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1.
The relationship between diet and oral health is widely known, yet data on dental caries prevalence is lacking for many indigenous groups with traditional or rapidly modernizing diets. This research documents caries prevalence in two Maya communities from northern Yucatán (Mexico) with significantly different levels of market integration, subsistence, and diet: Yalsihón, with a traditional, maize‐based subsistence economy, and Dzilam, with access to globalized food markets. Each sample was subdivided by sex into 15–19, 20–24, and 25–30 years‐of‐age classes. Caries prevalence was considered separately both when the lesion affected the enamel superficially (grade 1+) and when it reached the dentin (grade 2+). In both villages, females of all age classes manifest more caries than males. Results show higher prevalence of caries at Dzilam than at Yalsihón, except for grade 1+ caries among 15–19‐year‐old males and grade 2+ caries among 15–19‐year‐old females. Though differences are not significant, earlier pregnancies among 15–19‐year‐old females at Yalsihón could be a causative factor. A survey indicated a more balanced diet at Yalsihón despite a heavier intake of maize than at Dzilam. Striking differences were documented in the ingestion of soda and globalized foods; sodas were virtually absent at Yalsihón, while at Dzilam they were ingested daily in great quantities. The decline in oral health at Dzilam is inferred to result from consumption of industrially processed foods and drinks, while a traditional diet leads to less caries despite daily heavy consumption of maize, which must be considered when interpreting caries rates in archaeological samples. Am J Phys Anthropol 153:190–202, 2014. © 2013 Wiley Periodicals, Inc. 相似文献
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Five sets of herbivore exclosures situated in mesic and semi‐arid savannas in Hluhluwe‐iMfolozi Park, South Africa were used to investigate the effects of mammal browsers and savanna type on plant traits relating to leaf nutrient content, defense, and growth in seven Acacia species. Mostly, browsing did not significantly affect leaf nutrient content but for a few species (i.e., increasing foliar N and P, decreasing C/N, and total polyphenols). Browser effects on structural defenses tended to be more pronounced than for leaf nutrient content and chemical defenses, particularly for semi‐arid species, resulting in longer, thicker, and denser spines, and a lower bite size index on browsed plants for most semi‐arid species. Browsing had no significant effect on growth rates for all species. Secondly, we investigated the effect of savanna type (mesic vs. semi‐arid) on the same set of plant traits and growth rates. A trade‐off in defense strategy was evident where mesic species had lower quality leaves and invested more heavily in growth and chemical defenses, while semi‐arid species generally had higher nutrient content leaves and invested more in structural defenses and higher levels of ramification. These findings suggest that the previously documented trade‐off in plant growth, resprouting ability and architecture between herbivore versus fire‐adapted savanna woody species can possibly be extended to include browse quality and defense type. 相似文献
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Johnattan Hernandez‐Cumplido Bastien Forter Xoaquín Moreira Martin Heil Betty Benrey 《Biotropica》2016,48(3):342-348
Thousands of plant species throughout tropical and temperate zones secrete extrafloral nectar to attract ants, whose presence provides an indirect defense against herbivores. Extrafloral nectaries are located close to flowers and may modify competition between ants and pollinators. Here, we used Lima bean (Phaseolus lunatus L.) to study the plants interaction between ants and flower visitors and its consequences for plant fitness. To test these objectives, we carried out two field experiments in which we manipulated the presence of ants and nectar production via induction with jasmonic acid (JA). We then measured floral and extrafloral nectar production, the number of patrolling ants and flower visitors as well as specific plant fitness traits. Lima bean plants under JA induction produced more nectar in both extrafloral nectaries and flowers, attracted more ants and produced more flowers and seeds than non‐induced plants. Despite an increase in floral nectar in JA plants, application of this hormone had no significant effects on flower visitor attraction. Finally, ant presence did not result in a decrease in the number of visits, but our results suggest that ants could negatively affect pollination efficiency. In particular, JA‐induced plants without ants produced a greater number of seeds compared with the JA‐treated plants with ants. 相似文献
4.
