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

South American sub-continent, housed the largest diversity of river dolphins on the planet, here there are two species in the genus Sotalia and three species in the genus Inia. Tonina, present on the Orinoco basin, are expose to many different anthropogenic threats, such as: the fragmentation and loss of aquatic ecosystems; acoustic contamination; risk of collision with boats; entanglement; deaths by retaliation, resulting from biological and operational interactions with artisanal and industrial fisheries; biomagnification of heavy metals such as mercury in the aquatic trophic web; capture of individuals for their usage as bait for the fishery of Calophysus macropterus, primarily on borderline localities between Colombia and Venezuela; and finally, the negative effects of climate change. We conducted a study to determine population sizes and anthropogenic threats affecting river dolphins populations during the beginning of high-water season, between November 2018 and February of 2019, along 1,402 km. We calculated the degradation index for streams of continental waters and density of the river dolphins. Water quality, habitat transformation, species exploitation, and the increment in number of human settlements were identified as the main conservation stressor in the analyzed area. We obtained density values by habitat type for different aquatic environments and population sizes for river dolphins and the value in the index of degradation, with a potential increment in value through time. River confluences were identified as priority areas for the conservation of the species. Water quality, habitat modification, and species exploitation were particularly intense. Our results highlight a potential transformation of the ideal conditions that allow for the establishment of the species, explaining its distribution with predicted values between 46.6 % and 70.1 % for the evaluated timeframe due to the effects of climate change on aquatic ecosystems. The Meta River, has the highest value for the index of freshwater ecosystems degradation followed by the Orinoco basin, water quality and species exploitation appear to be the major stressors for dolphins in these areas. Finally, river confluences were identified as conservation hot spots for dolphin populations. We point out on the importance of river dolphins as bioindicator, sentinel species, and one of the most susceptible to the negative effects of climate change.

The identification of taxa with small range sizes is important both from an ecological and conservational perspective. As other small mammals, several species of rodents have restricted geographical distributions, a situation that could increase their immediate risk of extinction. Species having restricted ranges and/or low population sizes have usually lower genetic variation than wide-ranging relatives, being highly susceptive to disruptive treats, such as new or introduced competitors, pathogens, and predators, severe climatic events, cataclysms, and/or population-level phenomena. We reviewed the most recent compilations on South American rodents to identify those only known from their type locality (i. e., an area with a maximum latitudinal and longitudinal range of < 10 km). This restriction is in accordance with an extent of occurrence < 100 km2, which fits partially with the criterion B1 of the IUCN for an extent of occurrence of a critically endangered species. For each species, we recorded the year of description, country of origin, main habitat use, use of substrate, and conservation status. We identified 58 species of South American rodents that are known only from their type localities or their vicinities. These species belong to two suborders, seven families, and 29 genera. The family with more species in this list is Cricetidae, which accounted for a half of the included species. Most species in our list were described during the decades of 1890-1930 and 1990 to recent. The habitat type with more species in the list was tropical forest. Almost a third of the species are considered under the highest categories of threat, such as CR, EN o VU. Two species within the list are considered to become extinct in historical times, including the akodont Juscelinomys candango and the vizcacha Lagostomus crassus. Almost half of the species in our list are referred as DD. Fifty eigth rodent species from South American are only known from their type localities and their surroundings; i. e., ca. 9 % of the currently approximately 650 recorded species of the subcontinent. The species list provided here need to be depurated trough additional field and collection based work. Even when some species could be removed from this list (due taxonomical changes or additional records from other localities), it is also possible than others could be included. Most species in our list are found at or close to highland areas, such as the Andes or the Serra do Mar, suggesting that at least partially the rarity of some of them could be related to the relative inaccessibility of these places. As in previous contributions focused on geographically restricted taxa, most species in our list are considered as DD in the IUCN Red List. This is unfortunate, since species listed as DD usually do not gain much attention (i. e., conservation programs, founds) as those considered as CR, EN or VU. Previous authors discussed this point, suggesting the need to designate as CR all species geographically restricted to their type localities, at least when no recent records (i. e., in the last 25 years) exists.

