Abstract:  Caiman is one of the five extant genera of alligatorid crocodylians. While several quantitative and qualitative studies exist on morphological variation in the genus, little is known about ontogenetic effects. Here, we quantify ontogenetic variation in morphology for Caiman yacare and C. latirostris in a phylogenetic context. A linear regression analysis on twelve skull measurements of C. yacare and C. latirostris against a measure of size (the first axis of a PCA of all variables) showed high correlation coefficients (r ²=0.89– 0.99) and negative allometry. Eight allometric trajectories showed common slopes at different intercepts, reflecting a common ontogenetic pattern of morphological growth fixed early in ontogeny. The anterior width of the snout and the posterior width of the skull table are suitable to discriminate between the two species. The relationship between snout width and snout length is isometric in C. latirostris while it is negatively allometric in C. yacare. These results confirm that the snout shape is a distinctive feature between species established early in ontogeny. The narrowing and lengthening of the snout in C. yacare during ontogeny results in adult forms widely represented in other extant taxa within the genus. The broader and shorter snout in C. latirostris is probably an autapomorphic feature of this species within Caimaninae.

Keywords: ONTOGENY, CAIMAN LATIROSTRIS, CRANIAL VARIATION, CAIMAN YACARE, ALLOMETRY

Abstract: Documenting elevational gradients in species richness is important to understand the determinants of spatial distributions. We studied anuran richness along an elevational gradient in an Atlantic Rainforest area to evaluate i) how anuran richness and elevation are related; ii) if the data support the hypothesis of the mid-domain effect or the Rapoport effect and iii) if there is seasonal variation in species richness and abundance of leaf litter anurans in the studied site. Sampling was carried out using time-constrained visual encounter surveys and plot (quadrat) methods at six elevational levels. We found 406 individuals belonging to 19 anuran species. The most abundant frog species were Ischnocnema parva (6.2 individuals per 100 m²) and Adenomera marmorata (2.0 individuals per 100 m²). The overall leaf litter frog abundance was 11.2 ind/100 m², with highest values at 150 m (26.6 ind/100 m²) and 300 m (25.6 ind/100 m²) elevations. We found high species turnover across altitudes. Our data neither supported the mid-domain effect nor the elevational Rapoport effect. There was no significant difference in frog abundance among seasons, although most of the leaf litter frogs species were found in the wet season (235 individuals or 69.3%). Our study demonstrates a high local frog species richness and abundance in combination with an abundance decreasing with elevation.

Keywords: AMPHIBIA, MID-DOMAIN EFFECT, ALTITUDE, RANGE SIZE, MONTANE RAINFOREST, RAPOPORT EFFECT

Abstract:  Chelonoidis chilensis is an endangered tortoise that inhabits arid regions in Argentina, Bolivia and Paraguay. Blood samples were obtained from wild specimens from the Argentinan distribution range together with samples from specimens of known morphotype but unknown provenance. Cytogenetic analysis using Giemsa staining showed that the diploid chromosome complement was 2n=52 for all twenty-five tortoises analysed. Two different karyomorphs, termed A and B, were identified, with a karyotypic formulae of 7:5:14 and 6:5:15, respectively. G-band analysis suggests that karyomorph B may originate from a chromosomal fission event involving chromosome pair 7 of karyomorph A. In addition, all specimens analysed using Fluorescence In Situ Hybridisation (FISH) with a telomeric probe showed telomeric signals only at the terminal regions of chromosomes. This evidence suggests that the karyotype of C. chilensis does not have telocentric chromosomes, and that interstitial telomeric sequences have not played a major role during the recent chromosomal evolution of this species. Our data agree with recent molecular evidence supporting the existence of one instead several species for the C. chilensis complex. Our data further suggest a possible correlation between chromosomal variation and geographical distribution: karyomorph A is present in tortoises from the Dry Chaco Eco-region, whereas karyomorph B characterises tortoises living in the Monte of Steps and Plains Eco-region. Morphology appears to vary independently of cytomorph variation.

Keywords: CHELONOIDIS CHILENSIS, FLUORESCENCE IN SITU HYBRIDISATION (FISH), CRYPTODIRA, KARYOTYPIC EVOLUTION, TESTUDINES

Abstract: Recent surveys for the amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) in Africa have documented the infectious disease in frogs and caecilians from forested habitats in multiple areas of Central and East Africa. We tested 166 frogs for the presence of Bd from 45 localities representing a diverse array of habitats and elevations (793–2852 m.a.s.l.) in the Albertine Rift (AR) region of eastern Democratic Republic of the Congo during four field seasons from 2008–2011. Fifty-eight of these frogs were positive, for an overall Bd-prevalence of 34.9%. Three genera of frogs (Callixalus, Chrysobatrachus and Nectophryne) are reported to be Bd positive for the first time. Behavioural observations of Bd-positive frogs calling for mates and basking suggest the AR amphibian fauna was not severely affected by chytridiomycosis during the survey. Given the enormous levels of endemism and conservation value of the AR amphibian fauna, additional studies of Bd should focus on the region.

