Animal and Plant Species in Antagonistic and Mutualistic Networks, a Multispecies Mean Field Model

We construct a dynamic system model of a web of NA?animal species interacting with NP plant species using a system of coupled differential equations. The model has a parameter which represents the effect of animal on plant species that can be positive (mutualistic interaction) or negative (antagonistic interaction). We work a Multispecies Mean Field Model MMFM in which the full set of NA and NP variables are reduced to a couple of an average animal and plant species. We study the conditions for existence of the MMFM and relate the result to the difference between animal and plant species in the network. We compare our results with empirical data from pollinators (mutualistic) and herbivorous insect (antagonistic) networks. We conclude by combining analytical and empirical work that antagonistic networks present fewer animal species in relation to plant species than mutualistic ones.

Combined Effects of Temperature and Nutrient Availability on Growth and Phlorotannin Concentration of the Brown Alga <i>Sargassum patens</i>(Fucales;Phaeophyceae)

Global warming is predicted to affect plant-herbivore interactions. However, little is known about the effects of temperature on marine plant secondary chemistry and how these effects may impact plant-herbivore interactions. As marine macroalgae can become physiologically stressed due to warm water temperatures and nutrient-poor conditions during summer, we conducted a culture experiment to test the combined effects of temperature (10°C, 20°C, 30°C) and nutrient availability (seawater enriched with 25% PESI medium and non-enriched seawater) on relative growth rate (RGR) and concentration of phlorotannins (i.e., defensive compounds) in the upper and lower parts of shoots of the brown alga Sargassum patens. RGR was affected by temperature but not by nutrient availability. Phlorotannnin concentration was affected by nutrient availability but not by temperature, although there was a significant interaction between temperature and part of the shoots. Correlations between RGR and phlorotannin concentration were significant for the upper part of the shoots but not for the lower part. These correlations were slightly positive in the nutrient-enriched medium but negative in the non-enriched medium. These results suggest that temperature affects phlorotannin concentration of S. patens indirectly via changes in the growth rate and that its effect depends on the part of the shoot and nutrient availability.

Brazilian Tropical Grassland Ecosystems: Distribution and Research Advances

A few decades ago we sought the understanding of the functioning of Brazilian ecosystems. During these years, changes in the way land use were influenced primarily by economic issues involving the process of valuation of land in different regions. Furthermore, developments in research have provided productive increments that were well characterized in some phases. This paper aims to trace a brief history of the distribution of grassland ecosystems in Brazil and show how it has been the advances in research on forages and pastures in the country, pointing its evolution, transition times and trends. Moreover, it purports to show a perspective of the dynamics of occupation of Brazilian territory by these ecosystems. The information is presented on three occasions, seeking to encourage understanding of where livestock grazing occurs and how the dynamics of occupation of the area was favored by the search. Also, it shows how the research was fundamental for Brazil occupy little arable areas considered, making the country one of the largest producers of cattle in the world.

Coevolutionary insights between promoters and transcription factors in the plant and animal kingdoms

The divergence and continuous evolution of plants and animals contribute to ecological diversity.Promoters and transcription factors(TFs) are key determinants of gene regulation and transcription throughoutlife.However,theevolutionary trajectories and relationships of promoters and TFs are still poorly understood. Here, we conducted extensive analysis of large-scale multi-omics sequences in 420 animal species and 223 plant species spanning nearly a billion years of evolutionary history. Results showed that promoter GC-contentandTFisoelectricpoints,as features/signatures that accompany long biological evolution, exhibited increasing growth in animal cells but a decreasing trend in plant cells. Furthermore, the evolutionary trajectories of promoter and TF signatures in the animal kingdom provided further evidence that Mammalia as well as Aves evolved directly from the ancestor Reptilia. The strong correlation between promoter and TF signatures indicates that promoters and TFs formed antagonistic coevolution in the animal kingdom, but mutualistic coevolution in the plant kingdom. The distinct coevolutionary patterns potentially drive the plant-animal divergence, divergent evolution and ecological diversity.

