Family Richness Research Articles

Reduced riparian zone width compromises aquatic macroinvertebrate communities in streams of southern Brazil.

Recent changes in Brazilian legislation reduced the width of riparian forest buffer needed to be preserved in private properties from 30 to 15m or less. The consequences of these modifications can be dramatic, mainly because riparian buffer width is an important parameter for riparian forest structure and functioning. Our study assessed whether (1) macroinvertebrate family richness and Ephemeroptera, Plecoptera, and Trichoptera (EPT) family richness decrease with reduced riparian buffer width; (2) taxonomic composition and functional feeding group (FFG) composition of macroinvertebrates vary with a reduced riparian buffer width; and (3) reduced riparian buffer width similarly influence the macroinvertebrate community in different stream substrates. We selected three fragments with different riparian buffer widths (>40, <30, and <15m) in three streams (fourth and fifth orders) in the Sinos River watershed, southern Brazil. Our results show that on all substrate types, reducing the width of the riparian buffer altered neither the macroinvertebrate richness nor EPT richness. However, EPT richness was greater in the substrates stone and gravel than leaf litter, independent of riparian buffer width. There was a significant difference in macroinvertebrate composition among riparian buffer widths. The macroinvertebrate composition and FFG differed among substrates, independent of riparian buffer width. This study showed that riparian buffer widths <15m altered the macroinvertebrate community. A width greater than 15m is necessary to maintain the composition and trophic conditions of macroinvertebrate families similar to those found in reference states of conservation.

Assessing Congruence and Surrogacy Among Wetland Macroinvertebrate Taxa Towards Efficiently Measuring Biodiversity

Aquatic macroinvertebrates are a biodiverse component of wetlands. Knowing the degree to which the different groups show congruence in their diversity and composition is therefore necessary if we are to optimize cost effectiveness of macroinvertebrate-based monitoring tools. Here we used published family lists of macroinvertebrate assemblages from 381 wetlands spread across the Western Palearctic and the Nearctic geographic regions, comprising both temporary and permanent waters. In order to determine the magnitude and nature of the spatial variability in the composition of molluscans, crustaceans and insects, we first examined beta diversity patterns for these groups. We then assessed which pairs of these taxonomic groups, or sub-groups (i.e. molluscan and crustacean classes, and insect orders), had a higher congruence in taxonomic richness and composition. We finally tested if any particular combination of groups could serve as a useful surrogate to estimate overall taxonomic richness. We found Mollusca composition could be better predicted than Crustacea and Insecta compositions. Mollusca (M), Hemiptera (H) and Coleoptera (C) family richnesses showed highest congruence with the rest of the groups. We subsequently combined the family richness of these groups (MHC) and observed that this metric was highly correlated with non-MHC family richness. We thus suggest that MHC should be considered when implementing new, or adapting existing, wetland biodiversity monitoring programs.

Family Richness and Biomass of Understory Invertebrates in Early and Late Successional Habitats of Northern New Hampshire

In the northeastern United States, many vertebrate species rely on early successional forest habitats (ESHs). ESHs may also support higher invertebrate diversity and abundance than late successional habitats (LSHs). We assessed the differences in family-level richness and biomass of understory terrestrial invertebrates during the summer season in paired ESH (3–7 years since harvest) and LSH (50 years since last harvest) stands in the northern hardwood forests of northern New Hampshire. Invertebrate family richness was 1.5 times greater in ESH, with 35 families found only in ESH compared with 5 families found only in LSH. Invertebrate biomass was 3.2 times greater in ESH than in LSH. Our sampling methodology and time frame were limited, and taxonomic resolution was relatively coarse. Nevertheless, our results suggest that including ESH stands in northeastern managed forest landscapes may help maintain high levels of invertebrate diversity and are consistent with the use of ESH by many insectivorous vertebrates.

Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages.

