Patterns of diversity and composition of Mediterranean ground ant communities tracking spatial and temporal variability in the thermal environment

The present study analyzed ant community structure and the factors affecting it in the Spanish Mediterranean area. The aim of this study was to test whether temperature controls the composition and diversity of the ground ant fauna and the spatial and temporal distribution of dominance groups along adjacent communities. The main descriptors of community structure (except perhaps species richness) were found to vary along the gradient of vegetation cover: increased vegetation cover resulted in an increase in the relative abundance of the most common species, which led to a significant decrease in species evenness, together with a reduction in total ant density on the ground. In open habitats, dominant and subordinate species were abundant during different periods of the day, and this led to an increase in species evenness. In areas with high vegetation cover, dominants benefited from the lower temperatures by lengthening their periods of activity. This resulted in a decrease in the abundance of subordinate species, and in lower evenness. Seasonal patterns in community structure tracked temperature fluctuations and varied between habitat types. Evenness was similar in the two habitat types in spring, but increased in grasslands and decreased in shrublands/forests in summer. Species richness did not vary between seasons or habitat types. The relative abundance of dominance groups in the two types of habitats showed a different pattern between seasons. In grasslands, subordinates increased and dominants decreased their relative abundance from spring to summer, while in shrublands/forests, the opposite pattern was found. The overall conclusion from this study is that ground ant communities in open areas are primarily regulated by temperature variations, while in shrublands and forests, dominant species are more abundant, and competitive interactions appear to be the major structuring force.Peer Reviewe

Sobre la fundación de la sociedad en la hormiga Cataglyphis iberica (Emery, 1906) (Hymenoptera, Formicidae)

Colony founding in Cataglyphis iberica, a monogynous and polydomous ant species, has been studied. Nest population, worker size distribution and queeníworker dimorphism has been analyzed. Males and virgin females are found only in queenless nests. Virgin females have a relatively small fat content (36+8%) and after mating, they fly and go away from their original nest. Solitary mated queens are usually found in the field, but they never reach to found new societies in laboratory conditions. The contribution of these results to clarify the colony founding process, and the relationships between this process and polydomy phenomenon is discussed.Se ha estudiado el modo de fundación de la sociedad en la hormiga Cataglyphis iberica, especie monogínica y policálica. Se ha analizado la población de 10s nidos, la biometria de las obreras y el dimorfisme reina/obrera. Los sexuados se encuentran únicamente en 10s nidos sin reina de las colonias. Las hembras vírgenes tienen un contenido relativamente bajo en lípidos (36f 8%). Tras la cópula (siempre en el suelo: carrera nupcial) las hembras emprenden el vuelo y se alejan del nido madre. Se encuentran hembras solitarias y fecundadas por el campo, pero instaladas en el laboratorio mueren sin descendencia. Se discute la aportación de estos resultados en favor de 10s diversos tipos posibles de fundación, y su relación con la policalia

Metric of a Slow Rotating Body with Quadrupole Moment from the Erez-Rosen Metric

A metric representing a slowly rotating object with quadrupole moment is obtained using a perturbation method to include rotation into the weak limit of the Erez-Rosen metric. This metric is intended to tackle relativistic astrometry and gravitational lensing problems in which a quadrupole moment has to be taken into account

A multidimensional functional trait analysis of resource exploitation in European ants

The major factors explaining ecological variation in plants have been widely discussed over the last decade thanks to numerous studies that have examined the covariation that exists between pairs of traits. However, multivariate relationships among traits remain poorly characterized in animals. In this study, we aimed to identify the main multivariate trait dimensions that explain variance in important functional traits related to resource exploitation in ants. To this end, we created a large ant trait database. This database includes information on 11 traits that are important in ant resource exploitation; data were obtained for 150 European species found in different biomes. First, we examined the pairwise correlations between the traits included in the database. Second, we used multivariate analyses to identify potential trait dimensions. Our study shows that, to a great extent, resource exploitation strategies align along two main trait dimensions. The first dimension emerged in both the overall and group-specific analyses, where it accounted for the same pairwise trait correlations. The second dimension was more variable, as species were grouped by levels of taxonomy, habitat, and climate. These two dimensions included most of the significant pairwise trait correlations, thus highlighting that complementarity, but also redundancy, exists among different pairs of traits. The first dimension was associated with behavioral dominance: dominance was associated with large colony size, presence of multiple nests per colony, worker polymorphism, and a collective foraging strategy. The second dimension was associated with resource partitioning along dietary and microhabitat lines: it ranged from species that consume liquid foods, engage in group foraging, and mainly nest in the vegetation to species that consume insects and seeds, engage in individual foraging, and demonstrate strictly diurnal activity. Our findings establish a proficient ecological trait-based animal research that minimizes the number of traits to be measured while maximizing the number of relevant trait dimensions. Overall, resource exploitation in animals might be framed by behavioral dominance, foraging strategy, diet, and nesting habitat; the position of animal species within this trait space could provide relevant information about their distribution and abundance, for today as well as under future global change scenarios.Peer reviewe

