THERYA

Community of medium and large-sized mammals and functional diversity in a tropical rainforest of Southern México under different degrees of human pressure

Mon, 22 Apr 2024 00:00:00 +0000

Functional diversity quantifies the distribution and range of functional traits of species that influence ecosystem processes. We evaluated the functional diversity of the medium and large-sized mammals in a tropical rainforest in Southern Mexico to determine which landscape characteristics associated with human activities affected the composition of mammal functional diversity and functional group abundances. We used camera-traps to document the diversity and composition of medium and large-sized mammals at four sites with different levels of protection and management. We estimated species richness, diversity, and functional diversity for each site, and compared these indices between sites to understand the effects of biodiversity loss in ecosystem dynamics and to detect ecological patterns driven by human perturbation. The density of human settlements was the main covariate related to low species richness and low abundance of large mammals with specialized diets and low population densities. Poaching and other human activities in forested areas near human settlements might have caused large herbivore and specialized carnivore populations to decrease, and populations of medium-sized rodent species to increase. Our results indicated that human perturbation in forested areas had also an impact at the functional level reducing the abundance of some functional groups, and this might have negative consequences for tropical rainforest functions in the long term. Effective management actions should be implemented in Protected Areas with a high density of human settlements nearby to prevent the decline of mammals’ functional groups and negative consequences for tropical rain forests’ ecological functions.

Non-volant mammals in the central Andes Yungas: the Pampa Hermosa National Sanctuary

Klauss Cervantes, Edith Arias, Adela Aguilar, César Larico, Víctor Pacheco — Tue, 23 Apr 2024 00:00:00 +0000

The Pampa Hermosa National Sanctuary (SNPH) is a Natural Protected Area (11,543 ha) that encompasses a large extension of central Yungas; however, despite its high priority status for the conservation of biodiversity, the non-volant mammals have been poorly documented. This study reports the non-volant mammals from the Yungas of the SNPH and its buffer zone, for the first time. We sampled four localities: Podocarpus (1,900 m), Los Cedros (1,600 m), Santa Isabel (1,450 m), and Nueva Italia (1,370 m), which encompass very humid premontane and montane forests. We used capture methods for small mammals; and direct and indirect records for medium and large-sized mammals. The capture effort was 6,860 traps-night (Sherman and Victor traps) and 490 buckets-night (pitfall traps). We recorded 31 native species: six marsupials, one cingulate, two primates, 18 rodents, two carnivores, and two artiodactyls, including the threatened species Lagothrix lagotricha tschudii and two endemic rodents. The most diverse orders were rodents and marsupials (77 %). The analysis of true diversity (^qD) showed that the montane forests of SNPH (1,600 to 1,900 m) had the highest values: Los Cedros (⁰D = 18.80) when order q = 0; and Podocarpus (¹D = 6.34; ²D = 4.99) when order q = 1, 2. The rank-abundance curves indicated the same taxa group (Hylaeamys yunganus, Akodon cf. A. aerosus, and species of Neacomys) as the most abundant at all localities. The species Marmosa (Micoureus) constantiae, Hylaeamys yunganus, Rhipidomys gardneri, Euryoryzomys nitidus, Oligoryzomys microtis, and Neacomys macedoruizi are the first records for the region of Junín. One species of Neacomys and another of Oecomys might be new species to science. A beta diversity analysis showed that the Yungas of SNPH are more similar to the Manu National Park (21 %) and the Tingo María National Park (20 %); highlighting that dissimilarity is high even between relatively close communities. Our study indicates that the SNPH allow connectivity with other nearby Yungas, especially for medium and large-sized mammals that need pristine and preserved forests. Nevertheless, the real diversity of the region is still far from being completely inventoried; additional evaluations with a diverse array of methods are needed toward that goal. In addition, the local and regional governments should get involved in conserving these fragile forests where the changes in land use may affect many key and endemic species.

