Mark-recapture techniques were used to investigate population size, age distribution, size distribution and sex ratio in a population of the lacertid lizard Podarcis bocagei in an abandoned gravel pit in northwest Spain. The study was carried out over a 2-year period. Despite relatively high maximum longevity, the population age distribution was characteristic of small, short-lived lizard species (i.e., there was a relatively high proportion of immature individuals). Population size declined over the study period, largely because of a drop in the number of immature animals: this may be partially attributable to density-dependent factors, but was probably due largely to a decline in habitat favourability as a result of colonisation of the study site by vegetation. The sex ratio was significantly female-biased in all cohorts studied, not only among adults but also among juveniles and sub-adults. However, sex ratio at hatching (as investigated by laboratory hatching of clutches laid by captured pregnant females) did not differ significantly from one-to-one. There was no difference found in survival probabilities between males and females. The observed bias in sex ratio must therefore be attributed to between-sex differences in net emigration.
The three lacertid lizards species of the Iberolacerta genus, which have recently been described or recognised as different species, are reptiles that live strictly at the highest altitudes in Europe, from elevations of near 1900 up to more than 3000 m a.s.l. in the Pyrenees (Spain, Andorra, France). In this paper, the reproductive cycle and reproductive characteristics of these species are described for the first time. Data were obtained from field studies carried out in different high-mountain Pyrenean locations from 1989–2002. In addition we also conducted hatching studies in laboratory. Due to the harsh climatic conditions in the high mountains the activity cycle of these species is very short, just over 4 months, from mid-May to late September or beginning of October. This affects their reproductive cycle (i.e., only one annual egg-clutch is produced), as well as other reproductive characteristics, as the existence of a very advanced embryonic development at oviposition, which is interpreted as an advanced stage in the tendency towards viviparity, and diverse life history characteristics as a very little annual growth which greatly delays sexual maturity to 4 years in males and 4–5 years in females. Clutch size correlates significantly with female snout-vent length (SVL) in all three species. The average clutch size is 2.53 eggs in I. aurelioi (the smallest species), 3.03 in I. bonnali and 3.44 in I. aranica (the biggest species). Notwithstanding the differences in egg number the three species have a similar egg volume. The incubation period in the laboratory is very short with an average of 30–36 days among the species. The low reproductive potential observed in these three species and revealed in this paper is a strongly threatening factor which, together with their extremely reduced distribution area, endangers these endemic, rare and very threatened species.
We studied the reproductive ecology of a population of the lacertid lizard Lacerta monticola at a lowland location in A Coruña (NW Spain) from 1997 to 2002. The timing of the reproductive cycle was examined based on mark-recapture records of individual lizards in the field. The characteristics of the eggs and hatchlings were obtained from clutches laid in the laboratory by pregnant females that were temporarily removed from the study area. Our results indicate that mating took place between late March and July. The smallest female with signs of sexual maturity had a snout-vent length (SVL) of 52.4 mm and the smallest male was 50.7 mm. Sexual maturity was attained at the age of 2 years by 41% of the individuals, while the remaining 59% of the lizards matured at the age of 3 years. The laying period occurred between June and the beginning of August considering all years. About 61% of the reproductive females produced a single clutch annually, while 39% of the females produced two clutches per year. Females that produced two clutches were generally larger (average SVL = 70.9 mm) than those that laid a single annual clutch (average SVL = 62.6 mm). The mean clutch size was 6.4 eggs (range 4-9). Both clutch size and clutch mass increased significantly with female SVL. The mean egg mass in a clutch decreased significantly with clutch size. Hatching occurred between August and September. Hatching success in the laboratory was 71.7%. The mean SVL was higher in female hatchlings than in males.
The reproductive characteristics of the slow worm (Anguis fragilis) were studied in A Coruña (Galicia, NW Spain) in 1999, 2000, 2001 and 2002. Data were mainly obtained through pregnant females captured in natural populations which subsequently gave birth under controlled conditions in the laboratory and the resulting neonates were examined. Marked individuals in a field population were also monitored. This field study allowed us to gain knowledge of the activity and reproductive cycle of the monitored population. A total of 68 births and 468 neonates were obtained, allowing us to determine the basic reproductive characteristics of the populations studied such as the litter size, offspring weight, offspring size and minimum maturity size for females: 135-150 mm snout vent length (SVL). The relationship between several variables related to offspring and their mothers showed a positive relation between size and mass of the litter and offspring with maternal size. A relationship between maternal tail length and litter mass was not observed. Unlike other studied populations of this species, most of the females of the A Coruña population (88.8%) reproduce annually. We found a probable relationship between female annual reproductive output and latitude, likely related to differences in environmental temperature. The activity cycle for the monitored population (from February to mid-December) is the longest known for the species.
