taxonomic distinctness indices provide a rapid and cost-effective method for assessing the environmental condition of estuaries, particularly those with limited spatial or temporal reference data.

Do different facets of littoral macroinvertebrate diversity show congruent patterns in a large lake system?

Modern biodiversity research focuses on multiple diversity facets because different indices may describe different ecological and environmental processes, as well as the effects of varied disturbances of natural and anthropogenic origins. We investigated littoral macroinvertebrate diversity in a large boreal lake system and specifically explored congruence of indices within and between the three diversity facets: species diversity, functional diversity and taxonomic distinctness. First, we found that the indices of taxonomic distinctness were the most sensitive indicators of eutrophication. Second, we observed that most correlations between the indices within the same diversity facet, and between the indices of functional and species diversity, were relatively strong. However, the indices of taxonomic distinctness (Δ+ and Λ+) were weakly associated with other metrics of diversity, emphasising the importance of taxonomic distinctness as a complementary dimension of biodiversity. Therefore, our observations support the importance to examine multiple facets for mapping biodiversity or for assessing the effects of anthropogenic disturbances on biological communities.

A community-based approach to identifying defence of microalgae against protozoan grazing

It has increasingly been recognized that defence of microalgae against predator grazing is a passive response to increase algal population density by excreting chemicals with a change in physical properties. As common biological pollutants in the cultivation of the microalgae, the community-based method was used to identify the ability of two microalgae, Chlorella sp. and Nannochloropsis oceanica, to defend against protozoan grazing. Mature protozoan samples with 14-day age were collected, using microscopy glass slides, in coastal waters of the Yellow Sea, northern China. For both microalgae, a gradient of concentrations was designed as 100 (control), 104, 105, 106 and 107 cell ml−1, respectively. Results showed that both test algal species represented strong defence effects on protozoan grazing, especially at high density levels. Species richness, abundance and taxonomic distinctness of the protozoan assemblages showed a sharp decrease at high concentration level (107 cell ml−1) of both algae. A significant variation in protozoan community structures was found to be driven by the gradient of the algal concentrations. The paired taxonomic distinctness indices of the protozoan communities showed an increasing trend of departure from the expected taxonomic pattern with increase of algal concentrations. Based on the results, we suggest that the community-based bioassay might be used as a feasible tool for identifying defence against protozoan grazing of microalgae.

Taxonomic distinctness of soft-bottoms mollusks from Gulf of Batabanó, Cuba

Taxonomic distinction is a measure of diversity that has a number of advantages that provides relevant connotation to theoretical and applied ecology. The usefulness of this type of measure as an alternative method for assessing the biodiversity of soft-bottom benthic marine ecosystems was tested using the indices of average taxonomic distinctness (Delta+) and variation in taxonomic distinctness (Lambda+) for mollusk communities of the Gulf of Batabanó (Cuba). For this purpose, inventories of soft bottom benthic mollusk species obtained in the period 1981-1985 and the years 2004/2007 were used. Both species lists were analyzed and compared at spatial and temporal scales. The taxonomic composition, between the period 1981-1985 and years 2004 and 2007, consisted of 3 classes, 20 orders, 60 families, 137 genera and 182 species observed. With the exception of the class level, a non-significant decrease of this composition in 2004 and 2007 was detected. At a spatial scale, a significant decrease in the taxonomic richness was observed in 2004. Significant differences were not detected in Delta+ and Lambda+ to time scale, but at spatial scale, results revealed significant differences that could be attributed to the combined effect of increased anthropogenic activities in the region with hurricane induced effects. These results suggest that the pair of indices, Delta+ and Lambda+, are good descriptors of the biodiversity of soft-bottom benthic mollusk communities in the Gulf of Batabanó.

The taxonomic distinctness diversity of fish community in Lake Honghu during the past 50 years

基于洪湖1959-2004年鱼类群落状况的调查研究，应用分类学多样性指数分析洪湖鱼类群落分类学多样性的变动. 结果显示：受江湖阻隔及人为干扰加剧等因素影响，洪湖鱼类种、属的数目在1981年表现出下降的趋势，科以上的分类阶元的数目则在1993年之后明显减少. 对洪湖鱼类组成进行NMDS排序，1959、1964和1981年的鱼类群落组成较为类似，1993和2004年的群落组成则发生了较大的变化. 随着时间推移，分类差异性指数Δ⁺表现出先上升后下降的趋势，而变异分类差异性指数Λ⁺则表现出先下降后上升的趋势，表明随着人为干扰的增加，洪湖鱼类群落的分类学进化树的平均路径长度和均匀度发生了不同程度的变化. 零假设模型显示，5个时期的Δ⁺值都位于置信区间内，而1993和2004年的Λ⁺值却位于置信区间的上方，显示分类学进化树的均匀度显著下降. Δ⁺和Λ⁺值的变化提供了与物种数变化所蕴含的不同信息，在多样性评价研究中可以作为经典多样性指数的补充. 洪湖鱼类Λ⁺值随干扰程度的加剧而增加，表明这一指数在多样性保护和评价中具有良好的应用价值.;Based on the published literatures about fish assemblages in Lake Honghu, we measured the long-term changes in two taxonomic diversity indices (average taxonomic distinctness, Δ⁺ and variation in taxonomic distinctness, Λ⁺) at five periods (1959, 1964, 1981, 1993, 2004) during the half past century. The results showed that the numbers of species and genera declined from 1981, whereas the numbers of families and higher taxa decreased from 1993. Non-metric multidimensional scaling analysis based on species composition led to a separation of two groups, one grouping 1959, 1964 and 1981, the other gathering 1993 and 2004. Taxonomic distinctness indices displayed a first increase and subsequent decrease of Δ⁺, and a consistent increase of Λ⁺ through time. The five periods all fell within the 95% confidence interval for Δ⁺, but 1993 and 2004 fell significantly above the confidence interval for Λ⁺, indicating a higher unevenness of the distribution of taxa across the taxonomic tree than random expectations. Δ⁺ and Λ⁺ could provide complementary information about the variability of biodiversity in addition to traditional diversity indices, thus we proposed that taxonomic distinctness indices can be used as promising tools in studies of biodiversity and environmental assessment.