El Colegio de la Frontera Sur
  • San Cristóbal de las Casas, Quintana Roo, Tabasco, Chiapas, Campeche, , Mexico
Recent publications
Sustainable farming near tropical forests can buffer ecosystems at risk of biodiversity loss. In mountainous forest frontiers however, many smallholders raise cattle using practices that degrade land, also endangering future livelihoods. Silvopasture, a type of agroforestry, enables cattle farming, biodiversity conservation and can have climate benefits. But its adoption is slow, and ambiguity remains regarding the most relevant predictors for the adoption of agroforestry more broadly. In the context of a pilot silvopastoral project in La Sepultura Biosphere Reserve, we model livelihood diversity as a predictor of both farmers' participation in the project and their adoption of silvopasture (trees grown after a year). We use data collected with a novel token-based approach (n = 104) and account for selection bias. The findings show that livelihood diversity is significantly associated with the two outcomes, but with opposite directions: higher participation and lower adoption levels. Our results provide insight to design and target policies to encourage innovative and sustainable agriculture, especially in contexts of multiple interventions and policy mixes. For example, programmes including economic incentives may consider helping participants overcome different barriers at each stage of the adoption process: in the initial decision to try and during implementation.
Members of the parasitic copepod family Pennellidae are highly transformed ecto- or mesoparasites infecting a wide array of marine teleosts. Currently, this family contains more than 20 valid genera. The pennellid genus Cardiodectes Wilson, 1917 is currently known to contain 15 nominal species. Some pennellids exhibit a complex life cycle involving an intermediate host; it is known that planktonic pteropod molluscs are intermediate hosts for Cardiodectes. Pennellid mesoparasites can be detected by the conspicuous female egg-carrying trunk on the host external surface. The copepod cephalothorax is deeply embedded in the host muscle tissue. Members of Cardiodectes have been reported from several teleost families, mainly Myctophidae and Engraulidae. From the parasitological examination of a juvenile individual of a scarid teleost collected in a reef lagoon of Roatan Island, Honduras, Central America, several ovigerous female individuals of a mesoparasitic pennellid copepod were found; these specimens were recognized as representative of an undescribed species of Cardiodectes Wilson, 1917. The new species, C. roatanensisn. sp., differs from its known congeners in several respects, including the presence of neck lobes, paired posterior protuberances of the trunk, trunk shape and proportions, structure of cephalothorax lobes, cephalothorax relative size, and number of legs. The new species from Roatan is the second member of this copepod genus to be reported from the Caribbean region, after C. boxshalli Bellwood, 1981 from off Jamaica (Bellwood 1981). It is also the second report of Cardiodectes on a parrotfish.
The interaction between the mirid predator Engytatus varians (Distant) and a Mexican isolate (SeSIN6) of Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) was examined under laboratory conditions. In a choice test, E. varians females and males demonstrated no preference for virus-infected Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) second instar compared with non-infected at two different post-inoculation times (48 and 72 h). Similarly, prey search time (5–6 h) did not differ significantly for each type of prey. Bioassays were performed to confirm the viability of occlusion bodies (OBs) from predator’s faces collected at 48, 96, and 144 h after exposure to virus-infected S. exigua larvae. The proportion of larval mortality was between 0.20 and 0.62 across all times and both E. varians sexes. Another experiment was performed to evaluate the dispersal of SeSIN6 OBs by physical contact with E. varians adults on tomato (Solanum lycopersicum Miller) leaflets treated with the pathogen. Engytatus varians adults were exposed to OB-treated tomato leaflets during 24 or 48 h using a clip cage. After each exposure time, these adults were removed and placed on clean uncontaminated leaflets for periods of 4–48 h. These leaflets were then exposed to groups of S. exigua second instars in clip cages. The proportion of virus-induced larval mortality of S. exigua (ranging from 0.45 to 1.0) was significantly affected by the duration of exposure of E. varians adults on OB-treated or untreated tomato leaflets. Our results reveal the potential of E. varians as an agent for the dispersal of SeMNPV OBs.
