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Optimal egg size in a suboptimal environment: reproductive ecology of female Sonora mud turtles (Kinosternon sonoriense) in central Arizona, USA
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We studied the reproductive ecology of female Sonora mud turtles (Kinosternon sonoriense) at Montezuma Well, a chemically-challenging natural wetland in central Arizona, USA. Females matured between 115.5 and 125 mm carapace length (CL) and 36-54% produced eggs each year. Eggs were detected in X-radiographs from 23 April-28 September (2007-2008) and the highest proportion (56%) of adult females with eggs occurred in June and July. Clutch frequency was rarely more than once per year. Clutch size was weakly correlated with body size, ranged from 1-8 (mean = 4.96) and did not differ significantly between years. X-ray egg width ranged from 17.8-21.7 mm (mean 19.4 mm) and varied more among clutches than within. Mean X-ray egg width of a clutch did not vary significantly with CL of females, although X-ray pelvic aperture width increased with CL. We observed no evidence of a morphological constraint on egg width. In addition, greater variation in clutch size, relative to egg width, suggests that egg size is optimized in this hydrologically stable but chemically-challenging habitat. We suggest that the diversity of architectures exhibited by the turtle pelvis, and their associated lack of correspondence to taxonomic or behavioral groupings, explains some of the variation observed in egg size of turtles.
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Are there real sexual morphometric differences in yellow-bellied toads (Bombina spp.; Bombinatoridae)?
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In this study, we explored the level and pattern of sexual size dimorphism and sexual shape dimorphism in two closely related Bombina species that have low levels of sexual dimorphism in body size and shape. We applied an experimental protocol to explore sexual variations in morphological traits, including a preliminary evaluation of the measurement error. Mean measurement error (MME) and measurement error index (MEI) were estimated on each of the eleven morphometric variables to exclude any possible subjective factor in measuring and to perform, for the first time, an objective functional and statistical evaluation of sexual size differences in the two species. Even if statistically significant, each difference that lies below the level of uncertainty of the measure could not be reliable. Therefore, statistically significant differences in head shape have been rejected, due to an average difference between males and females smaller than the possible MME. We detected significantly longer distal segments of the hind limbs in males, which could account for their use in mating behaviour (e.g. scramble competition, water-wave communication). However, major and more reliable evidences of sexual dimorphism have been found on forelimb measures (MEI > 1), in particular humerus length and amplexus, which are significantly larger in males than in females. These results indicate a mating related sexual dimorphism, when larger and stronger forelimbs can give an advantage during coupling as well as during male-male fighting. The mean measurement error values and formulas provided in this work could be applied to future morphometric studies on Bombina species.
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Sexual and environmental variation in the space requirements of the Critically Endangered geometric tortoise, Psammobates geometricus
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Psammobates geometricus has a limited distribution in the southwestern Cape, South Africa, where it occurs in small habitat fragments separated by agricultural and urban developments. Space use and its determining factors thus represent critical information for the effective conservation of this species. We used radiotelemetry and thread-trailing to study the movement patterns and space use of geometric tortoises over an annual cycle, and estimated home ranges with minimum convex polygons and fixed-kernel methods. Home range size of geometric tortoises showed large inter-individual variation, and for females, a positive relationship to body size. Females, the larger sex, had larger home ranges and mean daily displacements than males had. Female space use was high through most of the year, except in the wet season, when food was abundant, temperatures relatively low, and soft soils allowed easy nesting. Males used more space and displaced further in the non-nesting than nesting season, perhaps to optimise mating opportunities in the non-nesting season before females ovulate. Home ranges were more elongate and overlapped more in fallow fields than in natural vegetation, suggesting that habitat degradation alters home range structure. The space geometric tortoises used for their annual activities ranged from 1.02 to 44.85 ha. The large home ranges and effects of habitat degradation should influence the size of reserves, and the destiny of geometric tortoises in small habitat fragments.
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Effects of geographic isolation on anti-snakes responses in the wall lizard, Podarcis muralis
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Alteration in anti-predatory behaviour following geographic isolation has been observed in a number of taxa. Such alteration was attributed to the effect of relaxed selection in the novel environment, reinforced by the cost of anti-predatory behaviours. We studied aspects of anti-snake behaviour in 987 adult and juvenile wall lizards Podarcis muralis from two mainland areas (heavy snake predatory pressure) and two islands (low snake predatory pressure), isolated from the mainland 5000 and 7000 years ago. We conducted a scented retreat site choice experiment using the odours of five different snake species (saurophagous, piscivorous or generalist feeder). Mainland lizards avoided shelters scented by saurophagous snakes, but not those scented by non saurophagous snake species. Long isolated lizards (7000 years ago) showed no anti-predator response to any snake, suggesting a total loss of anti-predatory behaviour towards saurophagous snakes. More recently isolated lizards (5000 years ago) however showed anti-snake behaviour towards a former sympatric adder species, and a tendency to avoid the scent of a sympatric generalist feeder snake. There was no difference in the anti-snake responses between adult and juvenile wall lizards from all four sites, suggesting a limited role for experience (behavioural plasticity) in the expression of anti-snake behaviour in wall lizards.
