Local Diversity Patterns Research Articles

Once Is Not Enough: Seasonal Patterns in Abundance of Hydromedusae Are Not Consistent in the Coastal Waters of the Bay of Panama.

Hydromedusae and other gelatinous zooplankton are poorly understood but important consumers in the plankton. Blooms of large-bodied medusae which may have detrimental ecological impacts have captured significant attention, yet the seasonal patterns of local abundance and diversity, and the factors that control them, are not well documented for the much more diverse tiny hydromedusae. There is virtually no published information on their phenology or ecology in tropical coastal systems. It has previously been suggested that increased productivity stimulated by upwelling promotes production of tiny hydromedusa and blooms as their abundance can be much higher during upwelling than during non-upwelling periods in the tropics. However, this conclusion was based on a single year of sampling in the Bay of Panama. To determine if a single year of sampling is sufficient to understand seasonal patterns in abundance and occurrence of blooms, we repeated this study 20 years later. Sampling 153 times between April 2022 and April 2023, we found similar genus-level diversity and overall counts of animals compared to the previous study, with medusae of Bougainvillia, Campalecium, Obelia, and Turritopsis accounting for 79% of the animals collected. However, we found that relative abundance was much higher during the non-upwelling season compared to the upwelling season, the opposite result compared to the previous study. These results highlight how strong baseline understanding of phenologies and the ecological conclusions drawn from them must be based on multiple years of data, even in regions with very strong seasonal changes in environmental conditions. In the case of the upwelling regions of the Tropical Eastern Pacific, further research is necessary to understand the generalizability of these patterns, and to determine if contrasting results are due to inter-annual differences in oceanographic drivers or changing environmental baselines.

Fragmentation Level Drives Local Fish Assemblage Diversity Patterns in Fragmented River Basins

Longitudinal connectivity is the main attribute of river ecosystems and is essential for the maintenance of aquatic biota. When longitudinal connectivity decreases in a river network, abundance of some fish species decreases, and local extinctions may occur. Such abundance decreases and extinctions affect local assemblage structure (alpha diversity) and result in a high degree of dissimilarity among local assemblages (higher beta diversity). Specific ecological mechanisms that are behind these biodiversity changes induced by connectivity loss remain poorly understood. Here, we assessed the effects of fragmentation at the local and basin level, as well as local environmental variables on local fish diversity patterns in eight Andean river basins in central Chile (32–39° S). The results indicated that fish assemblages inhabiting pool habitats in highly fragmented basins were characterized by significantly lower species richness and alpha diversity mainly driven by absence of fish species with high dispersion capacities. Our results highlight the importance of the effects of barrier cascades upstream as drivers of local native fish diversity. Sustainable hydropower development necessitates system scale planning of the placement of future barriers and should consider both local and basin scale biodiversity indicators.

Contrasting influence of seascape, space and marine reserves on genomic variation in multiple species

Marine reserves are being established worldwide to conserve and manage marine resources, and are also often assumed to conserve the evolutionary potential of marine populations. However, comparisons of genomic patterns inside and outside marine reserves in multiple species are scarce. Here, we aim to fill this gap by 1) comparing genomic variation in protected versus unprotected areas in a network of eight reserves in the Mediterranean Sea, and 2) disentangling the effect of seascape, space and marine reserves on this genomic variation in 1297 individuals from four species genotyped at more than 10 000 SNPs each. We report homogeneous patterns of local genetic diversity within and outside reserves in three of the four species (the white seabream Diplodus sargus, the striped red mullet Mullus surmuletus and the European spiny lobster Palinurus elephas). Surprisingly, the comber Serranus cabrilla shows lower genetic diversity in protected areas, highlighting an apparent conservation paradox that may be due to increased predation by protected fishes in the reserves. Multivariate analyses reveal that seascape factors (salinity, temperature and chlorophyll) and space exert a significant influence on genomic variation in some cases, while protection status has no detectable effect. Nevertheless, four marine reserves (Cabo de Palos, Cerbère‐Banyuls, Cap de Creus and Illes Columbretes) harbor singular genetic variation in one or two species. This pattern, observed in the four species, suggests that reserves contribute to preserve genetic variation locally. Our study illustrates that we can document key aspects of the genetic variation of marine species and their interaction with seascape factors, space and protection status in multiple species. It stresses the need for a multi‐species approach to inform marine conservation planning, opening up new perspectives at the community level.

