Abstract: Serum dipeptidyl peptidase IV (DPPIV) activity was characterized in three divergent and sympatric species of West African crocodiles. The serum of the Nile crocodile (Crocodylus niloticus) exhibited higher DPPIV activity than that of the African dwarf crocodile (Osteolaemus tetraspis) and the slender-snouted crocodile (Mecistops cataphractus). Kinetic analyses showed that the rate of product formation was higher in serum of C. niloticus with respect to time, and it was confirmed by double reciprocal plot analysis that the V_max for serum of C. niloticus was higher than the other two species. However, the Michaelis constants were very similar for all three species, indicating that the C. niloticus DPPIV enzyme may be a more efficient catalyst. Thermal activity profiles demonstrated that the serum DPPIV activities of all three species increased substantially with temperature. Although activity of C. niloticus was higher than that of O. tetraspis and M. cataphractus at all temperatures investigated, linear increases of activity with temperature were noted for all three species. The results from this study show that three diverse species of West African crocodilians express soluble serum DPPIV.

Keywords: CROCODYLUS NILOTICUS, OSTEOLAEMUS TETRASPIS, INNATE IMMUNITY, T-CELL ACTIVATION, MECISTOPS CATAPHRACTUS, DPPIV, REPTILIAN

Abstract: Smooth snakes (Coronella austriaca) confined to cold-humid environments in Iberian high mountains may be threatened by the effects of climate warming, such as the expansion uphill of competing southern smooth snakes (C. girondica), but demographic studies allowing the assessment of population tendencies are lacking. Here, we determined the distributions and abundances of both species at Serra da Estrela based on records over 18 years (1993–2010). Smooth snakes comprised an isolated population at altitudes above 800 m. Abundances were highest above 1300 m, with densities of about one smooth snake per hectare above 1580 m. The distributions of the two species overlapped at altitudes of about 800–1600 m. We did not find any evidence for range shifts, or changes in smooth snake abundance over the past 18 years. Sex ratios were even, and high dietary specialization may contribute to the species' vulnerability. Efforts to conserve the smooth snake at Serra da Estrela should encompass studies aiming to improve knowledge of the species' demography, as well as continued monitoring to evaluate potential threats posed by climate warming. Our study may provide a baseline tool for future research on this poorly known snake.

Keywords: CORONELLA AUSTRIACA, ABUNDANCE, DISTRIBUTION, CORONELLA GIRONDICA, CONSERVATION

Abstract:  Rana sauteri Boulenger, 1969 and R. multiderticulata Chou & Lin, 1997 are two sister species of brown frogs in Taiwan. They are distinguishable by the number of labial tooth rows (LTR) of tadpoles. We investigated morphometric and genetic (mtDNA cytb sequences) traits of 331 tadpoles of the two species and their putative hybrids from 32 locations along two transects. LTR correlated significantly with other morphometric traits and showed a longitudinal cline that increased from west to east across the central mountain range. Genetic differentiation was significant between the two transects, and correlated significantly with geographic distances. However, mtDNA haplotype distributions were indiscernible between the three LTR groups and uncorrelated with other morphometric traits. Individuals of the two sister species also failed to form monophyletic lineages. We argue that LTR is a phenotypically plastic trait related to stream current determined by elevation and monsoon rainfalls, and conclude that R. sauteri is the sole representative species, with R. multiderticulata being its synonym.

Keywords: TADPOLE, MTDNA CYTB SEQUENCES, RANA MULTIDERTICULATA, TAXONOMY, MORPHOMETRIC TRAITS

Abstract: The left and right testes often differ in size, and testis asymmetry is particularly well studied in birds. The compensation hypothesis states that asymmetry in testes mass covaries with male quality. We tested this idea in the dark-spotted frog Rana nigromaculata, a species where large males have a mating advantage over small males. The left testes were significantly larger than the right testes. Larger and older males tended to have relatively larger testes, but did not show a higher degree of testis asymmetry than younger males. A negative correlation between male body size and testis asymmetry is in line with the hypothesis that the right testis has a compensatory role when the left testis is malfunctioning.