Julián E. García‐Rejón Mildred P. López‐Uribe María Alba Loroño‐Pino Roger Arana‐Guardia Maria Puc‐Tinal Genny M. López‐Uribe Carlos Coba‐Tún Carlos M. Baak‐Baak Carlos Machain‐Williams Guadalupe C. Reyes‐Solis Saul Lozano‐Fuentes Karla Saavedra‐Rodriguez William C. Black IV Barry J. Beaty Lars Eisen 《Journal of vector ecology》2012,37(2):365-372
We collected mosquito immatures from artificial containers during 2010–2011 from 26 communities, ranging in size from small rural communities to large urban centers, located in different parts of Yucatán State in southeastern México. The arbovirus vector Aedes (Stegomyia) aegypti was collected from all 26 examined communities, and nine of the communities also yielded another container‐inhabiting Aedes mosquito: Aedes (Howardina) cozumelensis. The communities from which Ae. cozumelensis were collected were all small rural communities (<6,000 inhabitants) in the north‐central part of Yucatán State. These new collection records for Ae. cozumelensis demonstrate that this mosquito has a far broader geographic range in the Yucatán Peninsula than previously known. Ae. cozumelensis immatures were collected from both residential premises and cemeteries, with specimens recovered from rock holes as well as various artificial containers including metal cans, flower vases, buckets, tires, and a water storage tank. The co‐occurrence with Ae. aegypti in small rural communities poses intriguing questions regarding linkages between these mosquitoes, including the potential for direct competition for larval development sites. Additional studies are needed to determine how commonly Ae. cozumelensis feeds on human blood and whether it is naturally infected with arboviruses or other pathogens of medical or veterinary importance. We also summarize the published records for Ae. cozumelensis, which are restricted to collections from México's Yucatán Peninsula and Belize, and uniformly represent geographic locations where Ae. aegypti can be expected to occur. 相似文献
5.
Patrick A. Omeja Aerin L. Jacob Michael J. Lawes Jeremiah S. Lwanga Jessica M. Rothman Charles Tumwesigye Colin A. Chapman 《Biotropica》2014,46(6):704-711
While overall numbers of African elephant have declined dramatically in recent times, some populations are now confined to protected areas and are locally overabundant—an undesirable situation for both biodiversity conservation and elephants. In forested protected areas, options to manage elephants are limited because it is difficult to safely approach animals, yet it is vital that these populations are managed because browsing by elephants can dramatically alter forest ecosystems. Using data collected over 50 yr in Kibale National Park, Uganda, we examine the prediction that increasing elephant numbers and associated changes in their foraging behavior have caused a shift in tree community composition. Although the relative abundance of elephants increased significantly between 1996 and 2010, the population structure of their preferred tree food species did not change, nor did tree community composition change in favor of species able to re‐sprout after elephant damage. Furthermore, over the last 50 yr Kibale elephants have not become more selective foragers, as would be expected if more nutritious tree species were declining. However, elephants are more abundant in disturbed areas dominated by shrubs and grasses and appear to have arrested forest succession in these areas. At their current abundance, elephants have not selectively altered the composition of intact old growth forest, but they do inhibit the regeneration of disturbed areas. 相似文献
6.
