Seasonal dietary niche contraction in coexisting Neotropical frugivorous bats (Stenodermatinae)

Tropical dry forests are characterized by punctuated seasonal precipitation patterns that drive primary production and the availability of fruits, seeds, flowers, and insects throughout the year. In environments in which the quantity and quality of food resources varies seasonally, consumers should adjust their foraging behavior to maximize energy intake while minimizing overlap with competitors during periods of low food availability. Here, we investigated how the diets of frugivorous bats in tropical dry forests of NW Mexico varied in response to seasonal availability and how this affected dietary overlap of morphologically similar species. We performed stable isotope analyses to understand temporal and interspecific patterns of overall isotopic niche breadth, trophic position, and niche overlap in the diet of six frugivorous species of closely related New World leaf-nosed bats (family Phyllostomidae, subfamily Stenodermatinae). We estimated seasonal changes in resource abundance in two complementary ways: (a) vegetative phenology based on long-term remote sensing data and (b) observational data on food availability from previously published insect and plant fruiting surveys. In all species, there was a consistent pattern of reduced isotopic niche breadth during periods of low food availability. However, patterns of niche overlap varied between morphologically similar species. Overall, results from our study and others suggest that seasonal food availability likely determines overall dietary niche breadth in Phyllostomidae and that despite morphological specialization, it is likely that other mechanisms, such as opportunistic foraging and spatiotemporal niche segregation, may play a role in maintaining coexistence rather than simply dietary displacement.     

Bat flies (Diptera: Streblidae) of phyllostomid bats (Chiroptera: Phyllostomidae) from the mountainous central region of Veracruz,Mexico

Systematic Parasitology - The studies of bat flies of the family Streblidae Kolenati, 1863 in Mexico have intensified in the last five years, usually providing new geographical records of species...     

Foraging strategies,craniodental traits,and interaction in the bite force of Neotropical frugivorous bats (Phyllostomidae: Stenodermatinae)

1. Bats in the family Phyllostomidae exhibit great diversity in skull size and morphology that reflects the degree of resource division and ecological overlap in the group. In particular, the subfamily Stenodermatinae has high morphological diversification associated with cranial and mandibular traits that are associated with the ability to consume the full range of available fruits (soft and hard).
2. We analyzed craniodental traits and their relationship to the bite force in 343 specimens distributed in seven species of stenodermatine bats with two foraging strategies: nomadic and sedentary frugivory. We evaluated 19 traits related to feeding and bite force in live animals by correcting bite force with body size.
3. We used a generalized linear model (GLM) and post hoc tests to determine possible relationships and differences between cranial traits, species, and sex. We also used Blomberg''s K to measure the phylogenetic signal and phylogenetic generalized least‐squares (PGLS) to ensure the phylogenetic independence of the traits.
4. We found that smaller nomadic species, A. anderseni and A. phaeotis , have a similar bite force to the large species A. planirostris and A. lituratus; furthermore, P. helleri registered a bite force similar to that of the sedentary bat, S. giannae. Our study determined that all the features of the mandible and most of the traits of the skull have a low phylogenetic signal. Through the PGLS, we found that the diet and several cranial features (mandibular toothrow length, dentary length, braincase breadth, mastoid breadth, greatest length of skull, condylo‐incisive length, and condylo‐canine length) determined bite force performance among Stenodermatiane.
5. Our results reinforce that skull size is a determining factor in the bite force, but also emphasize the importance of its relationships with morphology, ecology, and phylogeny of the species, which gives us a better understanding of the evolutionary adaptions of this highly diverse Neotropical bat group.