Two-year seasonality (2017, 2018), export and long-term changes in coccolithophore communities in the subtropical ecosystem of the Gulf of Aqaba, Red Sea

A two-year (2017, 2018) study of coccolithophores was undertaken in the Gulf of Aqaba in the northern Red Sea to 1) determine the local diversity and community succession patterns with high temporal and taxonomic resolution, 2) determine the contribution to exported inorganic carbon and 3) evaluate changes in communities relative to those in the mid-1970's reported in Winter et al. (1979). As typical, the oceanographic conditions in the Gulf alternated between stratified, oligotrophic through spring/summer, and mesotrophic during winter due to deep convective mixing. Noticeably, the second summer of 2018 was warmer resulting in a more pronounced thermocline. Overall, the coccolithophore dynamics followed the seasonal changes in oceanographic conditions. During the mixing period, coccolithophores were denser (>25 coccospheres mL−1) and were estimated to account on average for 3.46% of the total Chl-a. The communities were fairly homogeneous through depths and over time with a marked dominance of Emiliania huxleyi and Gephyrocapsa ericsonii. During the stratified season, coccolithophore densities were lower, particularly at the surface, such that coccolithophores were estimated to represent on average 0.72% of the total Chl-a. However, the diversity was higher and a clear vertical zonation developed with well-defined upper, intermediate and deep-dwelling communities. These included Umbellosphaera spp., Rhabdosphaera clavigera, a variety of Syracosphaera spp., holococcolithophores and Florisphaera profunda, respectively, as typical in oligotrophic systems. This further underscores the pelagic nature of the Gulf of Aqaba. Noticeably, however, coccolithophores declined in abundances and diversity during 2018, possibly due to the warmer conditions. The relative export of inorganic carbon by coccolithophores largely correlated with the density of living communities, representing <4% and <10% of total inorganic carbon exports during the stratified and mixing periods, respectively. A marked differentiation between different coccolithophore life phases was also detected. Broadly, holococcolithophores inhabited preferentially shallow, oligotrophic water layers in the stratified season, while heterococcolithophores prevailed in deeper water layers or in winter. Yet, species-specific deviations to this pattern were also detected. Finally, comparisons with the 1970's revealed marked changes compared to current communities. G. ericsonii appeared less prevalent and Umbellosphaera spp. displayed a wider temporal residence through spring/summer. Moreover, F. profunda and other deep dwelling species absent in the past are now common during the peak of summer. These observations are indicative of changes in local microbial communities, possibly linked to the ongoing rise in sea temperatures. This study provides a detailed baseline information on coccolithophores for future reassessments of community changes in the GoA.

Elevation and plant species identity jointly shape a diverse arbuscular mycorrhizal fungal community in the High Arctic.

Knowledge about the distribution and local diversity patterns of arbuscular mycorrhizal (AM) fungi are limited for extreme environments such as the Arctic, where most studies have focused on spore morphology or root colonization. We here studied the joint effects of plant species identity and elevation on AM fungal distribution and diversity. We sampled roots of 19 plant species in 18 locations in Northeast Greenland, using next generation sequencing to identify AM fungi. We studied the joint effect of plant species, elevation and selected abiotic conditions on AM fungal presence, richness and composition. We identified 29 AM fungal virtual taxa (VT), of which six represent putatively new VT. Arbuscular mycorrhizal fungal presence increased with elevation, and as vegetation cover and the active soil layer decreased. Arbuscular mycorrhizal fungal composition was shaped jointly by elevation and plant species identity. We demonstrate that the Arctic harbours a relatively species-rich and nonrandomly distributed diversity of AM fungi. Given the high diversity and general lack of knowledge exposed herein, we encourage further research into the diversity, drivers and functional role of AM fungi in the Arctic. Such insight is urgently needed for an area with some of the globally highest rates of climate change.

