The role of competition by dominants and temperature in the foraging of subordinate species in Mediterranean ant communities

In this paper we test the influence of temperature and interference competition by dominant species on the foraging of subordinate species in Mediterranean ant communities. We have analyzed the changes in resource use by subordinate species in plots with different abundances of dominant ants, and in different periods of the day and the year, i.e., at different temperatures. The expected effects of competition by dominant species on foraging of subordinates were only detected for two species in the number of baits occupied per day, and for one species in the number of foragers at pitfall traps. In all three cases, subordinate species were less represented at baits or in traps in plots with a high density of dominants than in plots with a medium or low density of dominants. The number of workers per bait, and the foraging efficiency of subordinate species did not differ in plots differing in dominant abundance. Daily activity rhythms and curves of temperature versus foraging activity of subordinate species were also similar in plots with different abundance of dominant species, indicating no effect of dominants on the foraging times of subordinates. Instead, temperature had a considerable effect on the foraging of subordinate species. A significant relationship was found between maximum daily temperature and several variables related to foraging (the number of foragers at pitfall traps, the number of baits occupied per day, and the number of workers per bait) of a number subordinate species, both in summer and autumn. These results suggest that the foraging of subordinate ant species in open Mediterranean habitats is influenced more by temperature than by competition of dominants, although an effect of dominants on subordinates has been shown in a few cases. In ant communities living in these severe and variable environments, thermal tolerance reduces the importance of competition, and the mutual exclusion usually found between dominant and subordinate species appears to be the result of physiological specialization to different temperature ranges.Peer Reviewe

Enhancing magnetorheological effect using bimodal suspensions in the singlemultidomain limit

We demonstrate a new route to enhance the magnetorheological effect using bimodal suspensions in the single-multidomain limit. Experimental results are satisfactorily compared to 3D finite element method simulations. The physical reason behind this enhancement is the coating of the larger particles by the smaller ones due to the remnant magnetization of the latter.This work was supported by MAT 2016-78778-R and PCIN 2015-051 projects (FEDER FUNDS and MINECO, Spain). A J F Bombard is grateful to FAPEMIG grants: APQ-01824-17, PEE-00081-16, RED-00144-16, ETC-00043-15, PEP-00231- 15, APQ-00463-11 and RDP-00164-10. J R Morillas acknowledges FPU14/01576 fellowship

Neutral molecular markers support common origin of aluminium tolerance in three congeneric grass species growing in acidic soils

Aluminium (Al) toxicity is the main abiotic stress limiting plant productivity in acidic soils that are widely distributed among arable lands. Plant species differ in the level of Al resistance showing intraspecific and interspecific variation in many crop species. However, the origin of Al-tolerance is not well known. Three annual species, difficult to distinguish phenotypically and that were until recently misinterpreted as a single complex species under Brachypodium distachyon, have been recently separated into three distinct species: the diploids B. distachyon (2n = 10) and B. stacei (2n = 20), and B. hybridum (2n = 30), the allotetraploid derived from the two diploid species. The aims of this work were to know the origin of Al-tolerance in acidic soil conditions within these three Brachypodium species and to develop new DNA markers for species discrimination. Two multiplex SSR-PCRs allowed to genotype a group of 94 accessions for 17 pentanucleotide microsatellite (SSRs) loci. The variability for 139 inter-microsatellite (ISSRs) markers was also examined. The genetic relationships obtained using those neutral molecular markers (SSRs and ISSRs) support that all Al-tolerant allotetraploid accessions of B. hybridum have a common origin that is related with both geographic location and acidic soils. The possibility that the adaptation to acidic soils caused the isolation of the tolerant B. hybridum populations from the others is discussed. We finally describe a new, easy, DNA barcoding method based in the upstream-intron 1 region of the ALMT1 gene, a tool that is 100 % effective to distinguish among these three Brachypodium species

Multiple founder events explain the genetic diversity and structure of the model allopolyploid grass Brachypodium hybridum in the Iberian Peninsula hotspot

