Biology subjects

Gazzola, A.

Publications and source records attributed to Gazzola, A..

4 recordsLinked to original sources

bioRxiv2019

Lizard colour plasticity tracks background seasonal changes

Environmental heterogeneity on spatial and temporal scale fosters organisms capacity to plastically alter coloration. Predation risk might favour the evolution of phenotypic plasticity in colour patterns, as individuals, which change colour throughout the year, could be able to improve their fitness. Here we explored the change in dorsal pigmentation of the Italian wall lizard (Podarcis siculus campestris) along three time points (March, July and October) during the period of activity. Lizard dorsal pictures were collected on the field, with the support of a reference chart to quantitatively estimate chromatic variables (hue, saturation and value, HSV). At the same time, pictures of grassy coverings (the most representative portion of the environment subjected to normal seasonal change), were collected. Our findings show that lizards are capable of altering dorsal coloration during seasonal change. They vary from green, at the onset of spring, to brownish in the middle of summer, and greyish colour in October. This modification closely followed environmental background colour variation and enhanced lizard crypsis during each season.

evolutionary biology↗

bioRxiv2019

Exposure during embryonic development to Roundup(R) Power 2.0 affects lateralization, level of activity and growth, but not defensive behaviour of marsh frog tadpoles

As glyphosate-based herbicides, sold under the commercial name Roundup(R), represent the most used herbicides in the world, contamination of the freshwater environment by glyphosate has become a widespread issue. In Italy, glyphosate was detected in half of the surface waters monitoring sites and its concentrations were higher than environmental quality standards in 24.5% of them. It can last from days to months in water, leading to exposure for aquatic organisms and specifically to amphibians larvae that develop in shallow water bodies with proven effects to development and behaviour. In this study, we tested the effects of a 96h exposure during embryonic development of marsh frogs tadpoles to three ecologically relevant Roundup(R) Power 2.0 concentrations. As expected, given the low concentrations tested, no mortality was observed. Morphological measurements highlighted a reduction in the total length in tadpoles exposed to 7.6 mg a.e./L, while an increase was observed at lower concentrations of 0.7 and 3.1 mg a.e./L compared to control group. Tadpoles raised in 7.6 mg a.e./L also showed a smaller tail membrane than those raised in the control solution. Regarding behaviour, we tested tadpoles in two different sessions (Gosner stages 25 and 28/29) for lateralization, antipredator response and basal activity. Lower intensity of lateralization was detected in tadpoles raised at the highest Roundup(R) concentration in the first session of observation, while no significant difference among treatments was observed in the second one. In both sessions, effects of glyphosate embryonic exposure on antipredator response, measured as the proportional change in activity after the injection of tadpole-fed predator (Anax imperator) cue, were not detected. Tadpoles exposed during embryonic development to Roundup(R) exhibited lower basal activity than the control group, with the strongest reduction for the 7.6 mg a.e./L treatment. Our results reinforce the concern of glyphosate contamination impact on amphibians.

zoology↗

bioRxiv2019

Nutritional ecology provides insights into competitive interactions between closely-related marten species

For generalist, closely-related predators as those belonging to the genus Martes, it is a hard task to differentiate the effects on feeding habits of variation in food availability from those of resource competition. To overcome this obstacle, we reviewed dietary studies that assessed the relative bulk of each food item, as either percent biomass or percent mean volume, in the diet of both the pine-(M. martes) and stone-(M. foina) marten, and calculated the nutrient profiles (intakes of protein, lipids and carbohydrates, expressed as percentages of total metabolizable energy) of each diet. Both martens diets tightly clustered (average values: 47% protein-, 39% lipid- and 14% carbohydrate energy), but, most interestingly, in allopatry the nutritional niches of the two species did not differ, while the stone marten ate more carbohydrates and less protein when sympatric with the pine marten. Our data suggest that stone marten frugivory is the result of interspecific competition.

zoology↗

bioRxiv2018

Continuous and discrete quantity discrimination in tortoises

The ability to estimate quantity, which is crucially important in several aspects of animal behaviour (e.g., foraging), has been extensively investigated in most taxa, with the exception of reptiles. The few studies available, in lizards, report lack of spontaneous discrimination of quantity, which may suggest that reptiles could represent an exception in numerical abilities among vertebrates. We investigated the spontaneous ability of Hermanns tortoises (Testudo hermanni) to select the larger quantity of food items. Tortoises showed able to choose the larger food item when exposed with two options differing in size (0.25, 0.50, 0.67 and 0.75 ratio) and when presented with two groups differing in numerousness (1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 items). The tortoises succeeded in both size and numerousness discrimination, and their performance appeared to depend on the ratio of items to be discriminated (thus following Webers Law). These findings in chelonians provide evidence of an ancient system for the extrapolation of numerical magnitudes from given sets of elements, shared among vertebrates.

animal behavior and cognition↗