Abstract
Background
Restoration practices usually emphasize on the structural part of the biodiversity; also, most studies have focused on plants and very few have been conducted on arthropods and ...its function after restoration. The Pedregal de San Angel Ecological Reserve (PSAER) is a protected area immersed in Mexico City and it has been drastically affected by different anthropogenic disturbances. The aim of this study was to compare the relative diversity, richness, and abundance of species level identification, but also the composition through an analysis of ordination of taxonomic (species, family, and order level) and functional (trophic guild) traits of arthropods in three sites subjected to ecological restoration within the PSAER. Restored sites were also compared to conserved and disturbed sites, to evaluate whether restoration efforts are effective at the reserve.
Methods
Arthropods were sampled using pan traps during September 2013 in 11 sites (three restored, four conserved and four disturbed) inside the PSAER. All sampled species were taxonomically identified at species of morphospecies (inside a family) and assigned to a trophic guild. Differences in diversity, richness and abundance were evaluated through effective number of species, comparisons of Chao’s1 estimated richness and a non-parametric Kruskal–Wallis test, respectively. Both taxonomic and trophic guild composition were evaluated using a multivariate analysis and a post hoc test.
Results
We found some differences in richness, abundance, and diversity between sites, but not a clear pattern of differentiation between restored to disturbed sites. The NMDS showed differences at species and order level, and with trophic guilds, among site types. Families were not useful to differentiate types of sites. Regarding guilds, predators were more abundant in conserved sites, while phytophagous insects were more abundant in disturbed sites.
Conclusions
Species and order level were useful to identify differences in communities of arthropods in sites with different management. The trophic guild approach provides information about the functional state of the restored sites. Nevertheless, our quick evaluation shows that restoration efforts at PSAER have not been successful in differentiate restored to disturbed sites yet.
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•Cities are novel ecosystems that generate selective pressure on living organisms.•Dragonflies and damselflies inhabit cities all over the world.•We studied dragonfly and damselfly ...communities along an urbanization gradient in Central Mexico.•Damselfly species richness and abundance are affected by urbanization.•Dragonflies seem resilient to urban conditions.
Cities function as ecological systems composed of a geosphere, a biosphere and an anthroposphere, interacting with each other and generating various selection pressures on urban organisms. Odonates (damselflies and dragonflies) are frequent inhabitants of urban areas, showing no clear or unique responses to urbanization. Thus, we defined an urbanization gradient using a habitat integrity index (HII) calculated for 19 sites in central Mexico, and investigated: a) changes in species richness and abundance along the urbanization gradient; and, b) the relationship between presence of waste of anthropic origin, chemical conditions of water, macrophyte cover, and odonate species richness, abundance and community composition. We analyzed the data for the whole odonate community, as well as for dragonfly and damselfly communities separately in each site. We found higher damselfly species richness and abundance in sites with low urbanization than in sites with high urbanization, and no differences in dragonfly communities along the gradient. We found a positive relationship between dragonfly species richness and abundance and waste percentage and macrophyte cover, and a negative relationship with dissolved solids in water. Our results indicated that odonate communities were fairly tolerant to urbanization and dragonflies were less affected than damselflies. However, we suggest that during design and restructuring of cities, the care and conservation of water bodies and all the life forms that inhabit there, be considered.
1. Interspecific interactions have a fundamental role in plant population dynamics, as they may set the conditions for species coexistence. Parasitic plants, like dwarf mistletoes, offer the ...opportunity to study competition for resources that are different from those consumed by most plants, allowing for a better understanding of the interaction. 2. We explored how interspecific interactions between two dwarf mistletoe species (Arceuthobium), co-infecting the same host species (even sharing the same individual tree of Pinus hartwegii) affect their infection dynamics at two different stages of population development (colonization of new hosts and subsequent growth), and if heterogeneity in resource availability (host density and size structure) affects these interactions. For that purpose, we integrated these processes into a spatially explicit model of density-dependent population growth. 3. We found that self-regulation (density-dependence) was strong for both species; however, the intensity and sign of interspecific interactions changed depending on host size and demographic process. Population growth in Arceuthobium globosum was reduced by competition, except for smaller hosts where A. globosum growth was facilitated by Arceuthobium vaginatum. Arceuthobium vaginatum was facilitated by A. globosum regardless of host size. Colonization of new hosts by A. globosum was enhanced by previous infection by the other species, showing intraguild facilitation. 4. Demographic importance of interactions depended on stand structure: in homogeneous, low-density forests, facilitation predominates, increasing the population sizes of both species, whereas the opposite occurs in heterogeneous and dense forests. Both species achieved stable coexistence, fulfilling the invasibility criterion because each mistletoe species can invade a forest that is already infected by the other species. 5. Synthesis. Despite the fundamentally different mechanisms underlying the interactions between mistletoes compared with non-parasitic plants, our results reveal that their behaviour at the population level is similar. Stabilizing mechanisms, like strong self-limiting population growth, allow dwarf mistletoe coexistence. Interactions shift as populations develop, and they depend largely on environmental factors such as forest structure. Intraguild mutualism is shown as a relevant process for colonization of new spaces, highlighting the complexity of competitive/facilitative interactions between parasitic plants, a formerly unexplored subject. Interactions can only be fully understood when integrating all their components at the population level. Analysing these interactions may contribute to the understanding of plant–plant interactions in general, and convey interesting implications for forest management.