Atlantic Bonefish (Albula vulpes) are economically important due to their popularity with recreational anglers. In the State of Florida, USA, bonefish population numbers declined by approximately 60% between the 1990s and 2015. Habitat loss, water quality impairment, chemical inputs, and other anthropogenic factors have been implicated as causes, but the role of pathogens has been largely overlooked, especially with respect to viruses. We used a metagenomic approach to identify and quantify viruses in the blood of 103 A. vulpes sampled throughout their Western Atlantic range, including populations in Florida that have experienced population declines and populations in Belize, Mexico, Puerto Rico, and The Bahamas that have remained apparently stable. We identified four viruses, all of which are members of families known to infect marine fishes (Flaviviridae, Iflaviridae, Narnaviridae, and Nodaviridae), but all of which were previously undescribed. Bonefish from Florida and Mexico had higher viral richness (numbers of distinct viruses per individual fish) than fish sampled from other areas, and bonefish from the Upper Florida Keys had the highest prevalence of viral infection (proportion of positive fish) than fish sampled from any other location. Bonefish from Florida also had markedly higher viral loads than fish sampled from any other area, both for a novel narnavirus and for all viruses combined. Bonefish viruses may be indicators of environmentally driven physiological and immunological compromise, causes of ill health, or both.
Despite the crucial role of highly social bees (Hymenoptera, Apidae) in crop production, agricultural practices that embrace the use of chemicals for pest control put these important pollinators at risk. Most studies that have evaluated the expression of enzymatic routes involved in xenobiotic removal in these species, including pesticides, have been carried out in the honey bee, Apis mellifera . These results have been used to figure out the response of non- Apis bees to pesticides, but recent works suggest that such response may be species-specific. We tested this possibility by evaluating the glutathione S-transferase (GST), cytochrome P ⁴⁵⁰ , acetylcholinesterase (AChE) and α-, β- and ρ-NPA esterases in foragers both of the stingless bee Scaptotrigona mexicana and of A. mellifera . Foragers from colonies of both species located in two sites in an agricultural landscape in Chiapas, Mexico were collected every four months for a year and enzymatic expression was measured. Scaptotrigona mexicana showed a higher enzymatic activity and AChE inhibition than A. mellifera in both sites. Neither site nor time affected statistically the expression of enzymes in each species. Our results suggest that A. mellifera cannot be used as a surrogate for other species, at least for S. mexicana . The higher enzymatic activities in S. mexicana related to A. mellifera can be explained by the presence of organochlorines and organophosphates in the study area, as revealed in previous studies, and the shorter fly range of S. mexicana .
Purpose This study evaluated the in vitro anthelmintic (AH) activity against Haemonchus contortus of ten extracts obtained from coffee pulp waste (Coffea canephora (Co)), maize comb waste (Zea mays (Zm)), pangola grass hay (Digitaria eriantha Steud (Di) and different mixtures of those materials. Methods Three batches prepared with individual feedstuffs (T1, T2 and T3), 3 batches formed with 2 feedstuffs (50:50 proportion; T4, T5 and T6), a batch combining 3 feedstuffs (T7) and 3 batches combining 3 feedstuffs (T8, T9 and T10). The batches of individual feedstuffs and mixtures were used to determine their chemical composition as well as preparing 10 methanol–water (70–30%) extracts. The in vitro tests used against H. contortus were egg hatch test (EHT), larval mortality test (LMT) and larval exsheathment inhibition test (LEIT). Results Chemical composition suggested that the nutritional value of Co and the batches including Co (T1, T4, T6 to T10) could be used for ruminant nutrition, but the Di and Zm showed very poor nutritional potential unless they are combined with Co. Extracts showing activity against eggs were T4 and T8 (P < 0.05). Significant L3 mortality was reported for extracts T1, T3, T4 and T8 (P < 0.05). Extracts of T3, T4, T7, T8 and T10 showed an EC50 < 1000 μg/mL for the L3 exsheathment inhibition (P < 0.05). Chemical analyses showed the presence of coumarins and flavonoids in all the extracts. Conclusion Extracts obtained from T4 and T8 showed the best overall activity in the three in vitro tests against H. contortus and a good nutritional quality that could be suited for ruminant nutrition. Graphical Abstract
