Spatiotemporal effects on dung beetle activities in island forests-home garden matrix in a tropical village landscape

Insects in seasonal tropics experience a wide range of temperatures along seasons, habitats, and a day. Therefore, the thermal tolerance of the insects can be a major driver for their habitat preference, temporal patterns of activity, and formation of communities. We examined the dung beetle communities of eleven pairs of neighboring open (home gardens) and closed habitats (sacred groves) during dry and wet seasons and diel periods (day and night) to understand the dung beetle activities along a spatiotemporal gradient constituted by the sacred groves—home garden matrix on a tropical village landscape. We tested the following hypotheses: (i) closed habitats have greater activities of dung beetles over open habitats; (ii) the diurnal communities of dung beetles are different from the nocturnal communities; and (iii) the diurnal-nocturnal activities of dung beetles could be predicted by the habitat and season. We considered abundance, richness, total biomass, and Shannon diversity of overall beetles, abundance of different functional groups, and species composition in communities as the quantitative measures in the predictive statistical models. In total, 2727 dung beetles belonging to 38 species, ten genera, and three functional groups were collected. The open habitat supported more number of dung beetles (N = 2318) than the closed habitat (N = 409). The diurnal communities were different from nocturnal communities, particularly in open habitat, where the temperature was different between day and night. The dominant species of the diurnal communities of open habitat hardly used the closed habitat in any context including dry–wet seasons, but the nocturnal communities of the open habitat were closer to the communities of closed habitat. The diel period and habitat predicted the abundance activity of functional groups; season was a poor predictor of dung beetle activities. Given that the species composition has turned over across habitats, and the closed habitat supported remarkably lesser number of beetles than the open habitats, the closed habitat is unlikely to be a thermal refuge for the open habitat species in village landscapes that have island forests, such as sacred groves, and home gardens form a matrix.

Day-Night and Inter-Habitat Variations in Ant Assemblages in a Mosaic Agroforestry Landscape

Throughout the Mediterranean basin, the long-term interaction between human activities and natural processes has led to the formation of unique ecosystems whose biodiversity may be higher than that of the “original” systems. This is particularly true in the case of transformations of continuous stretches of closed forest into a complex mosaic of open and closed habitat over the course of centuries. In this study, we assessed the variation in diversity of ant assemblages in a typical patchy landscape, sampling ants in the three most important constituting habitats: olive plantation, harvested forest, and mature forest. In the study we used two different sampling methods—pitfall traps and observation at baits—which provided information on species presence at different temporal scales. The three habitats displayed different species assemblages, and considerable variation in species composition was observed at different times of the day, particularly in the harvested forest. Functional group analysis showed that the olive plantation, although the most artificial habitat, displayed the highest number of functional groups, suggesting a wider spectrum of available ecological niches for ant species within this habitat type. Overall, it was concluded that each of the three habitats contributes to enhance diversity at the landscape scale, which is greater than that expected from a more homogeneous habitat composition.

Ambient light and mimicry as drivers of wing transparency in Lepidoptera

Transparency reduces prey detectability by predators. While the proportion of transmitted light in aquatic species is higher as light availability increases, less is known about such variation in terrestrial species. Transparency has evolved several times in the typically opaque winged Lepidoptera order (moths and butterflies), displaying a large diversity of degrees. Using two complementary approaches, we explore how the evolution of the differences in light transmittance relates to habitat openness, daytime activity and mimicry syndrome (bee/wasp versus dead-leaf mimic). First, by exposing artificial moth-like prey to wild avian predators in open and closed habitats, we show that survival increases at higher proportions of transmitted light in open habitats. Second, by analysing the evolution of wing features and ecological traits in 107 clearwing species, we confirm that diurnal open-habitat species show higher light transmittances than diurnal closed-habitat species. Additionally, bee/wasp mimics are more often diurnal and have higher and less variable light transmittances than dead-leaf mimics, which are more often nocturnal. Bright conditions, such as open habitats during the day, and mimicry of insects with transparent wings seem to promote high light transmittance. Habitat openness, daytime activity and species interactions play a crucial role in determining transparency design.

Attenuated Outer Primaries in Pigeons and Doves: A Comparative Test Fails to Support the Flight Performance Hypothesis

Sharp reduction of the inner web of the outer primary feather, hereafter referred to as the attenuated primary, is present in 54 of about 300 species belonging to the family Columbidae. The flight performance hypothesis (Goodwin 1983) suggests that attenuated primaries improve flight performance in cluttered habitats, presumably by enhancing maneuverability. This hypothesis predicts that the evolution of attenuated primaries should be associated with the use of closed habitats. A comparative analysis, using the contingent states test (Sillén-Tullberg 1993), was made to test this hypothesis. We found that 15 out of 17 independent instances of evolution of attenuated primaries occurred in clades using closed habitat, but because most species live in closed habitats, chance alone could explain this result. Atenuación de las Primarias Externas en Palomas: Un Análisis Comparativo No Apoya la Hipótesis de la Performance de Vuelo Resumen. En 54 de las aproximadamente 300 especies pertenecientes a la familia Columbidae se observa una abrupta reducción de la lámina interna de la pluma primaria distal, denominada primaria atenuada de aquí en adelante. La hipótesis de la performance de vuelo (Goodwin 1983) sugiere que las primarias atenuadas mejoran el desempeño de vuelo en ambientes cerrados, probablemente por conferir una mayor maniobrabilidad. Esta hipótesis predice que la evolución de primarias atenuadas debería estar asociada al uso de ambientes cerrados. Para evaluar esta hipótesis, se realizó un análisis comparativo usando el método de estados contingentes (Sillén-Tullberg 1993). Se encontró que 15 de 17 instancias independientes de evolución de primarias atenuadas ocurrieron en clados de ambientes cerrados, pero dado que la mayoría de las especies del grupo habitan estos ambientes, este resultado puede ser explicado simplemente por azar.