Background and Aims It is accepted that contemporary allopolyploid species have originated recurrently, but very few cases have been documented using multiple natural formations of the same species. To extend our knowledge, we have investigated the multiple origins, genetic variation and structure of the allotetraploid grass Brachypodium hybridum with respect to its progenitor diploid species B. distachyon (D genome) and B. stacei (S genome). For this, our primary focus is the Iberian Peninsula, an evolutionary hotspot for the genus Brachypodium. Methods We analysed 342 B. hybridum individuals from 36 populations using ten nuclear SSR loci and two plastid loci. The B. hybridum genetic profiles were compared with those previously reported for B. stacei and B. distachyon. In addition, phylogenetic analysis of the plastid data was performed for a reduced subset of individuals. Key Results The nuclear simple sequence repeat (SSR) genetic analysis detected medium to high genetic diversity, with a strong south-to-north genetic structure cline, and a high selfing rate in B. hybridum. Comparative genetic analysis showed a close relatedness of current B. hybridum D allelic profiles with those of B. distachyon, but a lack of similarity with those of B. stacei, suggesting another B. stacei source for the B. hybridum S alleles. Plastid analysis detected three different bidirectional allopolyploidization events: two involved distinct B. distachyon-like ancestors and one involved a B. stacei-like ancestor. The south-eastern Iberian Peninsula B. hybridum populations were more genetically diverse and could have originated from at least two hybridization events whereas north-eastern/north-western Iberian Peninsula B. hybridum populations were less diverse and may have derived from at least one hybridization event. Conclusions The genetic and evolutionary evidence supports the plausible in situ origin of the south-eastern and northern Iberian Peninsula B. hybridum allopolyploids from their respective local B. distachyon and unknown B. stacei ancestors. The untapped multiple origins and genetic variation detected in these B. hybridum populations opens the way to future evolutionary analysis of allopolyploid formation and genomic dominance and expression in the B. hybridum–B. distachyon–B. stacei grass model complex.info:eu-repo/semantics/publishedVersio

RecruitNet: A global database of plant recruitment networks

Plant recruitment interactions (i.e., what recruits under what) shape the composition, diversity, and structure of plant communities. Despite the huge body of knowledge on the mechanisms underlying recruitment interactions among species, we still know little about the structure of the recruitment networks emerging in ecological communities. Modeling and analyzing the community-level structure of plant recruitment interactions as a complex network can provide relevant information on ecological and evolutionary processes acting both at the species and ecosystem levels. We report a data set containing 143 plant recruitment networks in 23 countries across five continents, including temperate and tropical ecosystems. Each network identifies the species under which another species recruits. All networks report the number of recruits (i.e., individuals) per species. The data set includes >850,000 recruiting individuals involved in 118,411 paired interactions among 3318 vascular plant species across the globe. The cover of canopy species and open ground is also provided. Three sampling protocols were used: (1) The Recruitment Network (RN) protocol (106 networks) focuses on interactions among established plants (“canopy species”) and plants in their early stages of recruitment (“recruit species”). A series of plots was delimited within a locality, and all the individuals recruiting and their canopy species were identified; (2) The paired Canopy-Open (pCO) protocol (26 networks) consists in locating a potential canopy plant and identifying recruiting individuals under the canopy and in a nearby open space of the same area; (3) The Georeferenced plot (GP) protocol (11 networks) consists in using information from georeferenced individual plants in large plots to infer canopy-recruit interactions. Some networks incorporate data for both herbs and woody species, whereas others focus exclusively on woody species. The location of each study site, geographical coordinates, country, locality, responsible author, sampling dates, sampling method, and life habits of both canopy and recruit species are provided. This database will allow researchers to test ecological, biogeographical, and evolutionary hypotheses related to plant recruitment interactions. There are no copyright restrictions on the data set; please cite this data paper when using these data in publications. © 2022 The Authors. Ecology published by Wiley Periodicals LLC on behalf of The Ecological Society of America

Agricultural extensification enhances functional diversity but not phylogenetic diversity in Mediterranean olive groves: A case study with ant and bird communities

