Gustavo Romero - Academia.edu (original) (raw)

Papers by Gustavo Romero

Annals of botany, Nov 29, 2016

Bromeliads are able to occupy some of the most nutrient-poor environments especially because they... more Bromeliads are able to occupy some of the most nutrient-poor environments especially because they possess absorptive leaf trichomes, leaves organized in rosettes, distinct photosynthetic pathways [C3, Crassulacean acid metabolism (CAM) or facultative C3-CAM], and may present an epiphytic habit. The more derived features related to these traits are described for the Tillandsioideae subfamily. In this context, the aims of this study were to evaluate how terrestrial predators contribute to the nutrition and performance of bromeliad species, subfamilies and ecophysiological types, whether these species differ in their ecophysiological traits and whether the physiological outcomes are consistent among subfamilies and types (e.g. presence/absence of tank, soil/tank/atmosphere source of nutrients, trichomes/roots access to nutrients). Isotopic ((15)N-enriched predator faeces) and physiological methods (analyses of plant protein, amino acids, growth, leaf mass per area and total N incorpora...

Revista Brasileira de Biologia, 2000

The reproductive behavior and the seasonal occurrence of Psecas viridipurpureus were studied at t... more The reproductive behavior and the seasonal occurrence of Psecas viridipurpureus were studied at the Estação Ecológica do Noroeste Paulista, a small conservation area in the northwest region of São Paulo State, Brazil (49°22'50''W and 20°48'36''S). P. viridipurpureus occurred on "gravatá", a bromeliaceous plant (Bromelia balansae, Bromeliaceae) which does not accumulate rain water. During the courtship display the couple occupied the median region of the "gravatá" leaves, with the male always located in a higher position than the female. The males of P. viridipurpureus showed a complex courtship behavior, which included five motor patterns. The courtship and mating behavior occurred preponderantly during the rainy season and the juvenile recruitment between December and July. The retreat of P. viridipurpureus differs from the Salticidae pattern, since the egg sacs are covered with a plain silk cover and are not wrapped in cocoons.

Ecology, 2015

Local habitat size has been shown to influence colonization and extinction processes of species i... more Local habitat size has been shown to influence colonization and extinction processes of species in patchy environments. However, species differ in body size, mobility, and trophic level, and may not respond in the same way to habitat size. Thus far, we have a limited understanding of how habitat size influences the structure of multitrophic communities and to what extent the effects may be generalizable over a broad geographic range. Here, we used water-filled bromeliads of different sizes as a natural model system to examine the effects of habitat size on the trophic structure of their inhabiting invertebrate communities. We collected composition and biomass data from 651 bromeliad communities from eight sites across Central and South America differing in environmental conditions, species pools, and the presence of large-bodied odonate predators. We found that trophic structure in the communities changed dramatically with changes in habitat (bromeliad) size. Detritivore : resource ratios showed a consistent negative relationship with habitat size across sites. In contrast, changes in predator : detritivore (prey) ratios depended on the presence of odonates as dominant predators in the regional pool. At sites without odonates, predator : detritivore biomass ratios decreased with increasing habitat size. At sites with odonates, we found odonates to be more frequently present in large than in small bromeliads, and predator : detritivore biomass ratios increased with increasing habitat size to the point where some trophic pyramids became inverted. Our results show that the distribution of biomass amongst food-web levels depends strongly on habitat size, largely irrespective of geographic differences in environmental conditions or detritivore species compositions. However, the presence of largebodied predators in the regional species pool may fundamentally alter this relationship between habitat size and trophic structure. We conclude that taking into account the response and multitrophic effects of dominant, mobile species may be critical when predicting changes in community structure along a habitat-size gradient.

