Reorganization of interaction networks modulates the persistence of species in late successional stages

Ecological interaction networks constantly reorganize as interspecific interactions change across successional stages and environmental gradients. This reorganization can also be associated with the extent to which species change their preference for types of niches available in their local sites. Despite the pervasiveness of these interaction changes, previous studies have revealed that network reorganizations have a minimal or insignificant effect on global descriptors of network architecture, such as connectance, modularity and nestedness. However, little is known about whether these reorganizations may have an effect on community dynamics and composition.To answer the question above, we study the multi-year dynamics and reorganization of plant–herbivore interaction networks across secondary successional stages of a tropical dry forest. We develop new quantitative tools based on a structural stability approach to estimate the potential impact of network reorganization on species persistence. Then, we investigate whether this impact can explain the likelihood of persistence of herbivore species in the observed communities.We find that resident (early-arriving) herbivore species increase their likelihood of persistence across time and successional stages. Importantly, we demonstrate that, in late successional stages, the reorganization of interactions among resident species has a strong inhibitory effect on the likelihood of persistence of colonizing (late-arriving) herbivores.These findings support earlier predictions suggesting that, in mature communities, changes of species interactions can act as community-control mechanisms (also known as priority effects). Furthermore, our results illustrate that the dynamics and composition of ecological communities cannot be fully understood without attention to their reorganization processes, despite the invariability of global network properties

Incidencia de gallina ciega, sistemas de manejo campesinos y variabilidad climática en la comunidad de Napízaro, Michoacán (México)

Traditional agriculture continues to be an important practice in Mexico, however it is not homogeneous and presents a great diversity of managements that is reflected on crop yield and biodiversity maintenance. In recent times, due to excessive use of pesticides and the increase in monocultures, pest species have become and important problem. Particularly soil pest are causing annual losses; however evidence to decide which management strategies minimize pest effects upon harvest is lacking. In order to estimate the effect of management type upon white grub abundance, we evaluated three management systems in the community of Napizaro in the Pátzcuaro basin, Mexico. The studied systems were: conventional management, organic fertilization and crop rotation, in four different plots per system. In three consecutive years (2010-2012) during the agricultural cycle between June and December, we sampled white grub abundance once per month and we evaluated crop yield per hectare at the end of the season. Also we measured soil parameters such as pH and percent organic matter per plot. The evaluated plots present a management gradient that is reflected on white grub abundance and on maize yield. Organic fertilized and crop rotation plots presented lower abundances of soil pests in comparison with conventional plots (p<0.05), while crop yield was greater in conventional plots. On the other hand, soil parameters showed that organic fertilization indeed increased % soil organic matter and soil pH reached more adequate levels in crop rotation plots. White grub abundance was not related with crop yield, therefore we suggest further investigation into the direct effect of these insects upon maize plants. Organic fertilized and crop rotation plots where resilient to drought effects, particularly regarding white grub abundance.La agricultura campesina sigue siendo una práctica muy importante en México, sin embargo no se presenta de manera homogénea, existe una diversidad de manejos que repercuten en los rendimientos de la cosecha y en el mantenimiento de la biodiversidad. En tiempos recientes, dada la excesiva utilización de pesticidas y al aumento de los monocultivos, las plagas se han convertido en un problema muy importante. En particular las plagas del suelo ocasionan muchas pérdidas anualmente, sin embargo aún falta evidencia que permita decidir que estrategias de manejo minimizan el efecto de éstas sobre las cosechas. Para estimar el efecto del tipo de manejo sobre la abundancia de gallina ciega se evaluaron tres sistemas de manejo en la comunidad de Napízaro en la cuenca del lago de Pátzcuaro. Los sistemas evaluados fueron: cultivo convencional (SCC), fertilización orgánica (SFO) y rotación de cultivos (SRC) en cuatro parcelas de cada uno. Entre tres años consecutivos (2010-2012) durante la temporada de cultivo entre junio y diciembre se muestreó la abundancia de gallina ciega una vez por mes y al final de cada temporada se evaluó el rendimiento de maíz por hectárea en cada parcela. Así mismo se evaluaron los pará- metros químicos del suelo: pH y % materia orgánica en todas las parcelas. Las parcelas evaluadas muestran un gradiente de manejo que se ve reflejado tanto en la abundancia de gallina ciega como en el rendimiento de maíz. Las parcelas de fertilización orgánica y de rotación de cultivos presentaron una menor abundancia de gallina ciega en comparación con las convencionales (p<0.05), mientras que los rendimientos fueron mayores en las parcelas convencionales. Por otro lado los parámetros del suelo mostraron que la fertilización orgánica efectivamente aumenta el porcentaje de materia orgánica en el suelo y el pH resultó estar más cerca de los valores de equilibrio en los sistemas de rotación de cultivos. La abundancia de gallina ciega no estuvo relacionada con el rendimiento de las parcelas por lo que se sugieren nuevas investigaciones sobre el efecto directo de los insectos sobre las plantas de maíz en los diferentes sistemas de cultivo. Las parcelas con fertilización orgánica y rotación de cultivos fueron mas resilientes a los efectos de la sequía, particularmente en relación a la abundancia de gallina ciega

