Xavier Santos

Food availability induces geographic variation in reproductive timing of an aquatic oviparous snake (Natrix maura)

The viperine snake Natrix maura is a common water snake, which forages on aquatic prey such as fish and frogs in Western Mediterranean water bodies. Female viperine snakes collected from three populations at the Iberian Peninsula during the vitellogenesis period were compared. Mean clutch size and range, as well as the slope of the regression between body size and clutch size, did not show differences between populations. In contrast, mean size of enlarged follicles of females collected in May from the Ebro Delta proved significantly smaller than those of females from the Matarranya River (50 km far) and the Granada Depression (500 km far). There were no differences in climatic conditions between areas. However, seasonal variation in food availability was significantly different in the Ebro Delta. In this area, the rice fields are dry in early spring as men control the water flow, and prey are not available. This energetic constraint induced female viperine snakes to adjust reproductive timing according to seasonal availability and to delay vitellogenesis for at least one month. By contrast, other Mediterranean populations exhibited a rather high prey availability from early spring (e.g. Matarranya River), females being in good condition in this season and consequently vitellogenesis starting earlier than in the Ebro Delta. This study illustrates a new case of reproductive plasticity in snakes.

Comparing Filippi and Luiselli's (2000) method with a cartographic approach to assess the conservation status of secretive species: the case of the Iberian snake-fauna

The conservation status of the snake fauna of a given region or territory is often hard to estimate due the secretive habits of these animals, as well as of the lack of long-term demographic studies and generally low population densities. We examined the conservation status of the snakes from the Iberian Peninsula by applying two complementary methods. The first method, created by Filippi and Luiselli for a study of the Italian snakes conservation status, takes into account the ecological and non-ecological attributes which make species vulnerable to extinction. The second is a cartographic analysis which consists of calculating two indexes derived from the comparison of old and recent citations in UTM 10×10 km squares of Iberian snakes by means of extensive database sets. For each species, we calculated the percentage of recent citations, and the percentage of squares with both old and recent citations. Species with low proportion of recent citations and new squares appeared to be in decline. We found considerable coincidence between the two methods in the identification of the most threatened snake species: Vipera latastei, Coronella girondica ,a ndNatrix natrix. We suspect that the ecological specialisation and the low reproductive output make C. girondica and V. latastei prone to extinction when faced with environmental changes (i.e. habitat loss). For N. natrix, we argue that this semi-aquatic snake experiences suboptimal environmental conditions in Mediterranean habitats. A combination of both methods proved adequate to detect vulnerability to extinction of snake species, hence revealing an effective tool for establishing conservation strategies in snakes and other secretive faunas.

Reproductive Ecology of the Montpellier Snake, Malpolon monspessulanus (Colubridae), and Comparison with Other Sympatric Colubrids in the Iberian Peninsula

Abstract Two spermatogenetic cycles, vernal and aestival, have been described in temperate colubrid snakes. In both cycles, mating occurs in the spring, although vernal species produce spermatozoa in spring, just before mating, while aestival species use spermatozoa produced the previous summer. In this study, we describe the reproductive cycles of male and female Malpolon monspessulanus (Colubridae), and compare them to previously published cycles of five other snake species, four vernal and one aestival, inhabiting the same area. We also examine the consequences of both spermatogenesis cycles over the entire reproductive processes of male and female snakes in the south-eastern Iberian Peninsula. Vernal species mate later than do aestival species, as males must produce spermatozoa just prior to mating. However, vernal species are able to condense spermatogenesis and vitellogenesis processes, hence undertaking oviposition at the same time as aestival species. Here we discuss advantages of accomplishing the entire reproductive cycle in one (vernal species) or two (aestival species) calendar years. We also found that mature male M. monspessulanus exhibit decreased testes volume relative to body size. Large testes are expected in scenarios of sperm competition. The mating system of M. monspessulanus (territoriality, mate guarding, male–male combat) does not suggest sperm competition, hence it may be more advantageous for males of this species to invest in body size than in testes size.

Morphological variability of the Lataste's viper ( Vipera latastei ) and the Atlas dwarf viper ( Vipera monticola ): patterns of biogeographical distribution and taxonomy

The Latastes viper Vipera latastei is a medium-sized viper distributed throughout almost the entire Iberian Peninsula and north-west of Africa. Former morphological studies noted the existence of two subspecies, V. l. gaditana and V. l. latastei, as well as a full species, V. monticola, in the High Atlas, corresponding to the prior overall range described for V. latastei. However, some results remained unclear in these former studies, e.g. the specific status of the Medium Atlas populations, the intra-subspecific differences in V. l. gaditana and, the true status of some isolated populations of the northern range. For this reason, 45 morphological characters were analysed in 672 preserved specimens covering the entire range. Categorical Principal Components Analysis (CATPCA) and Discriminant Function Analysis (DFA) were used to assess geographic variability, treating specimens individually or assigning them ap riorito groups, respectively. Geographic groups were established according to the origin of specimens in isolated areas of mountain chains. As the percentage of correct assignment was low in DFA, initial groups were combined to maximize the percentage. The results from the multivariate analysis suggest morphological differentiation between populations. Some variables accounted for geographic variability: e.g. rows of dorsal scales at mid-body are taxonomically stable and clearly separate the African populations; and number of ventral scales showed a clinal variation from 126 to 143 ventrals in extreme populations. The three African groups manifested clear morphological differences, and especially specimens from the High Atlas (V. monticola) and Alger. On the contrary, a large number of initial Iberian groups were merged because of the low scores in the correct classification. The final groups showed a vast central area with low morphological differentiation as well as isolated populations in the NW, NE and SW Iberian Peninsula. This conclusion matches well with allopatric speciation processes during the Quaternary ice ages, which contributed to the contraction/expansion of range, isolation events, and peripheral population refugia. Morphological differentiation in external characters of V. latastei exhibited similar results with respect to V. aspis and V. ammodytes, the vipers occupying other southern European peninsulas. Molecular markers will contribute to elucidate the relationships between V. latastei populations and the history of colonisation across the Strait of Gibraltar.