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

Insect visitation rates to wild flowers increase in the presence of arid agriculture in South Sinai, Egypt

In temperate and tropical environments agricultural intensification has primarily negative consequences for pollinator conservation. However, in arid environments agriculture is often highly dependent on irrigation and farms can offer higher availability of floral resources than the external environment.This study compares floral visitation rates to wild plants inside and outside 40 agricultural gardens in South Sinai, Egypt. The mean number of flower visitors per plant during a 30 min focal watch was significantly higher inside the gardens than outside, and this was true of orders Diptera, Hymenoptera and Lepidoptera.In total, 23 insect families were recorded inside the garden and 17 outside. The average family richness per plant was significantly higher inside the gardens, with higher rates of family accumulation across focal plants. Pollinating insects (hoverflies, solitary bees and honeybees) all had higher visitation rates inside the gardens.Seed set was assessed for two common pollinator-dependent plants, Stachys aegyptiaca and Alkanna orientalis. Neither species showed a significant difference in the seed set achieved inside and outside of the gardens, but S. aegyptiaca produced a higher number of seeds per plant inside the gardens because plants tended to be larger.In contrast to many other studies, the presence of agriculture appears to increase the abundance and diversity of flower visitors in this under-studied system, with no negative effect on the seed set of two common wild species.

Monorchiid trematodes of the painted sweetlips, Diagramma labiosum (Perciformes: Haemulidae), from the southern Great Barrier Reef, including a new genus and three new species

Five monorchiid species are reported from Diagramma labiosum Macleay (Perciformes: Haemulidae) collected from Heron Island on the southern Great Barrier Reef (GBR): two described species, Helicometroides longicollis Yamaguti, 1934 and Diplomonorchis kureh Machida, 2005 and three new species, including one new genus, Asymmetrostoma heronensis n. g., n. sp., Lasiotocus arrhichostoma n. sp. and Proctotrema addisoni n. sp. Helicometroides longicollis and D. kureh were previously reported from the closely related species Diagramma pictum (Thunberg) from Japan. Two further monorchiid species known from D. pictum, Genolopa plectorhynchi (Yamaguti, 1934) and Paraproctotrema fusiforme Yamaguti, 1934, appear to be absent from the southern Great Barrier Reef. Previous reports of two other monorchiids from D. labiosum from the GBR, Paramonorcheides pseudocaranxi Dove & Cribb, 1998 and Helicometroides vitellosus (Durio & Manter, 1968), are shown to have been made in error. The high richness of monorchiids and other trematode families in D. labiosum is consistent with that seen in other haemulids elsewhere.

Family-Level Benthic Macroinvertebrate Communities Indicate Successful Relocation and Restoration of a Northeast Iowa Stream

A major stream relocation and restoration project was started in 2004 near Dorchester, Iowa. The project converted riparian cropland and stream bank trees to native tallgrass prairie vegetation while relocating Brook Creek to its original streambed. The goal of this project was to restore Brook Creek to conditions comparable with South Pine Creek, a nearby reference coldwater stream that was used as a model for Brook Creek. Benthic macroinvertebrates were monitored in 2005, 2007, 2010, and 2012 in both Brook Creek and South Pine Creek. Benthic macroinvertebrate family-level taxonomic richness, Ephemeroptera/Plecoptera/Trichoptera (EPT) family richness, and family-level biotic indices (FBI) were calculated. We found that Brook Creek’s FBI values were lowered and EPT richness values increased significantly from 2005 to 2012, indicating establishment of a high quality benthic macroinvertebrate community. Benthic macroinvertebrate communities in Brook Creek became increasingly similar to South Pine Creek over the course of this study as evidenced by a principle component analysis and percent similarity, from a 28.72% similarity in 2005 to 62.54% similarity in 2012. These results demonstrate the successful reestablishment of a benthic macroinvertebrate assemblage following stream reconstruction and similarity to a high-quality reference stream.

Global‐scale patterns of assemblage structure of soil nematodes in relation to climate and ecosystem properties

