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opencc-by-4.0Jul 2022View details →

Drought resistance enhanced by tree species diversity in global forests

The species diversity effect (theta) on drought resistance for global forest ecoregions. The species diversity effect was estimated based on a global analysis of the relationship between species richness and drought-induced changes in forest productivity, using a database that contains more than 0.7 million forest plots and satellite-based estimation of drought resistance.

Invasive plant species that experience lower herbivory pressure may evolve lower diversities of chemical defence compounds in the exotic range

ABSTRACT PREMISE Invasive plant species often escape from specialist herbivore species and are likely to experience herbivory mostly from generalist herbivore species in the exotic range. Consequently, the Shifting Defence Hypothesis (SDH) predicts that invasive plants will express higher concentrations of qualitative defence compounds to deter dominant generalist herbivores in the exotic range. Here, I additionally propose a Reduced Chemical Diversity Hypothesis (RCDH), which predicts that reduced herbivory pressure will select for invasive plant genotypes that produce lower diversities of defence compounds in the exotic range. METHODS I tested whether: (1) Invasive Brassica nigra populations express a lower diversity and an overall higher concentration of glucosinolate compounds than native-range B. nigra; (2) Brassica nigra individuals that express high diversities and concentrations of glucosinolates are more attractive to specialist and deterrent to generalist herbivores; (3) Tissues of invasive B. nigra are less palatable to two generalist herbivores Theba pisana and Helix aspersa than tissues of native-range B. nigra. RESULTS Invasive B. nigra populations expressed a significantly lower diversity of glucosinolate compounds and a marginally higher concentration of total glucosinolate compounds. Leaf tissues of the invasive B. nigra were significantly less palatable to T. pisana and marginally less so to H. aspersa. Brassica nigra individuals that expressed high concentrations of total glucosinolate compounds were visited by a low diversity of generalist herbivore species in the field. CONCLUSIONS The biogeographical differences in glucosinolate profiles of invasive and native-range populations of B. nigra may be the result of differential herbivore selection pressures in the respective ranges.

Determinants of genetic diversity and species richness of North American amphibians

Aim: Ecological limits on population sizes and the number of species a region can sustain are thought to simultaneously produce spatial patterns in population genetic diversity and species richness due to the effects of random drift operating in parallel across population and community levels. Here, we test the extent to which resource-based environmental limits jointly determine these patterns of biodiversity in amphibians. Location: North America. Taxon: Amphibians. Methods: We repurposed open, raw microsatellite data from 19 species sampled at 554 sites in North America and mapped nuclear genetic diversity at the continental scale. We then tested whether ecological limits defined by resource availability and environmental heterogeneity could simultaneously shape biogeographic patterns in genetic diversity and species richness with structural equation modeling. Results: Spatial patterns of population genetic diversity run opposite patterns of species richness and genetic differentiation. However, while measures of resource availability and niche heterogeneity predict 89% of the variation in species richness, these landscape metrics were poor predictors of genetic diversity. Main conclusions: Although heterogeneity appears to be an important driver of genetic and species biodiversity patterns in amphibians, variation in genetic diversity both within and across species makes it difficult to infer general processes producing spatial patterns of amphibian genetic diversity. This result differs from those found in endotherms and may be due to the considerable life history variation found across amphibians.

Population dynamics of Amazonian floodplain forest species support spatial variation on genetic diversity but not range expansions through time

Aim: We tested if historical demographic changes of populations occurring on the floodplains of a major Amazon Basin tributary could be associated with range expansions from upper and middle sections of the river, following the establishment of widespread river-created environments during the Late Pleistocene and Holocene. Location: Solimões River, Western Amazon, South America. Taxon: Myrmoborus lugubris, Thamnophilus cryptoleucus and Myrmotherula assimilis. Methods: We explored spatial patterns of genetic diversity and connectivity among sampled localities using thousands of Ultra-Conserved Elements. Range expansions were tested with alternative methods. We quantified habitat preference for the analyzed species to test whether the occupation of dynamic habitats could predict spatial patterns of genetic diversity. Results: Our study did not support shared population range expansions related to historical regionalized changes in habitat availability. We found considerable variation in the spatial distribution of the genetic diversity between studied taxa, and that species with higher levels of specialization to dynamic environments have a more heterogeneous distribution of genetic diversity and reduced levels of gene flow across space. Main conclusions: Our results suggest that demographic expansions along the Solimões River might be linked to spatially homogeneous oscillation in the distribution of floodplain environments, promoting effective population size changes but not range expansion. We found that habitat specificity might be a good predictor of population connectivity along the Amazonian floodplains.

