Search

Soil and water characteristics in micro basins with different land uses/land cover (LULC) can influence riparian vegetation diversity, stream water quality, and benthic diatom diversity. We analyzed 18 streams in the upper part of the La Antigua River basin, México, surrounded by cloud forests, livestock pastures, and coffee plantations. Concentrations of P, C, and N were elevated in the humus of forested streams compared to other land uses. In contrast, cations, ammonium, and total suspended solids (TSS) of water streams were higher in pastures and coffee plantations. These results indicate that LULC affects stream chemistry differently across land uses. Vegetation richness was highest (86–133 spp.) in forest streams and lowest in pastures (46–102), whereas pasture streams had the greatest richness of diatoms (9–24), likely due to higher light and temperatures. Some soil and water characteristics correlated with both true diversity and taxonomic diversity; soil carbon exchange capacity (CEC) correlated with vegetation diversity (r = 0.60), while water temperature correlated negatively (r = − 0.68). Diatom diversity was related to soil aluminum (r = − 0.59), magnesium (r = 0.57), water phosphorus (r = 0.88), and chlorophyll (r = 0.75). These findings suggest that land use affects riparian vegetation, while physical and chemical changes influence diatom diversity in stream water and soil. The lack of correlation between vegetation and diatom diversity indicates that one cannot predict the other. This research is an essential first step in understanding how land use changes impact vegetation and diatom diversity in mountain landscapes, providing valuable insights for environmental monitoring and conservation efforts in tropical cloud forests. [ABSTRACT FROM AUTHOR]

Gut microbial communities are part of the regulatory array of various processes within their hosts, ranging from nutrition to pathogen control. Recent evidence shows that dung beetle's gut microbial communities release substances with antifungal activity. Because of the enormous diversity of gut microorganisms in dung beetles, there is a possibility of discovering novel compounds with antifungal properties. We tested the antifungal activity mediated by gut microbial communities of female dung beetles against nine phytopathogenic fungi strains (Colletotrichum asianum-339, C. asianum-340, C. asianum-1, C. kahawae-390, C. karstii-358, C. siamense-220, Fusarium oxysporum-ATCC338, Nectria pseudotrichia-232, Verticillium zaelandica-22). Our tests included the gut microbial communities of three species of dung beetles: Canthon cyanellus (roller beetle), Digitonthophagus gazella (burrower beetle), and Onthophagus batesi (burrower beetle), and we followed the dual confrontation protocol, i.e., we challenged each fungal strain with the microbial communities of each species of beetles in Petri dishes containing culture medium. Our results showed that gut microbial communities of the three dung beetle species exhibit antifungal activity against at least seven of the nine phytopathogenic fungal strains. The gut microbial communities of Onthophagus batesi significantly decreased the mycelial growth of the nine phytopathogenic fungi strains; the gut microbial communities of Canthon cyanellus and Digitonthophagus gazella significantly reduced the mycelial growth of seven strains. These results provide a basis for investigating novel antifungal substances within gut microbial communities of dung beetles. [ABSTRACT FROM AUTHOR]

Background: We used Illumina paired-end sequencing to isolate and characterize microsatellites of Canthon cyanellus, a Neotropical roller dung beetle, encompassing several lineages within its distribution range. Methods and results: We examined C. cyanellus specimens collected at eight different localities in Mexico (two or three specimens per locality). We initially performed amplification tests with 16 loci, but two of which were unsuccessful. The 14 remaining microsatellites were polymorphic, with 2–16 alleles each. The expected and observed heterozygosity ranged from 0.11 to 0.76 and from 0.20 to 0.78, respectively. Conclusions: These microsatellites will help to assess structure at the population and lineage levels, identify zones of potential hybridization between lineages, and draw a more precise geographic delimitation of C. cyanellus lineages. [ABSTRACT FROM AUTHOR]

Studies involving Heteroptera biodiversity and ecology are incipient in tropical ecosystems and have mainly focused on taxonomy. We evaluated the relationship between Heteroptera diversity and habitat type, elevation, forest fragment size and periods of the year in the northernmost limit of Neotropical rainforest, Los Tuxtlas. We sampled Heteroptera using pitfall traps installed in pasturelands and forest fragments, which ranged from 25 to 560 ha in size and were located between 150 and 870 m.a.s.l. Heteroptera species richness and abundance were significantly higher in forest fragments than in pasturelands. In addition, Heteroptera species richness and abundance were negatively related to forest fragment size but were not significantly related to elevation. Lastly, species richness and abundance were significantly higher during spring and summer than during autumn and winter. The greater Heteroptera diversity observed in the forest fragments was likely the result of more than half of the species observed being unique to these habitats. This highlights the importance of habitat conservation in the maintenance of Heteroptera diversity. This study expands the incipient ecological knowledge of this group and provides a basis for future Heteroptera research within fragmented landscapes. [ABSTRACT FROM AUTHOR]

