Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Parasites play a crucial role in the ecology of animals. They also appear to be important in mechanisms underlying sexual selection processes. In this article we study the prevalence, effect and potential role in sexual selection of the protozoon Trypanosoma evansi in capybaras, Hydrochoerus hydrochaeris. We collected our samples from the annual capybara cull of a ranch in Venezuela, using the volume of the snout scent gland as an indicator of dominance; the residuals of body weight as indicators of condition; and the residuals of the spleen mass as indicators of immune function. Overall prevalence was 30.9% (N=97) with no difference between males and females and no relation between infection with T. evansi and condition. However, we found that infected animals had larger spleens (residuals), indicating an immunological cost of the infection. Further, males with larger snout scent glands (more dominant) were less likely to be infected than males with smaller glands (less dominant) suggesting that by choosing males with a large gland, females may be using the gland as an indicator of health, which is consistent with the “good genes” view of sexual selection.

Lepidaploa rufogrisea is a promising candidate in the search of natural herbicides, with compounds (sesquiterpene lactones-glaucolide B) which have been reported to present with phytotoxic potential against weeds. Thus, this work aimed to accomplish the phytochemical investigation of L. rufogrisea as well as the evaluation of its biological effects on the plant model Lactuca sativa. To this end, different extracts (aqueous, hydroalcoholic and hexane) of L. rufogrisea at different concentrations [0.25, 0.5, 1.0, 2.0 and 4.0 % (m/v)] were evaluated from macroscopic (percentage of germinated seeds, germination speed index and root length) and microscopic analysis (mitotic index and cell cycle alterations) in plantlets (150 per treatment) and meristematic cells (10 000 per treatment) of L. sativa var. Cristina. The extracts decreased the germination speed index and also the root growth of L. sativa plantlets. Cell proliferation was not significantly affected by the extracts. However, some chromosome and nuclear alterations in the mitotic spindle were observed, due to the interference of allelochemicals present in L. rufogrisea. Moreover, the plant model L. sativa demonstrated to be efficient for this kind of studies.  

Oreochromis niloticus has been introduced worldwide into freshwater reservoirs and represents an alternative food for local populations. Two annual marks on fish scales have been reported for fish in these environments, one of them is allocated to reproduction, while the other is thought to be formed following low temperatures, a reduction in oxygen concentration and/or high densities, among others. In order to explore the causes of this second ring, we designed an experimental study to analyze the influence of four factors: a reduction in food amount, an increase in density, a decrease in oxygen concentration and temperature. The experiment was carried out using five 215 L plastic tanks, each one divided into two sections, so as to have treatment replicates (each with 20 juveniles). The control conditions were optimal for the species: 5% of body weight in food, a density of 3 fish/L, a total oxygen saturation of 4.98 ± 0.5 mg/L, and a temperature of 25.0 ± 1.0oC; the treatments varied as follows: food of 2.5% of body weight, density of 6 fish/L, oxygen of 2.8 ± 1.2 mg/L and a temperature of 19.6 ± 1.0oC. Fish responses to stressors were estimated through variations in length, weight and inter-circuli spaces or circuli spacing in fish scales. Every third day it was measured the concentrations of ammonium, phosphates and nitrates with a photometer. Three stages for length/weight fish measurements and scales sampling were considered: 1) Initial stage: before experiment started, 2) Final stage: at the end of the experiment, and 3) Compensatory stage: when all the experimental treatments were adjusted to the Control conditions; the experiments lasted for three weeks. The results indicated that all the treatments caused a reduction in length, weight and inter-circuli spaces when compared to the controls (6.7 ± 0.5 cm; 5.2 ± 1.2 g; 5.4 ± 0.5 mm, respectively), but only the variables of temperature and food resulted significant (5.6 ± 0.4 and 5.8 ± 0.5 cm; 3.4 ± 0.7 and 3.3 ± 0.9 g; 3.4 ± 0.3 and 4.1 ± 0.6 mm for temperature and food treatments, respectively) (P < 0.05). When treatments were reversed to the control conditions for another three weeks compensatory growth was observed in the oxygen and density treatments, but not in the same way for the temperature and food treatments. We concluded that inter-circuli distances are a good indicator to stress periods in this species.