AbstractAimTo conduct the first global‐scale investigation of soil nematode assemblages using a standardized approach to quantify how environmental and climatic variables influence family assemblage structure in nematodes and determine whether nematode families have restricted distributions.LocationGlobal.MethodsWe collected soil nematodes within four 10 m × 10 m plots distributed evenly along a 900‐m transect at each of 12 sites representing multiple ecosystem types across a latitudinal gradient (68° Nto 77° S) on six continents. We assigned &gt; 28,000 individuals to family level and trophic group morphologically.ResultsWe recorded a total of 43 nematode families, but sites varied considerably in family richness (1–30). Families differed in their ranges with 12 families occurring at 10 or more sites, while 14 families occurred at three or fewer sites. Total nematode and trophic group abundances were generally related to soil characteristics, including bulk density and soil moisture, but we found no good predictor of family richness, diversity or evenness at the plot level. Family richness, diversity and evenness were considerably lower in the high‐latitude polar desert than elsewhere, but only family diversity showed a significant, albeit weak, latitudinal gradient. Nematode assemblage composition was quite strongly related to climate: 65% and 58% of the variation in assemblage composition across sites could be accounted for by mean annual rainfall and temperature, respectively.Main conclusionsNematode families display macroecological patterns similar to other organisms, such as a positive abundance–range size relationship and restricted distribution of some families. Local nematode abundances were related to soil characteristics, but we found no relationships between family richness and environmental or climatic variables. Family composition was related to mean annual rainfall and temperature, suggesting that climate is a good predictor of local assemblage structure. As a result, climate change may have a significant impact on nematode assemblages, with potential implications for ecosystem functioning.

Arthropods on plants in a fragmented Neotropical dry forest: A functional analysis of area loss and edge effects

Loss and fragmentation of natural ecosystems are widely recognized as the most important threats to biodiversity conservation, with Neotropical dry forests among the most endangered ecosystems. Area and edge effects are major factors in fragmented landscapes. Here, we examine area and edge effects and their interaction, on ensembles of arthropods associated to native vegetation in a fragmented Chaco Serrano forest. We analyzed family richness and community composition of herbivores, predators, and parasitoids on three native plant species in 12 fragments of varying size and at edge/interior positions. We also looked for indicator families by using Indicator Species Analysis. Loss of family richness with the reduction of forest fragment area was observed for the three functional groups, with similar magnitude. Herbivores were richer at the edges without interaction between edge and area effects, whereas predators were not affected by edge/interior position and parasitoid richness showed an interaction between area and position, with a steeper area slope at the edges. Family composition of herbivore, predator, and parasitoid assemblages was also affected by forest area and/or edge/interior situation. We found three indicator families for large remnants and five for edges. Our results support the key role of forest area for conservation of arthropods taxonomic and functional diversity in a highly threatened region, and emphasize the need to understand the interactions between area and edge effects on such diversity.

Water hyacinth, Eichhornia crassipes (Pontederiaceae), reduces benthic macroinvertebrate diversity in a protected subtropical lake in South Africa

The socio-economic impacts of the free-floating aquatic plant water hyacinth, Eichhornia crassipes (Pontederiaceae), on aquatic systems are well documented, yet the impacts on aquatic biodiversity, particularly invertebrate biodiversity, are less well understood. This study aimed to determine whether the presence of water hyacinth altered the diversity and assemblage structure of benthic macroinvertebrates in a conservation area. The benthic macroinvertebrate assemblage was sampled over 1 year at five sites under water hyacinth mats and at five sites without water hyacinth at Lake Nsezi—Nseleni River in the vicinity of Richards Bay, KwaZulu-Natal, South Africa. Artificial substrates were placed beneath water hyacinth mats or in the open water to allow for colonization by freshwater macroinvertebrates, and left for a period of 6 weeks, repeated on seven occasions. Twenty nine families comprising 18,797 individuals were collected, 817 (13 families) individuals were from under water hyacinth mat sites compared to 17,980 (27 families) individuals from open water sites. Ninety-eight percent of individuals collected were, however, the invasive snail, Tarebia granifera. Open water samples were separated from samples beneath the water hyacinth mat by non-metric Multidimensional Scaling, indicating reduced biodiversity associated with the presence of water hyacinth. Exclusion of the dominant Thiaridae from the analysis did not alter the groupings. Family richness(s) and abundance (N) were significantly higher in open water communities(S: H3 = 21.09; P = 0.0001; N: H3 = 22.58; P = 0.00001), while evenness (J’) was higher under water hyacinth mats (H3 = 20.13; P = 0.0002). The presence of water hyacinth had a significantly negative impact on aquatic macroinvertebrate biodiversity in a conservation area, and therefore the control of this invasive aquatic plant must play a major role in catchment management.