     

Enriching agroecosystems with fruit-producing tree species favors the abundance and richness of frugivorous and nectarivorous bats in Veracruz, Mexico

We evaluated how the abundance and richness of frugivorous and nectarivorous bat species differs among three types of common agroecosystems (diversified coffee plantations, simple coffee plantations and pastures) in Veracruz, Mexico, that represent a gradient of structural and floristic complexity. Using mixed effects models we demonstrated that both the richness and the total abundance of bats was higher in the diversified coffee plantations. We detected similar patterns on comparing the abundance of the four most abundant bat species. Neither season nor the season-agroecosystem interaction had any effect on the comparisons made. Using multiple regressions we found that the richness of plants that are useful to both people and bats had the most explanatory power for the richness and total abundance of frugivorous and nectarivorous bats, as well as for the abundance of Carollia sowelli, Glossophaga soricina and Sturnira spp. Our results indicate that agroecosystems value for conservation of fruit and nectar-eating bats increases as the fruit-bearing trees increases. For the effective conservation of these guilds of bats in tropical agroecosystems, a strategy of diversification with fruit-bearing species is highly recommended; such a strategy would benefit both agricultural producers and wildlife.     

Avian responses to selective logging shaped by species traits and logging practices

Selective logging is one of the most common forms of forest use in the tropics. Although the effects of selective logging on biodiversity have been widely studied, there is little agreement on the relationship between life-history traits and tolerance to logging. In this study, we assessed how species traits and logging practices combine to determine species responses to selective logging, based on over 4000 observations of the responses of nearly 1000 bird species to selective logging across the tropics. Our analysis shows that species traits, such as feeding group and body mass, and logging practices, such as time since logging and logging intensity, interact to influence a species'' response to logging. Frugivores and insectivores were most adversely affected by logging and declined further with increasing logging intensity. Nectarivores and granivores responded positively to selective logging for the first two decades, after which their abundances decrease below pre-logging levels. Larger species of omnivores and granivores responded more positively to selective logging than smaller species from either feeding group, whereas this effect of body size was reversed for carnivores, herbivores, frugivores and insectivores. Most importantly, species most negatively impacted by selective logging had not recovered approximately 40 years after logging cessation. We conclude that selective timber harvest has the potential to cause large and long-lasting changes in avian biodiversity. However, our results suggest that the impacts can be mitigated to a certain extent through specific forest management strategies such as lengthening the rotation cycle and implementing reduced impact logging.     

Detection of Batrachochytrium dendrobatidis in amphibians inhabiting cloud forests and coffee agroecosystems in central Veracruz,Mexico

The chytrid fungus Batrachochytrium dendrobatidis (Bd) is a threat to the survival of amphibians worldwide, a situation that is compounded by several other factors. In this study, we determined the prevalence of Bd and its relationship to biotic and abiotic variables for six amphibian communities in two cloud forest fragments and four coffee agroecosystems in central Veracruz, Mexico. A sampling effort of 768 person-hours and 109 skin swabs resulted in the detection of B. dendrobatidis in four amphibian species belonging to three families. The co-inertia model showed the following as the most important variables: tree density, fern species, temperature and elevation, fragment or site size, and structural index. Conversely, we did not find a clear relationship between Bd prevalence and the habitat management gradient. The highest prevalence was found in the second cloud forest, but a very similar result was found in one of the traditional agroecosystems; the lowest levels of prevalence were found in another second traditional agroecosystem and the first cloud forest. The degree of infection was highest in the cloud forests where the diversity of trees, orchids, and elevation was higher. Ecnomiohyla miotympanum was the most abundant species and was found to be infected in four of the five sites, presenting the highest degree of infection.     

The fishes of northern and central Veracruz,Mexico

The hydrographic structure of Abra Harbour, a tidal embayment located at the seaward end of the highly polluted estuary of Bilbao, is influenced by the inflow of a polluted estuarine plume, the asymmetry of the harbour basin, and the tidal circulation pattern. Multivariate analysis of the spatial variability of the zooplankton between May 1981 and May 1982 showed that significant differences in zooplankton abundance and species composition occurred from the inner-eastern to the outer-western side, related to the horizontal structure of the system. The annual temperature cycle, however, was the major source of temporal variability, and the seasonal stratification in the water column was responsible for the predominance of vertical differences in zooplankton composition during the spring-summer period. Wind-induced turbulence and tides were other sources of variation. With increasing turbulence (rough sea), the spatial gradients in zooplankton composition were not as clear, and with decreasing tidal height the compositional differences in the horizontal dimension tended to be more evident. Spionid larvae accounted for strong local differences within the Harbour. They were usually segregated from other taxa, and mainly associated to the deeper waters characterized by a greater hydrological instability.     

