Celia López-González

COMPOSITION AND STRUCTURE OF BAT ASSEMBLAGES IN PARAGUAY: A SUBTROPICAL–TEMPERATE INTERFACE

Abstract Little is known about geographic variation in the local composition of South American assemblages of mammals or the factors that may produce such variation. This is particularly unfortunate in Paraguay because it occurs at the interface of a number of phytogeographic regions (e.g., Cerrado, Chaco, Interior Atlantic Rainforest, and Pantanal) and is the point at which many temperate species reach their northern limits or at which tropical species reach their southern limits. Based on 2 years of intensive fieldwork, we documented the species and familial composition of bat assemblages at 25 sites throughout the country. We also estimated similarity among sites based on indices sensitive to presence or absence of species (Ochiais index), to rank abundance of species (rank correlation index), or to relative abundance of species (Euclidean index). Geographic distance between sites accounted for little variation in composition based on presence–absence or rank abundances of species but accounted significantly for variation related to both identity and relative frequency of species. Distinct assemblages of species do not correspond to the 7 distinct biomes of the country; rather, strong differences exist between sites east (mesic) and west (xeric) of the Río Paraguay. For the most part, these differences are related to dominance by molossids (e.g., Eumops patagonicus, Molossops temminckii, and Molossus molossus) and vespertilionids (e.g., Lasiurus ega, Myotis albescens, and M. nigricans) in dry regions versus phyllostomids (e.g., Artibeus fimbriatus, A. lituratus, and Sturnira lilium) in mesic regions. As a consequence, classification of sites into 2 broad biogeographic regions based on bat familial composition generally is concordant with that based on plants.

Elements of metacommunity structure of Paraguayan bats: multiple gradients require analysis of multiple ordination axes

Techniques to evaluate elements of metacommunity structure (EMS; coherence, species turnover and range boundary clumping) have been available for several years. Such approaches are capable of determining which idealized pattern of species distribution best describes distributions in a metacommunity. Nonetheless, this approach rarely is employed and such aspects of metacommunity structure remain poorly understood. We expanded an extant method to better investigate metacommunity structure for systems that respond to multiple environmental gradients. We used data obtained from 26 sites throughout Paraguay as a model system to demonstrate application of this methodology. Using presence–absence data for bats, we evaluated coherence, species turnover and boundary clumping to distinguish among six idealized patterns of species distribution. Analyses were conducted for all bats as well as for each of three feeding ensembles (aerial insectivores, frugivores and molossid insectivores). For each group of bats, analyses were conducted separately for primary and secondary axes of ordination as defined by reciprocal averaging. The Paraguayan bat metacommunity evinced Clementsian distributions for primary and secondary ordination axes. Patterns of species distribution for aerial insectivores were dependent on ordination axis, showing Gleasonian distributions when ordinated according to the primary axis and Clementsian distributions when ordinated according to the secondary axis. Distribution patterns for frugivores and molossid insectivores were best described as random. Analysis of metacommunities using multiple ordination axes can provide a more complete picture of environmental variables that mold patterns of species distribution. Moreover, analysis of EMS along defined gradients (e.g., latitude, elevation and depth) or based on alternative ordination techniques may complement insights based on reciprocal averaging because the fundamental questions addressed in analyses are contingent on the ordination technique that is employed.

TAXONOMIC STATUS OF MYOTIS (CHIROPTERA: VESPERTILIONIDAE) IN PARAGUAY

Abstract Qualitative and quantitative variation in morphology was assessed for 6 species of Myotis from South America to determine which taxa occur in Paraguay, characteristics that allow for their discrimination, and the degree of geographic and secondary sexual variation that occurs in Paraguayan forms. Secondary sexual dimorphism and geographic variation were evaluated from univariate and multivariate perspectives. Multivariate morphometric differences in cranial morphology among taxa, independent of size, and mensural characters that best separate species were determined using principal components analysis followed by size-adjusted discriminant function analysis. Five species, M. albescens, M. nigricans, M. riparius, M. ruber, and M. simus, occur in Paraguay and can be distinguished using combinations of cranial and external characteristics. No significant sexual dimorphism or geographic variation was detected in these taxa of Myotis in Paraguay. M. levis has not been recorded for Paraguay as previously reported, but it may occur in the country. M. simus, a species previously considered to be restricted to the Amazon Basin, occurs as far south as Paraguay and northern Argentina. Although M. simus varies significantly in size across its range, highly differentiated cranial and external morphology allows for recognition of this species across its range.