Honduras is the second largest country in Central America, but 63 % of its population lives in poverty and it is the Central American country with less scientific journals. Even though Honduras has been included in general studies about Latin American science, there are no specific bibliometric studies about the productivity of the country, so this is the first formal study about the most productive institutions, fields and authors in Honduras. The Science Citation Index Expanded (SCI-EXPANDED), Web of Science Core Collection was used to collect the bibliographic data. There are no Honduras publications from 1903 to 1972 in SCI-EXPANDED. Honduras publications from 1973 to 2015 were further analyzed. A total of 1 146 Honduras publications with 13 document types in the Science Citation Index Expanded from 1973 to 2015 were found. Nearly 95 % of the articles in the database are in English, suggesting that articles in this language have the greatest visibility in the database, similar to other Central American countries. The countries with which Honduras publishes (e.g. Mexico, other Central American countries) follow the geographic and cultural affinity model, i.e. researchers tend to collaborate with colleagues that have similar culture or that are geographically close. This pattern has been found for other Central American countries. The focus of Honduran scientists in health and agriculture problems is typical on the less developed countries; on this respect Honduras is more similar to its closest neighbor, Nicaragua, than to smaller but more developed Central American countries like Panama and Costa Rica. Overall, the situation of scientific research and output in Honduras is improving, with more articles and citation in the SCI-EXPANDED, and this positive trend should bring about benefits for the people of Honduras.

Pitcairnioideae is the second most diverse subfamily of bromeliads (Bromeliaceae), a group exclusive to tropical regions of the New World. Pitcairnioid bromeliads have floral traits assumed to promote outcrossing through biotic pollination systems; however, the reproductive biology of most of the species of this group has not been documented. Pitcairnia heterophylla is an epiphytic (seldom saxicolous) bromeliad occurring from Southern Mexico, into the Northern Andes. We studied the pollination and breeding system of P. heterophylla in an epiphytic population at a mountain forest in Costa Rica from January to April 2013. We performed hand pollination experiments (agamospermy, autonomous self-pollination, hand self-pollination and hand cross-pollination) on 89 flowers from 23 individuals (3-6 flowers per individual) in 2013 flowering season. Nectar production was measured on 18 unvisited flowers of six individuals with a hand-held refractometer. Simultaneously, floral visitors were recorded on eight individuals with trail cameras for a total of 918 hours (115 ± 52 hours per individual, mean ± SE). Under natural conditions, seed set (540.4 ± 55.2) was similar to manually selfed flowers (516.3 ± 41.5) and autonomously selfed flowers (521.1 ± 29.0), but lower to manually outcrossed flowers (670.2 ± 31.3). The flowers of P. heterophylla are self-compatible, capable of autonomous pollination, and non-agamospermous. Intrafloral self-pollination is facilitated by adichogamy and lack of floral herkogamy. The scentless red flowers of P. heterophylla with tubular corollas and nectar production suggested ornithophilic pollination which was confirmed by video recording of 46 hummingbird visits. The most common floral visitor was the short-billed hummingbird Lampornis calolaemus which accounted for 78 % of the visits. However, the visitation rate during the flowering season was low (0.6 visits per day per plant). Selfing in P. heterophylla might be explained as a mechanism of reproductive assurance and to reduce interspecific pollen flow with taxonomically unrelated plants.