In desert regions, species have adapted physiologically and behaviorally to the extreme conditions of their environment, such as a lack of water and extreme temperatures. This is the case of the mule deer (Odocoileus hemionus) a species which many aspects of its relationship between behavioral ecology and habitat characteristics are unknown. The objectives of this study were: 1) to characterize the daily activity pattern of female mule deer in relationship to three behavioral patterns: resting, feeding and moving, and 2) assess the relationship between these behavioral patterns and the characteristics of the habitat. This study was conducted in the Chihuahuan Desert, where six females of mule deer were monitored using VHF radiotelemetry between 2012 and 2014. We distinguish the behavioral patterns by sensors in the collar and we quantified the number of beeps emitted per minute. Moreover, we described the daily pattern associated with these activities using Kernel density graphs and evaluated the effect of habitat variables on the frequency of resting and feeding behaviors applying a generalized linear model (GLM). We identified the location in which feeding and resting behaviors occurred, and the type of plant associations present and the percentage of area they occupied. We recorded locations over 328 days/deer. Female mule deer spent most of their time resting (63.41 %), followed by moving (21.26 %), and feeding (15.34 %). Deer movement and feeding behaviors were most frequent during the crepuscule. The temperature was the only variable that influenced resting and feeding behaviors (deviance = 4.7; d. f. = 1; P = 0.02). The estimated area used for resting was 10.35 km2, while the corresponding area for feeding was 6.45 km2, in which the plant association with dominance of Larrea tridentata, Opuntia rastrera and Fouquieria splendens was the most common. Considering the high temperatures prevailing on the region, resting most of the day likely helps deer to have an adequate thermoregulation. The time dedicated to feeding is less than the dedicated to other activities; deer may be spending more time moving than feeding due to the spatial distribution of suitable food patches, or to avoid predators. The mule deer occupy the same areas to feed and rest; however, feeding areas are smaller those used to rest, these areas have been identified in previous studies as those with the greatest use (core areas). In the plant association with greater occupation within the feeding zones, there are species reported as an essential for the deer diet; these areas are located at the foot of the hill, which gives the deer thermal protection.

The combined application of ecological niche modeling in phylogeographic studies has contributed to better understanding the relationship between the patterns of genetic variation of species and the abiotic conditions where their populations have evolved.  This has allowed broadening and strengthening the spectrum of phylogeographic questions and hypotheses to be tested, based on the increasing availability of data, algorithms, and models.  However, when these two approaches are combined, some of their limitations are also added, despite taking advantage of their strengths.  This review explores some of the latest contributions of this application.  We found that 44 % of the studies reviewed address the effect of the environment on the diversification and structure of lineages; 20 % of the models concern mammals and 27 %, reptiles; and 34 % of the articles addressed the biota of the Nearctic region.  This review also explores the most important challenges and future perspectives resulting from this synergy.

We report the first record of Eptesicus innoxius in northwestern Ecuador, in the province of Esmeraldas, occurring in a disturbed area, at 134.3 km northwest from the nearest known locality in Ecuador, which represents an important latitudinal extension in the distribution of this species. A predictive distribution model is presented using a total of 43 records from localities of Ecuador and Perú, and its distribution area is determined by a minimum convex polygon (PMC). The sensitivity value obtained in the test data was 0.984 and the area under curve ROC (AUC) value obtained (0.979) indicates an acceptable confidence level. Based on new records and known records, we estimate its distribution area in 135,243 km2. The environmental variables with the greatest influence in the distribution of E. innoxius were: Precipitation seasonality (37.4 %), Minimum temperature of coldest month (20.1 %), Precipitation of driest month (14.5 %), and Mean temperature of wettest quarter (12.8 %). This data show that E. innoxius has been recorded mainly in tropical dry forest, but also has presence in humid areas. Within these new reports, we recommended an upgrade of its conservation status in Ecuador and Perú.

The state of Chiapas is home to multiple species of shrews (11 species), endemisms (three species from Mexico) and micro-endemisms (5 species from Chiapas). These species inhabit diverse physiographic regions and different types of habitats across the state. However, several are known by only very few specimens, mostly collected several years ago, making the knowledge about their natural history extremely scarce. This paper describes the efforts made by the authors along 16 years in search of shrews of Chiapas. Records were obtained from fieldwork, as well as by historical records from scientific collections and public databases. We estimated the relative abundances per species, identifying in each case the area of distribution and association with different types of vegetation and land use, current threats, and future research scenario for conservation purposes. The total trapping effort was 12,340 trap-nights across 13 sampling sites, with a total capture success of 0.18 %. In nine sampling sites, we succeeded in capturing 22 specimens of six species of shrews: Cryptotis griseoventris, C. lacandonensis, C. merriami, C. mexicanus, C. pueblensis, and Sorex cristobalensis. C. griseoventris had the highest relative abundance (31.81 %) and capture success (0.056), while C. lacandonensis showed the lowest relative abundance (4.54 %) and capture success (0.008). We present noteworthy records of shrews: 1) for being barely represented in scientific collections, as in C. griseoventris, and 2) for expanding the previously documented distribution area, as in C. lacandonensis and C. merriami. All of the species currently face serious conservation issues resulting from the loss of habitat. In particular, micro-endemic species such as S. sclateri and S. stizodon are seriously threatened. The specimens and records reported herein should foster further detailed research on the taxonomy, ecology, and biogeography to advance the knowledge of shrews inhabiting the southern border of Mexico.