The maintenance of interactions between plants and their floral visitors depends on factors such as resource variability, seasonality, and population dynamics. Changes in water availability along ...with different types and levels of anthropogenic disturbance may influence how plants and pollinators interact, especially in arid environments.
In a semi‐arid area of the southernmost Chihuahuan Desert (Mexico), we surveyed bee–plant interactions in the dry and rainy season at sites that differed in disturbance type. We used a mutualistic network approach to analyse our data.
We collected 946 bee individuals belonging to 32 bee species, almost a third of the total richness previously reported for Querétaro state. We detected a strong impact of seasonality on the structure of ecological interactions, with more complex and robust interactions among bee and plant species in the rainy season.
We did not find statistical support for a relationship among disturbance, nestedness, or niche overlap. We did find disturbance negatively affected plant robustness to secondary extinctions.
Four plants: Echinocactus platyacanthus, Opuntia stenopetala, Senna wislizeni var. painteri and Cylindropuntia imbricata comprised the core species that were primarily responsible for the resilience of the bee communities. The following bees conformed the generalist core of species: Diadasia rinconis, Lasioglossum (Dialictus) sp. 1, Apis mellifera, and Augochlorella pomoniella.
Overall, network nestedness and robustness differed significantly between seasons but not among sites with different levels of disturbance.
There is a strong impact of seasonality on the structure and assembly of bee–plant ecological interactions, promoting a more complex and robust system in the rainy season.
We did not find statistical support for a relationship among disturbance, nestedness, or niche overlap. However, we found that disturbance negatively affected plant robustness to secondary extinction.
The plants Echinocactus platyacanthus, Opuntia stenopetala, Senna wislizeni var. painteri and Cylindropuntia imbricata act as core species for the maintenance of resilient bee communities. The following bees formed the generalist core of species: Diadasia rinconis, Lasioglossum(Dialictus) sp. 1, Apis mellifera, and Augochlorella pomoniella.
Overall, network nestedness and robustness differed significantly between seasons but not among sites with different levels of disturbance.
The demand for food and the environmental damage linked to its production will increase significantly; thus, the need for protein sources that are nutritious, digestible, and sustainable in ...environmental terms is rising. Many bromatological studies show that insects possess high protein amounts, becoming an alternative to conventional livestock. However,
in vivo
studies on digestibility are scarce (either on humans or laboratory animals), particularly when analyzing assimilation efficiency. In this work, we measured weight gain, food intake, feces and urine quantification, protein assimilation efficiency, and food conversion ratio in Wistar rats fed with five different diets for 5 weeks. Three diets were based on different concentrations of orthopteran protein (
Sphenarium purpurascens
) and were compared against a control diet and a highly caloric treatment, which was heavy in sugar and refined flours. The diet based on 23% of
S. purpurascens
protein resulted in 2.0 and 20.8% more biomass accumulation than the control and the highly caloric diet, respectively. The diets with 18% and 23% insect protein exhibited an average feed conversion of 6.3, while the control group resulted in 8.5 and the caloric diet in 42.7. These results show that
S. purpurascens
protein yields higher or equal conversion values than a conventional diet, indicating that grasshoppers can be a sustainable and nutritious food for humans and an alternative to livestock. On the other hand, even if feeding insects to farm animals for human consumption is considered an option, it seems highly inefficient, mainly because this practice increases one trophic level in the energy flow. Therefore, incorporating insect protein into human diets represents a sustainable alternative to face future feeding and environmental challenges. Proposals like the one we present here have yet to be evaluated; however, our findings in laboratory animals project a promising future for human populations, where low environmental cost proteins could be obtained sustainably.