History predicts contemporary community diversity within a biogeographic province of freshwater fish

AbstractAimHistorical biogeography and community ecology both seek to uncover the patterns and processes governing the structure and composition of communities, though typically at different temporal and spatial scales. Recent work has called to integrate these two fields; however, it is typically assumed that history plays little role in assembling contemporary, local communities. We incorporated phylogeographic data into traditional metacommunity analyses of freshwater fish communities to analyse if history can shape local community structure.LocationStreams in the Nicaraguan Depression in north‐eastern Costa Rica.TaxonFreshwater fish communities.MethodsWe sampled community composition in 14 streams of the San Juan River Basin during the dry season of 2019 and evaluated variability in community composition in response to local and landscape‐scale environmental variability, spatial distance and historic processes using redundancy analyses. We measured environmental and spatial variables using typical methods utilized in metacommunity studies and approximated the effects of history with samova genetic groupings of three livebearing fishes native to the area. We also used PERMANOVAs to test if community composition exhibits similar spatial structure as seen in the genetic data of the three livebearing fishes used as historical proxies.ResultsLarge‐scale patterns of genetic diversity predicted the patterns of local community diversity with community composition showing similar spatial structuring. Additionally, history variables were the only variables that significantly explained community composition and accounted for 20.6% of the total variability.Main ConclusionsSpecies‐specific incidence patterns within Costa Rican freshwater fish communities vary according to biogeographic history, indicating that history can impact local community assembly. These observed patterns are likely due to colonization history following eustatic sea level change. Phylogeography can bridge the gap between classical biogeography and community ecology by enhancing inferences regarding community assembly through time and space, therefore studies should incorporate both genetic and local community data when assessing community assembly.

Altitudinal gradient drives regional and local diversity and composition patterns of epiphyllous bryophytes in ecological refuges.

'Brejos de altitude' is an ecosystem that has been subjected to severe exploitation, leading to an intense reduction in Brazil. Understanding the patterns of bryophyte diversity and composition, particularly of specialized species such as the epiphylls, to anthropic and abiotic variables is crucial for implementing protection measures. We investigated the relationship between composition and diversity of epiphyllous bryophytes and anthropic (edge effects) and abiotic (altitude) variables at local (within each 'Brejo') and regional (set of three 'Brejos') scale. Abiotic and anthropic variables were correlated with alpha and beta diversity (decomposed into species replacement and richness differences) using GLM. Their effects on species composition were evaluated using PERMANOVA. The localities at higher elevations harboured a richer bryoflora and overall beta diversity patterns were associated with altitude and locality, which acted over different scales. Regionally, the contribution of richness differences was limited with increasing altitude. Yet, dissimilarities among localities were associated with richness differences and replacement, denoting the importance of local factors. The composition was explained by local factors interacting with the regional altitudinal gradient. Anthropic activity was significant only when interacting with local factors and altitudinal gradient. Environmental filtering associated with altitude played a more important role in shaping the diversity and composition of epiphyllous bryophytes, at both regional and local scales. Each 'Brejo' acts as an ecological refuge, harbouring part of the whole environmental gradient, and presents a unique floristic composition. Moreover, partitioning beta diversity highlighted the interplay of local and regional forces shaping diversity patterns.

Legacy effects of seed dispersal mechanisms shape the spatial interaction network of plant species in Mediterranean forests