Diversity of Carabidae (Insecta, Coleoptera) in epiphytic Bromeliaceae in central Veracruz, Mexico

This paper documents the existence of carabid assemblages associated with bromeliads on the Cofre de Perote, Veracruz, Mexico. Based on bromeliads sampled over three altitudinal ranges, the assemblages included at least 26 species with an arboreal lifestyle and another 11 species that are not strictly arboreal. Seven species are new to science, urging us to pay attention to the arboreal fauna in forest conservation studies. Composition of carabid assemblages associated with bromeliads changes with altitude. In lowlands, it is comprised almost entirely of species of Lebiini, with the Platynini dominating assemblages found in bromeliads >1,000 m above sea level. Our data suggest that carabids use bromeliads to reduce stresses associated with drought periods, the exact timing of which depends on altitude. The unexpected low diversity of the carabid fauna associated with bromeliads at middle altitude is explained in terms of anthropogenic conversion of the original forest to pastureland. Given the importance of arboreal elements, further fragmentation of subtropical and tropical mountain forest significantly threatens overall carabid diversity.     

Gastrointestinal helminth parasitism in fruit-eating bats (Chiroptera, Stenodermatinae) from western Amazonian Brazil

In this paper we report endoparasites from a sample of 50 stenodermatine bats collected mainly over lick sites at the Parque Nacional da Serra do Divisor, westernmost extremity of Amazonian Brazil. Four helminth species were recovered (Hasstilesia tricolor, Vampirolepis elongatus, Cheiropteronema globocephala. and Capillaria sp.), most of them from small intestines. Overall helminth prevalence achieved 26% (13/50) and the more prevalent species was H. tricolor (20%). Previously unknown in bats and reported for the first time in Brazil, this digenetic trematode was found in seven of the 18 bat species studied here. We argue that the drinking behaviour of stenodermatines at lick sites may be implicated in the dissemination of helminth infection among these bats.     

Effect of artificial light on activity in frugivorous bats (Pteropodidae)

Journal of Ethology - Artificial lighting at nights (ALAN) affects behaviour in many animals, especially nocturnal species. However, its effect on frugivorous bats remains less explored, especially...     

Abundance of arbuscular mycorrhizal fungi spores in different environments in a tropical rain forest, Veracruz, Mexico

 The aim of this study was to compare mycorrhizal abundance and diversity in sites with different regimes of disturbance in a tropical rain forest at Los Tuxtlas, Veracruz, Mexico. Arbuscular mycorrhizal spores were quantified at two sites: closed canopy and gaps in the forest. Data were recorded during dry, rainy, and windy ("nortes") seasons. Spores of eight Glomus species, sporocarps of three Sclerocystis species, three species of Acaulospora and two of Gigaspora were found. Significant differences in the number of species and spores were found among seasons. The highest numbers of species and spores were observed during the dry season, with a marked decrease during the rainy season. Our results show that disturbance does not but seasonality does affect abundance and richness of mycorrhizal spores in this tropical wet forest. Accepted: 11 October 1998     

Roosting ecology of Stenodermatinae bats (Phyllostomidae): evolution of foliage roosting and correlated phenotypes

相似文献   

Fauna of Scarabaeidae-Laparosticti and Trogidae (Coleoptera: Scarabaeoidea) associated with Cloud Forest, shaded coffee plantations and transformed communities in Central Veracruz, Mexico