The increase in CO2 emissions produces heating and reduced pH in the oceans, which may have negative effects on many marine organisms. This is particularly important for those with calcified structures such as the molluscs and their larval stages. We studied Strombus gigas larvae, a gastropod of commercial importance in the Caribbean Sea, in order to know the effect of water temperature and acidification on their development, growth, mortality and calcification during the larval period. A larval culture with triplicate samples was carried out employing four treatments of temperature and pH (Control = 28 °C - pH 8.1, T1 = 28 °C - pH 7.6, T2 = 31 °C - pH 8.1 and T3 = 31 °C - pH 7.6) in August 2015. We registered hatching (No. of eggs – No. of larvae hatched) and organs development, while shell growth and mortality ratio were evaluated over time. Shell calcification was studied in 30 days old larvae using EDX and RAMAN analysis. Our results showed that organs development and shell growth were higher at 31 °C treatments (initial size of 230 ± 4.12 to 313.27 ± 11.34 µm, and final size from 829.50 ± 11.33 to 1 054.50 ± 11.13 µm; from T1 to T2 respectively), and the same pattern was recorded for hatching time (18 hr) and mortality rate (~ 57 %). The Calcium proportion (% wt) was similar between treatments (34.37 ± 10.05 to 37.29 ± 16.81 % wt). Shell Raman analysis showed aragonite in all experimental treatments, with the highest values in the control (1 039.54 ± 780.26 a.u.). Calcite was detected only in 31 °C treatments (174.56 ± 127.19 a.u.), while less intensity of aragonite and calcite were registered at pH 7.6. In conclusion, S. gigas could be adapted to ocean future predictions, however, shell biomineralization processes can be affected.

Although the wider Eastern Tropical Pacific has been systematically surveyed during summer/fall, relatively little effort has focused on shelf and slope waters of Nicaragua and Costa Rica. Such data are useful for establishing baseline information and assessing potential changes in cetacean occurrence and distribution relative to natural (e.g., El Niño-Southern Oscillation, climate change) and anthropogenic factors. A visual-acoustic survey for cetaceans occurred as part of a monitoring and mitigation program during an academic geophysical seismic study off Nicaragua and Costa Rica, during November-December 2004. Approximately 2 067 cetaceans representing at least seven species were seen in 75 groups during 373 h (3 416 km) of daytime observations from the seismic research vessel (R/V) Maurice Ewing. The humpback whale (Megaptera novaeangliae) and the pantropical spotted dolphin (Stenella attenuata) were the most frequently sighted species (30 % of all groups sighted); both were seen in shelf waters < 100 m deep and in slope waters. The bottlenose dolphin (Tursiops truncatus; 10 % of sightings) was the third most frequently sighted species and was only seen in water > 100 m deep. In addition, sightings were made of spinner dolphins (S. longirostris), short-beaked common dolphins (Delphinus delphis), Risso’s dolphins (Grampus griseus), short-finned pilot whales (Globicephala macrorhynchus), and unidentified dolphins and whales. Unconfirmed sightings of a minke whale (Balaenoptera acutorostrata) and a pod of false killer whales (Pseudorca crassidens) were also recorded. An additional six groups of dolphins (50 % confirmed to species, all pantropical spotted dolphins) were made during 187 h (1 549 km) of observation effort during darkness, two of which were detected within 30 m of the vessel bow using a night vision device. A total of 217 cetacean detections occurred during 633 h of passive acoustic monitoring. A small concentration of 12 humpback whales was seen in eight groups, and two humpbacks were recorded singing in the Gulf of Fonseca on 9 December 2004. To our knowledge, such concentrations of humpback whales, particularly singing humpbacks, have not been previously reported in this specific area. In addition, a humpback mother-calf pair, likely from the Northern Hemisphere population, was seen off Northern Costa Rica on 25 November 2004. Although cetacean sighting rates were significantly different during seismic and non-seismic periods even when corrected for differential detection probability related to sea conditions, our survey results do provide information to address previous data gaps on cetacean occurrence in shelf and slope waters off the Pacific coast of Central America during late fall. 