Ochoa G. Jos 《Biotropica》2000,32(1):146-164
The responses of small mammal communities to forest disturbance by logging were evaluated. The study area was located in the Imataca Forest Reserve (Venezuelan Guayana Region), where vegetation was predominantly lowland rain forest. Field analyses were based on a comparative inventory of species inhabiting primary forests and areas disturbed by selective logging. The taxonomic groups used as indicators of die ecological impact of logging belonged to the orders Didelphimorphia, Chiroptera, and Rodentia (families Sciuridae, Muridae, and Echimyidae). The following sampling methods were used: (1) mist nets; (2) traps in 2.4 ha grids (each with 120 stations: 60 at ground level and 60 in trees); and (3) diurnal and nocturnal sight surveys. Total sampling effort consisted of 1904 net‐hours, 10,320 trap‐nights, and 567 h of direct observations. At least 83 mammalian species inhabited die evaluated forests (74.7 percent corresponding to Chiroptera), of which 15.3 percent were restricted to primary forest. In logged areas, small mammal communities were characterized by: (1) higher abundances of individuals; (2) lower proportions of carnivorous and gleaning insectivorous bats; (3) increases in the relative abundance of frugivorous bat species that eat the fruits of colonizing plants; (4) higher proportions of aerial insectivores (Molossidae) at die lowest levels of die forest; (5) simplification in trophic structure of non‐volant species, widi semiarboreal predator‐omnivores being die dominant guild (followed by terrestrial frugivore‐omnivores); and (6) reduction in the relative abundance of mainly canopy‐associated species. These results are explained by: (1) lower availability of key resources associated with primary forest (e.g., roosts in hollow trunks of mature trees, canopy fruits, and tree‐crown continuity); (2) higher relative abundance of some food resources, such as terrestrial invertebrates and saprophytic plants, principally in areas where primary production is limited by low‐fertility soils; (3) increase of roosting sites under fallen trunks; (4) modification of microclimatic conditions at die understory level as a consequence of a greater incident sunlight after canopy opening; and (5) increase in density of early successional plants. The implications of these results to the conservation of biodiversity in forests managed for timber extraction in die Venezuelan Guayana Region are discussed. 相似文献
7.
A major global effort to enable cost‐effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large‐scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large‐scale natural regeneration followed forest clearing and non‐forest land use, and describe the social and ecological factors that drove these local forest transitions. The self‐organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large‐scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land‐use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost. 相似文献
8.
To gain a selective advantage for survival in stochastic environments, the growth of different body parameters of juvenile animals should be constantly adjusted according to prevailing conditions. Hormones, especially insulin‐like growth factor 1 (IGF‐1), are an important part of physiological mechanisms mediating life‐history variability in free‐living animals when connecting available resources (e.g. food) with pathways of somatic growth. We used an IGF‐1 injection treatment in free‐living European Pied Flycatcher Ficedula hypoleuca nestlings to mimic experimentally the differentiation of growth conditions for chicks with a similar genetic background. We showed that there is probably a physiological trade‐off for young animals between the growth rates of structural size and body mass, where IGF‐1 could be part of the physiological modulatory system of this trade‐off. By weakening internal constraints that limit growth, IGF‐1 could help to relieve the trade‐off between these competing body size parameters. 相似文献
9.
M. Lin M. Chevalier S. Lek L. Zhang R. E. Gozlan J. Liu T. Zhang S. Ye W. Li Z. Li 《Journal of fish biology》2014,85(2):343-354
This study tested whether eutrophication could influence life‐history traits of a cyprinid, Chanodichthys erythropterus, in 10 Chinese lakes. Using the von Bertalanffy growth model, the asymptotic length (L∞) and the growth performance index (IGRO) were significantly affected by eutrophication. The gonado‐somatic index (IG) and relative fecundity (FR) were significantly lower in mesotrophic lakes than in eutrophic and hypertrophic lakes. These results indicate that increasing eutrophication affects the life‐history tactics of a freshwater fish. 相似文献
10.
Extensive tropical forest loss and degradation have stimulated increasing awareness at the international policy level of the need to undertake large‐scale forest landscape restoration (FLR). Natural regeneration offers a cost‐effective way to achieve large‐scale FLR, but is often overlooked in favor of tree plantations. The studies presented in this special issue show how natural regeneration can become an important part of FLR and highlight the ecological, environmental, and social factors that must be considered to effectively do so. They also identify major knowledge gaps and outline a research agenda to support the use of natural regeneration in FLR. Six central questions emerge from these studies: (1) What are the ecological, economic, and livelihood outcomes of active and passive restoration interventions?; (2) What are the tradeoffs and synergies among ecological, economic, and livelihood outcomes of natural regeneration, restoration and productive land uses, and how do they evolve in the face of market and climate shocks?; (3) What diagnostic tools are needed to identify and map target areas for natural regeneration?; (4) How should spatial prioritization frameworks incorporate natural regeneration into FLR?; (5) What legal frameworks and governance structures are best suited to encourage natural regeneration and how do they change across regions and landscapes?; (6) What financial mechanisms can foster low‐cost natural regeneration? Natural regeneration is not a panacea to solve tensions and conflicts over land use, but it can be advantageous under some circumstances. Identifying under what conditions this is the case is an important avenue for future research. 相似文献
11.