Group structure and diurnal behavior in a large colony of Mimon cozumelae in Yucatán, México

Fri, 24 Nov 2023 00:00:00 +0000

The Phyllostominae is a Neotropical subfamily of bats that include species considered sensitive to habitat disturbance, but that are the poorly known. The Cozumelan Golden Bat, Mimon cozumelae, is a rare phyllostomine that inhabits forests and semi-deciduous tropical forests from central México to western Colombia. This study describes for the first time, the social organization and diurnal behavior of M. cozumelae to provide basic information about the social relationships of this elusive species. We captured and marked individuals inhabiting a cave in Yucatán, México in 2020 and 2021. Observations were carried out filming its behavior inside the cave in two seasons, breeding (March-July) and non-breeding (August-January). We constructed an ethogram and classified the observed behaviors into states and events in each season. A total of 103 individuals (47 females and 56 males) of M. cozumelae were captured. The sex ratio was not different from 1:1. The size of the groups did not vary throughout the seasons. The most frequent behaviors performed by M. cozumelae were resting, followed by flight, self-grooming, wing extension, and social grooming. The group composition most common in both seasons was multi-male, ruling out the typical formation of harems in the breeding season for this species. Copulation and maternal grooming were recorded for the first time in the reproductive season. This bat exhibits social grooming, which in theoretical terms could categorize it as a species that forms societies. This study contributes updated information regarding group size and composition, and especially diurnal behavior of M. cozumelae. It is suggested that this work serves as a baseline to investigate its social systems (behavioral ecology) in depth, and when carrying out conservation plans for this species.

Social arenas in the open habitat: the social role of waterholes for saiga antelope

Andrey Giljov, Karina Karenina — Tue, 07 May 2024 00:00:00 +0000

In wild animals, specific locations may function as ‘social arenas’ playing a significant role in various aspects of intraspecific interactions. The emergence of such social arenas is assumed to be particularly important under conditions of low visibility and density of individuals typical for forest dwelling species. In the forest, open areas with a high probability of meeting conspecifics such as waterholes and mineral licks can favor socialization. The paucity of studies on the open-habitat species limits our understanding of whether forest habitat is an essential condition for the emergence of social arenas. Here we address this issue by investigating whether resource hotspots function as social arenas in a species adapted to open habitat. The social behaviour in groups of saiga antelopes (Saiga tatarica tatarica) was recorded at large permanent waterholes (serving also as mineral licks) and away from them in the steppe environment. The frequency and variety of social interactions between the group mates were compared with a special effort made to minimize the potential impact of other factors besides the location. Also the focal individuals, interacting or not interacting with conspecifics at the waterholes, were traced continuously to explore the duration of their visit at the waterhole area. Finally, we recorded the number of individuals in the groups entering and leaving the waterhole. Active social interactions between group members occurred more often and were more varied near the waterholes as compared to the areas away from them. The participation in social interactions influenced the duration of individual waterhole visits. Males that interacted with others shortly after arrival stayed significantly longer compared to those who did not. Females whose calves engaged in social interactions with age-mates spent more time at the waterholes than females whose calves did not. The comparison of mean group sizes showed that saigas left waterhole areas in larger groups than they entered them. Our findings, together with previous studies, suggest that resource hotspots can function as social arenas in mammals regardless of the habitat type (open or closed). The emergence of specific locations having particular social significance may be especially important for highly dispersed species with large home ranges. The results of the study emphasize the significance of large permanent waterholes and mineral licks used by many individuals year after year for the social behaviour of saiga antelopes.

Molecular cytogenetics markers reveal the existence of a cryptic complex of Mazama temama species

Thu, 16 May 2024 00:00:00 +0000

Mazama temama, commonly named Central American red brocket deer, was described in Veracruz, east-central México. Cytogenetic studies have characterized differentiated karyotypes observed in captive individuals of the species with a diploid number (2n) = 49 to 50, in a recently collected neotype with a diploid number (2n) = 44 and fundamental number (FN) = 70, and in specimens collected in Campeche in the southeast of México with a diploid number (2n) = 47 and fundamental number (FN) = 70. Then, we used BAC probes derived from cattle genome aiming to describe the chromosomal differences in M. temama karyotypic variants. We compared three individuals from Campeche (CAM) and the Veracruz neotype (VER). A total of 38 clones have been mapped by fluorescent in situ hybridization onto the chromosomes of both variants and a comparative map has been established. We assessed Cytochrome b (Cytb) gene sequences to perform phylogenetic analyzes including M. temama individuals from these localities and other Neotropical deer. The integrated analysis of hybridization results showed the real and surprising differences between the specimens. Besides the morphological similarities between the M. temama specimens, the results showed a difference of 10 chromosomes involved in rearrangements that separate their karyotypic composition, associated with tandem and centric fused chromosomes. Bayesian Inference tree evidenced Campeche and Veracruz individuals in two separated subclades within M. temama clade. The observed chromosomal and genetic differences are a substantially evidence of a reproductive isolation mechanism between the Veracruz and Campeche individuals suggesting the existence of a cryptic complex of species under M. temama nomenclature. Therefore, conservation strategies should be considered separately for each population of central American red brocket deer.