Neotropical Entomology, 2005

Interações Entre Oncideres humeralis Thomson (Coleoptera: Cerambycidae) e Melastomataceae: Seleçã... more Interações Entre Oncideres humeralis Thomson (Coleoptera: Cerambycidae) e Melastomataceae: Seleção das Plantas Hospedeiras e Padrões de Uso no Sudeste do Brasil RESUMO-Oncideres humeralis Thomson (Cerambycidae) foi observado serrando o tronco principal de plantas da família Melastomataceae no sudeste do Brasil. Os principais objetivos deste trabalho identificar quais plantas hospedeiras O. humeralis seleciona no campo e quais as características das plantas preferidas. O. humeralis usou somente Melastomataceae como plantas hospedeiras, atacando quatro das 11 espécies presentes na área de estudo. Das quatro espécies atacadas, Miconia sellowiana Naudin e M. jucunda Triana, a espécie mais abundante e a maior, respectivamente, foram as preferidas. Quando as plantas eram altas, O. humeralis serrou o tronco em posições mais elevadas, indicando que as fêmeas selecionam plantas com diâmetro ótimo de tronco e ajustam o ponto para serrar em função da altura da hospedeira. As fêmeas também selecionaram plantas com maior número de ramos secundários. Estes resultados indicam que O. humeralis apresenta especificidade para determinadas espécies de Melastomataceae e que plantas hospedeiras são selecionadas pela sua abundância, tamanho ou número de ramos secundários. PALAVRAS-CHAVE: Brocador, floema intra-xilemático, interação inseto-planta, Miconia ABSTRACT-Oncideres humeralis Thomson (Cerambycidae) was observed girdling the main trunk of plants of the Melastomataceae family in southeastern Brazil. The main objectives of this work were to identify which host plants O. humeralis selects in the field and which are the characteristics of the preferred plants. O. humeralis specifically used Melastomataceae as host plants, attacking only four of the 11 species present in the study area. From the four attacked species, Miconia sellowiana Naudin and M. jucunda Triana were the preferred owes; they are the most abundant and the largest species, respectively. When the plants were taller, O. humeralis girdled the trunk at higher positions, indicating that females select plants with optimum trunk diameter and adjust the point to girdle according to the host height. Females also selected plants with greater numbers of secondary branches. These results indicate that O. humeralis is specific to certain species of Melastomataceae, and that host plants are selected on the basis of their abundance, size or number of secondary branches.

Journal of Natural History, 2005

The accuracy of the Content should not be relied upon and should be independently verified with p... more The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms &

Journal of Arachnology, 2007

Two allopatric species of Coryphasia (Araneae: Salticidae), both described for the first time in ... more Two allopatric species of Coryphasia (Araneae: Salticidae), both described for the first time in this study, have been found associated with Bromeliaceae in distinct phytophysiognomies (e.g., inselbergs, highland forests and restingas) from southeastern Brazil. In this study, we investigated whether these salticids were associated specifically with bromeliads, and whether they used bromeliads of different species and sizes in distinct geographic regions. The Coryphasia species were rarely found outside bromeliads, occupied larger bromeliad species among those available, and were generally more frequent on bromeliads in open areas, such as inselbergs on mountain tops. The two Coryphasia species were observed submerging in phytotelmata, possibly as an anti-predatory behavior. The patterns of spatial and microspatial distribution and the submergence behavior of these species were similar to those of other bromeliaddwelling salticids, which suggests a convergence among spiders that live on bromeliads.

Journal of Arachnology, 2004

Ecology, 2004

We examined the effects of the sit-and-wait spider Misumenops argenteus (Thomisidae) on the herbi... more We examined the effects of the sit-and-wait spider Misumenops argenteus (Thomisidae) on the herbivore assemblage and fitness of the perennial woody shrub Trichogoniopsis adenantha (Asteraceae). Because crab spiders prey on both pollinators and phytophagous insects, they can have potentially negative and positive effects on plants. In a manipulative experiment using paired plants, spiders decreased the density of sucking and some endophagous herbivores on the leaves and capitula and reduced the number of damaged achenes produced by the plants. Damaged capitula had a higher proportion of fertilized achenes in plants with spiders than without spiders, but not undamaged capitula. These results indicate that M. argenteus exerted a double positive effect on seed production in T. adenantha. The effect of M. argenteus on herbivores may be taxon specific and vary among years with different herbivore abundances.