Socioeconomics explain tree diversity, abundance, and composition in the compact city of Barcelona, Spain

Altres ajuts: acords transformatius de la UABTrees are frequently unevenly distributed in urban areas, and their diversity, abundance, and composition vary spatially. Some studies have shown that the unequal distribution of urban trees can be associated with demographic and socioeconomic factors. However, most studies have been conducted in diffuse urban systems using remotely-sensed tree cover within single or aggregated land-use types. We examined if the relationship between tree diversity, abundance, composition, and socioeconomic factors varied across land-use types (parks, streets, zonal areas, and total) in the compact city of Barcelona, Spain. We calculated tree species richness and abundance across 73 neighborhoods using 229,962 geo-referenced records of individual trees sampled in 2021. Life expectancy positively explained tree richness and abundance across land-use types, reinforcing that access to urban green infrastructure promotes longer life spans. In contrast, income did not positively explain tree richness or abundance, indicating that tree distribution does not directly result in biodiversity and green space inequalities for disadvantaged groups in terms of income. Total tree composition across neighborhoods responded to socioeconomic gradients, evidencing that neighborhood appearances are socially stratified. Street tree abundance increased in densely populated neighborhoods, possibly because intense street tree plantings in these neighborhoods compensate for the lack of other green infrastructure. Urban tree planting, particularly in streets, can be an effective strategy to increase green spaces in compact cities to overcome the disparities resulting from the unequal distribution of urban vegetation. Long-term data on socioeconomic factors and urban tree distribution are necessary to determine how social stratification affects urban diversity

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

Edge influence on diversity of orchids in Andean cloud forests

Cloud forests harbor high levels of orchid diversity. However, due to the high fragmentation of these forests in the Andes, combined with the pressure for new agricultural land, orchid diversity is highly threatened. Despite this worrying scenario, few studies have assessed the effects of habitat loss specifically on orchid assemblages in the Andes. The aim of this study was to analyze the edge effect on orchids in cloud forest fragments of varying size. We measured forest structure, neighboring land cover and edge effect on orchid abundance, species richness and beta-diversity, by sampling assemblages along edge-to-interior transects in six different sized Andean (southwest Colombia) forest remnants. We recorded 11,127 stem-individuals of orchids in 141 species. Within the forest, edges sustained equal or more species than interior plots. Our results revealed neither patch metrics nor forest structure showed any significant association to orchid diversity at any scale. Nonetheless, from our observations in composition, the type of neighboring cover, particularly pastures, negatively influences interior species (richness and composition) in larger reserves. This might be due to the fact that some species found in interior plots tend to be confined, with sporadic appearances in regeneration forest and are very scarce or absent in pastures. Species richness differed significantly between matrix types. Our results suggest that (1) orchid diversity shows spatial variability in response to disturbances, but the response is independent from forest structure, patch size and patch geometry; (2) orchid communities are negatively affected by covers, and this pattern is reflected in reduced richness and high species turnover; (3) orchid richness edge effect across a pasture-interior gradient. Two forest management implications can be discerned from our results: (1) management strategies aiming to reduce edge effects may focus on improvement regeneration conditions around pasture lands; and (2) local scale management and conservation activities of natural forests in cloud forests will favor small reserves that harbor high levels of richness