Land-use change and habitat fragmentation of Leopardus pardalis in Highlands of Puebla, Mexico

Thu, 30 May 2024 00:00:00 +0000

Ocelots are relatively tolerant to habitat modification. However, it has been observed that they may be sensitive to habitat loss and fragmentation as a result of human development. The Sierra Norte de Puebla is considered a potential habitat for ocelots and other tropical felines. However, it has suffered heavy loss and fragmentation of its natural ecosystems, which considerably affects habitat availability and quality. This study analyzed the land-use changes and habitat fragmentation in the distribution range of the ocelot in the Sierra Norte de Puebla, Mexico, from 1993 to 2020. Habitat suitability was determined using potential distribution models and vegetation and land-use maps from 1993, 2003, and 2020, obtained using supervised classification of Landsat images. The resulting maps were reclassified in terms of the habitat suitability for Leopardus pardalis according to their quality. Land-use changes and habitat loss were quantified with a transition matrix, and fragmentation was assessed using the Morphological Spatial Pattern Analysis tool of the program GUIDOS. These habitat fragments were quantified using the integral index of connectivity with the CONEFOR Sensinode program. We estimated that 22.2 % of the study area has suitable conditions for ocelots. From 1993 to 2020, the area covered by natural vegetation decreased 16 % at an annual rate of -2.4 %. During this period, the mean fragment size and shape index decreased; on the other hand, the number of fragments and the Euclidean distance between fragments increased. The percentages of edge, branch, and islet vegetation dropped from 1993 to 2003 but increased in 2020. The connectivity analysis indicated that two habitat fragments showed high values of the integral index of connectivity. The increase in anthropogenic cover and the habitat loss for L. pardalis between 1993 and 2020 affected mainly vegetation fragments considered optimal for the persistence of this species. In these ecosystems, agricultural and livestock practices are expanding vigorously, increasing edge habitats and decreasing the core area of habitat fragments. The areas that recorded the presence of ocelots have optimum conditions to serve as biological corridors in the Sierra Madre Oriental, particularly in the portion of the Sierra Norte de Puebla. The fragmentation of the ocelot habitat is of particular concern and should be addressed strategically for the long-term conservation of the ocelot and regional biodiversity.

Morphological variation in the Cerralvo Island pocket mouse Chaetodipus siccus from the Baja California Peninsula, México

Sergio Ticul Álvarez-Castañeda — Thu, 30 May 2024 00:00:00 +0000

Chaetodipus siccus is a microendemic species with a restricted distribution and two geographically isolated populations, one on Cerralvo Island and its counterpart on the Baja California Sur peninsula, each associated with dissimilar environmental conditions. The hypothesis to test is that each population is adapted to its distinct environment and has its own evolutionary trend that can be used to differentiate them. The analysis of the skull shows that each population has a differential development of the region associated with chewing muscles. The statistical analyses of the Procrustes (shape) and Mahalanobis (size) distances confirm these differences statistically (P < 0.05). The set of differences in skull shape associated with the chewing muscles, craniodental measurements, external morphological traits, genetic isolation, and association with a different environment support the hypothesis that each population has its own evolutionary tendency.