Abstract Seed dispersal by frugivores plays a key role in structuring and maintaining tree diversity in forests. However, little is known about how the spatial legacy of seed dispersal and early recruitment shapes spatial patterns and the spatial interaction network of plant species in mature forest communities. We analysed two fully mapped mixed Pine–Oak forest communities using spatial point pattern analysis to determine (a) the detailed structure of the intraspecific spatial patterns of saplings and adults, (b) the intra‐ and interspecific spatial interaction of saplings, adults and saplings relative to adults, (c) the spatial patterns of species richness at the community level and (d) whether seed dispersal mechanisms affect the plant–plant interaction networks and the ratio of adult to sapling neighbourhood densities used as surrogate for spatial self‐thinning. The intraspecific spatial patterns of saplings and adults showed in general complex nested cluster structures that were similar for sapling and adult stages, despite substantial self‐thinning in some dry‐fruited species. The spatial network of saplings was characterized by positive spatial interactions. Adults of several tree species facilitated saplings in their proximity; however, adults of dry‐fruited species, but not those of fleshy‐fruited ones, lost almost all positive interactions that occurred at the sapling stage. Besides, interaction strength between adults was positive and often significantly stronger if both species were fleshy‐fruited. At the community level, the forests were structured into multispecies clumps across all life stages. Synthesis. Our analyses highlight the importance of the spatial legacy of seed dispersal and early recruitment in the assembly of plant communities. Particularly, animal seed dispersal can lead to multispecies clusters and positive spatial associations across life stages in Mediterranean forests, with surprisingly little signatures of negative interactions. Our analysis suggests that changes of the spatial structure across plant life stages are driven by seed dispersal mechanisms and subsequent spatial self‐thinning, generating a spatial footprint at the sapling stage that conditions the long‐term interactions between adult plants. Combining spatial point pattern analysis with network analysis and species traits is a promising way to disentangle the processes underlying observed patterns of local diversity.

MÉTODOS QUANTITATIVOS PARA MENSURAR A DIVERSIDADE TAXONÔMICA EM PEIXES DE RIACHO

Species diversity is defined as the variety of species and their relative abundances, and can be decomposed in local (alpha), regional (gamma) and between-communities (beta) diversity. For decades, studies with Brazilian stream fish focused on the relationship between local environmental variables and diversity patterns. However, dispersal gained notoriety for being important to the organization of communities. Besides, large scale variables are increasingly being perceived as good predictors of diversity, complementing the role of habitat variables. We present here a brief review of the methods to obtain alpha and beta taxonomic diversity, considerations regarding their predictors, and their main analysis.

Spatial scaling of plant and bird diversity from 50 to 10,000\xa0ha in a lowland tropical rainforest

While there are numerous studies of diversity patterns both within local communities and at regional scales, the intermediate scale of tens to thousands of km2 is often neglected. Here we present detailed local data on plant communities (using 20 × 20 m plots) and bird communities (using point counts) for a 50 ha ForestGEO plot in lowland rainforest at Wanang, Papua New Guinea. We compare these local diversity patterns with those documented in the surrounding 10,000 ha of lowland rainforest. Woody plant species richness was lower within 50 ha (88% of 10,000 ha richness), even when both were surveyed with identical sampling effort. In contrast, bird communities exhibited identical species accumulation patterns at both spatial scales. Similarity in species composition (Chao-Jaccard) remained constant while similarity in dominance structure (Bray–Curtis) decreased with increased distance between samples across the range from < 1 to 13.8 km for both plant and bird communities. The similarity decay was more rapid in plants, but in both cases was slow. The results indicate low to zero beta-diversity at the spatial scale represented here, particularly for birds but also for woody plants. A 50 ha plot provided a highly accurate representation of broader-scale diversity and community composition within 10,000 ha for birds, and a relatively good representation for woody plants. This suggests potential for wider generalization of data from ForestGEO plots which are almost always locally unreplicated, at least for those in lowland tropical forest.

Local distribution patterns of fleshy‐fruited woody plants – testing the orchard hypothesis