Biotropica, 2007

Two common South American species of lynx spiders, Peucetia rubrolineata and P. flava (Oxyopidae)... more Two common South American species of lynx spiders, Peucetia rubrolineata and P. flava (Oxyopidae), were surveyed on three localities in southeastern Brazil to determine plant choice. Both species were found to be associated with plants bearing glandular trichomes. A literature review and complementary data show that ten Peucetia species are associated with up to 55 plant species bearing glandular trichomes in at least 20 distinct vegetation types (phytophysiognomies) in more than 36 localities in the Neotropical, Neartic, Afrotropical, and Paleartic regions. The main plant families used by the spiders were Solanaceae, Asteraceae, and Melastomataceae. The specialization of the Peucetia species for plants bearing glandular trichomes may have evolved because insects adhered to these sticky structures may be used as prey by the spiders.

Austral Ecology, 2010

Habitat complexity is a main predictor of the distribution of arthropods on vegetation. However, ... more Habitat complexity is a main predictor of the distribution of arthropods on vegetation. However, it remains poorly known whether plant architecture and fine-scale spatial distribution affect the species richness and composition of associated arthropod guilds. In this study, we extensively sampled bromeliad species with a variety of rosette architectures in a megadiversity region. The aims were to investigate whether (i) possible differences in spider species composition among bromeliad species are related to the distinct architectures of the plants, and (ii) bromeliad architectural complexity (an intrinsic feature) and vertical distribution (an extrinsic feature) are good predictors of spider abundance and richness. Contrary to our expectations, spider species composition did not vary significantly among bromeliad species with different architectures. We found a positive effect of the mean number of leaves on spider abundance and species richness, but it occurred indirectly through spider abundance; factoring out the indirect effect revealed a negative effect of leaf number on species richness. Bromeliad species with wider vertical distributions harboured more spider species. Our results suggest that the dominance of a few spider species and reduced space for orb-web spiders to attach their webs are the main explanations for lower spider richness on bromeliad species with higher architectural complexity. Our findings highlight the importance of both intrinsic and extrinsic plant features as co-determinants of predator arthropod diversity.

Journal of Arachnology, 2009

Several spider species use plants as shelter and foraging sites, but the relationships among thes... more Several spider species use plants as shelter and foraging sites, but the relationships among these organisms are still poorly known. Lynx spiders of the genus Peucetia do not build webs, and many species live strictly in plants bearing glandular trichomes. Peucetia flava Keyserling 1877 inhabits Solamtm thomasiifoHum in southeastern Brazil and usually preys on herbivores and other small insects adhered to the glandular trichomes of its host plant. To evaluate the potential anti-herbivore protection of this spider species for S. thomasiifoHum, we glued termites used as herbivore models on trichomes of S. thomasiifoliiim and on neighboring plants lacking glandular trichomes. Leaf miner damage and spider density were recorded for S. thomasiifolium plants in July 1997. There was a positive relationship between plant size and spider density. The removal of termites in S. thomasiifolium by P. flava was higher than in plants without glandular trichomes. The leaf miner damage was negatively related to spider density. Our results suggest that P. flava may be an important plant bodyguard in the defense of S. thomasiifolium from its natural herbivores.

Nature Communications, 2020

Changes in global and regional precipitation regimes are among the most pervasive components of c... more Changes in global and regional precipitation regimes are among the most pervasive components of climate change. Intensification of rainfall cycles, ranging from frequent downpours to severe droughts, could cause widespread, but largely unknown, alterations to trophic structure and ecosystem function. We conducted multi-site coordinated experiments to show how variation in the quantity and evenness of rainfall modulates trophic structure in 210 natural freshwater microcosms (tank bromeliads) across Central and South America (18°N to 29°S). The biomass of smaller organisms (detritivores) was higher under more stable hydrological conditions. Conversely, the biomass of predators was highest when rainfall was uneven, resulting in top-heavy biomass pyramids. These results illustrate how extremes of precipitation, resulting in localized droughts or flooding, can erode the base of freshwater food webs, with negative implications for the stability of trophic dynamics.