Estrategias alternativas en el ciclo de vida de tres hormigas mediterráneas

Se ha estudiado el ciclo biológico de tres especies de hormigas mediterráneas, y se han constatado importantes diferencias entre ellas. Cataglyphis cursor hibema sin descendencia y completa un ciclo de nidada entre los meses de abril y septiembre. Aphaenogaster senilis hibema sin nidada y produce pupas durante un amplio periodo de tiempo, desde abril hasta octubre, aunque los valores mtiximos (que coinciden con el pico de actividad exterior) se dan en primavera y principio de verano. Ambas especies fundan la sociedad por fisión colonial, por lo que la descendencia obrera es la que condiciona decisivamente el ciclo de vida de las colonias. En cambio, Camponotus cruentatus funda la sociedad de manera independiente, por lo que debe producir un elevado número de sexuados que contrarresten la elevada mortalidad que tiene lugar durante el apareamiento. Su ciclo difiere de los anteriores en que hay una importante producción primaveral de sexuados y de obreras, que se solapan en el tiempo en el interior de los nidos. Las variaciones en los ciclos de vida de las tres especies se discuten en relación con la actividad estacional y las características ecológicas de cada una de ellas.Colony life cycles of three mediterranean ants have been analyzed, and important differences have been found among them. Cataglyphis cursor does not keep brood during the winter, and rears new individuals from egg to adult in only one activity period, from April to September. Aphaenogaster senilis spends the winter with brood, and produces new workers during a long period of the year, from April to October. Both species produce a small number of alates because they form new colonies by fission. Therefore, worker brood is the decisive factor that determines colony life cycles of both species. Camponotus cruentatus has an independent mode of colony founding, in which colonies produce a high number of alates in order to override the extremely high mortality of colony-founding queens during mating. Its colony cycle differs from the others in that there is a high spring production of alates and workers, which overlap into the nests. Variations in colony life cycles of these species in relationship with their seasonal activity pattem and their ecological features are discussed

És homogènia la recuperació, després del foc, de les comunitats de plantes i de formigues dels boscos de Catalunya?

Es presenten les principals conclusions de diversos estudis amb l'objectiu d'avaluar la resiliència dels boscos de Catalunya després d'un incendi. Es mostra que hi ha un ventall ampli de respostes, que inclou boscos amb una alta resiliència al foc i que recuperen ràpidament l'espècie o espècies arbòries dominants, però també altres boscos en què l'espècie dominant abans del foc no es recupera i són substituïts per altres formacions boscoses o arbustives. La substitució de les espècies dominants i estructuradores del bosc comporta que tota la comunitat de plantes i de formigues que hi viuen tinguin menor resiliència al foc que les dels boscos que mantenen les mateixes espècies dominants d'abans del foc. Aquests resultats impliquen repensar algunes idees sobre les possibles conseqüències dels focs sobre la biodiversitat i quins han de ser els objectius de la gestió de determinades zones cremades.¿Es homogénea la recuperación, tras el incendio, de las comunidades de plantas y de hormigas de los bosques de Cataluña? Se presentan las principales conclusiones de diversos estudios con el objetivo de evaluar la resiliencia de los bosques de Cataluña después de un incendio. Se muestra que existe un amplio abanico de respuestas, que incluye bosques con una alta resiliencia al fuego y que recuperan rápidamente la especie o especies arbóreas dominantes, pero también otros bosques donde la especie dominante no se recupera y son sustituidos por otras formaciones boscosas o arbustivas. La sustitución de estas especies dominantes y estructurantes del bosque supone que toda la comunidad de plantas y de hormigas que viven tengan menor resiliencia al fuego que las de los bosques que mantienen las mismas especies dominantes antes del fuego. Estos resultados implican replantear algunas ideas sobre las posibles consecuencias de los fuegos sobre la biodiversidad y cuáles deben ser los objetivos de gestión de determinadas zonas quemadas.Is homogeneous the postfire recovery of plant and ant communities in Catalan forests? We presents the main conclusions of different studies to analyze the forest resilience in Catalonia after fire. It shows how there is a sufficiently broad range of responses, which include forests with high resilience to fire and quickly recover the species or dominant tree species, but also other forests where before fire, the dominant species are not recovered and then, are replaced by other types of woodland and shrubs. In these cases, the replacement of dominant species and forest structure means that the whole community of plants and ants that live in these forests have less resilience to fire than forests that maintain the same dominant species before fire. These results imply think about the possible consequences of fires on biodiversity and also what should be the objectives of management of certain areas burned