The expansion of the oxygen minimum zone (OMZ) associated with global warming has generated interest in its variability during the last two millennium. Several oceanographic mechanisms, as advection of dissolved oxygen and depletion of dissolved oxygen by oxidation of exported marine productivity, could explain the variability of δ¹⁵N in organic matter as a denitrification indicator of the water column in the Pacific Ocean. Our objective was to infer local or remote forcing mechanisms that lead to the strengthening or weakening of the OMZ in the Eastern Tropical North Pacific. A 42 cm sediment core was recovered at 680 m of depth in the Magdalena margin and sectioned every 1 cm for carbon and nitrogen stable isotope analysis. During the periods 1260–1420 CE and 1670–1800 CE, the desynchronization of δ¹⁵N between the Pescadero and Magdalena margins with respect to the Santa Barbara Basin confirms a decrease in denitrification in the Mexican Pacific. During the Little Ice Age (LIA: 1450 to 1800 CE), the δ¹⁵N indicated a reduction in denitrification in the Magdalena margin and the Santa Barbara Basin, but not in the Pescadero margin. This suggests an intense advection of dissolved oxygen from tropical waters during the LIA. In the Pescadero margin, denitrification conditions persisted over the same period, while exported productivity maintained a high oxygen demand.
The coffee leaf miner, Leucoptera coffeella (Guérin-Mèneville), is one of the main coffee pests (Coffea spp.) in the Neotropical region. This moth species develops exclusively on leaves of Coffea plants. In this study, we investigated the oviposition preference and performance of L. coffeella in environmentally stressed Coffea arabica L. plants. These plants were exposed to three independent treatments: (a) shade levels (0%, 50%, and 100%), (b) water availability (constant and intermittent irrigation), and (c) the application of phytohormones (salicylic acid, SA; or methyl jasmonate, MeJA). Groups of leaves from these treatments were exposed to individual L. coffeella-mated females, and the number of eggs laid per leaf and the performance in terms of the duration of the immature stages and survival of L. coffeella was recorded. Our results showed that oviposition preference was indistinct among the evaluated treatments. However, leaf miner larvae developed faster under 50% shade level, whereas survival was lower in plants under 100% shade level. Individuals reared on plants under 100% shade level showed slower larval development and smaller adult size. Constant plant irrigation decreased the L. coffeella survival. The application of MeJA delayed larval development, while the application of SA increased adult size. Our results suggest that plant environmental stress should be considered when studying the performance of specialist insect herbivores.
Coastal wetlands face the growing problem of altered fire regimes that compromise ecosystem structures and functions, as well as the ecosystem services from which society benefits. In this review of the state of fire management research in coastal wetlands, we identified 81 publications on the topic over the last 35 years. Most studies analyzed the relationships between fire and ecosystems using geospatial tools and were conducted in swamps, marshes, savannas, mangroves, dunes and hammock forests. Productive activities in the coastal zone like agriculture, cattle ranching, and hunting as well as the increased demand of water for human consumption directly or indirectly favor a rise in both the frequency and intensity of fires in coastal wetlands. In addition to the local impacts of this altered regime, there are synergistic effects with alterations in the hydrological regime, land use changes and atmospheric changes that increase the susceptibility to unwanted fire in these ecosystems. We emphasize the need to move towards focuses that adopt a socio-ecological and interdisciplinary perspective to conserve and restore the fire regimes in coastal wetlands.