Nature Climate Change, 2018

How climate affects biotic interactions is a question of urgent concern 1-3. Theory predicts that... more How climate affects biotic interactions is a question of urgent concern 1-3. Theory predicts that biotic interactions are stronger at lower latitudes 4-6. However, the role of climate in governing these patterns is typically assumed, rather than explicitly tested. Here, we dissected the influence of climatic descriptors on predation pressure using data from a global experiment with model caterpillars. We then used projections of future climate change to predict shifts in predation pressure. Climate, particularly components of temperature, explained latitudinal and elevational patterns of predation better than latitude or elevation by themselves. Projected predation pressure was greater under higher temperatures and more stable climates. Increased climatic instability projected for the near future predicts a general decrease in predation pressure over time. By identifying the current climatic drivers of global patterns in a key biotic interaction, we show how shifts in these drivers could alter the functioning of terrestrial ecosystems and their associated services. Human activities are impacting the Earth's climate at an unprecedented rate 7. Climate warming, temperature instability and extreme precipitation events are all increasing in intensity 8,9. These climate changes can alter the frequency, direction and magnitude of biotic interactions 2 , and result in major biodiversity loss through the collapse of such interactions 3,10. Efforts to successfully manage and restore the ecosystems may be futile without a clearer understanding of the influence of accelerating climate change on the strength and frequency of biotic interactions 2,3. Many types of biotic interactions tend to be stronger and more frequent towards lower latitudes 6,11-14 (but see ref. 15) and elevations 11,14. These global (latitude) and local or regional (elevation) patterns indicate that climatic conditions may be a common driver underlying the strength and frequency of biotic interactions. However, previous macroecological studies of latitudinal and elevation gradients in biotic interactions (Fig. 1a) do not directly test the effect of climatic variables 16,17. Moreover, climatic conditions do not always correlate with changes in latitudinal and elevational gradients 18,19-a mismatch that can lead to spurious relationships between latitude and/or elevation, and biological responses 20. Large-scale patterns are typically inferred from a set of experiments and observations that vary in their methods and protocols 21 , thus

Ecology letters, 2018

Ecologists have extensively investigated the effect of warming on consumer-resource interactions,... more Ecologists have extensively investigated the effect of warming on consumer-resource interactions, with experiments revealing that warming can strengthen, weaken or have no net effect on top-down control of resources. These experiments have inspired a body of theoretical work to explain the variation in the effect of warming on top-down control. However, there has been no quantitative attempt to reconcile theory with outcomes from empirical studies. To address the gap between theory and experiment, we performed a meta-analysis to examine the combined effect of experimental warming and top-down control on resource biomass and determined potential sources of variation across experiments. We show that differences in experimental outcomes are related to systematic variation in the geographical distribution of studies. Specifically, warming strengthened top-down control when experiments were conducted in colder regions, but had the opposite effect in warmer regions. Furthermore, we found ...

Ecology letters, Jan 2, 2017

Global change affects ecosystem functioning both directly by modifications in physicochemical pro... more Global change affects ecosystem functioning both directly by modifications in physicochemical processes, and indirectly, via changes in biotic metabolism and interactions. Unclear, however, is how multiple anthropogenic drivers affect different components of community structure and the performance of multiple ecosystem functions (ecosystem multifunctionality). We manipulated small natural freshwater ecosystems to investigate how warming and top predator loss affect seven ecosystem functions representing two major dimensions of ecosystem functioning, productivity and metabolism. We investigated their direct and indirect effects on community diversity and standing stock of multitrophic macro and microorganisms. Warming directly increased multifunctional ecosystem productivity and metabolism. In contrast, top predator loss indirectly affected multifunctional ecosystem productivity via changes in the diversity of detritivorous macroinvertebrates, but did not affect ecosystem metabolism....