Keywords: COMPENSATION HYPOTHESIS, DIRECTIONAL TESTIS ASYMMETRY, MALE QUALITY

Abstract: Laboratory studies focusing on the ability of squamate reptiles to discriminate among prey chemical cues have been the foundation for many important contributions in animal behaviour and ecology. In this study, we examined the ability of rosy boas (Lichanura trivirgata) to discriminate among several sources of prey chemicals. Because of the high frequency of neonatal mammals in the diet of erycine boas, we focused on chemical cues from female mice (Mus musculus) with and without litters of dependent young. We presented chemical stimuli on cotton-tipped applicators in one set of experiments; in a second set, we presented chemical cues as trails placed in an observation arena with test subjects. The cotton swab assays did not reveal a difference in response to prey chemical cues, but in the arena-based assays we found that snakes showed an attraction to chemical cues from female mice with litters of young. This attraction could be caused by either the feeding experiences of these individuals, an innate ability to recognize chemical cues from neonatal mammals, or both.

Keywords: PREY CHEMICAL CUES, CHEMOSENSORY BEHAVIOUR, CHARINA TRIVIRGATA, CHEMOSENSORY BIOASSAY

Abstract: We describe, through hypothesis testing and observations on life-history traits, the ecology of the snake Philodryas nattereri in a semi-arid region in north-east Brazil, where it is widespread and occurs at high abundance. We document sexual dimorphism in snout–vent length and relative tail length. The species is diurnal and semi-arboreal, and most active during the warmest periods of the day. It is active year-round, with peaks of activity during periods of maximum precipitation and temperature. Adults feed on a variety of prey types, whereas juveniles are lizard specialists. The reproductive season extends over at least nine months of the year. We conclude that, due to its high abundance, foraging skills and fecundity, P. nattereri is a major predator in the Brazilian semi-arid region.

Keywords: SNAKE, SERPENTES, DIET, REPRODUCTION, CAATINGA, ACTIVITY, DIPSADIDAE

Abstract: We studied the feeding ecology of the neotropical lizard Ameiva ameiva in a semiarid area in the state of Rio Grande do Norte, Brazil. The main food items ingested were insect larvae and pupae, gastropods, beetles, spiders, roaches and orthopterans. The population specialized more in the consumption of larvae and pupae in the rainy season, and consumed different types of prey more evenly in the dry season. The population niche width in the rainy season was narrower, due largely to a lower degree of individual specialization, despite individual niche widths that did not differ significantly between seasons. Individual specialization was stronger in the dry season, causing an expansion in the population niche width. Sexual differences in diet were small, despite sexual dimorphism in body size. Maximum, average and range of prey sizes were positively correlated with lizard body size, but minimum prey size remained constant, resulting in a positive relationship between body size and individual niche width. Despite differences between adult and juvenile lizards in maximum and average prey sizes, the fact that adults continue to feed on small prey suggests that there may be competition for food resources between age classes.

Keywords: SQUAMATA, LIZARD ECOLOGY, SEASONALITY, INDIVIDUAL SPECIALIZATION, OPTIMAL FORAGING, DIET, TEIIDAE, SEMIARID

Abstract: Counting shell growth rings is a common method of determining the ages of young tortoises, but the accuracy must be validated for each species. The objective of this study was to test if the age of Egyptian tortoises Testudo kleinmanni can be reliably determined by counting the growth rings on their shells. Our results suggest that as individuals become larger and older, age is more difficult to determine. Seventy-five percent of individuals below 90 mm carapace length (n=24) exhibited a one ring per year relationship, which was the case for only 6% of the 16 individuals with a carapace length above 90 mm. Ring counts were relatively reliable for determining ages of tortoises five years or younger, as 76.2% of these individuals exhibited a one ring per year relationship. The threshold age for the reduced reliability of ring counts is around six years of age, as only 16% of the tortoises six years or older exhibited a one ring per year relationship.

Keywords: GROWTH RINGS, CHELONIANS, ANNULI