El complejo gallina ciega (Coleoptera: Melolonthidae) y su relación con el suelo y el manejo agrícola

El término gallina ciega designa a las larvas de 1179 especies de escarabajos, principalmente de la familia Melolonthidae en México, algunas de las cuales son consideradas plaga. La identificación de la especie (o género) y con ello sus hábitos generales (rizófagas estrictas, facultativas, o saprófitas), las características del suelo y el manejo agrícola que inciden en la diversidad son puntos fundamentales para diseñar estrategias de control agroecológicas. Hoy, gracias a la estadística multivariada, es posible indagar más sobre los factores que afectan a las comunidades de insectos. El objetivo de este trabajo fue estudiar cuáles variables resultan más relevantes en la incidencia de gallina ciega. Las características del suelo relacionadas con la zona donde se encuentran las parcelas son el factor más relevante en la incidencia total de las larvas y en la ordenación de parcelas; sin embargo, el tipo de manejo parece ser más importante en términos de riqueza de especies.Gallina ciega is the name of more than 1179 species of beetles mainly of Melolonthidae family in Mexico, some of which are considered pests. The identification of the species (or genus) and their general habits (strict or facultative rhizophagous, or saprophytes), and the soil characteristics and agricultural management that affect the diversity, are key points to design agroecological strategies of control. Today, thanks to statistical tools, we find out more about relationships and factors affecting communities of these insect. The objective of this work was to study which factors are determinant for gallina ciega incidence. Soil characteristics related to the area are the most important factor in the overall larvae incidence and in ordination of plots; however the type of management seems to be more important in terms of species richness.Eje A1 Sistemas de producción de base agroecológica (Trabajos científicos)Facultad de Ciencias Agrarias y Forestale

El complejo gallina ciega (Coleoptera: Melolonthidae) y su relación con el suelo y el manejo agrícola

El término gallina ciega designa a las larvas de 1179 especies de escarabajos, principalmente de la familia Melolonthidae en México, algunas de las cuales son consideradas plaga. La identificación de la especie (o género) y con ello sus hábitos generales (rizófagas estrictas, facultativas, o saprófitas), las características del suelo y el manejo agrícola que inciden en la diversidad son puntos fundamentales para diseñar estrategias de control agroecológicas. Hoy, gracias a la estadística multivariada, es posible indagar más sobre los factores que afectan a las comunidades de insectos. El objetivo de este trabajo fue estudiar cuáles variables resultan más relevantes en la incidencia de gallina ciega. Las características del suelo relacionadas con la zona donde se encuentran las parcelas son el factor más relevante en la incidencia total de las larvas y en la ordenación de parcelas; sin embargo, el tipo de manejo parece ser más importante en términos de riqueza de especies.Gallina ciega is the name of more than 1179 species of beetles mainly of Melolonthidae family in Mexico, some of which are considered pests. The identification of the species (or genus) and their general habits (strict or facultative rhizophagous, or saprophytes), and the soil characteristics and agricultural management that affect the diversity, are key points to design agroecological strategies of control. Today, thanks to statistical tools, we find out more about relationships and factors affecting communities of these insect. The objective of this work was to study which factors are determinant for gallina ciega incidence. Soil characteristics related to the area are the most important factor in the overall larvae incidence and in ordination of plots; however the type of management seems to be more important in terms of species richness.Eje A1 Sistemas de producción de base agroecológica (Trabajos científicos)Facultad de Ciencias Agrarias y Forestale