Vieja melanura is a Neotropical cichlid occurring in the Petén-lake district systems of Guatemala, as well as the Río Grijalva-Usumacinta basin, and other systems in Southern México, Belize, and Guatemala. A caudal stripe, extending forward from the caudal peduncle, is characteristic of this species. This stripe is sloped downward in nearly all individuals of V. melanura, but the degree of the slope is highly variable throughout its range. The slope and shape of the stripe has previously been used in diagnosing and differentiating between species of Vieja. The purpose of this study was to use objective methods to investigate morphological variation in the caudal stripe and body shape throughout the range of V. melanura. We studied geometric morphometric analyses of body shape and empirical measurements of the slope of the caudal stripe in 215 specimens of V. melanura. We also used the mitochondrial cytochrome b marker to study population level patterns within V. melanura. Results from our analyses showed significant geographic variation in body shape and patterns of coloration with little mitochondrial phylogeographic structure. These patterns likely correspond to differences in riverine habitats throughout the species’ distribution. In conclusion, these results can be used to inform other studies of color and shape variation as it applies to taxonomy and systematics.

The emergence patterns of tropical odonates (dragonflies and damselflies) are scarcely known. We studied the emergence patterns of odonates in a freshwater lotic system in Giro, Northern Santiago de Cuba, between January and December 2008. We visited the locality between 09:00 and 14:00, on a weekly basis, and collected exuviae from a fixed section (8 x 1 m2) offshore, along the riparian vegetation. We collected data on species composition and, for each species, abundance, relative biomass and emergence pattern. We collected 443 exuviae belonging to 22 species: seven Zygoptera and 15 Anisoptera. Half of the annual Odonata emergence took place in the dry season (December to March) with the highest value in February (25 %). For species for which we found seven or more exuviae per month, Enallagma coecum and Macrothemis celeno tended to be a synchronal emergence. We also found temporal segregation of the emergence pattern between M. celeno and Protoneura capillaris, Neoneura maria, Progomphus integer and Scapanea frontalis. These differences were probably related to the highest annual fluctuations of temperature, relative humidity and number of rainy days per month. We concluded that there is an asynchrony and heterogeneity in Odonata emergence times in the studied freshwater lotic system.

Understanding and predicting adaptations in body size of megabenthic invertebrates remains a major challenge in marine macroecology. This study was conducted in order to investigate size variations of benthic megafauna in the tropics and to identify the effect of biotic and abiotic factors that may produce changes to these organisms, testing unresolved hypothesis and paradigms of deep sea ecology from subtropical and temperate areas. The study area covered the continental shelf of the Colombian Caribbean. The samples were collected during 1998, 2001 and 2005, using semi-globe demersal net for a water depth of 10 to 500 m. The most common species were selected for further study: Eudolium crosseanum, Cosmioconcha nitens, Nuculana acuta (mollusks), Astropecten alligator, Brissopsis atlantica, B. elongata (equinoderms), Anasimus latus, Chasmocarcinus cylindricus and Achelous spinicarpus (crustaceans). Generalized Additive Models were used to detect significant changes in size and to infer the effects of biotic and environmental factors on organisms’ size. The dependent variable was size and the predicting model variables were depth, temperature, intraspecific density, interspecific density, richness, latitude, and longitude. A total of 7 000 individuals were measured. Six species showed an increase in body size towards deeper and colder sites. These species inhabit shallow and deep environments that exceed a variation in temperature of 10 °C. There was a remarkable size reduction in areas affected by the Magdalena River, possibly due to major physicochemical changes caused by the river. This region has the lowest planktonic primary productivity within the study area. An increase in sizes was observed north of the Magdalena River (long 74°W - 71°W & lat of 11°N - 13°N), which may be attributable to the coastal upwelling occurring in this part of Colombia. The relationship between the density of benthic organisms and size was not clear. However, five species showed an inverse relation with intraspecific density and three with interspecific density. Temperature and depth were the variables that best explained the variations in size. Most of the studied species showed an increase in body size when temperature dropped along the bathymetric range. The trend of increasing size in deeper zones is contrary to the prediction of the optimal size theoretical model (but consistent with recent studies), which indicates a reduction in organisms’ size in the deep sea, due to food limitation with increasing depth. It is possible that this increase in size is an adaptation to maximize energy, which is frequently observed in the coldest habitats of several species. Future studies in Caribbean should examine variations in size of benthic megafauna towards deeper zones (more than 500 m), were temperature is less variable and then other factors can play a more important role determining the size of these organisms.