Context: The effects of habitat loss and fragmentation on biodiversity involve a series of mechanisms and processes that cannot be studied in isolation, mainly because human-modified landscapes are spatially heterogeneous. Despite the recent evidence on how habitat quality and landscape structure may regulate species composition and community structure, there is no empirical information on how ant-plant co-occurrence networks respond to landscape changes.Objectives: In this study, we used tools derived from landscape ecology and graph theory to model how habitat loss and forest fragmentation affect ant-plant co-occurrence networks at two different spatial levels (local and landscape) in a human-modified tropical rainforest in Mexico. Methods We sampled ant-plant co-occurrence networks in 16 landscapes and calculated species and co-occurrence diversity as well as the specialisation of the networks. For each landscape, we measured a series of biotic and abiotic variables at the local level and another set of variables at the landscape level.Results: We found that the landscape context (i.e. forest cover and landscape heterogeneity) was a better predictor of plant diversity and diversity of ant-plant co-occurrences compared with local characteristics. Moreover, we also observed that network specialisation was positively related to the amount of forest cover in landscapes.Conclusions: In short, our results highlight the importance of studying the diversity of species and co-occurrence networks within a landscape approach to predict the impact of habitat loss and fragmentation at different spatial levels and contexts. [ABSTRACT FROM AUTHOR]

Ants in tropical forests participate in a wide variety of processes, but human activity can disturb their communities and cause the loss of key species. In this study, we evaluated the effects of human disturbance on the alpha and beta diversity of ant assemblages in a successional gradient of secondary forests growing in abandoned maize fields of the Lacandon region, previously covered by tropical rain forest. Our results show that the alpha diversity of ant species and genera increases with the age of the secondary forests; however, deforestation could cause the loss of certain genera. The turnover of ant species is low along the successional gradient and it is regulated by ecological filters. Secondary forests serve as a refuge for certain ant species and as their successional age increases, they tend to recover the species richness of the mature forest. [ABSTRACT FROM AUTHOR]

Theory predicts that asymmetry between contenders influences their ability to defend resources. More recently, some theoretical approaches have also examined the circumstances that might promote sharing of the disputed resources. We tested these hypotheses in males of the ball roller beetle Canthon cyanellus cyanellus. Males fight for possession of a food ball, which is a vital resource used for nesting. We evaluated the role of food resource ownership, body size and reproductive status on the outcome of contests (win, lose or share) between males that rolled a food ball (owners or finders) either alone or with a female partner, when faced with male intruders (or joiners). Large owners of a food ball had a higher probability of victory than small intruders, and small owners had a high probability of losing when faced with large intruders. The reproductive status of both contenders also influenced their chances of winning: previously mated owners of a food ball had a higher probability of winning than virgin owners. Males of a similar size tended to split the food ball, thereby sharing the resource. Our results suggest that competitors may adjust the intensity of their aggression depending at least on their own resource holding power (RHP), the value of the resource in dispute and perhaps even the RHP of their opponents. Sharing the food ball emerges as a fresh solution between similarly matched contestants. [ABSTRACT FROM AUTHOR]

Field observation and laboratory experiments were conducted to investigate sperm competition and patterns of sperm fertilization under different experimental conditions in the carrion ball-roller beetle Canthon cyanellus cyanellus. Males in nature can mate with females whose spermathecae contains fertile sperm from other males. Sperm precedence was investigated using a visible genetic marker. The progeny of red (homozygous recessive) virgin females mated once with a red male and afterward, once with a green beetle (homozygous dominant) and vice versa, revealed that regardless of its color, the last male to mate fertilized c.a. 50% of the eggs, suggesting strong sperm competition. Males were able to achieve higher levels of paternity (more than 80%) when mated ad libitum with previously mated females, although large amount of variance in paternity does not exclude the possibility of first male sperm precedence or female cryptic choice. These results suggest that repeated mating and sperm replacement are the mechanisms by which last males achieve sperm precedence. [ABSTRACT FROM AUTHOR]

The purpose of this study was to characterize five crater lakes in Los Tuxtlas, Mexico, on the basis of morphological, physical, chemical, and biological features. A bathymetric map of each lake was obtained and morphometric parameters were calculated. Physical and chemical parameters (temperature, transparency, nutrients, pH, conductivity, cations) and chlorophyll a were measured for three periods: the cold season (January), the dry season (May), and the rainy season (October) of 2000. The trophic state of each lake was determined using Carlson's indices for transparency and chlorophyll a. The lakes studied have the morphometric characteristics of maar-type volcanic lakes. Majahual, Chalchoapan, and Manantiales are the deepest lakes with elliptical basins and are classified as warm monomictic systems; Verde and Mogo are shallow lakes with conic basins and are warm polymictic. Majahual and Chalchoapan had an anoxic hypolimnion, while at Manantiales a metalimnetic oxygen maximum was measured. Sodium was the dominant cation in the five lakes, while bicarbonate was the dominant anion. Nutrient and chlorophyll a concentrations, transparency, and trophic indices suggest that Chalchoapan, Verde, and Mogo are eutrophic lakes with tendencies toward hypereutrophy; Manantiales and Majahual, in contrast, can be classified as mesotrophic lakes. The trophic state of lakes was indirectly related to deforestation and to the use of agricultural fertilizer in Los Tuxtlas as well as to certain morphometric characteristics. [ABSTRACT FROM AUTHOR]