Wide food availability favours intraspecific trophic segregation in predators: the case of a water snake in a Mediterranean river

In complex aquatic ecosystems, intraspecific competition for food can evolve into dietary differences related to body size, gender, capture ability, and habitat use. The diet of the viperine snake, Natrix maura, an aquatic predator which forages on fish and amphibians, has been studied in parallel with food availability in a small locality of the Matarranya River (NE Spain). Fish abundance values in this Mediterranean river, which hosts one of the highest rates of fish diversity in Europe, were estimated through electrofishing. Natrix maura fed on four of the ten fish species available and captured the only amphibian detected. Three of these fishes were the most abundant species in the river. The fourth fish was the river blenny, a small and rare benthonic species of which the males protect eggs laid under stones at the bottom of the river during reproductive periods. This behaviour makes it easy prey for N. maura. However, the river blenny was caught mostly by small- and medium-sized snakes, while larger individuals, particularly females, fed on larger and more mobile prey that were more abundant and energetically more profitable. Similar diet differences according to size and gender have been described in other water snakes. We discuss whether this coincidence may be related to the great tropic availability in aquatic environments for fish-eating snakes.

Factors Influencing Schoolchildren's Responses to a Questionnaire in Wildlife Conservation Education

Questionnaires are important tools for assessing attitudes regarding conservation issues. However, they are not easily comparable and their reliability has been insufficiently assessed. We examined factors influencing responses to open- and closed-ended questions about animal conservation to more than 600 schoolchildren (9 years old on average). We analysed the level of understanding, controllable (e.g. sample size) and less controllable factors (e.g. affectivity). Most children responded appropriately to the questions, but subtle changes in the phrasing influenced the answers. Affectivity towards endearing species and spontaneity also influenced the responses whereas small sample sizes (∼50 children) provided relatively stable patterns. Overall, we suggest that standardization of questionnaires administered over large spatial and time scales is needed to accurately assess childrens attitudes towards conservation issues.

First helminthological data on Iberian vipers: Helminth communities and host-parasite relationships

European vipers are ambush predators with sporadic feeding events, thereby maintaining the digestive tract empty for long periods. According to previous studies relating lizards’ dietary habits and their helminth faunas, we predict poor gastrointestinal helminth communities in vipers. To test this hypothesis, we have examined the digestive tract of 86 specimens of Vipera aspis (L., 1758) and V. latastei Boscá, 1878, from several localities of the Iberian Peninsula. We found adults of only two nematode species Kalicephalus viperae (Rud., 1819) and Ophidascaris sp. and cysts adhering to the external wall on the stomach in case of two other nematode species Ascarops strongylina (Rud., 1819) and Spirurida gen. sp. All these nematodes are common parasite species in snakes, although Ophidascaris sp. has never before been recorded in Vipera sp. The low prevalence and small number of parasite species in Iberian vipers matched their low feeding rates. However, our results contrast with studies in Poland and Belarus of V. berus species, in which nematodes, as well as trematodes, are common and abundant. Rainfall rates are lower in the Iberian Peninsula than in eastern Central Europe, where amphibians are more available and consumed by V. berus. Amphibians, intermediate hosts for these helminths, have been recorded only sporadically as prey for V. aspis and V. latastei, thus supporting the absence of trematodes in both Iberian viper species. Among populations of Iberian vipers, the prevalence of parasites correlates with the feeding rate (i.e. percentage of vipers with prey), suggesting a linkage between the two parameters. In conclusion, our results suggest that several factors, including climatic characteristics of localities, feeding rates of predators, and type of prey consumed, influence the number and type of parasites in Iberian vipers.

Predation on Trachylepis socotrana by Lanius meridionalis

This work was undertaken with the support of The Mohamed bin Zayed Species Conservation Fund, project no 13055714, and grant CGL2012-36970 from the Ministerio de Economia y Competitividad, Spain (co-funded by FEDER). R. Vasconcelos and X. Santos are supported by Postdoctoral grants from the Fundacao para a Ciencia e Tecnologia (FCT) (SFRH/BPD/79913/2011 and SFRH/BPD/73176/2010). The Environmental Protection Agency (EPA) aided and permitted the field work in Socotra.