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Fernando Martinez-Freiria, Marcial Lorenzo and Miguel Lizana

Abstract

Zamenis scalaris is a generalist active forager Mediterranean snake for which knowledge on spatial ecology is very limited. We report insights into the spatial and temporal patterns, and habitat use of four snakes, obtained through one-year radio-tracking monitoring in a citrus orchard landscape, in Eastern Iberia. Snakes showed a highly secretive behaviour, remaining hidden most of the annual cycle (>96% of records). Annual home ranges and movements were reduced in contrast to the expected energetic requirements of the species. Despite a similar pattern of non-activity during winter and a subsequent increase of movement rate and home range size in spring, each snake adopted a distinct spatial behaviour in summer and autumn. Abandoned citrus orchards and accessory constructions were the most frequent habitats selected by snakes, offering abundant prey and shelter. These resources are likely playing a crucial role in the spatial ecology of Z. scalaris.

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Jéssica S. Kloh, Cleber C. Figueredo and Paula C. Eterovick

Abstract

Tadpole diet is likely to vary in response to environmental conditions and nutritional needs throughout growth and development. We investigated seasonal variation in diet composition of Bokermannohyla saxicola tadpoles and compared diets between two developmental stages with a significant difference in size. We found that the diet of B. saxicola tadpoles was dominated by periphytic algae, in accordance with their benthic habits. Considering number of cells ingested, tadpole trophic niches were broader in more advanced developmental stages. Tadpole trophic niches were narrower during the summer (wet season) than during the winter (dry season), which may reflect increased consumption of more energetic food items during the warm period when primary productivity is expected to be higher. Tadpole metabolism is likely to be higher in the summer and increased energetic needs might be supplied in this manner. However, results differed when biovolume was considered instead of number of cells ingested, with larger items assuming a greater importance and niches being usually larger in the summer. In these cases, the increased ingestion of diatoms (likely to be more nutritive) in the summer may decrease the relative importance of large algae (e.g., Mougeotia sp.) that form the bulk of the diet. Both food availability/accessibility and tadpole feeding behaviour driven by nutritional needs may influence patterns of food acquisition. Given the importance of biofilms to tadpole diet, studies on the mechanisms by which tadpole nutritional needs and environmental conditions interact are likely to provide important insights into the dynamics of aquatic food webs.

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Arie L. Spaans, Otte H. Ottema and Jan Hein J.M. Ribot

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Guilherme Augusto-Alves, Simone A. Dena and Luís F. Toledo

Abstract

Advertisement call is the most common signal used by anurans for intraspecific communication. However, some species have lost the ability to emit these vocalizations and are denoted as mute. Alternatively, these species may communicate by visual, tactile and chemical signals. The lack of advertisement call could be explained by the high background noise of breeding microhabitats. A model group to study alternative communication tactics is the genus Megaelosia, which is composed by seven mute species that inhabit noisy streams, and for which no information on intraspecific communication is available. We monitored a population of M. apuana and described its visual signalling during aggressive interactions between males. This interaction included visual signalling, physical combat, and the retreat of the smaller individual. No audible sound was detected during the whole aggressive interaction, reinforcing the genus muteness. This is the first report of any communication behaviour for the genus Megaelosia.

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Lixia Zhang, Dong An, Yuxiao He, Zhibing Li, Bohao Fang, Xiaohong Chen and Xin Lu

Abstract

Life-history theory predicts that organisms inhabiting harsh environments such as high altitudes should invest less in reproduction and more in survival. Testis size is associated with the intensity of male-male competition for mating and thus may be treated as an indicator of male reproductive investment. Hence, it may be expected that organisms will reduce their testis size with increasingly harsh environments. Here we test this prediction in a toad species, Scutiger boulengeri, endemic to the Tibetan plateau using data from three populations located at altitudes of 4078, 4276, and 4387 m. Consistent with the prediction, male toads exhibited smaller testes at higher altitudes, despite the relatively narrow altitudinal span. It is likely that cold climates and strong seasonality constrain the ability of high-altitude male toads to allocate more energy into reproduction, thereby leading to small testis size. In addition, the left testis was significantly heavier than the right one and the degree of size asymmetry was unrelated to either altitude or body condition.

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Tao Tang, Yi Luo, Chun Hua Huang, Wen Bo Liao and Wen Chao Huang

Abstract

The competition for fertilization among sperm from different males can drive variation in male reproductive investments. However, the mechanisms shaping reproductive allocation and the resulting variations in reproductive investment relative to environmental variables such as resource availability and male-male competition remain poorly known in frogs. Here, we investigated inter-population variation in male somatic condition and testis mass across four populations of the swelled vent frog Feirana quadranus along an altitudinal gradient. We found that relative testis mass did not increase with altitude, which was inconsistent with previous predictions that an increase in latitude and/or altitude should result in decreased sperm production in anurans due to shortened breeding seasons and the decline in resource availability. We also found no increase in somatic condition and male/female operational sex ratio with altitude. However, the somatic condition exhibited a positive correlation with testis mass, which indicated the condition-dependent testis size in F. quadranus. Moreover, an increase of testis mass with increasing male/female operational sex ratio suggest that male-male competition can result in an increased intensity of sperm competition, thereby increasing testis mass.

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Maria Maust-Mohl, Joseph Soltis and Diana Reiss

Abstract

Common hippos (Hippopotamus amphibius) live in murky waters and produce a variety of acoustic signals including underwater click trains considered to be social in function. We tested the hypothesis that click trains may function for underwater detection. We used observational and experimental methods involving 16 captive hippos to document the occurrence of click trains in different contexts and describe the acoustic parameters of the clicks. Male and female hippos produced click trains correlated with searching underwater for food items placed in their pools. Males produced click trains when alone supporting the hypothesis that these signals function for detection and are not only social in function. The frequency bandwidth of individual clicks varied and most were below 10 000 Hz. Click train production by hippos during underwater searches suggests a rudimentary form of echo-ranging that may function when other sensory systems are limited in their aquatic environment.

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Hublester Domínguez-Vega, Iriana Zuria and Leonardo Fernández-Badillo

Abstract

Salamanders are usually seen as typical inhabitants of temperate and humid habitats. Among Plethodontids, Isthmura bellii has the broadest altitudinal range of any salamander in the world and it is considered a habitat generalist. Nonetheless, even for this species, dry environments are thought unsuitable. We report the first records of I. bellii in arid tropical scrub from two localities within central Mexico. We analyze the environmental differentiation of these new localities in relation to the known distribution range of the genus. Our study shows that among the new localities, there is at least one site where I. bellii appears to have established in arid tropical scrub. An environmental model reveals that these new localities present different conditions than most of the records of Isthmura spp.

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Arie L. Spaans, Otte H. Ottema and Jan Hein J.M. Ribot

Open Access

Eva Ringler

Abstract

Skin swabbing, a minimally invasive DNA sampling method recently proposed for adult amphibians, was tested on the dendrobatid frog Allobates femoralis. I compared DNA yield from skin swabs and toe clips by evaluating obtained DNA concentrations and purity of extracts, as well as amplification success using eleven polymorphic microsatellite loci. I also tested whether storing skin swabs for two months at −20°C affected the properties of the extract or microsatellite analysis. Results show that skin swabs of adult A. femoralis suffered from high contamination and yielded significantly lower DNA quality and quantity, resulting in insufficient genotyping success, than DNA obtained from toe clips. The relatively dry skin in dendrobatid frogs may have impeded the collection of sufficient viable cells, and the presence of skin alkaloids and microbiota in the frog mucus may lead to high contamination load of skin swabs.