Effects of Soil Nutrient Heterogeneity and Earthworms on Aboveground Biomass of Experimental Plant Communities

Soil nutrients are commonly heterogeneously distributed and earthworms are one of the most common soil organisms.While effects of both soil nutrient heterogeneity and earthworms have been well studied,their interactive effect on plant community productivity has rarely been tested.In a greenhouse experiment,we constructed experimental plant communities by sowing seed mixtures of four grasses,two legumes and two forbs in either a heterogeneous soil consisting of low and high nutrient soil patches or a homogeneous soil where the low and high nutrient soil patches were evenly mixed.The earthworm Eisenia fetida was either added to these soils or not.Aboveground biomass of the whole communities,grasses and legumes did not differ between the homogeneous and heterogeneous soils or between the soils with and without earthworms.However,soil nutrient heterogeneity reduced aboveground biomass of forbs,and such an effect did not interact with earthworms.In response to soil heterogeneity and earthworms,biomass ratio of the three functional groups showed similar patterns as that of their biomass.At the patch level,aboveground biomass of the whole community,grasses and legumes were greater in the high than in the low nutrient soil patches within the heterogeneous soil.A similar pattern was found for the forbs,but this was only true in the absence of earthworms.Our results suggest that soil nutrient heterogeneity and earthworms may not influence aboveground biomass of plant communities,despite the fact that they may modify the growth of certain plant functional groups within the community.

New Reports of Spiders in Three Mexican Ant-Acacias

The richness of spider species on the foliage of Mexican ant-acacias in Los Tuxtlas (Veracruz), and Santiago Pinotepa Nacional (Oaxaca) was documented. A total of 11 species, grouped into five families were found;in Los Tuxtlas five species representing two families were identified, whereas in Santiago Pinotepa Nacional, the number of taxa was eight, belonging to five families. The richness of spiders in Santiago Pinotepa Nacional was higher than that found in Los Tuxtlas. In both locations Nephila clavipes Linnaeus and Eustala illicita O. Pickard-Cambridge, both from Araneidae, were found;these species had been previously reported as common inhabitants of Central American ant-acacias. The presence of E. illicita in Mexican myrmecophytic acacias was confirmed. A total of 10 species grouped into five families are reported for the first time inhabiting Mexican ant-acacias, increasing the richness of spider interactions documented in Mexico. This study showed that the occurrence of spiders in the Vachellia-Pseudomyrmex mutualism system has been overlooked and is likely more common than what has been reported until now. This opens an opportunity for the study of the evolution of spider-ant-plant interactions.

Rodent abundance triggered switch between the relative mutualism and predation in a rodent-seed system of the subtropical island forest

Density-dependent non-monotonic species interactions are important in maintaining ecosystem stability and function,but empirical evidences are still rare.Rodents,as both seed dispersers and seed predators,have dual effects on plant regeneration and may result in non-monotonic rodent-plant interactions.According to the non-monotonic models,the relative positive or negative effects of rodents on seedling establishment can be measured based on the positive or negative association of seedling recruitment rate and rodent abundance.In this study,we investigated the fates of acorns of Quercus serrata by tracking tagged seeds on 21 fragmented subtropical islands in the Thousand Island Lake,China.We found that the proportion of germinated seeds of all released seeds showed a dome-shaped association with rodent abundance per seed.The proportion of removed seeds and cached seeds showed a saturated-and a weak dome-shaped association with rodent abundance per seed,respectively.Our results demonstrated a clear empirical evidence that rodent abundance per seed triggered a switch between the relative mutualism and predation in a rodent-seed system.Our study implied that the observed non-monotonic interactions between plants and animals may play a significant role in maintaining biodiversity and ecosystem function.We appeal for more investigations of the complex non-monotonic interactions in various ecosystems.