Agroforests are of well-known importance for biodiversity conservation, especially in the tropics, because they are structurally stable and may resemble natural forests. Previous studies have characterized jointly taxonomic, functional and phylogenetic diversity in these agro-ecosystems to comprehensively examine the mechanisms by which agriculture impacts on biodiversity. However, this approach has been barely applied to other woody crops of economic importance, such as olive grove, which is a remarkable overwintering habitat for frugivorous/insectivorous birds from central and northern Europe, and whose original distribution overlaps with the Mediterranean biodiversity hotspot. We examined the effects of landscape complexity and intensive management practices at a local scale (recurrent plowing and pesticides use) on the functional and phylogenetic diversity of animal communities inhabiting olive groves. Since the response of functional traits or clades may vary across different taxonomic groups, we conducted our study at two levels: ants, which are considered semi-sessile organisms, and birds, which exhibit a high dispersal capacity. In birds, neither management type nor landscape complexity had an effect on phylogenetic diversity (PD) indices. Extensively managed farms harbored bird communities with higher values of functional diversity (FD), but this effect only was evident when considering cultivated (productive) zones within the farm (i.e., infield diversity). Ant assemblages on intensively managed farms exhibited a lower level of phylogenetic clustering than those located in extensive farms, but this effect vanished when excluding non-cultivated zones. Ant functional diversity increased with landscape complexity. Our results indicate that PD and FD exhibit different responses to farming intensification in olive groves. Although intensive management does not erode PD due to the existence of phylogenetic redundancy, the loss of species associated to modern farming leads to a reduction in FD being this indicative of functional complementarity. This study provides evidence that land-use extensification (extensive farming and landscape diversification) promotes more functionally rich assemblages than modern intensive practices in olive groves. Our findings also show the need to set apart the effect of non-cultivated zones (e.g., hedgerows, margins) when evaluating the effectiveness of agri-environment schemes as the joint consideration of non-cultivated and cultivated areas may obscure the benefits of local extensification on infield biodiversity.info:eu-repo/semantics/publishedVersio

Neutral molecular markers support common origin of aluminium tolerance in three congeneric grass species growing in acidic soils

Relaciones genéticas entre accesiones de Brachypodium tolerantes y susceptibles a aluminio

Geographic and temporal variation in the ant-seed dispersal assemblage of the perennial herb Helleborus foetidus L. (Ranunculaceae)

Spatio-temporal variations in the composition of the animal interactive assemblages may result in variations in selective pressures on the plants. In ant-seed dispersal mutualisms, the study of the magnitude of spatial and temporal variation of ant assemblages is rarely studied, limiting inferences and generalizations on the evolution of this mutualism. Here, we describe the ant-disperser assemblage of the myrmecochorous herb Helleborus foetidus in 14 populations across the Iberian Peninsula, and dissect the variation in the assemblage into spatial and temporal components as a first step to evaluate the evolutionary potential of this interaction. The ant-visitor assemblage of H. foetidus was mainly represented by species of Formicinae and it was highly diverse and variable in composition and function. Ants behaving as legitimate dispersers and those with mixed behaviour numerically dominated the assemblage compared with elaiosome consumers. The magnitude of the spatial variation was higher than the temporal variation, suggesting that the relative frequency of each functional group will be more foreseeable among years in each population than among populations. At the expense of further analysis of the effects of such variation on dispersal success, we can envisage a selection mosaic scenario, where local adaptive responses of plants might arise as a result of local variations in the specific composition and function of the assemblage. © 2007 The Linnean Society of London.Peer Reviewe

Adaptive advantages of myrmecochory: The predator-avoidance hypothesis tested over a wide geographic range

The predator-avoidance hypothesis states that once released from the parent plant, myrmecochorous seeds are rapidly taken by ants to their nests, where they are protected from predators. Previous studies conducted to test this hypothesis have frequently neglected two major aspects necessary for its verification: 1) the influence of processes acting after the seed release and 2) the spatial evenness of such processes. Thus, large-scale variations in the mechanisms acting beyond seed release, and possibly influencing seed escape from predators, remain poorly documented. Here, we present the results of a post-dispersal seed-removal experiment on the myrmecochorous herb Helleborus foetidus, aimed at verifing the predator-avoidance hypothesis by considering two key post-release aspects of seed fate: seed destination (dispersed or nondispersed) and seed burial (buried or not buried). Experiments were performed in four different regions in the Iberian Peninsula. After three days of exposure of seeds to the main predator (fieldmice Apodemus sylvaticus), ca 30% of the seeds were removed. Seed destination affected the proportion of seeds escaping predation, but the sign, magnitude and statistical significance of the effect varied among the geographical regions. In the southern region (Cazorla), seeds dispersed in ant nests or intermediate destinations suffered scarcely any predation, but seeds under reproductive-age plants experienced losses ca 50%. Conversely, in the northern region (Caurel), seeds in nests suffered significantly greater losses than seeds under plants or intermediate destinations, suggesting that nests were especially unsafe destinations. Seed burial had a strong impact on seed escape from predators, and its effect was highly consistent among geographical regions. In view of the consistency of its effect at different spatial scales, seed burial was a more general mechanism for predation avoidance than seed relocation to ant nests, which was habitat- and/or ant-species-dependent. Our results thus only partially support the predator-avoidance hypothesis for the evolution of myrmecochory. Copyright © Ecography 2005.Peer Reviewe