Bassaricyon medius is a medium-sized olingo that inhabits in forested areas from central Panama to west of the Andes of Colombia and Ecuador. The species was described based on a specimen from the Colombian Chocó. However, it has been little studied at a national scale. In Colombia, the species is currently known only from the Andean and Pacific regions. We document a new record of B. medius from the Caribbean region of Colombia, representing both a geographic and an ecological extension into the dry forest of northern Colombia. To update the distribution, we searched for historical records in the literature, collection vouchers, and databases. The new record is based on photographs on a live adult female B. medius and the skull of the same specimen deposited in the zoological collection of the University of Cordoba. We provide cranial and external morphometric data from the specimen, and we compare this information with morphological descriptions of previous records from Colombia in literature. The new record comes from the area around Sierra Chiquita, Department of Córdoba, and increases the distribution range into the dry forest of northern Colombia. We compiled 18 historical records of the species in the country, all form the Andean and Pacific regions. This record confirms the presence of B. medius in the Colombian Caribbean, updating the known distribution of the species in Colombia that currently includes the departments of Antioquia, Cauca, Chocó, Córdoba, Nariño, and Valle del Cauca.

Mormopterus kalinowskii, is an insectivorous species restricted to the Andean western slopes of Peru and Chile, it is rare and has very scarce available information. We evaluated sex ratio, roost use, and relationship between reproductive patterns and monthly seasonal variation throughout a 13-month period. In addition, we performed the first description and characterization of its echolocation calls. The study area was located in the Ite Valley, Tacna department (southwestern Peru) at the northernmost part of the Atacama Desert, one of the driest deserts in the world. Bats were caught using mist-nets. Sex ratio in the population was calculated from all individuals captured, and its difference with regard to a 1:1 ratio was assessed through a Binomial Coefficient Test. Roost use was assessed through observation and inspection of the study area. Pearson and Spearman correlation coefficients were calculated to establish the relationship between the number of captures and temperature and precipitation data. Echolocation calls were recorded using a Petterson D240x Ultrasound detector plugged to a digital recorder. Spectrogram displays of recorded calls allowed describing structural patterns within echolocation calls and to measure frequency and time parameters. 79 individuals of M. kalinowskii were captured; 30 males and 49 females. Sex ratio obtained, 1:1.63, evidenced more females in the study area. M. kalinowskii uses crevices as roosts and has a single reproductive cycle per year. Higher capture rates are correlated with temperature (r = 0.526), but not precipitation (r = 0.096). Calls in search phase exhibited long duration pulses and a descending quasi-constant frequency (QCF) component from 39 to 33 kHz, reducing length and increasing bandwidth when attempting to catch prey. The sex ratio, 1:1.63 (≈ 2), suggests that M. kalinowskii is a polygamous species, as occurs in the others molossids, whereas the single annual reproductive cycle shown by M. kalinowskii would indicate a seasonal monoestrous reproductive pattern. Echolocation calls share several traits observed in other molossids; however, the frequency values for M. kalinowskii search phase pulses could be the highest recorded among the molossid bats of the Pacific coastal desert, allowing them to detect smaller prey as a strategy to mitigate food competition among insectivorous bats in arid environments.

The Colombian weasel Mustela felipei is considered the rarest Neotropical carnivore only known from four localities in Colombia and one in Ecuador.  It is considered Vulnerable on the IUCN Red List along its distributional range.  We present an unexpected photographic record of a living specimen from Colombia that shed lights on its distribution on the Western Cordillera of Colombia, where it was previously known from single a record obtained on 1986.  This is the first confirmed record of the Colombian weasel during the 21st century.  Finally, we discuss the species’ occurrence in protected areas of Colombia, to provide tools for the conservation of this rare species.

Over recent decades, dispersal and philopatry in natural populations have been addressed together. However, philopatry, or the tendency of an individual to remain in its birthplace, has received little attention, despite the fact that this trait is present in a considerable number of vertebrates. In this paper we discuss hypotheses that state philopatry generators: life-history variables, ecological constraints, benefits of philopatry and agonistic behaviors. Additionally, we propose that genetic microstructure may be an outcome of such behavior. We conducted an analysis based on the above hypotheses in order to explain the presence of philopatry in rodents of arid environments.