Plant distribution patterns are influenced by many different factors. We examined mechanisms behind local distribution patterns of boreo‐nemoral fleshy‐fruited woody plants with seed dispersal mainly mediated by birds. It has been suggested that guilds of these plants develop ‘orchards', i.e. locally aggregated occurrences composed of several species. We analysed spatially explicit occurrence data of different life stages of a local guild of fleshy‐fruited woody plants in south‐eastern Sweden, and conducted a seedling recruitment experiment for a subset of ten species. Spatial point pattern analyses showed that the guild of fleshy‐fruited species was aggregated at small (&lt; 10 m) spatial scales. Saplings were more common under canopies of heterospecific reproductive individuals than expected by chance. These results show that the local guild of fleshy‐fruited species is distributed as orchards, i.e. clusters consisting of individuals of different species and life stages. We found no evidence of negative distance dependence between saplings and reproductive conspecific individuals. Results from the recruitment experiment suggest that recruitment is seed limited and generally low among the studied species. At the site‐scale (circular areas with 50 m radius), there was no difference in seedling recruitment between sites with and without reproductive conspecific individuals for most species included in the recruitment experiment. This further suggests that the aggregated patterns found are not simply a result of spatial concordance in suitable habitats across life stages. Instead, we suggest that the sheer number of seeds from species in the guild deposited under the crowns of fruit bearing individuals is the main mechanism behind the build‐up of orchards. Although further studies are needed to fully disentangle the processes underlying the observed patterns of local diversity, we argue that describing patterns and contrasting them to the predictions of ecologically relevant hypotheses is a useful first step.

Microgeographic divergence of functional responses among salamanders under antagonistic selection from apex predators.

A predator's functional response determines predator-prey interactions by describing the relationship between the number of prey available and the number eaten. Its shape and parameters fundamentally govern the dynamic equilibrium of predator-prey interactions and their joint abundances. Yet, estimates of these key parameters generally assume stasis in space and time and ignore the potential for local adaptation to alter feeding responses and the stability of trophic dynamics. Here, we evaluate if functional responses diverge among populations of spotted salamander (Ambystoma maculatum) larvae that face antagonistic selection on feeding strategies based on their own risk of predation. Common garden experiments revealed that spotted salamander from ponds with varying predation risks differed in their functional responses, suggesting an evolutionary response. Applying mechanistic equations, we discovered that the combined changes in attack rates, handling times and shape of the functional response enhanced feeding rate in environments with high densities of gape-limited predators. We suggest how these parameter changes could alter community equilibria and other emergent properties of food webs. Community ecologists might often need to consider how local evolution at fine scales alters key relationships in ways that alter local diversity patterns, food web dynamics, resource gradients and community responses to disturbance.

Spatial and Temporal Ecological Uniqueness of Andean Diatom Communities Are Correlated With Climate, Geodiversity and Long-Term Limnological Change

National Socio-Environmental Synthesis Center (SESYNC) from the US NSF DBI-1639145 National Geographic Society 8672-09 Comision Nacional de Investigacion Cientifica y Tecnologica (CONICYT) CONICYT FONDECYT LIFE14/IPE/FI/023 project FRESHABIT LIFE IP LIFE14/IPE/FI/023 National Science Foundation (NSF) EAR-1338694

Do single Pollard transects represent the local butterfly community? A case study from the Spitzberg near Tübingen, Germany

Abstract Information on butterfly population size and distribution is a key tool for verifying species conservation status. Such data are rare and tend to be available on local rather than on regional scales. One important data source are monitoring schemes that have been implemented in several countries, e.g. the German butterfly monitoring scheme (TMD). The main goal of the present study was to examine how representative single transects of the TMD are able to identify local or regional diversity patterns of butterflies. Total butterfly population size, density of individuals and species diversity pattern of a 624 ha large study area (Spitzberg) were recorded by intensive surveys. Almost all butterfly species present at the Spitzberg were recorded by the TMD transects. For 22 species, local estimates based on records of the TMD transects ranged between 0 and 10% of the regional population size. Accordingly, the study demonstrates that population size changes of most of the species can potentially be identified. Increasing cover of forest has a negative effect on species diversity and butterfly density, while the cover of nutrient‐poor grassland and the diversity of biotope types has a positive impact on butterfly density and species diversity. Solar insolation has a positive effect on butterfly density. Based on the results of the species–habitat relationships, the location of TMD transects could be optimised by aiming to cover the complete butterfly diversity of the study area. Additionally, monitoring of some of the species might be improved if winter surveys of eggs and larvae were implemented in the monitoring scheme.