Rediscovery of Oryzomys fulgens: implications for the taxonomy of Oryzomys

Thu, 30 May 2024 00:00:00 +0000

The rodents belonging to the genus Oryzomys are among the most widely distributed groups inhabiting North America. Currently, 13 species with continental, peninsular, or insular distributions are known. However, this genus also faces significant conservation challenges, primarily due to climate change and other human-related activities. One such enigmatic species is Oryzomys fulgens. Its main challenge lies in the fact that it was originally described from an imprecise type locality, simply labeled as "Mexico." Fortunately, recent research has delimited its range to the Basin of México. Nonetheless, the lack of comparison between its holotype and other specimens of the genus in México has hindered the accurate assignment of its name to any known taxon, despite being one of the oldest names within the genus, O. fulgens has rarely been used since its original description. During our research, we collected two specimens of O. fulgens from Xochimilco, México City, a remnant wetland situated within the Basin of México, nestled within one of the largest and most urbanized cities globally. To properly assess its taxonomic status, we compared our specimens with the holotype of O. fulgens, as well as with other species from southern and western México. The considerable morphological differences we observed in O. fulgens, coupled with its distinct and unique habitat as the sole species of the genus occupying temperate regions at high elevations, lead us to propose that it is indeed a distinct species, separate from O. mexicanus and O. albiventer. Historically, its distribution was likely limited to the Basin of México. Today, O. fulgens faces serious conservation problems, mainly due to the restriction of its current distribution, as far as we know, confined to Xochimilco. Although the ancestral agricultural system known as "chinampas" might provide an ideal environment for sustaining populations of this species, it remains under significant pressure from various human activities, predators, and competition with invasive species like the black rat. Urgent conservation efforts are needed to safeguard the unique habitat of O. fulgens and protect this enigmatic species from further decline.

Activity patterns of the white-tailed deer (Odocoileus virginianus) in a neotropical dry forest: changes according to age, sex, and climatic season

Luis Cueva-Hurtado, Andrea Jara-Guerrero, Rodrigo Cisneros, Carlos Ivan Espinosa — Thu, 30 May 2024 00:00:00 +0000

Mammalian daily activity is shaped by a combination of intrinsic and extrinsic factors. Age influences activity rhythms due to energy requirements, while physiological and reproductive traits cause differences between genders. In ecosystems with marked climatic seasonality, such as the seasonally dry tropical forest (SDTF), activity patterns adapt to extrinsic factors like resource availability and environmental stress. This study investigates how intrinsic factors, specifically age and sex, influence the white-tailed deer's (Odocoileus virginianus) daily activities, and how these vary between dry and rainy seasons. Between 2015 and 2018, we conducted a camera trapping study to monitor the daily activity of a population of white-tailed deer in the Arenillas Ecological Reserve, southwestern Ecuador. We estimated individual daily activity based on four parameters: total and diurnal relative abundance index (RAI), activity directionality, and activity overlap between groups. We used generalized linear models to evaluate the changes in RAI based on age-classes and sex of the individuals. The Watson test was employed to assess differences in directional patterns during activity hours, while the Wald test was utilized to evaluate significant variations in activity overlap. The same analyses were also performed to assess changes in daily activity between the dry and rainy seasons. The daily activity patterns of white-tailed deer varied by age and sex. Fawns were predominantly diurnal, whereas adults displayed continuous activity throughout the 24 hours of the day, with males being more active during the night than females. Females did not show significant differences in the activity pattern compared to fawns and juveniles. The daily activity pattern of white-tailed deer varied between seasons. Overall, there was an increase in daily activity during the dry season, but significant only for males. Females were the only group that showing seasonal variation in activity directionality, with more morning activity during the dry season. The daily activity patterns of white-tailed deer in the dry forest exhibit slight differences compared to those observed in other ecosystems, with extended daily activity periods. During the rainy season, reproductive and post-reproductive behaviors, rather than resource abundance, predominantly shaped the white-tailed deer's daily activity patterns. In contrast, the dry season presented a notable rise in overall activity and daily activity, accompanied by partition between groups. This partition likely stems from diminished resource accessibility and increased intraspecific competition. Given the slight differences in the white-tailed deer's daily activity from those noted in other regions, these insights are crucial for formulating management and conservation strategies tailored to specific environmental conditions.

Corrigendum: The Phillips kangaroo rat (Dipodomys phillipsi): Population parameters

Sandra Helena Montero Bagatella, Fernando A. Cervantes, Alberto González Romero — Mon, 23 Oct 2023 00:00:00 +0000

Corrigendum
Montero-Bagatella, S. H., F. A. Cervantes, and A. González-Romero. 2023. Population parameters of the Phillips kangaroo rat (Dipodomys phillipsii). Therya 14:351-359.

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Figure 3. Average sex and age breakdowns of captured PhillipsÂ´ kangaroo rat (Dipodomys phillipsii) by season for 2012-2016, from Perote, Veracruz.