USE OF ABANDONED MINES BY LONG-EARED BATS, GENUS CORYNORHINUS (CHIROPTERA: VESPERTILIONIDAE) IN DURANGO, MEXICO

Abstract Use of abandoned mines by Corynorhinus mexicanus and C. townsendii is documented for a sample of 25 mines in Guanaceví, Durango, Mexico, during 1 year. Presence–absence of bats was recorded, and significance of associations between bat presence and environmental and structural characteristics of mines was tested. Bats occupied 15 of 25 mines examined. Males and females were observed in low numbers, and scattered throughout mine workings. Mines were used as hibernation roosts in winter, and as day roosts and temporary night roosts during the rest of the year. A maternity colony of endemic C. mexicanus was observed in 1 mine. Temperature and adit length were significantly associated with bat occupancy. Bats were more commonly found in mines that were at least 50 m long, had temperatures <10°C in winter, and temperatures >16°C the rest of the year. Mines might be providing an alternative refuge for these species in heavily deforested habitats.

Acoustic identification of Mexican bats based on taxonomic and ecological constraints on call design

1. Monitoring global biodiversity is critical for understanding responses to anthropogenic change, but biodiversity monitoring is often biased away from tropical, megadiverse areas that are experiencing more rapid environmental change. Acoustic surveys are increasingly used to monitor biodiversity change, especially for bats as they are important indicator species and most use sound to detect, localise and classify objects. However, using bat acoustic surveys for monitoring poses several challenges, particularly in mega-diverse regions. Many species lack reference recordings, some species have high call similarity or differ in call detectability, and quantitative classification tools, such as machine learning algorithms, have rarely been applied to data from these areas. 2. Here, we collate a reference call library for bat species that occur in a megadiverse country, Mexico. We use 4,685 search-phase calls from 1,378 individual sequences of 59 bat species to create automatic species identification tools generated by machine learning algorithms (Random Forest). We evaluate the improvement in species-level classification rates gained by using hierarchical classifications, reflecting either taxonomic or ecological constraints (guilds) on call design, and examine how classification rate accuracy changes at different hierarchical levels (family, genus, and guild). 3. Species-level classification of calls had a mean accuracy of 66% and the use of hierarchies improved mean species-level classification accuracy by up to 6% (species within families 72%, species within genera 71.2% and species within guilds 69.1%). Classification accuracy to family, genus and guild-level was 91.7%, 77.8% and 82.5%, respectively. 4. The bioacoustic identification tools we have developed are accurate for rapid biodiversity assessments in a megadiverse region and can also be used effectively to classify species at broader taxonomic or ecological levels. This flexibility increases their usefulness when there are incomplete species reference recordings and also offers the opportunity to characterise and track changes in bat community structure. Our results show that bat bioacoustic surveys in megadiverse countries have more potential than previously thought to monitor biodiversity changes and can be used to direct further developments of bioacoustic monitoring programs in Mexico.

Ectoparasites Associated to Two Species of Corynorhinus (Chiroptera: Vespertilionidae) from the Guanaceví Mining Region, Durango, Mexico

Abstract As a part of an inventory of bats in abandoned mines at the municipality of Guanaceví, Durango, Mexico, a sample of long-eared bats (genus Corynorhinus) was collected and ectoparasites were taken. Twenty-three specimens of Corynorhinus mexicanus Allen, 1916, and 18 of Corynorhinus townsendii (Cooper, 1937) were collected in four sampling periods coincident with the seasons. In total, 98 ectoparasites of 10 species and seven families were examined. Five species are recorded for the first time on C. mexicanus and four on C. townsendii. Macronyssus cyclaspis and Trichobius corynorhini had the highest frequency of infestation in both bats. Differences in number of arthropods per bat among seasons were nonsignificant for both species.

Bats of Northwestern Durango, Mexico: Species Richness at the Interface of Two Biogeographic Regions

Abstract An updated list of the bats of northwestern Durango, based on recent collections and literature records, is presented. A total of 43 species were recorded, five for the first time in the state (Balantiopteryx plicata, Artibeus hirsutus, Artibeus intermedius, Chiroderma salvini, and Myotis carteri). Comparisons with other intensively sampled localities across Mexico indicate that species richness in the Sierra Madre Occidental of northwestern Durango is comparable to that of Mexican rainforests, resulting from high diversity of habitats in relatively small areas. Species composition in this region is dominated by vespertilionid and molossid bats, whereas phyllostomids dominate tropical rainforests; thus, species assemblages are considerably different. Moreover, anthropogenic pressure is comparatively lower than in most of the humid tropics of Mexico. Nonetheless, no protected area exists that includes the complete spectrum of habitats of the region. An immediate conservation strategy is urgently needed if this largely unknown region of Mexico is to be preserved.

A checklist of the mammals (Mammalia) of Chihuahua, Mexico

An updated list of the mammals of Chihuahua state, Mexico was assembled from the literature and from museum specimens. We documented 133 species (15 endemic to Mexico and 11 new for Chihuahua), representing 25 families, 75 genera, and 27.4% of the Mexican terrestrial mammalian fauna. Four species are probably extirpated from the state. Four major ecoregions have been defined for Chihuahua: Arid, Valleys, Sierra, and Quebradas. Species richness was the highest in Valleys, and consisted mostly of species with Nearctic affinities. In contrast, Quebradas were the least species-rich, but included mostly Neotropical species that occur only in this ecoregion of Chihuahua. Despite the fact that Chihuahua harbors considerable biodiversity and unique Mexican biomes, conservation efforts are insufficient. The current rate of anthropogenic modification in the state requires a comprehensive strategy if Chihuahua’s biodiversity is to be preserved.