Phylogenetic data for: High diversity of new and known Phytophthora species from phylogenetic Clade 10 in natural ecosystems of Asia, Europe and the Americas

During extensive surveys of Phytophthora diversity, 14 new species were detected in natural ecosystems in Chile, Louisiana, Sweden, Ukraine, Vietnam and Indonesia. Multigene phylogeny based on the nuclear LSU, rpl10, ITS, ßtub, enl, hsp90, tef-1α, ras-ypt1 and tigA and the mitochondrial cox1, nadh1 and rps10 gene sequences demonstrated that they belong to phylogenetic Clade 10 which is structured into three subclades. Subclades 10a and 10b comprise soil- and waterborne species with nonpapillate sporangia and variable breeding systems, including the known P. afrocarpa, P. gallica and P. intercalaris and the new P. ludoviciana, P. procera, P. pseudogallica, P. scandinavica, P. subarctica, P. tenuimura, P. tonkinensis and P. ukrainensis. In contrast, all species in Subclade 10c are airborne with papillate sporangia and homothallic breeding system, including the known P. boehmeriae, P. kernoviae and P. morindae and the new P. celebensis, P. chilensis, P. javanensis, P. multiglobulosa, P. pseudochilensis and P. pseudokernoviae. All new species differed from each other and from related species by a unique combination of morphological characters, the breeding system, cardinal temperatures and growth rates. The biogeography and evolutionary history of Clade 10 are discussed and the hypothesis put forward that the extant subclades originate from early divergences of pre-Gondwanan ancestors (>175 Mya) into water-/soilborne and airborne lineages which during their global spread experienced multiple allopatric and sympatric radiations.

Underestimated Neotropical diversity: Integrative taxonomy reveals two unrelated look-alike species in a suboscine bird (Pachyramphus albogriseus)

We applied an integrative taxonomic framework to evaluate the systematics of the Neotropical Black-and-white Becard, Pachyramphus albogriseus Sclater 1857. Combining phylogenomic (ultraconserved elements), morphological, and vocalization data, we confirmed that this species is polyphyletic; some individuals form a clade sister to P. polychopterus and should be afforded species rank as P. salvini Richmond 1899 (Slender-billed Becard), whereas the remaining subspecies of P. albogriseus (Broad-banded Becard) are sister to P. major. We found that P. salvini differs from P. albogriseus in song, color of the lores, wing-bar width, body size, and bill width. Whereas P. albogriseus occurs in montane forest in Costa Rica and Panama (ssp. ornatus) and along the eastern slope of the Andes from to N Venezuela to S Peru (ssp. albogriseus), P. salvini is found in the lowlands from Pacific Colombia south to NW Peru and in the Río Marañón drainage. The latter also occurs, possibly only seasonally, along the eastern slope of the Andes, where the two species' ranges approach closely. We treat P. a. guayaquilensis Zimmer 1936 as a junior synonym of P. salvini Richmond 1899, and P. a. coronatus Phelps and Phelps 1953 as a junior synonym of P. a. albogriseus Sclater 1857. This study provides a striking example of a major problem for comparative biology: underestimated and mischaracterized diversity. We argue that there are likely many more cases like this awaiting discovery.

opencc-zeroSep 2022View details →

Feeding habits influence species habitat associations at the landscape scale in a diverse clade of Neotropical fishes

Aim. A primary goal of community ecology is to understand the mechanisms that drive species' spatial distribution and habitat associations. Species' geographic distribution can be influenced by the distribution of their prey partly because consumers' behavior is oriented to optimal energy use during foraging. We analyzed how differences in dietary preferences influence the spatial distribution and habitat associations of species at the landscape scale. We hypothesized that differences in feeding guilds will lead to divergent habitat association patterns among species. Location. Amazon River drainage basin. Taxon. Characiform fishes in the family Serrasalmidae (piranhas and pacus). Methods. We used diet data to classify species into feeding guilds (frugivores, herbivores, piscivores, fin and scale feeders, and planktivores). We used three proxies of habitat association derived from satellite products: floodplain extent, landscape heterogeneity, and flood duration, in three distance buffers. We implemented Phylogenetic Generalized Least Squares models to evaluate the relationship between habitat association and feeding guilds. Results. Frugivores, piscivores, and fin and scale feeders presented similar patterns of habitat associations, with frugivores occupying wider areas of floodplain and greater landscape heterogeneity. Herbivores and planktivores were associated with smaller floodplain extents and lower landscape heterogeneity. All feeding guilds were associated with similar levels of flood duration. Main conclusions. Differences in resource distribution (assessed through feeding guilds) can influence habitat association. Considering the hydrological variability (i.e., floodplain extent) and landscape heterogeneity that characterize floodplains, the patterns of habitat association vary with the spatial scale considered. This work highlights the importance of understanding species habitat associations by fish as well as food resource dynamics and floodplain dependence. This realization is critical for assessing the impact of anthropogenic activities on freshwater ecosystems.