The Hondo River is the natural border between Mexico and Belize, and it is part of the distribution area of the Endangered Antillean manatee Trichechus manatus manatus. Currently, the Hondo River does not have any special protection. Employing qualitative research methods, we documented the social perception and local knowledge from riverside communities to assess conservation status and trends of manatees in the area. Fifty semi-structured interviews were carried out to river users in 16 Mexican communities, distributed in six segments along the riverbed. The claims of the inhabitants agree with boat-based surveys: most of the current and historical manatee sightings were reported in segments of the main watercourses, but also in small tributaries, which are usually shallow and rich in aquatic vegetation. Additionally, the local perception about manatee conservation status can be helpful to understand population trends and threats: 48% of the interviewees claimed that nowadays the number of sighted manatees is less than that observed 10 years ago. The responders identified water pollution due to cane cultivation practices, motorized vessels traffic, and presence of fishing nets as potential threats to manatees. This study provides evidence of relevant local knowledge about the manatee ecology and its habitat, critical in the construction of binational conservation strategies for the species. Therefore, local resources users may play an increasingly significant role in manatee management and monitoring. Although manatees are poached for their meat in several areas of their distribution, the most common value attributed to manatees in Hondo River was non-use existence values. Local people recognize the challenges to observe this cryptic species in this river, but also identified manatees as potential flag species, suggesting that it may represent a valuable resource for ecotourism. We suggest that the non-extractive use of manatees has the potential for promoting species conservation and local economic growth.
Background and aims Triglycerides are the initiators of the metabolic changes that lead to atherogenic dyslipidemia (AD). The APOA5 and APOA1 genes are involved in the response and metabolism of serum lipids and lipoproteins, where single nucleotide polymorphisms (SNP) rs662799 (promoter region) and rs5070 (intronic region) have been associated with the susceptibility to dyslipidemia. Until now, few studies evaluate the association of these polymorphisms with the presentation of hypertriglyceridemia and AD among Mexican children. Therefore, the objective was to determine the association between rs662799 and rs5070 with hypertriglyceridemia and AD in a pediatric population of southeastern Mexico. Materials and methods A case–control analysis was performed including 268 infants aged 2–16 years, anthropometric, clinical variables, and serum lipid profiles were analyzed. DNA was extracted from blood samples and genotyping of polymorphisms was executed with the TaqMan SNP genotyping assay. Allele and genotypic frequencies were calculated. For genetic association analysis, logistic regression models were fitted according to models of inheritance. Results The SNP rs662799 (C) was significantly associated with hypertriglyceridemia in the overdominant model (OR = 3.89, p = 0.001) and AD in the dominant model (OR = 4.01, p = 0.001). The SNP rs5070 (T) has a protective effect against hypertriglyceridemia in the additive risk model (OR = 0.68, p = 0.03). Conclusion Polymorphism rs662799 was significantly associated with cases of hypertriglyceridemia and AD in minors in southeastern Mexico. On the other hand, rs5070 polymorphism was not associated with cases of hypertriglyceridemia or AD.
Global processes manifesting as activities in local places have led to an increase in documented conservation conflicts. Conservation conflicts are sometimes labelled human-wildlife conflict, focusing only on the direct negative impact of species (usually wildlife) on humans or vice versa. However, many authors now recognize that conservation conflicts arise between people with diverse views, when one party acts against the interests of another. They are thus human-human conflicts and not merely an impact on or from conservation. Conflict is not always directly correlated with impact because perceptions of risk, levels of tolerance and conservation values influence human responses. This review aims to define the concept of ‘conservation conflict hotspots’ and explore its practical applications in conservation. We propose that the interaction of impact, risk perception, level of tolerance in a context of conservation values can be mapped at a local scale, with spatial visualization assisting the prediction, understanding and management of such hotspots. The term conservation value incorporates measures of indigeneity, endemicity and demography along with emotional or cultural attachment to species or places. The umbrella terms of risk perception and tolerance capture many of the aspects of attitude, values and individual demographics that can influence people’s actions, enabling contextualization of relevant social factors at local scales. Spatially mapped layers enable us to plan and target conservation efforts towards human as well as ecological factors. The concept of ‘conservation conflict hotspot’ emphasizes the need for transdisciplinary research to understand underlying drivers of conflict and for dialogical and peace-building approaches to facilitate trust and cooperation amongst actors. We can thus address conflicts and achieve sustainable outcomes.