Deciphering the effects of disperser assemblages and seed mass on patterns of seed dispersal in a rodent community

The sizes of both seed dispersers and seeds are traits that are likely to interact to influence seed fate in many synzoochoric plant species.Here,we examined whether members of a granivorous rodent community consist­ing of species of different body size vary in their effectiveness as seed dispersers,and how this relationship may be altered by seed size.We marked northern red oak(Quercus rubra)acorns with plastic tags and placed them in size-selective rodent exclosures.The exclosures allowed differential access of rodent groups based on dif­ferent body size:(i)small(e.g.Peromyscus spp.);(ii)small and medium(e.g.Tamias striatus);and(iii)small,medium and large(e.g.Sciurus carolinensis)species of rodents.Acorn removal did not differ among exclosure types,but more seeds were missing when removed by small rodents,probably because of larderhoarding.The treatments did not influence the relative frequency of acorn consumption.However,small rodents cached con­siderably fewer and partially ate more acorns than the other 2 groups.The mean dispersal distance was the lon­gest for cages with medium openings,intermediate for cages with large openings and the shortest for cages with small openings.Acorn mass positively affected the probability of caching and this relationship was unaffected by exclosure type.In conclusion,granivorous rodents of different body sizes strongly differed in their interac­tions with acorns,with small rodents acting primarily as acorn predators and medium and large species contrib­uting significantly more to dispersal of red oaks.

Weak correlation of flower color and nectar-tube depth in temperate grasslands

Aims Nectar is one of the most common floral rewards offered to pol-linators by plants.Depending on the plant species,nectar is offered openly or in tubes of various lengths restricting accessibility of this resource for flower visitors with short mouthparts.if attract-ing pollinators that match floral morphology increases pollination efficiency,flowers could profit from signaling nectar-tube depth to pollinators.Since flower colors are important signals in plant-pol-linator communication,we investigated whether and which differ-ent chromatic or achromatic aspects of flower color might indicate nectar-tube depth or whether flower colors facilitate the differen-tiation between flowers with long nectar tubes by means of high chromatic uniqueness.Methods To this end,we collected flower reflectance spectra of 135 grassland plant species.We analyzed flower colors as raw reflectance spectra in principal component analysis(PCA)and in the color space of honeybees.Important Findings The correlation between flower colors and tube depths was weak.From the bee’s point of view,blue flowers had on average deeper tubes than green,blue-green and UV-green flowers potentially allow-ing insects to predict tube depths based on blue color.Spectral purity did not correlate with nectar-tube depth,nor did the chromatic uniqueness of flower colors in the honeybee color space.Dominant wavelength showed a significant but very weak correlation with tube depth.The achromatic green contrast decreased with increasing tube depth as did brightness;thus deep tubes were less conspicuous than shallow tubes.Chromatic components resulting from PCA did not or only slightly correlate with tube depth.Our results illustrate that flower colors may have a certain potential to indicate tube depth,i.e.nectar accessibility,from a bee’s perspective.

Small size does not restrain frugivory and seed dispersal across the evolutionary radiation of Galapagos lava lizards

Frugivory in lizards is often assumed to be constrained by body size;only large individuals are considered capable of consuming fruits, with the potential of acting as seed dispersers. However, only one previous study has tested the correlation of frugivory with body and head size at an archipelago scale across closely related species. All nine lava lizards (Microlophus spp.) were studied on the eleven largest Galapagos islands from 2010 to 2016 to investigate whether frugivory is related to body and head size. We also tested whether fruit abunda nee in flue nces fruit con sumption and explored the effect of seed ingestion on seedling emergence time and percentage. Our results showed that across islands, lava lizards varied considerably in size (64-102 mm in mean snoutvent length) and level of frugivory (1-23%, i.e., percentage of droppings with seeds). However, level of frugivory was only weakly affected by size as fruit consumption was also common among small lizards. Lava lizards consumed fruits throughout the year and factors other than fruit abundance may be more importa nt drivers of fruit selecti on (e.g., fruit size, energy con tent of pulp). From 2,530 droppings, 1,714 seeds of at least 61 plant species were identified, 76% of the species being native to the Galapagos. Most seeds (91%) showed no external structural damage. Seedling emergence time (44 versus 118 days) and percentage (20% versus 12%) were enhanced for lizardingested seeds compared to control (uningested) fruits. De-pulping by lizards (i.e., removal of pulp with potential germi nation inhibitors) might in crease the chances that at least some seeds find suitable recruitment conditi ons. We con eluded that lizards are importa nt seed dispersers throughout the year and across the whole archipelago, regardless of body size.