Keywords: DEMOCRATIC REPUBLIC OF THE CONGO, ANURAN, INFECTIOUS DISEASE, ENDEMISM

Abstract: Lizards that live in the harsh climate of the Argentinean Patagonia (40°–53° S) are active for a period restricted to spring and summer when vitellogenesis, pregnancy and birth take place. Herein, we present data on the female reproductive cycle, body size at sexual maturity, litter size and fat-body cycle of one of the world's southernmost reptiles, Liolaemus sarmientoi. We also provide preliminary data on the reproductive cycle of a sympatric species, L. magellanicus. Females of both species start vitellogenesis in late spring, probably arrested or continued at very low rates during brumation resumed in the spring of the next year. Pregnancy starts in spring and births of L. sarmientoi (2 to 7 offspring) and L. magellanicus (3 to 4 offspring) occur over a month in midsummer. Females that give birth earlier can start a new vitellogenic cycle before autumn and perform an annual reproductive cycle. However, females which give birth later delay the start of a new vitellogenic cycle until the next spring, performing a biennial reproductive cycle. Thus, females have the potential to adjust their frequency of reproduction according to the energetic restrictions imposed by environmental conditions in the southernmost lands of South America.

Keywords: LIFE HISTORY, LIOLAEMUS SARMIENTOI, LIOLAEMUS MAGELLANICUS, ANNUAL-BIENNIAL REPRODUCTIVE CYCLE, COLD CLIMATE, VIVIPARITY, FAT BODIES

Abstract: The investigation of historical factors which determine assemblage structure is largely based on the idea that closely-related species have similar ecological characteristics due to a shared evolutionary history. We used a Pseudocommunity Analysis (PA), Principal Component Analysis (PCA) and Canonical Phylogenetic Ordination (CPO) to evaluate the influence of phylogeny on microhabitat use, diet composition and morphology in an assemblage of 15 anuran species occupying temporary ponds in the semiarid Caatinga. Closely-related species used the same microhabitats, although at different proportions, and showed a high diet niche overlap. The PA showed that competition does not appear to regulate the assemblage. Closely-related species showed a high degree of morphological similarity, suggesting that body shape is a conservative trait. The CPO analysis revealed a historical influence on microhabitat use in the Hylidae and Leptodactyliformes dichotomy, and in the diet composition of the genus Physalaemus and Leiuperinae. Although resource use patterns reflect phylogenetic relationships among species, our results suggest that ecological factors such as competition further shaped the studied anuran assemblages.

Keywords: PHYLOGENETIC INFLUENCE, MORPHOMETRY, ASSEMBLAGE STRUCTURE, DIET, CANONICAL PHYLOGENETIC ORDINATION, MICROHABITAT USE, ECOLOGICAL INFLUENCE

Abstract: Sexual size dimorphism (SSD) is a widespread phenomenon commonly attributed to sex-specific patterns of selection on body size. Using data from Dengchigou population of the Omei treefrog (Rhacophorus omeimontis) in Fengtongzhai National Nature Reserve, southwestern China, we evaluated the hypothesis that direct phenotypic selection on both males and females can produce SSD. Female biased-SSD was generally driven by selection on females due to fecundity advantage of large body size rather than sexual selection favouring large male body size. Furthermore, differences in life-history traits (i.e. growth rate and/or time available for growth) between the sexes also resulted in female biased-SSD. Our findings suggest that the relationship between female size and fecundity supports the prediction that selection for fecundity drives female biased-SSD.

Keywords: OMEI TREEFROG, SEXUAL SIZE DIMORPHISM, STANDARDISED SELECTION GRADIENTS

Abstract: Brain size variation across the animal kingdom can be interpreted as a trade-off between selective advantages of higher cognitive ability and the prohibitively high energy demands of a large brain. The Expensive-Tissue Hypothesis (ETH) predicts that brains are costly, and increases in brain size will decrease the size of other metabolically costly tissues. Here, we tested this prediction using the anuran Rana omeimontis. Brain size was negatively correlated with gut length, supporting the ETH. We did not find associations between brain size and the size of other organs (heart, liver, lungs, kidneys), but found positive correlations between brain mass and testes as well as limb muscle mass when correcting for the effects of body condition. The negative correlation between gut length and brain mass suggests that diet quality may play a role in the evolution of brain size in R. omeimontis.

Keywords: ORGANS, RANA OMEIMONTIS, EXPENSIVE-TISSUE HYPOTHESIS, BRAIN SIZE