Data from Norwegian spring‐spawning herring Clupea harengus, were used empirically to assess the performance of a regression method aimed at detecting the time of the onset of maturation from growth trajectories. At the level of the whole dataset, the piecewise linear‐regression method was accurate and showed only a minor bias (?0·17 years) relative to age at maturation visually read from scales. The method, however, was relatively imprecise and provided an estimate of age at maturation equal to the one read from the scale in less than half of the cases (47·6%). Moreover, bias was strongly dependent on age at maturation: the age at maturation of early maturing fish was often overestimated, whereas the opposite was true for late‐maturing fish. Accuracy and precision of the regression method relative to visual readings also depended on the growth type (determined by the nursery area of young C. harengus) and cohort but not on sex. Modifying the original regression method enabled marginally improving the precision of the approach but a strong maturation age‐dependent bias persisted. The results with C. harengus suggested that age‐at‐maturation estimates from the piecewise linear regression method should be treated with caution. 相似文献
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α‐Glycosidase is a catalytic enzyme and it destroys the complex carbohydrates into simple absorbable sugar units. The natural phenolic compounds were tested for their antidiabetic properties as α‐glycosidase and α‐amylase inhibitors. The phenolic compounds investigated in this study have been used as antidiabetic common medicines. This paper aimed to consider their capability to inhibit α‐amylase and α‐glycosidase, two significant enzymes defined in serum glucose adjustment. These examination recorded impressive inhibition profiles with IC50 values in the range of 137.36–737.23 nM against α‐amylase and 29.01–157.96 nM against α‐glycosidase. 相似文献
14.
We used horn measurements from natural and hunted mortalities of male thinhorn sheep Ovis dalli from Yukon Territory, Canada, to examine the relationship between rapid growth early in life and longevity. We found that rapid growth was associated with reduced longevity for sheep aged 5 years and older for both the hunted and natural mortality data sets. The negative relationship between growth rate and longevity in hunted sheep can at least partially be explained by morphologically biased hunting regulations. The same trend was evident from natural mortalities from populations that were not hunted or underwent very limited hunting, suggesting a naturally imposed mortality cost directly or indirectly associated with rapid growth. Age and growth rate were both positively associated with horn size at death for both data sets, however of the two growth rate appeared to be a better predictor. Large horn size can be achieved both by individuals that grow horns rapidly and by those that have greater longevity, and the trade-off between growth rate and longevity could limit horn size evolution in this species. The similarity in the relationship between growth rate and longevity for hunted and natural mortalities suggests that horn growth rate should not respond to artificial selection. Our study highlights the need for the existence and study of protected populations to properly assess the impacts of selective harvesting. 相似文献
15.
1. Fish community structure depends on biotic interactions and abiotic variables. Abiotic variables appear to gain importance in highly variable freshwater systems, such as tropical wetlands where a marked seasonal hydroperiod (dry and wet seasons) modifies water quality and quantity, differentially affecting fish survival and, consequently, modifying species richness and abundance. 2. We evaluated the relationship between abiotic variables and fish community structure in variable (temporary) and stable (permanent) pools that were interconnected in a tropical wetland with marked annual dry and wet seasons. 3. All fish species were able to occupy any of the studied pools, but our results showed distinctive fish community structures in permanent and temporary pools. Community structure was related to temperature, depth, pH and macrophyte coverage. Total fish abundance in the wetland was negatively related to water depth and positively related to macrophyte coverage. 4. Null models of co‐occurrence indicated a non‐random pattern at the wetland scale and a random pattern within groups of pools with similar characteristics, suggesting that fish communities are structured according to habitat features. We conclude that seasonal abiotic variation and habitat characteristics in this highly variable pristine wetland play major roles in structuring fish communities. 相似文献
16.