The most recent glacial cycles of the Pleistocene affected the distribution, population sizes, and levels of genetic structure of temperate-forest species in the main Mexican mountain systems. Our objective was to investigate the effects these cycles had on the genetic structure and distribution of a dominant species of the “mexical” vegetation across North and Central America. We studied the genetic diversity of Juniperus deppeana , a conifer distributed from the Southwestern United States to the highlands of Central America. We combined information of one plastid marker and two nuclear markers to infer phylogeographic structure, genetic diversity and demographic changes. We also characterized the climatic niche for each variety to infer the plausible area of suitability during past climatic conditions and to evaluate climatic niche discontinuities along with the species distribution. We found a marked phylogeographic structure separating the populations North and South of the Isthmus of Tehuantepec, with populations to the South of this barrier forming a distinct genetic cluster corresponding to Juniperus deppeana var. gamboana . We also found signals of population expansion in the Northern genetic cluster. Ecological niche modeling results confirmed climatic niche differences and discontinuities among J. deppeana varieties and heterogeneous responses to climatic oscillations. Overall, J. deppeana ’s genetic diversity has been marked by distribution shifts, population growth and secondary contact the North, and in situ permanence in the South since the last interglacial to the present. High genetic variation suggests a wide and climatically diverse distribution during climatic oscillations. We detected the existence of two main genetic clusters, supporting previous proposals that Juniperus deppeana and Juniperus gamboana may be considered two separate species.
The objective of this study was to estimate the risk that glyphosate residues in pollen pose to honey bees and humans. From June 2015 to May 2016, we quantified glyphosate from freshly collected pollen from ten colonies from two sites in Chiapas, Mexico. Residues were extracted by the QUECHERS method and analyzed using a standardized enzymatic immunoassay. Glyphosate was detected in all samples (3.71–7.29 µgkg − 1 ). Risk analysis (pollen hazard quotient) indicates that such quantities do not pose an acute threat to honey bees and humans, according to ADI/ARfD – AOEL values. In conclusion, we found that the risks that glyphosate in pollen represent to human and honey bees are apparently low in our study site.
In the Caribbean Sea and the Gulf of Mexico, 15 species of sabellariids have been described. Since Kirtley’s (1994) worldwide review, at least seven species have not been re-recorded for this region. Therefore, the aims of this contribution were: a) to review the sabellariids held in scientific collections, b) to generate standardized descriptions, and c) to provide taxonomic identification keys for the species of the region. The sabellariids of two Mexican and one US scientific collection were reviewed. Five new species are described: Lygdamis pechi sp. nov. from Veracruz, Gulf of Mexico, Mariansabellaria caribbea sp. nov. from Quintana Roo, Mexico, Phalacrostemma danieli sp. nov. from southwest of Grenada, Tetreres israeli sp. nov. from the Virgin Islands, and T. oscari sp. nov. from Florida. Another morphospecies, Phalacrostemma sp., is characterized by a single incomplete specimen from the Bahamas. Also, new records of Phalacrostemma perkinsi Kirtley, 1994, and P. dorothyae Kirtley, 1994 were made.
The sterile insect technique has been used for the eradication or control of numerous tephritid fruit flies. However, mass-rearing and sterilization can affect the microbiota and sexual performance of male tephritid fruit flies. Despite the addition of postteneral protein food which contributes to the enhancement of the sexual performance of mass-reared males, in some cases, they are less competitive than their wild counterparts. Alternatively, the addition of probiotics may improve the sexual performance of mass-reared sterile males. In this study, we evaluated the effect of a postteneral Lactobacillus casei-enriched diet on the sexual competitivity, pheromone emission, and cuticular hydrocarbons of mass-reared sterile and fertile Anastrepha ludens (Loew) (Diptera: Tephritidae) males. Flies were fed either with sugar, standard diet (sugar and protein, 3:1), sugar + probiotic, or standard diet + probiotic. The addition of the probiotic improved the sexual competitivity of fertile and sterile males that were devoid of protein but led to a negative effect on males fed with a standard diet. As compared to males that were fed with the standard diet + probiotic/only sugar, the males fed with the standard diet or those fed on sugar + probiotic displayed a higher number of mating instances. Sterile males that fed on sugar + probiotic had a higher relative amount of anastrephine, epianastrephine, n-methyl octacosane, and 2-methyl triacontane than those fed on sugar only. Overall, these compounds were common in the treatments where males had the best sexual performance. Our results suggest that the probiotics offer nutritional advantages to males whose food lacks protein.