opencc-zeroDec 2021View details →

Reciprocal bark exchange helps to disentangle tree species dependent bark and wood trait effects on invertebrate diversity

1. Previous studies showed that bark cover at early-decay stage had profound control on the invertebrate assemblages of bark and wood, with possible consequence for the decomposition process. However, previous experimental designs could not disentangle how bark versus wood traits affect the invertebrate assemblage process in bark and/or wood separately because wood traits of different tree species may vary independently from bark traits. Furthermore, we do not know whether such tree species specific bark trait effects are still influential at mid-decay stage. 2. To unravel whether and how bark and wood traits influence invertebrate communities in tree logs at mid-decay stage, we introduce reciprocal bark transplantation within pairs of different tree species as a new method. We applied this method to two pairs of phylogenetically contrasting species of gymnosperms (pair I: Araucaria araucana and Cryptomeria japonica, pair II: Picea abies and Thuja plicata) and another gymnosperm (Chamaecyparis lawsoniana) set as disturbance control to test for potential bark manipulation artefacts on invertebrate community composition. 3. Our bark exchange experiment revealed that both bark and wood host abundant and divergent subsets of invertebrates on mid-decay logs of different tree species. We further documented that the invertebrate community composition was predominantly shaped by the traits of host tissue per se, while also being significantly but less strongly affected by the traits of the other tissue, i.e. the adjacent bark or wood. Our results indicated that bark trait effects faded with time and how long bark trait effects persist greatly depends on bark thickness. 4. Synthesis. Our study suggests that maintaining deadwood heterogeneity related to variation between tree species, and to bark versus wood, is important for nursing a large biodiversity of invertebrates. Combined with bark removal methodology, our bark exchange method can be further extended to more decay stages and more forest biomes to track bark trait effects and bark induced priority effects on deadwood decomposition, and its associated invertebrate and microbial communities.

opencc-zeroOct 2022View details →

Beetle diversity in dead wood is lower in non-native than native tree species, especially those more distantly related to native species

1. Non-native tree species are widely used in forest plantations. This may have negative consequences for biodiversity. Hitherto, most studies have compared species diversity between native and non-native forest stands, which makes it difficult to separate the impact of tree species per se from stand characteristics. Our study, conducted in the south of Sweden, compares saproxylic beetle diversity across different nutritional groups, in dead wood of two native and four non-native tree species in a block design after one and three seasons. Such an approach allows analysis of the impact of non-native tree species per se. 2. Mean species richness (±SD) per log was lower in non-native than in native tree species (non-native trees: lodgepole pine: 10.7 (± 5.3); Sitka spruce: 8.5 (± 4.3), Douglas fir: 7.1 (± 4.3), Japanese larch 9.4 (± 4.6); native trees: Norway spruce: 12.0 (± 6.0), Scots pine: 12.3 (± 5.2)). Sample-based rarefaction revealed that when only native tree species were pooled, the species richness was higher than for all tree species combined. The difference in species composition among tree species was strongly driven by bark and wood consumers in the first season, while for predators and fungivores, the differences were smaller. Species composition differed more after one season. 3. Dissimilarity in beetle species composition was positively correlated with phylogenetic distances of the tree species. Species richness was lower in non-native tree species that are only remotely related to native trees species. Of the studied non-native tree species, lodgepole pine was more closely related to native tree species and consistently harboured higher species richness. 4. Synthesis and applications. Although non-native tree species also harbour saproxylic beetle communities, the use of non-native tree species, especially those only remotely related to native tree species, reduces local diversity of saproxylic beetles. Thus, for biodiversity conservation, an extensive use of non-native tree species is not recommended as this increases the risk of losing forest biodiversity, especially when they are only distantly related to native tree species.