INTERACCIONES ENTRE ESPECIES HIDRÓFITAS DOMINANTES DE HUMEDALES DEL OCCIDENTE DE MÉXICO MEDIADAS POR EL FUEGO Y LA CONCENTRACIÓN DE NITRATOS

La dinámica de comunidades vegetales de humedales está influenciada por factores abióticos, como los nutrimentos y el fuego. En humedales en donde hay especies invasoras, determinar el papel de factores abióticos en las interacciones planta-planta es fundamental para entender la dinámica de la comunidad y para su manejo. En este estudio, la interacción entre pares de especies fue cuantificada entre una no invasora (Schoenoplectus americanus), una que puede volverse sobredominante como consecuancia de disturbios humanos (Typha domingensis) y una que posee un linaje que es invasor en norteamérica (Phragmites australis), las cuales crecieron bajo diferentes concentraciones de nitrato y fueron sometidas al efecto del fuego. Todas las especies respondieron a la adición de nitratos incrementando su crecimiento.Phragmitesrespondió en altura y biomasa de raíces,Typhaen biomasa aérea y de raíces ySchoenoplectuspara todas las variables. Las interacciones entre especies fueron complejas y variaron entre años. Durante el primer año, sólo el efecto deTyphaen si misma fue significativo. Para el segundo año, el efecto deTyphafue negativo en Phrangmites, el efecto deSchoenoplectusfue negativo en sí mismo y el efecto deTyphayPhragmitesfue negativo enTypha. El fuego fue significativo paraPhragmitesySchoenoplectus, las plantas no quemadas fueron más altas. Se detectaron efectos del fuego en las interacciones, la presencia de Schoenoplectus benefició el desempeño deTypha, y viceversa. En etapas tempranas, las interacciones más fuertes ocurrieron entre las especies no invasoras, permitiendo a la invasora responder a la concentración de nitratos, y el fuego tuvo su mayor efecto en la interacción entre nativas y no con la invasora

Information arms race explains plant-herbivore chemical communication in ecological communities

Plants emit an extraordinary diversity of chemicals, 1 providing information about their identity and mediating interactions with insects. However, most studies have focused on a few model species in controlled environments, limiting our capacity to understand plant-insect chemical communication in ecological communities. Here, by integrating information theory with ecological and evolutionary theories, we show that a stable information structure of plant volatile organic compounds (VOCs) can emerge from a conflicting information process between plants and herbivores. We corroborate this information arms-race theory with field data recording plant-VOC associations and herbivore-plant interactions in a tropical dry forest. We reveal that plant VOC redundancy and herbivore specialization can be explained by a conflicting information transfer. Information-based communication approaches can increase our understanding of species interactions across trophic levels

Magnitude and Timing of Leaf Damage Affect Seed Production in a Natural Population of Arabidopsis thaliana (Brassicaceae)