Environmental vs. spatial drivers of submerged macrophyte community assembly in different seasons and water depths in a mesotrophic bay of Erhai Lake, China

The relative importance of environmental and spatial drivers in shaping local plant diversity patterns remains unclear. Here, we investigated the environmental and spatial drivers regulating species composition of the submerged macrophyte community in Erhai Lake, China, over different seasons and water-depth gradients. Results showed that environmental and spatial drivers significantly affected species composition of the submerged macrophyte community at the local and fine scale, with shared environmental and spatial drivers explaining 28.3%–38.4% of the variation in species composition for all four seasons. The unique spatial drivers demonstrated a relatively stable contribution (11.8%–16.0%) over the four seasons, but the contributions from the unique environmental drivers showed seasonal variability, being high in summer and winter. In shallow water (0–3 m), spatial drivers were more important in the process of community assembly; in deep water (3–6 m), however, environmental and spatial drivers both significantly affected community assembly. The different water areas also showed strong seasonal changes in the explanatory power of environmental and spatial drivers of submerged macrophyte community variation. Thus, future studies should consider sampling macrophytes over different seasons and at different water depths to better trace the indicators regulating submerged macrophyte community assembly in lakes.

Are cities hotspots for bees? Local and regional diversity patterns lead to different conclusions

With the decline of natural habitats, there is an ongoing debate about the importance of the urban environment for pollinating insects. Our research assessed patterns in wild bee species composition, as well as α-, β- and γ-diversity patterns and the nestedness structure in urban, suburban and rural areas. For three years bees were collected along 18 sampling transects in the Poznań area in western Poland. The average species diversity (α-diversity) and the average number of specimens per sample (local abundance) did not differ significantly between the three classes of urbanization. The rarefaction analysis, however, was partly contradictory to the results recorded on the local scale. The highest dissimilarity in the species composition among the samples was observed in the rural areas, while the lowest (more homogenous) was in the urban areas. The differences were significant. This resulted in the highest γ-diversity (cumulative number of species) in the rural areas and the lowest in the urban areas. Furthermore, the bee community in the habitats studied was significantly nested, indicating that species-poor sites (sites with high rank) constituted subsets of species-rich sites (sites with low rank) and that this pattern was not random. Samples collected in urban areas had a significantly higher nestedness rank compared to samples from the other two classes of urbanization, thus suggesting that the urban bee community is a subset of the rural bee community. This is an important conclusion, which emphasises that different components of species diversity need to be screened to identify the real biological impact of urbanisation on bee communities.

Rapid recovery of the beetle richness‐elevation relationship and its environmental correlates after a major volcanic event in northwestern Patagonia, Argentina

ABSTRACT Volcanic eruptions often modify the structure and function of ecosystems at large geographical scales. However, the extent to which species diversity patterns respond to these major natural disturbances is still poorly known. We tested the shape of the species richness – elevation relationship (SRER) and its environmental correlates (thermal environment at ground level, vegetation structure and soil attributes) before and 6 months after (in the first summer) the most recent eruption of the Puyehue Cordon Caulle volcanic complex (PCCVC), which caused an extensive ash accumulation in northwestern Patagonia, Argentina. We re‐established 32, 100‐m2 sampling plots of nine pitfall traps, placed every 100 m of altitude from the base to the summit of three mountains differentially affected by ash deposition, and from which we had pre‐eruption data on richness and environmental variables. Coverage‐based rarefaction/extrapolation curves showed a local post‐eruptive decrease in richness on only one mountain. Generalised additive models (GAMs) showed no significant differences between pre‐ and post‐eruptive SRER shapes. Partial least squares structural equation modelling (PLS‐SEM) showed that woody vegetation and the thermal environment accounted for most of the variation in richness before and after the eruption. Soil attributes were only indirectly associated with beetle richness and the association was mediated by woody vegetation. Ash accumulation ameliorated the thermal environment, promoting a local increase in beetle richness. The rapid recovery of the SRER shape and its environmental correlates suggest that the structuring of local diversity patterns at temperate latitudes of the southern hemisphere is resilient to major volcanic eruptions.