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Nest site fidelity in the Slovakian population of the European pond turtle Emys orbicularis
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In many places in Europe, the pond turtle Emys orbicularis (Linnaeus, 1758) is an endangered species. Establishing its reproductive pattern is critical for the understanding and protection of this turtle. In this study, which took place from 1998 to 2009 in the Tajba National Nature Reserve, Slovakia (48°23′N, 21°47′E), are presented the results concerning the spatial and temporal aspects of nesting habits of individual turtles. From the total monitored group of 39 turtles, eight individuals which laid eggs more than four times during the whole study period were selected for statistical evaluation. It was found that five individuals from this group demonstrated a fidelity to the nesting area, and that the egg-laying period starts in mid-May and continues until late June. During the investigation, six turtles nested twice per year with an interval of about 24 days. The average distance between the nests of an individual turtle was close to 138 metres, and the distance of the nests from water was about 349 metres. The data obtained on the space and time requirements of the European pond turtle for successful reproduction are helpful to protect this species more efficiently, not only in the Tajba National Natural Reserve, but also in other similar sites in Europe.
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Revision of the extinct Pleistocene tortoise Testudo lunellensis Almera and Bofill, 1903 from Cova de Gràcia (Barcelona, Spain)
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Testudo lunellensis Almera and Bofill, 1903 from the Middle Pleistocene of Cova de Gràcia (Park Güell, Barcelona, Spain) is a valid species belonging to the clade of the extant Testudo hermanni – a diagnostic feature being the narrowed vertebral scutes. Thanks to still unpublished material, T. lunellensis is diagnosed for the first time and its shell morphology described in detail. This species is uniquely characterized, among others, by tall peripheral bones and by a peculiar shape of the anterior lobe of the plastron, somewhat recalling the species referred to Testudo s.s. (the clade containing the extant species Testudo graeca, Testudo kleinmanni and Testudo marginata). Given that the purported valid species from Lunel-Viel (Middle Pleistocene, France) is still unnamed and undescribed, T. lunellensis from Cova de Gràcia is currently the stratigraphically youngest extinct Testudo species. The co-occurrence in T. lunellensis of characters typical of both T. hermanni and Testudo s.s. further testifies the phenotypic plasticity of tortoises and the mosaic distribution of morphological characters, which hinders a clear-cut assessment of the relationships of extant tortoises when based exclusively on morphology. Further analyses of the phylogeny of Testudo should consider fossil and extant taxa together, as well as both morphological and genetic characters.
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Effects of pine invasion on anurans assemblage in southern Brazil coastal ponds
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The destruction of wetlands due to afforestation areas is a common activity in temperate and subtropical regions in Southern America. The expansion of pine in the Coastal Plain of Southern Brazil is out of control and its impacts on aquatic biodiversity are little known. We tested the following hypotheses: the pine occurrence diminishes the anuran richness and abundance in ponds and it changes the anuran composition; the beta-diversity between pine and native grassland matrix ponds (natural ponds) is determined mainly by nestedness. Sampling was carried out from 2007 to 2009 in five ponds in pine invasion matrix and five ponds in native grassland matrix. The natural ponds showed a greater richness of tadpoles (10 species) than pine ponds (5 species). The mean richness of adults was higher in natural ponds than pine ponds throughout the entire study. The species composition was different between natural and pine ponds, for both adults and tadpoles. Comparing natural ponds with each other and the pine ponds with each other, our results showed that neither nestedness nor turnover was determinant for beta-diversity. However, when natural ponds were compared with pine ones, we found that the contribution of nestedness was higher for the anurans beta-diversity than turnover. Increases in the nestedness mechanism indicated that the pine occurrence results in species loss in Southern Brazil ponds. Since 90% of its wetland has been already affected, the removal of Pinus in the conservation areas in southern Brazil is important to minimize their impacts on aquatic biodiversity.
