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Microhabitat occupation and functional morphology of four species of sympatric agamid lizards in the Kyzylkum Desert, central Uzbekistan  [PDF]
N. Clemann,,J. Melville,N. B. Ananjeva,M. P. Scroggie
Animal Biodiversity and Conservation , 2008,
Abstract: We examined microhabitat occupation and functional morphology of four sympatric agamid lizards (Phrynocephalus helioscopus helioscopus, P. interscapularis, P. mystaceus galli and Trapelus sanguinolentus) at three sites in the arid zone of central Uzbekistan. At two sites located in sand dunes, substrate attributes played a key role in habitat selection by three syntopic species. At a third flat, stony site, P. helioscopus selected habitat non-randomly, tending to occur close to sparse, low vegetation. Syntopic taxa were separated in morphospace, and there was a trend for taxa with proportionally longer limbs to have faster field escape speeds. Field escape distances and predator avoidance tactics differed between species, with two main escape strategies (crypsis or sand-diving following an escape sprint). We caution that broad-scale threatening processes such as over-grazing and salinity may be having a detrimental effect on microhabitat features important to terrestrial reptiles in Uzbekistan.
Daily activity and microhabitat use of sympatric lizards from Serra do Cipó, southeastern Brazil
Filogonio, Renato;Del Lama, Fernanda S.;Machado, Leonardo L.;Drumond, Michelle;Zanon, Isabella;Mezzetti, Nathália A.;Galdino, Conrado A. B.;
Iheringia. Série Zoologia , 2010, DOI: 10.1590/S0073-47212010000400008
Abstract: we studied the influence of seasonality on the daily activity pattern and microhabitat use of three sympatric lizard species, cnemidophorus ocellifer spix, 1825 (teiidae), tropidurus montanus rodrigues, 1987 and eurolophosaurus nanuzae (rodrigues, 1981) (tropiduridae), in an area of campos rupestres (rocky fields) habitat in state of minas gerais, brazil. cnemidophorus ocellifer exhibited low density and activity concentrated within the hottest hours of the day, and was observed mainly on shaded rocks. tropidurus montanus and e. nanuzae had similar activity patterns that did not vary between seasons. activity of t. montanus was related to environmental temperatures. however, we did not find such relationships for e. nanuzae during the dry season. both t. montanus and e. nanuzae were sighted mainly on exposed rocks. extension of activity varied between seasons, shorter for c. ocellifer and longer for t. montanus and e. nanuzae during the rainy season.
Trophic ecology and microhabitat utilization by the Bufo gargarizans, Rana guentheri, and Rana limnocharis in southwestern China
Yu, Tonglei;Guo, Yanshu;
Zoologia (Curitiba) , 2012, DOI: 10.1590/S1984-46702012000100006
Abstract: we studied the trophic ecology and microhabitat use of the asiatic toad, bufo gargarizans cantor, 1842; guentheri frog, rana guentheri (boulenger, 1882); and the ricefield frog, rana limnocharis (boie, 1834). these three species are common around nanchong city, in southwestern china, where they live in the same habitat before hibernation. the main objective of this study was to analyze the diets and patterns of coexistence relative to the microhabitat of each species. in the asiatic toad, based on index of relative importance, the diet was dominated by adult coleoptera, isopoda, and hymenoptera (29.53%, 22.07%, and 15.20%, respectively), while the guenther's frog and ricefield frog ingested predominantly orthoptera (67.44% and 40.94%, respectively). the standardized feeding niche breadth of the asiatic toad (0.277) was wider than that of the guentheri frog (0.177) and ricefield frog (0.269). the overlap in the trophic niche (prey proportion) between the toad and two species of frog was low (toad vs. guentheri frog, ch = 0.526; toad vs. ricefield frog, ch = 0.521), while this was high for the two species of frogs (ch = 0.942). the three species also differed in microhabitat use. asiatic toads showed strong preference for small roads close to shrubs or pre-harvest corn, while guenther's frogs preferred bare surfaces on habitat edges, and ricefield frogs showed a preference for bare surfaces as feeding sites in the middle of habitat. the difference in diet observed during three species seems to be explained by the difference in microhabitat use and body size of three species.