Macroinvertebrate Richness Importance in Coastal Tropical Streams of Esmeraldas (Ecuador) and Its Use and Implications in Environmental Management Procedures

This study was aimed at determining the performance of some indices and community attributes frequently used to assess river quality and test the role of macroinvertebrate taxa richness as element of bioindication in several coastal tropical streams of western Esmeraldas (Ecuador). In addition, a macroinvertebrate taxon list of this region was provided for the first time. Thirteen sampled points distributed across nine streams were selected for this study and nineteen parameters and attributes of bioindication were tested. The differences between nonimpact and impact places were evaluated mainly using one-way analysis of variance. Jackknife 2 and Clench were used to estimate the regional richness and the quality of the inventory, respectively. Seventy taxa (principally genus and family) of the main groups of macroinvertebrates were collected. Measured richness and family richness were the best metric followed by Biological Monitoring Working Party/Colombia (BMWP/Col), Odonata richness, Shannon-Weiner, and EPT richness (Ephemeroptera + Plecoptera + Trichoptera) indices. Only a slight right trend (Ephemeroptera, Trichoptera, and Chironomidae attributes) or incorrect performances (Average Score Per Taxon (ASPT) and % EPT) were showed by frequently used metrics. Finally, several recommendations were made about taxonomic level used, the ranks of quality of taxa richness, and the effort-results relationship in the field of bioindication.

Influence of peak flow changes on the macroinvertebrate drift downstream of a Brazilian hydroelectric dam.

Successive daily peak flows from hydropower plants can disrupt aquatic ecosystems and alter the composition and structure of macroinvertebrates downstream. We evaluated the influence of peak flow changes on macroinvertebrate drift downstream of a hydroelectric plant as a basis for determining ecological flows that might reduce the disturbance of aquatic biota. The aim of this study was to assess the influence of flow fluctuations on the seasonal and daily drift patterns of macroinvertebrates. We collected macroinvertebrates during fixed flow rates (323 m3.s-1 in the wet season and 111 m3.s-1 in the dry season) and when peak flows fluctuated (378 to 481 m3.s-1 in the wet season, and 109 to 173 m3.s-1 in the dry season) in 2010. We collected 31,924 organisms belonging to 46 taxa in the four sampling periods. Taxonomic composition and densities of drifting invertebrates differed between fixed and fluctuating flows, in both wet and dry seasons, but family richness varied insignificantly. We conclude that macroinvertebrate assemblages downstream of dams are influenced by daily peak flow fluctuations. When making environmental flow decisions for dams, it would be wise to consider drifting macroinvertebrates because they reflect ecological changes in downstream biological assemblages.

Biodiversity in eutrophicated shallow lakes: determination of tipping points and tools for monitoring

Nutrient-rich freshwater ecosystems are generally considered as having low ecological quality and low associated biodiversity. In such systems we analysed the effects of water quality on biodiversity of several species groups, to determine tipping points and tools for monitoring. We investigated the water quality of 99 eutrophic and hypertrophic shallow lakes with extensive fish culture during a 3-year study, through the measures of physico-chemical parameters, phytoplankton biomass and structure. In a second step, we related the water quality with richness of aquatic plants, macroinvertebrates and dragonflies. With concentrations of chlorophyll-a above 30 or 70 μg l−1, shallow lakes are normally classified, respectively, in a poor or bad ecological state. However, our results show that chlorophyll-a concentrations up to 78 μg l−1 could be found together with relatively high species or family richness of aquatic plants, invertebrates and dragonflies. We identified most tipping points with 50–60 μg l−1 of chlorophyll-a, values above which a significant decrease of species diversity was found. For monitoring of these shallow lakes we propose to use chlorophyll-a concentrations in combination with water transparency during spring. These parameters are easily applicable and cheap and they yield a good forecast of the biodiversity for the species groups studied.

Bright lights, big city: influences of ecological light pollution on reciprocal stream–riparian invertebrate fluxes

Cities produce considerable ecological light pollution (ELP), yet the effects of artificial night lighting on biological communities and ecosystem function have not been fully explored. From June 2010 to June 2011, we surveyed aquatic emergent insects, riparian arthropods entering the water, and riparian spiders of the family Tetragnathidae at nine stream reaches representing common ambient ELP levels of Columbus, Ohio, USA, streams (low, 0.1-0.5 lux; moderate, 0.6-2.0 lux; high, 2.1-4.0 lux). In August 2011, we experimentally increased light levels at the low- and moderate-treatment reaches to 10-12 lux to represent urban streams exposed to extremely high levels of ELP. Although season exerted the dominant influence on invertebrate fluxes over the course of the year, when analyzed by season, we found that light strongly influenced multiple invertebrate responses. The experimental light addition resulted in a 44% decrease in tetragnathid spider density (P = 0.035), decreases of 16% in family richness (P = 0.040) and 76% in mean body size (P = 0.022) of aquatic emergent insects, and a 309% increase in mean body size of terrestrial arthropods (P = 0.015). Our results provide evidence that artificial light sources can alter community structure and ecosystem function in streams via changes in reciprocal aquatic-terrestrial fluxes of invertebrates.