Beetles were collected from April 2002 to July 2003 from the following sites in the centre of the state of Veracruz located every 200 m along an altitudinal gradient (1000 - 1400 m asl): three fragments of cloud forest, three shaded coffee plantations, an open canopy coffee plantation, secondary forest, and a pasture. A total of 9,982 specimens were captured, belonging to the families Scarabaeidae and Trogidae, and representing 21 genera and 50 species. The genera Ataenius Harold, Onthophagus Latreille and Aphodius Illiger represented 48% of the species of Scarabaeidae. Species richness was found to decrease with increasing altitude; there were 36 species at 1000 m asl, 27 species between 1200 and 1300 m asl, and 26 species at 1400 m asl. Abundance along the altitudinal gradient follows a pattern of few abundant species and many species with few specimens. Beetle activity is related to precipitation. In the nine communities studied, species richness was observed to increase when precipitation was greater than 100 mm at the beginning of the rainy season. On the landscape scale, there were 44 species during the rainy season, 22 during the windy nortes season, and 24 during the dry season. In terms of trophic guild, 40% of the beetles captured were saprophagous that feed on decomposing organic material from plants and 60% were saprophagous that feed on decomposing organic material from animals (30% necrophagous, 26% coprophagous, 4% telio-necrophagous).     

Structure and ecology of epiphyte communities of a cloud forest in central Veracruz,Mexico

Abstract. 39 species of vascular epiphytes were found in a 625-m² plot in a cloud forest in Veracruz, Mexico. Epiphyte biomass was estimated for all species in six zones distinguished on each tree > 10 cm in DBH: stem base, lower stem, upper stem, branches > 20 cm, branches from 5 — 20 cm and branches < 5 cm diameter. Branches were additionally separated according to their position in the upper, middle or lower canopy. Total dry matter of green organs was 318 kg/ha. Dominance/diversity curves fitted best to the lognormal model. Principal Coordinate Analysis showed that canopy height and branch thickness are both important factors and also that the stem base was the most distinct zone. Microhabitat preferences and niche overlap of the frequent species proved some degree of resource partitioning within the canopy. Ecophysiological characters possibly responsible for these preferences and implications for conservation are discussed.     

A new species of Ponthieva (Orchidaceae, Cranichidinae) from Veracruz, Mexico

Ponthieva rinconii, a new orchid species from the foothills of the Sierra Madre Oriental in Veracruz, Mexico, is described and illustrated. It is similar in overall appearance to the wide-ranging upland speciesP. schaffneri, but differs from it in habitat preferences (tropical semi-evergreen forest at 650 m elevation), presence of a loose raceme, and three-lobed labellum with a basal cavity.     

A new species of Ceratozamia (Zamiaceae, Cycadales) from Veracruz, Mexico

Ceratozamia huastecorum sp. nov. is from an isolated meseta or tepui-like mountain in the Huasteca region of northern Veracruz State, Mexico. It has affinity to C. morettii Vázq.Torres & Vovides from the Mexican transvolcanic mountain range, which lies over 200 km to the south. The most notable differences are in female cone colour, leaf and leaflet morphology and length. The specific epithet is chosen in honour of the Huasteca ethnic region of great cultural importance to northern Veracruz.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 395–398.     

Composition and ecology of vascular epiphyte communities along an altitudinal gradient in central Veracruz,Mexico

Abstract. Vascular epiphytes were studied in forests at altitudes from 720 to 2370 m on the Atlantic slope of central Veracruz, Mexico. The biomass of all trees of each species > 10 cm diameter at breast height within plots between 625 and 1500 m² was estimated. The number of species per plot ranged between 22 and 53, and biomass between 9 and 249 g dry weight/m². The highest values, both of species and biomass, were found at an intermediate altitude (1430 m). Habitat diversity may contribute to epiphyte diversity in humid forests, but the importance of this effect could not be distinguished from the influence of climate. A remarkably high number of bromeliads and orchids grew in relatively dry forests at low altitudes. In wet upper montane forests, bromeliads were replaced by ferns, while orchids were numerous at all sites, except for a pine forest. The number of epiphytic species and their biomass on a tree of a given site were closely related to tree size. According to Canonical Correspondence Analysis, the factor determining the composition of the epiphytic vegetation of a tree was altitude and to some extent tree size, whereas tree species had practically no influence. The only trees which had an evidently negative effect on epiphytes were pines, which were particularly hostile to orchids and to a lesser degree to ferns, and Bursera simaruba, which generally had few epiphytes due to its smooth and defoliating bark.     