Ecological Segregation in Space, Time and Trophic Niche of Sympatric Planktivorous Petrels  [PDF]
Joan Navarro, Stephen C. Votier, Jacopo Aguzzi, Juan J. Chiesa, Manuela G. Forero, Richard A. Phillips
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0062897
Abstract: The principle of competitive exclusion postulates that ecologically-similar species are expected to partition their use of resources, leading to niche divergence. The most likely mechanisms allowing such coexistence are considered to be segregation in a horizontal, vertical or temporal dimension, or, where these overlap, a difference in trophic niche. Here, by combining information obtained from tracking devices (geolocator-immersion and time depth recorders), stable isotope analyses of blood, and conventional morphometry, we provide a detailed investigation of the ecological mechanisms that explain the coexistence of four species of abundant, zooplanktivorous seabirds in Southern Ocean ecosystems (blue petrel Halobaena caerulea, Antarctic prion Pachyptila desolata, common diving petrel Pelecanoides urinatrix and South Georgian diving petrel P. georgicus). The results revealed a combination of horizontal, vertical and temporal foraging segregation during the breeding season. The stable isotope and morphological analyses reinforced this conclusion, indicating that each species occupied a distinct trophic space, and that this appears to reflect adaptations in terms of flight performance. In conclusion, the present study indicated that although there was a degree of overlap in some measures of foraging behaviour, overall the four taxa operated in very different ecological space despite breeding in close proximity. We therefore provide important insight into the mechanisms allowing these very large populations of ecologically-similar predators to coexist.
Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake
Moncayo-Estrada, Rodrigo;Lind, Owen T;Escalera-Gallardo, Carlos;
Neotropical Ichthyology , 2011, DOI: 10.1590/S1679-62252011005000003
Abstract: significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. the diets of three closely related zooplanktivorous silversides belonging to the atherinopsidae species flock of lake chapala , mexico, were analyzed at two sites (chirostoma jordani, c. labarcae, and c. consocium). diets were described in critical shallow (august 2000) and volume recovery conditions (august 2005). diets included mainly cladocerans (bosmina, ceriodaphnia, and daphnia) and copepods (cyclops). a significant difference in diets was detected when comparing years (mrpp analysis, a = 0.22, p < 0.0001) and sites at different years (mrpp analysis, a = 0.17, p = 0.004). according to niche breadth mean values, species were classified as specialized and intermediate feeders. in shallow conditions, the small range of niche breadth (1.72 to 3.64) and high diet overlap values (d = 0.64, l = 8.62) indicated a high potential for interspecific exploitative interaction. when the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96) and low niche overlap values (d = 0.53, l = 2.32) indicated a reduction of the species interaction. the mann-whitney u-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006). the increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution.
Trophic interactions among sympatric zooplanktivorous fish species in volume change conditions in a large, shallow, tropical lake  [cached]
Rodrigo Moncayo-Estrada,Owen T Lind,Carlos Escalera-Gallardo
Neotropical Ichthyology , 2011,
Abstract: Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium). Diets were described in critical shallow (August 2000) and volume recovery conditions (August 2005). Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia) and copepods (Cyclops). A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p < 0.0001) and sites at different years (MRPP analysis, A = 0.17, p = 0.004). According to niche breadth mean values, species were classified as specialized and intermediate feeders. In shallow conditions, the small range of niche breadth (1.72 to 3.64) and high diet overlap values (D = 0.64, L = 8.62) indicated a high potential for interspecific exploitative interaction. When the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96) and low niche overlap values (D = 0.53, L = 2.32) indicated a reduction of the species interaction. The Mann-Whitney U-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006). The increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution. La reducción significativa en el volumen de agua de los lagos someros impone una restricción en la segregación de las especies y promueve una mayor interacción en las relaciones tróficas. Se analizó la dieta de tres especies cercanamente emparentadas de zooplanctívoros pertenecientes al flock de Aterinópsidos del lago de Chapala en dos sitios (Chirostoma jordani, C. labarcae y C. consocium). Las dieta fue descrita en una condición somera crítica (Agosto 2000) y en una condición de recuperación del lago (Agosto 2005). En la dieta se incluyen principalmente cladóceros (Bosmina, Ceriodaphnia y Daphnia) y copépodos (Cyclops). Se detectó una diferencia significativa en la dieta cuando se comparan los a os (análisis MRPP, A = 0.22, p < 0.0001) y los sitios en los diferentes a os (análisis MRPP, A = 0.17, p = 0.004). De acuerdo a los valores promedio de amplitud de nicho, las especies fueron clasificadas como especialistas y consumidores intermediarios. En condiciones someras, el peque o intervalo de la amplitud de nicho (1.72 a 3.64) y los altos valores
Uso del microhábitat por hembras grávidas de la rana de hojarasca Craugastor loki en la selva alta perennifolia de Los Tuxtlas, Veracruz, México Microhabitat use by the leaf litter frog Craugastor loki gravid females in the tropical rainforest at Los Tuxtlas, Veracruz, Mexico  [cached]
José Nicolás Urbina-Cardona,Víctor Hugo Reynoso
Revista mexicana de biodiversidad , 2009,
Abstract: Craugastor loki es la especie de anfibio más abundante en la selva alta perennifolia de Los Tuxtlas, registrándose 1 251 individuos (58% adultos) durante un a o de muestreo a lo largo de gran variedad de microhábitats en 6 fragmentos de selva. A pesar de que C. loki se considera una especie tolerante a la modificación del hábitat, el 71% de las hembras grávidas se encontraron en las áreas mejor conservadas. Hubo un mayor registro de hembras grávidas en el fragmento de selva continuo (473 ha), prefiriendo hábitats con una distancia mayor a 50 m del borde y suelos con cobertura y espesor de hojarasca altas, cobertura herbácea alta, humedad relativa alta, pero independientes de la distancia a los cuerpos de agua. En el presente estudio se demuestra que las hembras grávidas, un eslabón crítico para el mantenimiento de la especie, son vulnerables a la perdida de hábitat y efectos de borde. Un cambio en las zonas conservadas pudiera afectar la abundancia y estructura poblacional de C. loki, generando a futuro una peligrosa disrupción en la cadena trófica y en la estructura de las comunidades de la selva. Craugastor loki is the dominant amphibian in the Los Tuxtlas tropical rainforest. We recorded 1 251 individuals (58% adults) in a sampling year within a great variety of microhabitats in 6 forest fragments. Although C. loki is considered tolerant to habitat disturbance, 71% of all gravid females were found in most highly conserved sites. Gravid females were mostly found in the largest forest fragment with continuous rainforest (473 ha), preferring habitats with distances to the edge over 50 m, soils with high leaf litter cover and depth, high understory density, high relative humidity but independent of the distance to water bodies. Gravid females, a critical element to maintain the species, are very vulnerable to habitat loss and edge effects. A change in conserved habitats may affect C. loki abundance and population structure, potentially seriously disrupting the trophic chains and community structure of the rainforest.