Abstract Parasitoids have long proven to be model organisms in studying resource‐related constraints on immature development. Here we examine the relationship between host cocoon (= pupal) size in the gregarious endoparasitoid wasp, Cotesia glomerata, and development time and adult size in the solitary idiobiont hyperparasitoid, Pteromalus semotus. Little is known about the biology or ecology of this ecto‐hyperparasitoid species, although it is one of the major secondary hyperparasitoids of C. glomerata. The size of the adult wasp covaried with the size of the host cocoon at parasitism. Moreover, female wasps were larger than male wasps for a given cocoon size. Adult wasps have remarkably long life‐spans, 3 months on average. Longevity did not significantly differ with sex. We also examined how larvae of P. semotus exclude other potential competitors. P. semotus is protandrous, with females taking significantly longer to complete their development than males. In experiments where several eggs of P. semotus were placed on individual pupae of C. glomerata, newly hatched hyperparasitoid larvae moved rapidly over the surface of the host and destroyed the eggs of any conspecifics by biting them before they would initiate feeding on host tissues. Our results are discussed in relation to those with other studies with solitary ichneumonid idiobiont hyperparasitoids of C. glomerata. 相似文献
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Bacteria in the genus Streptomyces are ubiquitous in soil and are well‐known for their production of diverse secondary metabolites, including antibiotics that can inhibit soil‐borne plant pathogens and suppress disease. Pathogen‐suppressive soil bacteria have the potential to influence plant community composition and diversity, but remain relatively unexplored in tropical forest soils. To estimate the potential for disease suppression among Streptomyces communities in tropical dry forests, we cultured soil‐borne Streptomyces from plots in two forests in northwestern Costa Rica (Santa Rosa and Palo Verde) and quantified antibiotic‐mediated pathogen inhibition against three plant pathogens. The potential for pathogen inhibition and disease suppression by Streptomyces was highly variable across the landscape. Densities of pathogen‐suppressive Streptomyces varied by over ten‐fold and were correlated with soil nutrients across the plots. In particular, Streptomyces communities became more pathogen‐suppressive as labile soil P decreased. Inhibitor densities were significantly higher in Santa Rosa than Palo Verde, which may be related to differences in soil texture and/or plant community composition between the two forests. Our findings suggest potential differences in the degree and specificity of antibiotic‐mediated disease suppression in tropical dry forest soils of Costa Rica, and highlight the need for further studies on the drivers of pathogen‐suppressive phenotypes as well as the consequences of spatially variable pathogen inhibition for plant community composition in tropical forest ecosystems. 相似文献
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Ren Bolom‐Huet Eduardo Pineda Francisco Díaz‐Fleischer Antonio L. Muoz‐Alonso Jorge Galindo‐Gonzlez 《Biotropica》2019,51(5):731-746
Chytridiomycosis caused by fungus Batrachochytrium dendrobatidis (Bd) is one of the decline global causes of amphibians. Currently, it is distributed throughout a broad range of climates and ecosystems around the world. An epidemic wave of chytridiomycosis began in North America, resulting in population decline and local extinction of many species, reconfiguring species composition of amphibian communities in the Americas. In Mexico, Bd has caused an amphibian population decrease, and its potential distribution area has not been determined. We reviewed the number of species infected, obtaining Bd frequency of infection by land use and vegetation type, and by elevation range. We examined the known distribution of Bd, estimated the potential distribution, and obtained the bioclimate variables relevant for Bd. Our results indicate that in Mexico, Bd has been detected in 78 species of amphibians in 10 families, from 29 different land use and vegetation types, with cloud forest having the highest number of cases (139) and infected species (15). Bd occurs over an elevation range of 1–3,300 m asl and is most frequent at 1,200–1,500 m asl (36%). In addition to the regions previously described as suitable for Bd, our model included desert, coastal, and tropical forest regions, revealing an increase in the area where amphibians could be at risk of infection. Distribution of Bd is mainly associated with temperature of the wettest quarter and potential evapotranspiration of the warmer quarter. We offer an estimate of the ideal conditions for Bd in Mexico, also information for future studies on Bd and the conservation of amphibians. Abstract in Spanish is available with online material. 相似文献