Scientific Reports, 2017

One fundamental question in prey luring systems is to understand how visual signals are interpret... more One fundamental question in prey luring systems is to understand how visual signals are interpreted by the receiver. Predators lure prey by falsely imitating the signal of a model, or may exploit sensory preferences of the receivers, which search for rewarding signals. Crab spiders reflect ultraviolet (UV) light, ambush pollinators on flowers, and manipulate flower UV signals altering the behavior and response of prey. Whereas crab spiders typically depend on flowers to forage, adult Epicadus heterogaster departs from this standard behavior by preying on pollinators upon green leaves, even in the absence of flowers nearby. This species has a conspicuous abdomen resembling the shape of a flower, which may reflect UV signals similar to that of flowers, and thus attract pollinators. Nevertheless, no empirical evidence is available that E. heterogaster foraging on leaves mimics flowers, nor how this crab spider interacts with its prey. Field and laboratory experiments demonstrated that UV reflection of adult E. heterogaster is the main signal responsible for the attraction of pollinators. This is the first study to demonstrate that a crab spider attracts pollinators regardless of flower UV signal, which may represent an evolutionary pathway beyond the dependence of flowers. Mimicry occurs when one species, the mimic, emits a signal similar to that of a model species to deceive the receiver with the purpose of avoiding predation or capturing prey 1-3. Ever since Bates 4 investigated color mimicry in butterflies in the Amazon, mimicry systems have been explored either from the perspective of the mimic emitting signals to deceive the predator (protective mimicry) or the mimic emitting signals to deceive potential victims, thereby increasing the odds of well-succeed attacks (aggressive mimicry) 5-7. In aggressive mimicry, predators or parasites lure and attract prey by falsely imitating the signal of a model 5, 8. This is the case of assassin bugs that hunt web-building spiders by mimicking the vibrations generated by insect prey 8 , and of bolas spiders which imitate the pheromones from female moths to attract the males 8, 9. Recently, the orchid mantis Hymenopus coronatus was demonstrated to mimic flowers and to attract and lure their pollinator prey at rates even higher than flowers 5, 6. Alternatively, the attractiveness in prey luring systems may also happen regardless of mimicry, when the predators induce a deceptive response in the sensory bias of the receiver 10-12. For instance, some orb-web spiders, like Gasteracantha fornicate, have conspicuous body coloration and lure prey by inducing a deceptive signal, which is not necessarily similar to a model or object that might induce prey interest 10, 11. Instead, it maximizes color and luminance contrast with background 10, 11. Additionally, these polymorphic spiders and sympatric flowers exhibit notable color convergence for receivers 12. It is likely that this predator is exploiting sensory preferences of the receiver for rewarding signal flowers 11, 12. In cases in which deceptive signals resemble a more specific signal, polymorphism can evolve by combining multiple models 10. Thus, the diversity of body color may converge with the diversity of floral color signals in space and time 10. Crab spiders (Thomisidae) reflect light in the ultraviolet (UV) wavelength range of the spectrum 13, 14. These spiders usually ambush pollinators on flowers, are capable of manipulating flower UV signals, and thus alter the behavior and response of their prey 15, 16. Although some crab spiders camouflage on flowers and become cryptic to their visiting prey 17, 18 , Thomisus spectabilis is not cryptic on flowers of Chrysanthemum frutescens and attracts prey by a UV color contrast of the spider against the flower petals 14. Whereas all these spiders depend on flowers to forage, the crab spider Epicadus heterogaster, first observed by Bates in the Amazon, is an exception to the

PloS one, 2016

Predator activities may lead to the accumulation of nutrients in specific areas of terrestrial ha... more Predator activities may lead to the accumulation of nutrients in specific areas of terrestrial habitats where they dispose of prey carcasses. In their feeding sites, predators may increase nutrient availability in the soil and favor plant nutrition and growth. However, the translocation of nutrients from one habitat to another may depend on predator identity and diet, as well as on the amount of prey intake. Here we used isotopic (15N) and physiological methods in greenhouse experiments to evaluate the effects of the identity of predatory ants (i.e., the consumption of prey and nest sites) on the nutrition and growth of the bromeliad Quesnelia arvensis. We showed that predatory ants with protein-based nutrition (i.e., Odontomachus hastatus, Gnamptogenys moelleri) improved the performance of their host bromeliads (i.e., increased foliar N, production of soluble proteins and growth). On the other hand, the contribution of Camponotus crassus for the nutritional status of bromeliads did...