Representativeness of tree diversity in the modern pollen rain of Andean montane forests

AbstractQuestionsTo assess the relationship between modern pollen rain and Andean montane forest vegetation for diversity, and provide a basis for interpretations of palaeoecological data in the northern Andes, we asked: (1) can the reduction of plant and pollen data to family level preserve information about diversity in both data sets; (2) how precisely do tree pollen and spore types represent richness patterns along an altitudinal gradient on tropical mountains; and (3) how similar are tree pollen and spore family richness in relationship to tree family richness?LocationTropical montane rain forests, Podocarpus National Park in the Andes of South Ecuador (3°S, 79°W, 1000–3000 m a.s.l.).MethodsWe analysed tree diversity and species composition in three different rain forest types: Premontane (PMF), lower montane (LMF) and upper montane (UMF). We investigated modern pollen rain using pollen traps. After testing the reliability of a taxonomic surrogacy on the plant data, we compared abundance and representation, as well as diversity of the two data sets at family level. This was done using rarefaction and Sørensen indices.ResultsThe correlation between tree species and families was high (r = 0.81, P &lt; 0.001). Sample rarefaction on tree pollen and plant family data revealed highest pollen diversity on sites of the UMF, but highest tree diversity on LMF and PMF sites. The Sørensen indices indicate down‐drift of pollen from higher altitudes in PMF and LMF and up‐drift in UMF. Between 1% and 50% of pollen taxa of each sample originate from outside the plot.ConclusionsTaxonomic surrogacy at family level is a good tool for comparing presence–absence patterns of plant and pollen data in tropical regions with high tree diversity. On a family basis, pollen presence–absence data represent the corresponding tree vegetation data, but uncertainties increase with decreasing altitude. The higher diversity in pollen data of the UMF, but slightly lower diversity in the LMF and PMF, can at least partly be explained by wind patterns, local abundance of shrubs and herbs and differences in evenness.

Development of a benthic multimetric index for the Serra da Bocaina bioregion in Southeast Brazil

Brazil faces a challenge to develop biomonitoring tools to be used in water quality assessment programs, but few multimetric indices were developed so far. This study is part of an effort to test and implement programs using benthic macroinvertebrates as bioindicators in Rio de Janeiro State. Our aim was first to test the Multimetric Index for Serra dos Órgãos (SOMI) for a different area--Serra da Bocaina (SB)--in the same ecoregion. We sampled 27 streams of different sizes and altitudes in the SB region. Despite the environmental similarities, results indicated biological differences between reference sites of the two regions. Considering these differences, we decided to develop an index specific for the SB region, the Serra da Bocaina Multimetric Index (MISB). We tested twenty-two metrics for sensitivity to impairment and redundancy, and six metrics were considered valid to integrate the MISB: Family Richness, Trichoptera Richness, % Coleoptera, % Diptera, IBE-IOC index, EPT / Chironomidae ratio. A test of the MISB in eleven sites indicated it was more related to land-use and water physico-chemical parameters than with altitude or stream width, being a useful tool for the monitoring and assessment of streams in the bioregion.