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Direct-developing frogs: ontogeny of Oreobates barituensis (Anura: Terrarana) and the development of a novel trait
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Within Anura, direct development involves ontogenetic changes of the biphasic ancestral pattern. The recent partitioning of the genus Eleutherodactylus, along with the proposition of the unranked taxon Terrarana, has renewed an interest to the morphological and ecological diversity among direct-developing frogs. The morphological changes during embryonic development of Oreobates barituensis is similar to those of other Neotropical direct-developing species, including the reduction or absence of several larval and embryonic characters (e.g., external gills and adhesive glands), heterochronic changes (e.g., early developing limbs and late persistence of ciliated epidermal cells), and the appearance of new structures (e.g., egg tooth). The tail achieves an extraordinary peramorphic development (encloses the entire embryo), and the location of its expanded part is interpreted as a heterotopic change resulting in a novel trait. An enveloping tail with apparently non-heterotopic fins, combined with the absence of gills, has been only reported for a species of the related genus Craugastor, and these morphologies suggest an informative perspective for the study of evolution of direct development in terraranans.
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Do cave salamanders occur randomly in cavities? An analysis with Hydromantes strinatii
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Underground environments are increasingly recognised as important habitats for the distribution of certain amphibians. However, very few analyses tested whether amphibians occur randomly in underground environments, or they select cavities with specific environmental features. We assessed the distribution of the cave salamander Hydromantes (Speleomantes) strinatii in an area of NW Italy during summer, and analysed relationships between salamander distribution and multiple cave features, considering parameters describing both the biotic and the abiotic environment. Using visual encounter surveys, species’ detection probability was high, indicating that this technique provides reliable information on distribution. Salamanders were associated to caves with cold and humid microclimate, presence of wet walls, and hosting large numbers of Meta spiders. The association with less luminous caves was close to significance. Distribution data were not affected by spatial autocorrelation, suggesting that cave features are more important than the proximity to other occupied caves in determining the pattern of occupancy. Caves are heterogeneous environments: cave salamanders are strongly related to the features of underground environments. Food availability and abiotic features are major determinants of suitability for cave salamanders. Inter-correlation among biotic and abiotic cave features makes it complex identifying the role of factors determining species distribution, but quantitative analyses and PCA help to unravel the cave habitat requirements for amphibians.
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Assessing patterns of nestedness and co-occurrence in coastal pond anuran assemblages
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Segregated species co-occurrence and nestedness are two ecological patterns used to measure assemblage structure. We investigated species co-occurrence and nestedness patterns in assemblages of tadpoles and adult anurans in 30 coastal ponds in southern Brazil. Ponds varied in hydroperiod and were classified as temporary or permanent. We explored whether co-occurrence or nestedness varied among ponds in each hydroperiod. Species co-occurrence patterns were analyzed using the C-score index and three null models. In order to quantify nestedness, we used the nestedness metric based on overlap and decreasing fill (NODF). We found seventeen anuran species; however, only 13 species were observed in breeding activity, and 11 species were observed as tadpoles. The co-occurrence and nestedness analyses showed that anuran assemblages exhibit non-random patterns that were generally contingent on the hydroperiod and pond area. Only species in non-breeding adult anurans assemblages showed significant segregation when randomizations were weighted by pond area and the pattern was similar among hydroperiods. Tadpole assemblages of permanent ponds showed an aggregated co-occurrence in weighted-fixed model. In temporary ponds, NODF showed that anuran assemblages were significantly nestedness in all three phases of life cycle. We obtained contrasting results depending on the hydroperiod. These results support the hypothesis that habitat nestedness, due to hydroperiod, might be an important factor structuring anuran assemblages along the different phases of their life cycle.
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Population genetics of the Halys pit viper (Gloydius halys) at the northern distribution limit in Siberia
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We studied the genetic structure and diversity of a vulnerable population of the Halys pit viper (Gloydius halys) living at the northern distribution limit of the species (Novosibirsk Region, West Siberia, Russia) and fairly isolated from the nearest known locations (180-200 km). 157 snakes from three locations (separated by 5-11 km) were genotyped using 8 microsatellite loci. In addition, nucleotide sequences of a mitochondrial marker gene (ND4) were obtained from 30 individuals. Two mitochondrial haplotypes differing by one synonymous substitution could be detected. Haplotype H1 had a prevalence of 96.7%. High levels of genetic diversity (mean H O = 0 . 76 ) were detected and no evidence of a recent bottleneck in any sampling site could be discovered. We found that G. halys exhibits a low, although significant, level of genetic differentiation on a fine geographic scale (overall FST = 0.013). The degree of differentiation is comparably low with regard to values reported for other vipers and more similar to those in Colubridae. In addition, using local based FST estimates, we detected a significant difference in the extent of genetic drift between the centrally located and marginal local populations as predicted by the stepping-stone model of migration. Thus, from a short-term perspective, primary attention should be given to the peripheral local populations, due to limited immigration and stronger influence of genetic drift. Since all habitat patches are situated along the river and have a linear order it is important to preserve each habitat site to maintain gene flow across the metapopulation.
