Browsing by Autor "Pascual J. Soriano"

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Dieta y patrón reproductivo de Rhogeessa minutilla (Chiroptera: VespertUionidae) en una zona árida de Los Andes de Venezuela
(2015) Maricela Sosa; Antonio De Ascenção; Pascual J. Soriano
En un estudio realizado durante un año en un arbustal espinoso en el bolsón xerofítico de Lagunillas, en Los Andes venezolanos se evaluó la dieta y condición reproductiva del murciélago Rhogeessa minutilla. El análisis de las muestras fecales reveló que la dieta de este murciélago vespertiliónido está constituida por insectos cuya longitud corporal oscila entre los 3- I 2 mm, representados en 10 ordenes y 29 familias. El 84.9% de la dieta está representada en cuatro ordenes: Diptera (42.5), Hymenoptera (18.2), Lepidoptera (13.3) y Coleoptera (10.9). La variación estacional de la dieta, la cual se manifiesta bajo un continuo reemplazo de los taxones consumidos y el amplio espectro de la misma parece señalar a R. minutilla como una especie oportunista en cuanto al tipo de presa, pero selectiva en cuanto al tamaño y dureza de la misma. La información reproductiva reveló un pico de preñeces en el lapsóman;o-mayo y la presencia de juveniles durante junio-julio, lo cual parece indicar que el patrón reproductivo de la especie consiste en una monoestría estacional, asociada a la mayor disponibilidad de insectos que parece existir durante la estación de lluvias.
Estudio Fenológico de Cactáceas en el Enclave Seco de la Tatacoa, Colombia1
(Wiley, 2000) Adriana Ruiz; Mery Santos; Jaime Cavelier; Pascual J. Soriano
A one-year phenological study of three columnar cacti, Stenocereus griseus (Haw.) Britton & Rose, Pilosocereus sp., Cereus hexagonus (L.) Mill., and a decumbent cactus Monvillea cf. smithiana (Britton & Rose) Backeberg., was carried out in the Andean arid region of La Tatacoa, Colombia. Pollinators and/or dispersers of the cacti species also were studied monthly, and fecal samples were collected for the identification of pollen and seeds. The flowering of all species was prolonged and showed bimodal, multimodal, or irregular patterns. Fruiting in all species also was prolonged and followed flowering with a lag of less than two months. Although there were no simple correlations between rainfall and flowering or fruiting, flower production during the dry season was higher for S. griseus, while Pilosocereus sp. and C. hexagonus showed higher flower production during the wet season. Fruit production was also seasonal, with higher production during the wet season for S. griseus and C. hexagonus. The patterns of flowering and fruiting in M. cf. smithiana showed no relationships with dry and wet seasons. The bats Glossophaga longirostris, Carollia perspicillata, Sturnira lilium, the birds Melanerpes rubricapillus (Picidae) and Mimus gilvus (Mimidae), and moths of the family Sphingidae, were identified as pollinators and/or fruit consumers of these cacti species.
Fructificación, frugivoría y disperción en el cactus globular Melocactus Schatzlii en el enclave semiárido de Lagunillas, Mérida, Venezuela
(2010) Roberto Casado B.; Pascual J. Soriano
The objectives of this study were: i) monitoring the fruiting process from anthesis to fruit emergency in the globular cactus Melocactus schatzlii in the Lagunillas semiarid enclave, Merida-Venezuela, and ii) to identify their main fruit consumers and detect their potential seed dispersers. The number of fruits produced was registered in 102 sexually mature cacti, five days/month, during an entire year. Composition and structure of frugivorous guilds associated to M. schatzlii fruit production were also studied, in a 398 hour film record. Fruit production occurs throughout the year, with two periods of maximum production, the first between May and June, the second between October and December. The average range between pollination and fruit formation was 60±12 (DE) days. Fruit production patterns seem to be highly correlated with precipitation regimes (r=0.86), as we inferred from forwarding one month of fruit production data. Vertebrates are the main fruit consumer of this species; represented in first place by lizards, which account for the 90% of the consumption events, represented mainly Ameiva provitae and Cnemidophorus lemniscatus, while the remaining 10% is represented by two species of birds, Tiaris bicolor and Mimus gilvus. Despite the fact that vertebrates were responsible for more than 90% of seed mobilization, we recorded 12 species of invertebrate fruit consumers. In this guild, Ectatomma ruidum ants employ the longest time of consumption, according to the film records (>50 hours; 23 diurnal and nocturnal 27) followed by Blattidae nymphs (>25 hours, primarily nocturnal). Seedling germination experiments revealed that: 50% (T 50 ) of the washed seeds germinated within 8 days; T 50 of the seeds bearing pulp withim 11 days; and T 50 of the seeds defecated by C. lemniscatus and A. provitae within 11 and 13 days, respectively. Regarding the controls of the washed seeds and of the seeds with remains of pulp, germination percentages were 96% and 92%, respectively; whereas, in the case of the controls of the seeds ingested by C. lemniscatus and A. provitae, germination rates were of 93% and 83%, respectively, confirming their role as seed dispersors of M. schatzlii. Statiscally significant differences were observed in all of the germination treatments when compared as pairs, save the pair seeds trated by C. lemniscatus and unwashed seeds. Potential germination inhibitors only appear to retard imbibhition onset. The lizards A. provitae and C. lemniscatus were the main fruit consumers and the responsible of seed movement of M. schatzlii, which support saurocory as the dispersion syndrome for the Melocactus genus.
Hábitos alimentarios de Glossophaga longirostrisMiller (Chiroptera: Phyllostomidae) en una zona árida de los Andes venezolanos
(2016) Pascual J. Soriano; Maricela Sosa; Rossell, Osman
Examinamos 163 muestras fecales, obtenidas de 223 ejemplares del murciélago Glossophaga longirostris, colectados entre enero de 1988 y diciembre de 1989, en un arbustalsemiárido ubicado junto la Laguna de Caparú, Estado Mérida, Venezuela (82 29' 16"N y 71° 20' l O'W). Detectamos de semillas de las cactáceas columnares Stenoeereus griseus, Subpiloeereus repandus, Pilosoeereus tillianus. de la Moraceae Chlorophora tinetoria y polen de cactáceas. Globalmente las semillas fueron más importantes (valor de importancia 0.68) que el polen (valor de importancia 0.32). La mayor frecuencia de aparición del polen corresponde a los meses secos, mientras que las semillas dominan durante los meses lluviosos. Proponemos que las diferencias estacionales entre la frecuencia de aparición de polen y semillas en las heces, son consecuencia de variaciones en la disponibilidad de recursos y no indican preferencias alimentarias.' La alternancia de los máximos de abundancia de los diferentes alimentos puede ser una estrategia adaptativa de las plantas, la cual les permite utilizar el mismo dispersor de semillas y probablemente el mismo polinizador sin competir por sus "servicios".
Spatial Associations, Size–Distance Relationships and Population Structure of Two Dominant Life Forms in a Semiarid Enclave of the Venezuelan Andes
(Springer Science+Business Media, 2006) Daniel M. Larrea‐Alcázar; Pascual J. Soriano