Shell occupation and microhabitat use by hermit crabs (Decapoda: Anomura) on Fortaleza beach, Ubatuba, S o Paulo
Pedro Henrique Cipresso Pereira,Jairo Zancaner Junior,Giuliano Buzá Jacobucci
Biotemas , 2009,
Abstract: Most species of hermit crabs use the empty shells of gastropods as mobile shelters. The variation of shell availability in different microhabitats can reduce competitive interactions between sympatric species, favoring their coexistence. This work aimed to characterize the occupation of gastropod shells by three species of hermit crabs, and assessing the availability of shells and evaluating the use of microhabitats crabs and gastropods in an infralitoral area on the north coast of S o Paulo state. For this purpose, transect lines were established and all hermit crabs, gastropods and empty shells found were collected, recording the type of microhabitat used. In a sub-sample, the hermit crabs were identified and classified into reproductive categories. The shells used by the crabs were identified and evaluated according to physical damage and incrustation. Three species of hermit crabs (Paguristes tortugae, Pagurus brevidactylus and Pagurus criniticornis) were recorded, using 15 species of gastropod shells and one of scaphopod (Dentalium sp.). Physical damage and incrustation of shells were significantly different among the hermit crab species. Considering microhabitat use, P. tortugae and P. brevidactylus were mainly found in calcareous algae, while P. criniticornis mainly occurred in sand substrate. Despite the differences in shell and microhabitat use, the high resource overlap, especially by the pagurids, indicates that competitive interactions are important regulatory factors for these populations.
Microhabitat partitioning of Apodemus flavicollis and Myodes glareolus in the sub-montane Alps: a preliminary assessment
Sabine Marlene Hille,Alessio Mortelliti
Hystrix : the Italian Journal of Mammalogy , 2011, DOI: 10.4404/hystrix-21.2-4458
Abstract: Interspecific competition can cause partitioning in habitat use by sympatric species. This study gives a preliminary contribution to the understanding of microhabitat partitioning of Apodemus flavicollis and Myodes glareolus in sub-montane habitats. A total of 1000 trap nights in the subalpine forest in the Austrian tscher mountain showed that high- and low-tree cover, high-shrub cover, plot location in or out of the forest, and distance from the forest edge were the variables which discriminated the sites of capture of the two species. A. flavicollis seemed to be more associated with the forest edge than M. glareolus, which, in contrast, preferred areas well within the forest with high tree and shrub cover. Our results suggest that the two species show some level of partitioning according to microhabitat structure.
Niche overlap and resource partitioning among five sympatric bufonids (Anura, Bufonidae) from northeastern Argentina  [PDF]
Marta I. Duré,Arturo I. Kehr,Eduardo F. Schaefer
Phyllomedusa : Journal of Herpetology , 2009,
Abstract: The niche overlap and resource partitioning were analyzed for five sympatric bufonids from Northeastern Argentina: Rhinella schneideri, R. bergi, R. fernandezae, R. granulosa, and Melanophryniscus cupreuscapularis. The primary objectives were to analyze the diet and pattern of coexistence relative to the microhabitats among species. The bufonids, which are primarily terrestrial, exhibited a preference for small, hard prey such as formicids or coleopterans. The smallest species preferably consumed ants, while R. schneideri preferred beetles. Significant differences were detected for the diets of these five species. In addition, significant overlap in the trophic niche was noted for all species except between R. granulosa and R. schneideri. Studying the diet behaviors and trophic parameters of sympatric species provides important data for understandingthe community and for the development of conservation guidelines.
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