Analyses towards determining Madagascar＇s place in global biogeography

The relationships of Madagascan plant and animal taxa have been the object of much fascination, Madagascar sharing numerous lineages with Africa, others with Asia, Australia, or the Americas, and many others being of uncertain relationships. In commonly accepted global regionalization schemata, Madagascar is treated together with Africa for animals, and with Africa, tropical Asia and the Pacific islands in the case of plants. Here we examine the similarities between the biotic assemblages of （i） tropical Africa, （ii） Madagascar, and （iii） the rest of the world, on a basic taxonomic level, considering the families of vascular plants and vertebrates as analysis units. The percentages of endemic families, families shared pair-wise between regions, or pre- sent in all three, are roughly similar between the two broad groups, though plant families with ranges limited to one region are proportionally fewer. In dendrograms and multidimensional scaling plots for different groups, Madagascar clusters together with Africa, Asia or both, and sometimes with smaller Indian Ocean Islands, but quite often （though not in plants） as a convincingly separate cluster. Our results for vertebrates justify the status of full zoogeographic region for Madagascar, though an equally high rank in geobotanical regionalization would mean also treating Africa and Tropical Asia as separate units, which would be debata- ble given the overall greater uniformity of plant assemblages. Beyond the Madagascan focus of this paper, the differences be- tween plant and vertebrate clusters shown here suggest different levels of ecological plasticity at the same taxonomic level, with plant families being much more environmentally-bound, and thus clustering along biome lines rather than regional lines [Current Zoology 58 （3）： 363-374, 2012].

Frugivory and seed dispersal in the Galápagos:what is the state of the art?

The Galápagos are considered a model oceanic archipelago,with unique flora and fauna currently threatened by alien invasive species.Seed dispersal is an important ecosystem function with consequences for plant population dynamics and vegetation structure.Hence,understanding the seed dispersal abilities of the assemblages of frugivores will inform scientists and managers of the dynamics of plant invasions and improve management planning.Here we provide the first comprehensive review of published information on frugivory and animal seed dispersal in the Galápagos.We collected data from a variety of sources,including notes of the first naturalist expeditions,gray literature available only in Galápagos collections,and peer-reviewed journal articles.Plant–animal frugivorous interactions were retrieved from 43 studies and compiled into an interaction matrix describing 366 unique interactions.Most studies focused on fruit consumption as a driving force for natural selection,but seed fate was seldom considered.Although most(71%)of the interactions involved native plants,more than one-quarter(28%)involved introduced species.Interactions involving birds are considerably more common than those of reptiles and mammals,probably reflecting a research bias towards birds.Despite the historical importance of the archipelago as the laboratory for evolutionary and ecological research,understanding of its seed dispersal systems is limited.We end the review by suggesting 3 priority areas of research on frugivory and seed dispersal in the Galápagos:(i)target research to close knowledge gaps;(ii)the use of a network approach to frame seed dispersal at the community level;and(iii)evaluation of the effect of seed dispersal as a selective pressure acting upon plants and frugivores.Finally,the output of this research has to be properly delivered to the Galápagos National Park Services to help increase management effectiveness.

Secondary seed dispersal by dung beetles in an Amazonian forest fragment of Colombia:influence of dung type and edge effect

Seeds of many plant species are secondarily dispersed by dung beetles,but the outcome of this interaction is highly context-specific.Little is known about how certain anthropogenic disturbances affect this plant-animal interaction.The aims of this study were to assess the effect of dung type on secondary dispersal by dung beetles in a forest fragment,and to determine whether this interaction is affected by edge effects.Using pitfall traps,we captured dung beetles attracted to dung of 2 frugivorous mammals:woolly monkeys and howler monkeys.We found differences between both dung beetle assemblages,but these differences were not consistent in time.Using seeds surrounded by both dung types,we carried out a field experiment using seeds of 2 plant species.We found that the probability of secondary dispersal by dung beetles was higher for seeds placed in woolly monkey dung.Finally,we carried out a field experiment using plastic beads as seed mimics to assess edge effects.We found that secondary seed dispersal by dung beetles was negatively affected by edges.The disruption of plant-animal interactions along anthropogenic forest edges could have long-term negative effects on forest dynamics by affecting processes of regeneration.