Identifying connectivity patterns among remnant bird populations and their relationship with land use practices and subjacent habitat fragmentation is key for implementing appropriate management strategies for species conservation. The coastal thorn scrub forest and dune vegetation complex in the northern Yucatan Peninsula has been affected by coastal development. These human induced processes of land use change can affect the Yucatan Wren ( Campylorhynchus yucatanicus ), an endemic bird to this vegetation types with a narrow distribution. To identify possible anthropogenic barriers to connectivity of populations of C. yucatanicus , we collected 140 samples from 14 localities and used seven nuclear microsatellite loci to describe the current structure and genetic diversity of populations of C. yucatanicus . We explored the relationship between the genetic variability of populations and landscape structure through regression models. In addition, we described the relationship between genetic distance and landscape resistance. We found four genetic populations with Bayesian clustering methods. Human settlements and availability of adequate habitat limit the connectivity between sites due to ongoing land use changes. We suggest some management actions for conservation of this species, and we propose to change the IUCN threat category to "endangered" because of today the species has a more restricted distribution, small population, habitat degradation, loss of connectivity, and loss of genetic variability.
Historical hydrological changes and the environmental characteristics of northern Middle America have promoted diversification and determined the distribution of fishes in the Grijalva and Usumacinta river basins of Mexico. In several taxa with wide distributions, cryptic diversity has been identified through molecular and morphological analyses. This study evaluated the intraspecific morphological variation of Dorosoma anale Meek, 1904 and Dorosoma petenense (Günther, 1867) along the Grijalva and Usumacinta river basins through geometric morphometric and linear biometric analyses. Little intraspecific differentiation was detected for either species. However, differences were identified between populations in the Grijalva basin and those from the upper Usumacinta River basins with respect to body height, head size, pelvic fin position, and anal fin size. The phenotypic expression of these attributes appears to be closely related to habitat type and geographic isolation. The morphological differences within D. petenense support the molecular hypothesis of two lineages existing in the Usumacinta River basin.
Humid mountain forests (HMF) in Mexico have been heavily degraded by anthropogenic activities. A key conservation strategy consists of propagating HMF species in forest nurseries for subsequent repopulation in degraded areas. We evaluated genetic diversity in three natural populations (Huitepec, Bazom, and Mitzitón) and one nursery population of Styrax magnus Lundell (Styracaceae) in Chiapas, Mexico. We expected a lower genetic diversity in the nursery than in wild populations. Styrax magnus is restricted to the Mexican state of Chiapas, close to the border with Guatemala and is likely to be at risk of extinction due to habitat loss and its low establishment rate. We used ten enzyme loci to determine genetic diversity. Genetic structure was examined by calculating genetic differentiation (Fst) and Nei’s genetic distances (Nei, Am Nat 106:283–292, 1972), in addition a Bayesian analysis was performed. The populations examined showed a moderate (He = 0.31) average genetic diversity. Bazom was the most distant and genetically differentiated population and showed the lowest genetic diversity (He = 0.21). Mitzitón was the most diverse population (He = 0.40), whereas the nursery population showed an intermediate diversity (He = 0.30). We found a high level of total genetic differentiation (Fst = 0.48, P < 0.001), suggesting a limited gene flow between the populations studied. Our results suggest that propagation in the nursery promotes an intermediate level of genetic diversity (He) relative to wild populations, likely because the nursery population was made up by random seed collection from several sites. The genetic monitoring of introduced populations is highly recommended for an in-depth assessment of the success of actions aiming to conserve and restore HMF in Chiapas.
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794 members
Ana Minerva Arce-Ibarra
  • Departamento de Sistemática y Ecología Acuática
José Nahed Toral
  • Agriculture Society and environment
Everardo Barba
  • Departamento de Ciencias de la Sustentabilidad
Juan F. Barrera
  • Departamento de Agricultura, Sociedad y Ambiente
San Cristóbal de las Casas, Quintana Roo, Tabasco, Chiapas, Campeche, , Mexico
Head of institution
Dra. Carmen Pozo de la Tijera
+52 9676749000