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Distribution of Testudo graeca in the western Mediterranean according to climatic factors
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Despite being one of the most charismatic elements of the Mediterranean Basin fauna and its threatened status, the western Mediterranean range of Testudo graeca is at present very poorly known. The present work provides the most detailed geographical and ecological description for the North African clade of T. graeca so far. We gathered 283 occurrence data of T. graeca in North Africa and modelled the distribution by means of presence-only distribution modelling tools. The obtained model was then projected to southern Europe in order to explore whether the environmental characteristics of European populations fall into the predicted niche of the species in North Africa. T. graeca showed a wide environmental range in North Africa. Presence localities ranged from the sea level to 2090 m of altitude and from 116 to 1093 mm of annual precipitation. The presence-only model indicates that distribution in North Africa is mainly related to rainfall, specifically rainfall values in the wettest and coldest quarter of the year. The distribution model showed a range of ca. 1 000 000 km2. The projection of the model to southern Europe showed that the southern Iberian and Balkan Peninsulas, as well as most Mediterranean islands, present climatic conditions within those found in the range of the species in North Africa.
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The effect of temperature on standard metabolic rate of Brown Anoles
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Understanding the influences of sex and ambient temperature on metabolic rates of reptiles is of fundamental interest to biologists because of the role that temperature-dependent metabolic rates play in shaping behaviour, life history evolution and geographic range. We investigated the effects of sex, body mass and temperature on standard metabolic rate, respiratory quotient (RQ), and Q10 in male and female Brown Anoles, Norops sagrei. When mass-adjusted, oxygen consumption increased linearly with temperature, and there was no effect of sex. RQ did not differ by sex or temperature. Q10 was within the range published for other lizards.
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Impact of introduced fish on Common frog (Rana temporaria) close to its altitudinal limit in alpine lakes
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Alien fish species have been introduced into naturally fishless mountain lakes worldwide, with negative consequences for native fauna. This study describes the impact of introduced Brook trout (Salvelinus fontinalis) on Common frog (Rana temporaria) in the Gran Paradiso National Park (Western Italian Alps). We conducted an extensive, six years long (2006-2011) monitoring campaign over 12 fishless and 8 stocked lakes, close to the new altitudinal limit of R. temporaria (2811 m a.s.l.). This new altitudinal limit is reported for the first time in this study. The presence of introduced fish was a factor of ecological exclusion, negatively affecting the presence of frogs and compromising the suitability of alpine lakes as breeding sites. These results are likely to depend on larval predation or to selective avoidance of stocked lakes by R. temporaria. Eradication of introduced fish is proposed as a conservation measure to recover amphibian populations in alpine lake ecosystems.
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Frequency of multiple paternity in the grass snake (Natrix natrix)
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Males can enhance their reproductive success through mating with multiple females. For females, however, one mating is usually sufficient to inseminate all of their ova. Females may benefit from multiple mating by producing genetically more diverse offspring, and by having the opportunity to choose sperm of the genetically most compatible male. We used five microsatellite loci to investigate the occurrence and frequency of multiple paternity in 11 clutches of the grass snake (Natrix natrix) in Switzerland. Using a very conservative estimate (program GERUD), two or more fathers were found in 27% of the clutches. However, based on the maximum likelihood estimate (program COLONY), multiple paternity occurred in 91% of the clutches with 2-5 contributing males per female. This is the first investigation demonstrating multiple paternity in a European natricine, with a frequency similar to those found in new world natricines.
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Genetic markers reveal high PIT tag retention rates in giant salamanders (Cryptobranchus alleganiensis)
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Estimation of population size using mark-recapture (MRR) methods are based on the fundamental assumption that individuals retain their marks throughout the course of study. Passive Integrated Transponder (PIT) tags are useful as a cost effective, reliable marking method in many amphibian and reptile species. Few studies however, use secondary methods to evaluate tag retention rates. Failure to do so can lead to biased population estimates, erroneous conclusions, and thus poor management decisions. Surprisingly, estimates of PIT tag retention are currently lacking for the majority of amphibian species, many of which are experiencing population declines. Herein, we use genetic tagging to assess the retention of PIT tags of the eastern hellbender (Cryptobranchus alleganiensis alleganiensis). We captured and tagged 78 individuals across 35 sites. Recapture rate was 24% and genetic tagging revealed 100% tag retention across all recaptured individuals.
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