A framework for considering ecological interactions for common non-timber forest product species:a case study of mountain date palm(Phoenix loureiroi Kunth)leaf harvest in South India

Introduction:Many economically important non-timber forest products(NTFPs)come from widespread and common plant species.Harvest of these species often is assumed to be sustainable due to their commonness.However,because of the ecological roles of common species,harvest may affect and be affected by ecological interactions at broader scales,which are rarely considered when evaluating the sustainability of harvest.We use a case study of the mountain date palm(Phoenix loureiroi Kunth),harvested in South India to produce brooms,to present a conceptual framework illustrating how intensive harvest of a common species interacts with other anthropogenic management practices,plant-animal interactions and surrounding environmental conditions.Methods:We apply this framework to understanding the impacts of mountain date palm harvest in the southern Western Ghats regions of the Indian states of Tamil Nadu and Karnataka.We integrate data on the extent and levels of commercial harvest,local management practices,the ecological context in which harvest occurs,and research on harvest effects.We use this information to document the intensity and extent of mountain date palm harvest in the study area,identify the ecological implications of harvest,and demonstrate how a framework that considers harvest in the context of ecological communities and ecosystems is important for assessing the impacts of harvest of common NTFP species.Results:We show that mountain date palm leaves are heavily harvested from natural areas in the southern Western Ghats but that harvest levels have declined in recent years.Mountain date palm management and harvest occur within a network of ecological interactions,linking human activities to population-,community-,and ecosystem-level processes.We demonstrate that understanding the effects of return interval of anthropogenic fire,herbivory by wild animals and livestock,as well as the light environment in which harvest occurs are critical to assessing the sustainability of mountain date palm harvest.Conclusions:By considering mountain date palm leaf harvest in the context of ecological interactions at multiple scales,our findings show that sustainability cannot be assessed only from a population-level perspective.This general framework highlights the need to incorporate ecosystem-and community-level properties and processes more frequently into assessments of the sustainability of NTFP harvest—especially for widespread and common species—to ensure that their important economic and ecological roles are maintained.

Forage offering and seasonal intake comparisons to evaluate European rabbit threat in Nothofagus forests of southern Patagonia

Background:The European rabbit(Oryctolagus cuniculus L.1758)was introduced into different regions of the world,generating significant trade‑offs that critically impacted native vegetation.Here,we evaluate the rabbit’s forage intakes in three vegetation types(forests,shrublands,and grasslands)along the four seasons in a temperate forest landscape in Southern Patagonia and discuss the potential threats over native vegetation.We formulated the following questions:(i)what is the forage offer at each vegetation type?(ii)what is the rabbit’s forage intake and how it varied across the seasons along the year?and(iii)which vegetation types and plant life forms were more used according to the rabbit’s forage intakes?Methods:We censused understory vegetation to characterize the forage offer at each vegetation type and determined seasonal dietary intakes using microhistological analysis of pellets.The plant species identified in the field were grouped according to life form classes(tree regeneration,shrubs,forbs,graminoids,orchids,ferns,bryophytes,and hemiparasites).Data were analysed through uni‑and multi‑variate analyses,determining relationships between forage offer and the rabbit’s forage intakes.Results:Forage intakes revealed changes in plant life form consumption across vegetation types,where intake pressure was considerably different for tree regeneration(p=0.001),graminoids(p=0.001),and hemiparasites(p=0.001).Besides,significant changes in consumption among seasons were detected for shrubs(p=0.001),ferns(p=0.030),and hemiparasites(p=0.002).Although many species play an important role in the rabbit’s forage intake networks(e.g.,Chiliotrichum diffusum,Holcus lanatus),the strongest intake linkages were found in exotic grasses(e.g.,Poa pratensis and Festuca sp.),native hemiparasites(e.g.,Misodendrum sp.),native shrubs(e.g.,Empetrum rubrum),and native trees(e.g.,Nothofagus sp.).The summer and autumn seasons presented higher intake compared to the winter and spring seasons.Furthermore,hemiparasites intake(e.g.,Misodendrum sp.)suggests that rabbits utilize different forage sources depending on the vegetation types.Conclusions:Rabbits regularly inhabit the forest,even though it is not their preferred vegetation type to live.Rabbit management entails isolating regions that are more favourable to intake and emphasizing the year’s season for rabbit control efforts.