opencc-zeroOct 2022View details →

Global patterns and drivers of herbivorous eriophyoid mite species diversity

Aim: Environmental drivers and host richness play key roles in affecting herbivore diversity. However, the relative effects of these factors and their effects on lineages characterized by high host specificity are not well known. In this study, we explored the extent to which contemporary climate, Quaternary climate change, habitat heterogeneity, and host plants determine the species richness and endemism patterns of herbivorous eriophyoid mites. Location: Global. Taxon: Eriophyoid mites (Acari: Eriophyoidea). Methods: We compiled a dataset comprising 4,278 eriophyoid mite species from 22,973 occurrence sites based on a comprehensive search of the published literature and the Global Biodiversity Information Facility (GBIF) as a basis for predicting their global distribution patterns. We measured the association of environmental variables and host plant richness with species richness and endemism of eriophyoid mites through multiple regression analyses using a simultaneous autoregressive (SAR) model, an ordinary least squares (OLS) model, and a random forest model. We examined the direct and indirect effects of these environmental variables and the host plant richness on eriophyoid mite diversity using structural equation models (SEMs). Results: The species richness and endemism patterns of eriophyoid mites are concentrated in temperate regions. Contemporary climate, Quaternary climate change, habitat heterogeneity, and host plants all significantly affected eriophyoid mite richness, while Quaternary climate change, habitat heterogeneity, and host plants contributed to the eriophyoid mite endemism. Abiotic factors indirectly influenced the species richness and endemism of eriophyoid mites, via biotic factors—host plants. Main conclusions: The species richness and endemism of eriophyoid mites peak in temperate regions, opposite to the patterns of plants and some other organisms. Complex interactions among biotic and abiotic factors shape the current eriophyoid mite species diversity.

opencc-by-4.0Aug 2017View details →

Individual-level trait diversity predicts phytoplankton community properties better than species richness or evenness

This archive includes the final summary tables used for the analyses.

opencc-by-4.0Aug 2011View details →

Supplementary material 1 from: Scacchetti P, Pansonato-Alves J, Utsunomia R, Oliveira C, Foresti F (2011) Karyotypic diversity in four species of the genus Gymnotus Linnaeus, 1758 (Teleostei, Gymnotiformes, Gymnotidae): physical mapping of ribosomal genes and telomeric sequences. Comparative Cytogenetics 5(3): 223-235. https://doi.org/10.3897/compcytogen.v5i3.1375

Nexus file of aligned COI and COII nucleotide sequences.

opencc-zeroApr 2024View details →

Ecological divergence despite common mating sites: Genotypes and symbiotypes shed light on cryptic diversity in the black bean aphid species complex

Different host plants represent ecologically dissimilar environments for phytophagous insects. The resulting divergent selection can promote the evolution of specialized host races, provided that gene flow is reduced between populations feeding on different plants. In black bean aphids belonging to the Aphis fabae complex, several morphologically cryptic taxa have been described based on their distinct host plant preferences. However, host choice and mate choice are largely decoupled in these insects: they are host-alternating and migrate between specific summer host plants and shared winter hosts, with mating occurring on the shared hosts. This provides a yearly opportunity for gene flow among aphids using different summer hosts, and raises the question if and to what extent the ecologically defined taxa are reproductively isolated. Here, we analyzed a geographically and temporally structured dataset of microsatellite genotypes from A. fabae that were mostly collected from their main winter host Euonymus europaeus, and additionally from another winter host and fourteen summer hosts. The data reveals multiple, strongly differentiated genetic clusters, which differ in their association with different summer and winter hosts. The clusters also differ in the frequency of infection with two heritable, facultative endosymbionts, separately hinting at reproductive isolation and divergent ecological selection. Furthermore, we found evidence for occasional hybridization among genetic clusters, with putative hybrids collected more frequently in spring than in autumn. This suggests that similar to host races in other phytophagous insects, both prezygotic and postzygotic barriers including selection against hybrids maintain genetic differentiation among A. fabae taxa, despite a common mating habitat.

opencc-zeroApr 2024View details →

Data from: Landscapes with higher crop diversity have lower aphid species richness but higher plant virus prevalence

Diversifying agricultural systems by growing more than one crop species in an area can decrease pest and disease pressure and increase crop yields. However, there is a lack of information on how crop diversity at larger spatial scales influences pest and disease pressure. Here, we investigated how landscape-scale crop diversity affects aphid vector communities and prevalence of non-persistently transmitted potato virus Y (PVY). To test the influence of landscape-scale crop diversity on PVY prevalence and aphid communities, we conducted a field study during the 2020 and 2021 field seasons in the San Luis Valley, Colorado where we quantified aphid communities and PVY incidence at multiple sites. We then determined the association of aphid species richness and abundance and PVY incidence with landscape variables (crop diversity metrics and percentage cover of crop species) within 1, 2 and 3 km buffers from study sites. Higher crop diversity (measured as Shannon diversity index) led to decreased aphid species richness at a 3 km buffer in the 2021 field season. Percentage of alfalfa was positively associated with aphid species richness in 2020 and aphid abundance in 2021 within a 1 km buffer. Higher crop diversity led to increased PVY incidence at a 2 km buffer in 2021 and 3 km buffer in 2020 and 2021. At a 3 km buffer in 2021, we found a positive influence of crop species richness on PVY incidence and a negative influence of crop species evenness on PVY incidence. Also in 2021, we found a positive influence of percentage of potato (virus host) on PVY incidence and a negative influence of percentage of barley (virus non-host) on PVY incidence. Synthesis and applications: In summary, we found that landscape-scale crop diversity impacts plant virus prevalence at spatial scales of >1 km. This suggests that potato growers could reduce PVY prevalence by geographically isolating potato fields from other potato or other PVY-hosts. Crop diversity had a negative influence on aphid vector communities so growers could reduce risk of virus spread by aphid vectors by using certified potato seed in a diversified landscape.