Effect of fasting on carbohydrate metabolism in frugivorous bats (Artibeus lituratus and Artibeus jamaicensis)

The compensatory changes of carbohydrate metabolism induced by fasting were investigated in frugivorous bats, Artibeus lituratus and Artibeus jamaicensis. For this purpose, plasma levels of glucose and lactate, liver and muscle glycogen content, rates of liver gluconeogenesis and the activity of related enzymes were determined in male bats. After a decrease during the first 48 h of fasting, plasma glucose levels remained constant until the end of the experimental period. Plasma lactate levels, extremely high in fed bats, decreased after 48 h of fasting. Similarly, liver glycogen content, markedly high in fed animals, was reduced to low levels after 24 h without food. Muscle glycogen was also reduced in fasted bats. The expected increase in liver gluconeogenesis during fasting was observed after 48 h of fasting. The activities of liver glucose-6-phosphatase and fructose-1,6-bisphosphatase were not affected by food withdrawn. On the other hand, fasting for 24 h induced an increase in the activity of liver cytosolic phosphoenolpyruvate carboxykinase. The data indicate that liver gluconeogenesis has an important role in the glucose homeostasis in frugivorous bats during prolonged periods of food deprivation. During short periods of fasting liver glycogenolysis seems to be the main responsible for the maintenance of glycemia.     

Feeding habits and trophic morphology of inshore lizardfish (Synodus foetens) on the central continental shelf off Veracruz, Gulf of Mexico

The inshore lizardfish, Synodus foetens, is one of the most common coastal demersal predators on the continental shelf of the Gulf of Mexico (GOM), but the biology and feeding ecology of this species is virtually unknown. Between November 2001 and January 2003 (10 collections), 603 individuals of S. foetens ranging from 112 to 420 mm standard length (SL) and 13 to 630 g (wet weight) were collected from the continental shelf of Alvarado, Veracruz, Mexico. About 60% of the individuals had empty stomachs with the stomach fullness of the remaining individuals being distributed as follows: 5% full (24.8%), 50–75% full (13.5%), and completely full (1.7%). The mean (± SD) wet weight of stomach contents was 12.1 ± 10.8 g during the rainy season, and 19.0 ± 13.0 g during the nortes season. Seventeen prey items were identified, with the majority thereof being fish. The most important prey items were Upeneus parvus, Loligo pealei, Engyophrys senta, Trachurus lathami, and Anchoa hepsetus. Seasonal changes in the diet were observed, with U. parvus and L. pealei being the most important prey during the nortes season, whereas E. senta and L. pealei were the main items during the rainy season. Prey size selection was evident among size classes of S. foetens, although no trophic overlap was observed among size classes (C_ik ≤ 0.004). High trophic level values were determined for all size classes by season (rainy season = 4.67, nortes season = 4.84), and indicated this species belongs to the piscivorous trophic guild that preys upon both demersal and pelagic species.     

Dinoflagellates (Dinophyta) of orders Dinophysiales and Prorocentrales of the Veracruz Reef System, Mexico

Dinoflagellates are a major taxonomic group in marine phytoplankton communities in terms of diversity and biomass. Some species are also important because they form blooms and/or produce toxins that may cause diverse problems. The composition of planktonic dinoflagellates of the orders Prorocentrales and Dinophysiales, in the Veracruz Reef System, were obtained during the period of October 2006 to January 2007. For this, samples were taken from the surface at 10 stations with net of 30 microm mesh, and were analyzed by light and scanning electron microscopy. Each species was described and illustrated, measured and their distribution and ecological data is also given. A total of nine species were found and identified, belonging to four genera: Dinophysis was represented by three species; Prorocentrum by three, Phalacroma by two, and only one species of Ornithocercus was detected. From the samples, four potentially toxin-producer species were found: Dinophysis caudata, D. rapa, Phalacroma rotundata and Prorocentrum micans. The number of species found in this study is low, especially considering the higher numbers observed in other areas of the Gulf of Mexico, where some reports have recorded up to 53 species of the order Dinophysiales and 14 for Prorocentrales. Identification keys for orders, genera and species for the study area are provided with this study.