Phenotypic trait matching predicts the topology of an insular plant–bird pollination network

Conceptualizing species interactions as networks has broadened our understanding of ecological communities.However,the factors shaping interaction patterns among species and,therefore,network structure remain unclear.One potentially important factor is the matching of phenotypic traits.Here,we tested for trait matching in a bird–flower visitation network from New Zealand.We first quantified the overall network structure and tested whether flower size could account for differences in the visitation rates of flowering plants.We then explored the relationship between the flower size and bill size.The results showed that the interaction network is nested.Plant species with large flowers received more visits from birds than plant species with small flowers.Moreover,plant species with large flowers were visited more frequently by birds with large bills,while species with smaller flowers were visited more frequently by birds with small bills.Overall,the interaction patterns between birds and flowering plants could be predicted by their morphology,suggesting that phenotypic trait matching is an important predictor of network structure.

Linking the hierarchical decision- making process of fruit choice and the phenotypic selection strength on fruit traits by birds

Aims Animals in search of fleshy fruits forage mostly according to the number of available fruits and then select individual fruits based on reward quality or advertised subtle traits.This hierarchical pat-tern of fruit choice would be translated into patterns of selection strength mediated by frugivores on fruit display traits.Thus,frugi-vores would exert higher selection pressures on fruit crop size and lower selection pressures on within-plant variation of phenotypic traits(infructescence,fruit and seed size).However,no attempt to link this behavioral mechanism of hierarchical trait selection to natural selection patterns has been made.Therefore,we sought to determine the relationship between the hierarchical decision-mak-ing process of fruit choice and patterns of natural selection on fruit traits.Methods We recorded bird visits and measured fruit-related traits(fruit crop size,fruit diameter and seed weight)in a natural population of Psychotria carthagenensis,a bird-dispersed treelet,in a Yungas for-est from Argentina.To assess phenotypic selection patterns on fruit display traits,we performed multivariate selection analysis,and to explicitly identify a hierarchy of fruit trait choice we used a classifi-cation tree as a predictive model.Important Findings Selection patterns on fruit display traits were in agreement with a hierarchical process of fruit choice made by birds.The strength of directional selection on the total number of fruits in a plant(i.e.fruit crop size)was nearly two times higher than on fruit size,and the classification tree analysis supported this hierarchical pattern.Our results support previous evidence that seed dispersers shape fruit crop size with higher intensity than subindividual fruit traits.Also,high levels of subindividual phenotypic variation of fruit display traits may be explained by relaxed selection pressures exerted by frugivores.Empirical studies also show that this pattern may consti-tute a general phenomenon among other plant-animal interactions.

To eat or not to eat-relationship of lichen herbivory by snails with secondary compounds and field frequency of lichens

Aims The biochemical defense of lichens against herbivores and its rela-tionship to lichen frequency are poorly understood.Therefore,we tested whether chemical compounds in lichens act as feeding defense or rather as stimulus for snail herbivory among lichens and whether experimental feeding by snails is related to lichen fre-quency in the field.Methods In a no-choice feeding experiment,we fed 24 lichen species to snails of two taxa from the Clausilidae and Enidae families and compared untreated lichens and lichens with compounds removed by acetone rinsing.Then,we related experimental lichen consump-tion with the frequency of lichen species among 158 forest plots in the field(schwäbische alb,germany),where we had also sampled snail and lichen species.Important findings In five lichen species,snails preferred treated samples over untreated controls,indicating chemical feeding defense,and vice versa in two species,indicating chemical feeding stimulus.Interestingly,com-pared with less frequent lichen species,snails consumed more of untreated and less of treated samples of more frequent lichen spe-cies.removing one outlier species resulted in the loss of a significant positive relationship when untreated samples were analyzed separately.However,the interaction between treatment and lichen frequency remained significant when excluding single species or including snail genus instead of taxa,indicating that our results were robust and that lumping the species to two taxa was justified.our results imply lichen-feeding snails to prefer frequent lichens and avoid less frequent ones because of secondary compound rec-ognition.This supports the idea that consumers adapt to the most abundant food source.