opencc-zeroApr 2024View details →

Data from: The potential of undersown species identity vs. diversity to manage disease in crops

In the absence of chemical control with its negative side effects, fungal pathogens can cause large yield losses, requiring us to develop agroecosystems that are inherently disease resistant. Grassland biodiversity experiments often find plant species diversity to reduce pathogen pressure, but whether incorporating high biodiversity levels in agricultural fields have similar effects remains largely unknown. We tested if undersown plant species diversity could reduce barley disease, and whether the effect was mediated through above- or belowground mechanisms, by combining an agricultural field trial with a soil transplant experiment. As predicted, barley disease decreased in the presence of undersown plants. Undersown species richness had no effect, but their abundance led to early season disease reduction. Aboveground mechanisms underpinned this disease reduction. Barley yield slightly decreased with increasing undersown species richness, and undersown species varied in their impact on yield. We identified two undersown species, Trifolium repens and T. hybridum, that contributed most to disease reduction and had the potential to increase barley yield. Furthermore, our results indicate that aboveground mechanisms caused this. We show that agroecosystem functioning can be improved without trade-offs on yield by targeted selection of undersown species.

opencc-by-4.0Feb 2024View details →

FIGURE 4 in A new species of Ancistrus (Siluriformes: Loricariidae), with a redescription of Ancistrus brevipinnis and further evidence of hidden diversity in the laguna dos Patos system, Brazil

FIGURE 4 | Arroio Cambaizinho, showing typical habitat of Ancistrus megacanthus.

opencc-zeroMay 2024View details →

The counteracting effects of human-driven speciation and extinction on mammal species richness and phylogenetic diversity

Human activities are causing massive increases in extinction rates, but may also lead to drastic increases in speciation rates – for example following the human-mediated spread of species to otherwise unreachable landmasses. The long-term net anthropogenic effects on biodiversity, therefore, remain uncertain. The aim of this paper is to assess the combined anthropogenic effects of extinctions and speciations on biodiversity over geological time scales. We estimate known anthropogenic and predicted future extinctions based on Red List categories from the International Union for Conservation of Nature. We infer potential anthropogenic speciations assuming that all introductions to isolated landmasses will over time evolve into distinct species. We then estimate changes in regional and global species richness and phylogenetic diversity due to these extinctions and speciations. We show that if all species introduced into new landmasses develop into new species, the number of anthropogenic speciation and extinctions eventually become similar. However, even after accounting for an anthropogenic increase in speciation, our estimates suggest recovery times for phylogenetic diversity of several million years. Our results highlight that while humans are causing drastic biodiversity losses, human-driven speciation could eventually counterbalance these losses in species numbers, while phylogenetic diversity at least within our simulation scenarios would remain permanently reduced. This conclusion, however, requires our pressures on biodiversity to cease soon and requires us to consider geological timescales rather than changes over this century.

opencc-by-4.0May 2024View details →

Are rice fields less diverse and more invaded by non-native species than less impacted habitats? A test with wetland microcrustaceans

Raw data of environmental variables and microcrustacean abundance community matrix R scripts used in the study

opencc-zeroMay 2024View details →

Data from: Species-environment sorting explains latitudinal patterns in spatiotemporal β-diversity for freshwater macroinvertebrates

Understanding how and why β-diversity varies along latitude is a long-standing challenge in community ecology and rarely addressed in both space and time. We aimed to explore the spatiotemporal variations in macroinvertebrate β-diversity and their underlying drivers in eight biogeographic regions covering a substantial latitudinal gradient of more than 40 degrees. By combining β-diversity partitioning and distance decay of community similarity analyses, we found that subtropical β-diversity varies more in space relative to in time compared with temperate β-diversity, as we predicted. This is probably because subtropical β-diversity is shaped by species-environment sorting (SS), caused by habitat heterogeneity and species specialization, more strongly in space relative to in time than temperate β-diversity. Our study highlights the importance of SS in shaping latitudinal gradients of β-diversity in space and time.