Araneae communities associated with the canopies of chestnut trees in the northeastern part of Portugal: The influence of soil management practices

Chestnut (Castanea sativa Mill.) is one of the economically more important trees in the north of Portugal. Spiders, as generalist predators, are potential controlling agents of pests, yet the composition of the community of spiders associated with this crop is only poorly known. The objective of this study was to determine the spider communities in the canopies of chestnut trees subject to three different soil management practices in northeastern Portugal. Three chestnut groves each subject to a different agricultural practice (grazed, tilled or untilled) were studied in 2008 and 2009. The Araneae communities were sampled by beating the branches and the individuals collected were identified to family and species when possible. To investigate the structure of the spider community in each grove the abundance and family richness of spiders were calculated and compared between managements. In total, 4172 spiders were collected and, in both years, the three most abundant families were Araneidae, Philodromidae and Linyphiidae. In 2008, there was a greater abundance of spiders in the grazed, followed by the tilled and untilled groves, but no significant differences among groves. However, in 2009 there was a greater abundance of spiders in the tilled grove, followed by grazed and untilled groves and the differences between the untilled and the other two groves were significant. Araniella, Oxyopes and Anyphaena were the most abundant genera in the three groves. This study showed that soil management may influence the diversity of spiders, but the effects were weak and not consistent between years. The reduction or absence of a suitable habitat for spiders under the trees in the tilled treatment might have resulted in the spiders migrating up into the canopy. However, based on the weak effects on spider abundance recorded and its potentially adverse effects on soils, tillage is not recommended for managing the incidence of pests in chestnut groves.

The ichthyofauna of the brazilian surf zone: a compilation for ecological comprehension per region.

The ichthyofauna of the surf zones of the Brazilian coast was determined and characterized by the territorial division of Brazil. We compiled 22 scientific papers published in scientific journals which presented the distribution of fish species in these sites. Two hundred and thirty-nine species belonging to seventy-one families of fish were validated and listed. The northern Brazil showed no study in this habitat. The southeast region showed a higher richness of species, families and uniqueness of species, whereas the southern had lower values of richness among the regions studied. In the northeast, most of the unique species are associated with reef environments and the southern presented species typical in freshwater among the unique ones. Finally, the presence of 239 fish species and 71 families represents a considerable number for the ichthyofauna of the Brazilian coast surf zone, for this environment has been scarcely studied. However, because there have been found species inhabiting other environments and by the presence of 61 species with 100% frequency of occurrence in the three regions studied, it can be concluded that it is an ecologically important site. Key words: fish, sea beaches, trawls, Brazil, bibliography

Pesticides reduce regional biodiversity of stream invertebrates

The biodiversity crisis is one of the greatest challenges facing humanity, but our understanding of the drivers remains limited. Thus, after decades of studies and regulation efforts, it remains unknown whether to what degree and at what concentrations modern agricultural pesticides cause regional-scale species losses. We analyzed the effects of pesticides on the regional taxa richness of stream invertebrates in Europe (Germany and France) and Australia (southern Victoria). Pesticides caused statistically significant effects on both the species and family richness in both regions, with losses in taxa up to 42% of the recorded taxonomic pools. Furthermore, the effects in Europe were detected at concentrations that current legislation considers environmentally protective. Thus, the current ecological risk assessment of pesticides falls short of protecting biodiversity, and new approaches linking ecology and ecotoxicology are needed.

Geographical patterns and determinants of species richness in Mexico across selected families of vascular plants: implications for conservation

Mexico is considered a megadiverse country containing more than 10% of the world's biodiversity. The distribution of this species richness and endemism is different among the different Mexican states. We examined the species richness patterns of 13 families of vascular plants (including ferns, gymnosperms and angiosperms) in Mexico using political divisions (states) as units of analysis. We analysed the species richness values (absolute richness, endemic richness and restrictive richness) of these plant families using stepwise multiple regression analysis, assessing their relationship with a set of 10 environmental variables (expressed as heterogeneity coefficients). A combined cluster analysis with multidimensional scaling analysis (MDS) and an analysis of similarities were also undertaken to define the spatial–geographical patterns. Additionally, we proposed a methodological strategy to determine which states of Mexico have priorities for conservation. Our results suggested that the three species richness values used were significantly predicted by environmental factors, especially by climatic heterogeneity. Notwithstanding that a linear pattern was recognized, the Mexican states were gathered in four groups, which were confirmed by the MDS and the cluster analysis: (1) the Yucatan Peninsula, (2) arid Mexico, (3) the Mexican Transition Zone and (4) the megadiverse states. We proposed that 12 Mexican states include all the environmental conditions and are candidates for developing conservation programmes: (1) Quintana Roo, Tabasco and Yucatán, (2) Baja California, Chihuahua and Sinaloa, (3) Guerrero, Jalisco and Nuevo León and (4) Chiapas, Oaxaca and Veracruz.