La Reserva Ecológica del Pedregal de San Ángel de Ciudad Universitaria (REPSA-CU) alberga una fracción del derrame original de lava del volcán Xitle y actualmente el suelo y la comunidad vegetal son ...afectados por la fragmentación del paisaje, el depósito de residuos de relleno (como cascajo y otros materiales) y las construcciones irregulares. Se realizó una descripción de las principales propiedades físicas del suelo en sitios con topografía contrastante (planos abiertos conservados y perturbados, grietas y hondonadas). Se encontró un efecto signif icativo de la topografía sobre las propiedades edáf icas. La materia orgánica mostró correlaciones positivas con la porosidad, la arcilla y la humedad; y mostró correlaciones negativas con la densidad aparente y real, la compactación, la acidez y el contenido de arena. El porcentaje de materia orgánica fue el atributo más importante para la clasif icación y el ordenamiento canónico de los sitios. Los planos abiertos perturbados siguieron una trayectoria edafogénica diferente de los sitios conservados y asemejan Urbanosoles. Se sugiere la implementación de estrategias encaminadas a lograr su restauración ecológica. La clasif icación del suelo de esta reserva corresponde a tres órdenes probables: 1) Entisol háplico, por la edad geológica de su deposición y los procesos de pedogénesis en curso; 2) Litosol volcánico, por la recurrencia de afloramientos rocosos lávicos de origen magmático y 3) Andosol vítrico por la naturaleza de su material parental y predominancia de arenas. Se concluye que el suelo de la REPSA-CU es incipiente y actualmente los horizontes de diagnóstico están en proceso de desarrollo. La importancia ambiental de su suelo radica en su capacidad de f iltración y retención de agua; su porosidad y compactación le permiten ser un banco de semillas y hábitat de diversas especies de insectos. La fragilidad de los agregados edáf icos y la predominancia textural de arena representaron un factor latente de erosión.
We evaluated the effect of arthropod presence on the growth of Tillandsia violacea in a Quercus spp.-Abies religiosa forest in Hidalgo, Mexico. We used 40 T. violacea individuals (<20 cm in diameter) ...attached to Quercus spp. trees. Insecticide was sprayed weekly on 20 plants during 1 y, another set of 20 plants located 100 m away were not sprayed. Both leaf number (N) and length (L) were recorded every 2 mo, and the foliar load was obtained. We found lower leaf production, leaf length, and foliar load in plants sprayed with insecticide than in nonsprayed plants. Our results show arthropod presence increases plant growth. We suggest this is due to the fragmentation activity of arthropods on litter, which promotes the decomposition process of the organic matter accumulated in epiphytes and increases nutrient release to the plant.
Human food waste is an essential resource for many animals that inhabit urban ecosystems and has allowed some species to proliferate in cities. Virginia Opossums (
Didelphis virginiana
) are ...considered a good example of this process; however, the real role of waste in this animal’s diet is still unclear. Therefore, this study aims to compare opossums’ diet from urban and natural areas in Mexico City. Opossums were live-trapped, and samples of hair and blood were taken to perform a stable isotope analysis of C and N. The results show that opossums from natural and urban areas, in general, have a very similar isotopic niche; however, one natural location fell out of this pattern, and here opossums based their diet on C3 plants. This suggests that opossum diets have a similar carbon source and occupy a similar trophic position in urban and natural areas. However, there is a separation between opossums in urban and natural areas, not so much in the isotopic niche, but in the feeding habits since natural areas, opossums prefer to feed in their distribution area despite the availability of better quality food in the nearby urban areas.
Abstract Anthropophony is a prominent component of soundscapes worldwide and is known to impact biota. While responses to anthropophony in terrestrial and marine animals have been relatively ...well-studied, there is still a lack of knowledge regarding freshwater animals. In fact, freshwater taxa are among the possibly most threatened groups, and unveiling the reasons for their threat is crucial. We investigated the effect of low-frequency sounds -usually associated with anthropophony- on the stridulation of Krizousacorixa femorata , a common water bug in Mexico City. Using aerial recordings, we estimated the Normalized Difference Soundscape Index (NDSI), which is the most commonly used index to measure anthropophony, to characterize soundscapes in six city sites throughout the year. Additionally, from underwater recordings in the same sites, we obtained the peak frequency (Pf) of the stridulations, as it is the frequency with the highest energy and, therefore, the one that can travel the farthest and can be identified even in the presence of overlapping sounds. Finally, we evaluated the relationships between soundscapes and Pf through a mixed linear model. There was a negative correlation between NDSI and Pf, indicating higher-pitched stridulations at sites with dominant anthropophony. While we cannot rule out other factors contributing to stridulation variation, we remain uncertain about how low-frequency sounds impact freshwater ecosystems and the intricate relationship between soundscapes and aquatic life in urban settings.
Phenotypic plasticity in macroscopic fungi has been poorly studied in comparison to plants or animals and only general aspects of these changes have been described. In this work, the phenotypic ...variation in the basidiomata of Thelephora sp. (Thelephoraceae) was examined, as well as some aspects of its ecology and habitat, using 24 specimens collected in the tropical forests of the Chamela Biological Station, Jalisco, Mexico. Our observations showed that this taxon has clavarioid basidiomata that can become resupinate during development and growth if they are in contact with rocks, litter or live plants, establishing in the latter only an epiphytic relationship. This tropical species may form groups of up to 139 basidiomata over an area of 32.2m2, and in both types of vegetation (tropical sub-evergreen and deciduous forest) were primarily located on steep (>20 degree) South-facing slopes. It is found under closed canopy in both tropical forests, but its presence in sub-evergreen forests is greater than expected.
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