Morphologic characterization of Peromyscus schmidlyi (Rodentia: Cricetidae), an endemic of the Sierra Madre Occidental, Mexico

Abstract Based on examination of 705 museum specimens, including the holotype and individuals identified using molecular attributes, we characterized Schmidlys deer mouse (Peromyscus schmidlyi) using a set of morphometric and morphological characteristics. Discriminant function analysis was performed on 14 cranial attributes to find those most useful to separate species. Factorial analysis of variance and multivariate analysis of variance were used to test for significant differences due to species, sex, age, and geographic location. We compared and contrasted P. schmidlyi with P. boylii rowleyi and P. spicilegus, morphologically similar and partially sympatric species, and reevaluated the distribution of the 3 species in the Sierra Madre Occidental (SMO) of Mexico. P. schmidlyi is a medium-sized Peromyscus distinguishable by a set of characters including overall size intermediate between P. spicilegus and P. boylii rowleyi, relatively wider braincase and zygoma, hourglass-shaped interorbital constriction, large auditory bullae, and strongly bicolored, tufted tail. Morphometric characterization is possible only when age and geographic location are taken into consideration. Several specimens previously identified as P. boylii rowleyi were reidentified as P. schmidlyi. Records available showed that P. schmidlyi is distributed in forested highlands of the SMO, from northern Chihuahua to northern Jalisco, between 1,550 (on the western versant) and 3,000 m of elevation. The species is sympatric with P. boylii rowleyi between 2,100 and 2,400 m along the eastern versant of the SMO and with P. spicilegus along a narrower band (1,550–2,000 m) on the steeper western slope. Distribution of these species closely reflects the most recent ecological regionalization of the SMO. Resumen Se examinaron 705 ejemplares de museo incluyendo el holotipo e individuos identificados usando citocromo-b mitocondrial, para caracterizar Peromyscus schmidlyi desde el punto de vista morfológico y morfométrico. Se midieron 14 variables craneales y se realizó un análisis de funciones discriminantes para encontrar aquellas más útiles para separar especies. Se utilizaron análisis de varianza univariados (ANOVA) y multivariados (MANOVA) factoriales para evaluar diferencias entre especies, sexos y distribución geográfica. P. schmidlyi se comparó con P. boylii rowleyi y P. spicilegus, especies morfológicamente similares y parcialmente simpátricas con P. schmidlyi. Finalmente, se reevaluó la distribución de las 3 especies en la Sierra Madre Occidental (SMO). P. schmidlyi es de tamaño mediano, distinguible por un conjunto de caracteres incluyendo: tamaño general intermedio entre P. spicilegus y P. boylii rowleyi, caja craneana y arco cigomático relativamente anchos, región interorbital en forma de reloj de arena, bulas auditivas grandes, y cola marcadamente bicolor con un pincel en la punta. La caracterización morfológica de P. schmidlyi requiere tomar en cuenta la edad relativa y localidad de los ejemplares. Individuos previamente identificados como P. boylii rowleyi fueron reidentificados como P. schmidlyi. Como resultado, se puede concluir que P. schmidlyi se distribuye en los bosques de coníferas y pino–encino de la SMO, del norte de Chihuahua al norte de Jalisco, entre 1,550 (en la vertiente occidental) y 3,000 m sobre el nivel del mar. Es simpátrica con P. boylii rowleyi entre 2,100 y 2,400 m a lo largo de la vertiente oriental, y con P. spicilegus sobre una angosta banda (1,550–2,000 m) en la abrupta cara occidental. La distribución de estas especies sigue muy de cerca la ecoregionalización más reciente de la SMO.

A checklist of the mammals (Mammalia) from Durango, western Mexico

An updated list of the mammals of Durango state, Mexico was built from literature records and Museum specimens. A total of 139 species have been recorded, representing 28.3 % of the Mexican terrestrial mammals, and 25.1 % species more compared to the previous account. Two species have been extirpated from the state, 23 are endemic to Mexico. Four major ecoregions have been previously defined for the state, Arid, Valleys, Sierra, and Quebradas. Species richness is highest at the Quebradas, a tropical ecorregion, whereas the aridlands are the least species-rich. The Sierra has the highest number of endemic species (11) followed by Quebradas (7), Valleys and Arid (3). Despite the fact that Durango harbors one of the largest diversities of mammals of the country, conservation efforts are minimal, and the current protected areas do not include the most species-rich regions. The current rate of anthropogenic modification in the state makes urgent to put in practice already existing plans to protect Durango’s unique biodiversity.