Changes in the coloration of the lacertid lizards Iberolacerta monticola and Podarcis bocagei with age in populations from NW Spain are described. The onset of sexual maturity in P. bocagei males involves a change in the ventral (yellow) and dorsal (green) colorations, which is different from immature males (dorsally brownish in color). In I. monticola males, the ventral coloration also changes to a deep green when they reach maturity, while the dorsal coloration remains brownish as in the immature specimens. In this species, the green dorsal coloration is acquired gradually after maturity. Only the oldest individuals have a predominantly green dorsal coloration. The differences between the two species in the time males take to acquire the green dorsal coloration could be related to their different longevity. The coloring is acquired gradually in the most long-lived species (I. monticola). A field study was carried out on the behaviour of adult males of I. monticola during the reproductive period. The males with green dorsal coloration were seen to pair with females significantly more frequently than those with the brownish dorsal color. The increase in the green dorsal coloration (conspicuous) with the size and age of the males of this species would appear to have a clear function as an intersexual or intrasexual signal.
n. Se ha estudiado la incidencia de infecciones externas en una población noroccidental ibérica del lacértido Podarcis bocagei. Estas infecciones llegaron a afectar al 20-30% de los individuos observados en el invierno de 1989-1990 y al 40-60% en el invierno 1990-1991. Los porcentajes de individuos afectados fueron mayores en los meses más lluviosos y fríos. No se encontraron diferencias en las tasas de recaptura entre los individuos afectados y no afectados, lo que parece indicar que estas afecciones no tienen un efecto directo detectable en las tasas de mortalidad. La presencia de esta enfermedad afectó a la reproducción: el 28% de las hembras adultas de talla grande (LCC > 55 mm) que habían estado infectadas, no participaron en el primer período de puestas, durante mayo, mientras que tan sólo el 2.2% de las no afectadas de la misma talla no se reprodujo en ese período. Los individuos jóvenes afectados mostraron tasas de crecimiento significativamente menores que los ejemplares de su misma edad no afectados. Por lo tanto, el efecto de estas infecciones sobre el éxito reproductor se manifiesta principalmente afectando a la participación en la reproducción de las hembras adultas y a las tasas de crecimiento de los individuos jóvenes.
We analysed the DNA sequences of the mitochondrial cytochrome b gene for 49 specimens of the Western spadefoot toad, Pelobates cultripes, from Spain, and one sample from France, with a focus on populations from Galicia in northwestern Spain. Our results point to a generally low mitochondrial differentiation of the species across its distributional range although some phylogeographic structure was detected. Galician populations from coastal localities, from the A Limia region, and from Monforte appeared to be closely related, whereas the only available sample from the relict Galician population from near O Barco de Valdeorras has the same haplotype as the samples from Burgos, in central Spain.
Numerous dietary studies have shown that European vipers (genus Vipera) present low feeding frequency and a specialist diet, which is characterised by a marked ontogenetic shift. However, how eco-geographic factors shape species’ feeding ecology remains scarcely addressed. We investigated the feeding ecology of the Iberian adder, Vipera seoanei, examining 402 specimens distributed across its distributional range and addressing how biological, temporal and eco-geographic factors relate to the species feeding activity and dietary consumption. Our results indicated a low feeding frequency in the species, higher in juveniles than in adults. Adult females showed higher rates of prey consumption than adult males, which match to the distinct reproductive demands of both sexes, although no differences between reproductive and non-reproductive females were found. V. seoanei preyed on a varied taxa spectrum, but showed a rather specialist diet based on small mammals. Amphibians and reptiles were also an important part of its diet, particularly in the juveniles. Body size was found as the single biological trait related to the consumption of major prey groups, supporting the occurrence of an ontogenetic shift in the diet. Two habitat and two climatic factors correlated to the consumption of major prey groups, reflecting the ecological requirements of prey across the viper’s range. Overall, this study extends the existing knowledge on the feeding ecology of European vipers, signalling how energy intake and allometric constraints shape the feeding activity and dietary consumption of the species across the geography, leading to distinct feeding strategies in juveniles and adults.
We determined DNA sequences of the mitochondrial cytochrome b gene for 44 specimens of the common frog, Rana temporaria parvipalmata, from 14 localities in Galicia, northwestern Spain. We found a low differentiation among all studied individuals, with a maximum of four mutational steps between haplotypes, including those from the southernmost isolated populations on the Manzaneda-Queixa and Trevinca-Segundeira massifs which thus probably originated by a rather recent colonization and likely maintained intermittent gene flow to more northern populations during climatically colder, glacial periods with a higher habitat connectivity.
Based on DNA sequences of fragments of the mitochondrial COI and 16S rRNA genes we provide a first assessment of genetic variability of Iberian treefrog populations that have been historically allocated to Hyla arborea, partly as subspecies H. a. molleri. Our data from 147 specimens and 33 populations confirm strong divergence between these frogs and Central European H. arborea but relatively low differentiation across their range, supporting their status as a separate species, H. molleri. Preliminary phylogeographic data indicate a possible weak genetic differentiation of populations from the northern coast of the region of Galicia. We suggest inclusion of nuclear markers and an extension of the sampling into the coastal regions of Asturias and Cantabria, as well as the identification of the contact zone between H. molleri and H. arborea in either the Spanish Basque country or in France, as priorities for future research on this species.