Local adaptation along a sharp rainfall gradient occurs in a native Patagonian grass, Festuca pallescens, regardless of extensive gene flow

Increasing global aridity combined with changing environmental conditions might cause irreparable alterations in arid and semiarid ecosystems. Knowledge of within-species genetic diversity and adaptive responses, especially along climatic gradients, becomes critical to inform management, conservation and restoration efforts. We combine the analysis of neutral (microsatellites) and adaptive divergence (morphological traits in common garden experiments) between populations along a sharp precipitation gradient in the native Patagonian grass Festuca pallescens, to disentangle patterns of local adaptation and genetic diversity. The identification of genetically based traits under divergent selection denoted the existence of local adaptation in spite of extensive gene flow. Two plant growth patterns were detected associated with two ecological regions. In arid environments, a trade-off between not resigning foliage production, and reducing the exposure to drying agents resulted in a compacted plant architecture; while in dry subhumid environments, populations exhibited a wide architecture to cope with rainfall and radiation interception. Increasing aridity and grazing might favor a compact plant architecture, and fragmentation might reduce genetic diversity across these environments. Being a widely distributed species, F. pallescens is an excellent model species to study adaptive responses across environmental gradients facing climate change predictions, especially in dryland rangelands that maintain multiple ecosystem functions.

Geographical distribution of Lasaia Bates, 1868 (Lepidoptera: Riodinidae) acrossthe biogeographical provinces of Mexico.

Riodinidae are one of the most diverse families of Lepidoptera, mainly in the Neotropical region; however, their biology, ethology, taxonomy, systematics, and biogeography are poorly known. In Mexico, the regional and local distributions of the family are still incomplete. We review the distributional data of the genus Lasaia Bates (Lepidoptera: Riodinidae), based on records from four national and seven international collections. We record five species and seven subspecies in Mexico, with 2722 records, distributed in 314 localities of 24 states. The states with higher species richness are Chiapas, Oaxaca, and Veracruz; also, the genus was recorded in 11 of the 14 biogeographical provinces of Mexico. The tropical semi-deciduous and deciduous forests, below of 1000 m a.s.l., contain most of the diversity of Lasaia. Historical data are crucial for the study of local and regional diversity and ecological patterns at large temporal scales. Data presented here show the morphological and ecological variation of Lasaia over the last 80 years, mostly from the XX century when anthropogenic disturbances were intensified. This kind of studies is the first step in recording the historical distribution of these taxa, which will lead to more complex analyses on distribution range shifts, their causes and consequences.

Disentangling spatio-temporal drivers influencing benthic communities in temporary streams

Temporary streams on the island of Mallorca support unique fauna that differ from other temporary streams on the mainland. It comprises many poor-dispersing endemics as well as more ubiquitous species with better dispersal abilities. To determine the importance of spatial and temporal drivers, this study assesses on the composition and biological traits of macroinvertebrate assemblages, and their variation among 26 non impaired streams corresponding to 3 temporary stream types (mountain, canyon and lowland) during two hydrological phases (flow and disconnected pools) sampled seasonally between 2005 and 2008. Mountain and canyon streams showed longer water permanence, and higher biodiversity than lowland streams, which were characterized by higher drying impact. Significant differences (PERMANOVA and PERMDIST) in species and biological traits composition were found among hydrological phases and stream types, indicating the high spatial and temporal heterogeneity of these temporary systems. The lack of desiccation-resistant forms was dominant in the temporary streams community, suggesting that taxa may survive and persist over the summer in other refugia, such as the hyporheic zone and/or groundwater springs. The environmental variables (physico-chemical, hydromorphological and basin land uses) explained only 40% of the distribution of macroinvertebrate composition (dbRDA analysis), leaving spatial characteristics and temporal variables the highest percentages of variance. Moreover, a significant influence of distance on the macroinvertebrate dispersion (within the surrounding 5 km) was found. Therefore, both neutral (dispersal processes) and niche explanations (local environmental conditions) contribute to patterns of local diversity. Our study highlights the importance of determining the spatio-temporal drivers which influence the ecology and composition of aquatic communities of temporary streams. Such improvement on our knowledge is highly needed for the appropriate design of monitoring programs, being urgently required in the lowlands streams, as they are the most vulnerable to climate change (longer seasonal and supra-seasonal droughts) and human impacts.