Background: The effect of herbivory on plant fitness varies widely. Understanding the causes of this variation is of considerable interest because of its implications for plant population dynamics and trait evolution. We experimentally defoliated the annual herb Arabidopsis thaliana in a natural population in Sweden to test the hypotheses that (a) plant fitness decreases with increasing damage, (b) tolerance to defoliation is lower before flowering than during flowering, and (c) defoliation before flowering reduces number of seeds more strongly than defoliation during flowering, but the opposite is true for effects on seed size. Methodology/Principal Findings: In a first experiment, between 0 and 75% of the leaf area was removed in May from plants that flowered or were about to start flowering. In a second experiment, 0, 25%, or 50% of the leaf area was removed from plants on one of two occasions, in mid April when plants were either in the vegetative rosette or bolting stage, or in mid May when plants were flowering. In the first experiment, seed production was negatively related to leaf area removed, and at the highest damage level, also mean seed size was reduced. In the second experiment, removal of 50% of the leaf area reduced seed production by 60% among plants defoliated early in the season at the vegetative rosettes, and by 22% among plants defoliated early in the season at the bolting stage, but did not reduce seed output of plants defoliated one month later. No seasonal shift in the effect of defoliation on seed size was detected. Conclusions/Significance: The results show that leaf damage may reduce the fitness of A. thaliana, and suggest that in this population leaf herbivores feeding on plants before flowering should exert stronger selection on defence traits than those feeding on plants during flowering, given similar damage levels

Global urban environmental change drives adaptation in white clover.

Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied among cities. Sequencing 2074 genomes from 26 cities revealed that the evolution of urban-rural clines was best explained by adaptive evolution, but the degree of parallel adaptation varied among cities. Our results demonstrate that urbanization leads to adaptation at a global scale

How much leaf area do insects eat? A data set of insect herbivory sampled globally with a standardized protocol

Herbivory is ubiquitous. Despite being a potential driver of plant distribution and performance, herbivory remains largely undocumented. Some early attempts have been made to review, globally, how much leaf area is removed through insect feeding. Kozlov et al., in one of the most comprehensive reviews regarding global patterns of herbivory, have compiled published studies regarding foliar removal and sampled data on global herbivory levels using a standardized protocol. However, in the review by Kozlov et al., only 15 sampling sites, comprising 33 plant species, were evaluated in tropical areas around the globe. In Brazil, which ranks first in terms of plant biodiversity, with a total of 46,097 species, almost half (43%) being endemic, a single data point was sampled, covering only two plant species. In an attempt to increase knowledge regarding herbivory in tropical plant species and to provide the raw data needed to test general hypotheses related to plant–herbivore interactions across large spatial scales, we proposed a joint, collaborative network to evaluate tropical herbivory. This network allowed us to update and expand the data on insect herbivory in tropical and temperate plant species. Our data set, collected with a standardized protocol, covers 45 sampling sites from nine countries and includes leaf herbivory measurements of 57,239 leaves from 209 species of vascular plants belonging to 65 families from tropical and temperate regions. They expand previous data sets by including a total of 32 sampling sites from tropical areas around the globe, comprising 152 species, 146 of them being sampled in Brazil. For temperate areas, it includes 13 sampling sites, comprising 59 species

Combination of searches for heavy spin-1 resonances using 139 fb−1 of proton-proton collision data at s = 13 TeV with the ATLAS detector

A combination of searches for new heavy spin-1 resonances decaying into different pairings of W, Z, or Higgs bosons, as well as directly into leptons or quarks, is presented. The data sample used corresponds to 139 fb−1 of proton-proton collisions at = 13 TeV collected during 2015–2018 with the ATLAS detector at the CERN Large Hadron Collider. Analyses selecting quark pairs (qq, bb, , and tb) or third-generation leptons (τν and ττ) are included in this kind of combination for the first time. A simplified model predicting a spin-1 heavy vector-boson triplet is used. Cross-section limits are set at the 95% confidence level and are compared with predictions for the benchmark model. These limits are also expressed in terms of constraints on couplings of the heavy vector-boson triplet to quarks, leptons, and the Higgs boson. The complementarity of the various analyses increases the sensitivity to new physics, and the resulting constraints are stronger than those from any individual analysis considered. The data exclude a heavy vector-boson triplet with mass below 5.8 TeV in a weakly coupled scenario, below 4.4 TeV in a strongly coupled scenario, and up to 1.5 TeV in the case of production via vector-boson fusion