Males and females face different selection pressures due to a sexually biased investment into reproduction. This often results in different morphologies. Sexual size dimorphisms (SSD) can give us ...important hints on the evolution and biology of a species. Salamanders are a perfectly suited system for investigating SSD, including a diversity of reproductive modes and behaviors, and patterns of SSD combined with life history traits in a phylogenetic context help us to understand the evolution of these processes. Because spectacled salamanders (genus Salamandrina) are the phylogenetically most basal taxon of the Salamandridae, they play a key role in reconstructing the evolutionary pattern of SSD. Combining extensive external and skeletal measurements of the cranium, limbs, and the pelvic girdle using high‐resolution micro Computer Tomography (μCT) yielded an integrative analysis of expressed SSD of morphology and osteology of Salamandrina perspicillata. Multivariate analysis of external characters showed that males generally had larger cloacae, heads, and limbs relative to body size, while females had larger trunks. Analysis of osteology confirmed this pattern but also revealed new dimorphic characters in the cranium and the pelvic girdle. Dimorphic characters in external morphology and osteology are likely linked to the different reproductive roles of the sexes and support sexual rather than ecological selection as the primary force acting on the phenotype of the phylogenetically basal salamandrids.
Combined extensive external and skeletal measurements of high‐resolution micro Computer tomography (μCT) datasets showed novel sexually dimorphic characters especially in the cranium and pelvic girdle of the terrestrial salamander Salamandrina perspicillata.
The diversity of the vertebrate cranial shape of phylogenetically related taxa allows conclusions on ecology and life history. As pleurodeline newts (the genera Echinotriton, Pleurodeles and ...Tylototriton) have polymorphic reproductive modes, they are highly suitable for following cranial shape evolution in relation to reproduction and environment. We investigated interspecific differences externally and differences in the cranial shape of pleurodeline newts via two‐dimensional geometric morphometrics. Our analyses also included the closely related but extinct genus Chelotriton to better follow the evolutionary history of cranial shape. Pleurodeles was morphologically distinct in relation to other phylogenetically basal salamanders. The subgenera within Tylototriton (Tylototriton and Yaotriton) were well separated in morphospace, whereas Echinotriton resembled the subgenus Yaotriton more than Tylototriton. Oviposition site choice correlated with phylogeny and morphology. Only the mating mode, with a random distribution along the phylogenetic tree, separated crocodile newts into two morphologically distinct groups. Extinct Chelotriton likely represented several species and were morphologically and ecologically more similar to Echinotriton and Yaotriton than to Tylototriton subgenera. Our data also provide the first comprehensive morphological support for the molecular phylogeny of pleurodeline newts.
We applied geometric morphometrics to cranial morphology in extant and extinct crocodile newts. Our data provides the first comprehensive morphological support for the molecular phylogeny of these newts. Further, we could show that life history traits correlate with head shape and that fossil Chelotriton show similarities in shape with some extant taxa allowing conclusions on its ecology.
This paper provides an overview of studies that estimate the inflation risk premium using inflation‐linked bond (ILB) yields. I categorize existing studies, outline their research designs and compare ...their estimates for the inflation risk premium. Furthermore, the importance of accounting for ILB illiquidity and an overview of existing ILB liquidity proxies are demonstrated. A discussion of current literature developments, such as the zero lower bound, and an outline for future research directions conclude the paper.
Caecilians (order Gymnophiona) are apodan, snake-like amphibians, usually with fossorial habits, constituting one of the most unknown groups of terrestrial vertebrates. As in orders Anura (frogs, ...tree frogs and toads) and Caudata (salamanders and newts), the caecilian skin is rich in mucous glands, responsible for body lubrication, and poison glands, producing varied toxins used in defence against predators and microorganisms. Whereas in anurans and caudatans skin gland morphology has been well studied, caecilian poison glands remain poorly elucidated. Here we characterised the skin gland morphology of the caecilian
, emphasising the poison glands in comparison to those of anurans and salamanders. We showed that
glands are similar to those of salamanders, consisting of several syncytial compartments full of granules composed of protein material but showing some differentiated apical compartments containing mucus. An unusual structure resembling a mucous gland is frequently observed in lateral/apical position, apparently connected to the main duct. We conclude that the morphology of skin poison glands in caecilians is more similar to salamander glands when compared to anuran glands that show a much-simplified structure.
BACKGROUND: Female sperm storage has evolved independently multiple times among vertebrates to control reproduction in response to the environment. In internally fertilising amphibians, female ...salamanders store sperm in cloacal spermathecae, whereas among anurans sperm storage in oviducts is known only in tailed frogs. Facilitated through extensive field sampling following historical observations we tested for sperm storing structures in the female urogenital tract of fossorial, tropical caecilian amphibians. FINDINGS: In the oviparous Ichthyophis cf. kohtaoensis, aggregated sperm were present in a distinct region of the posterior oviduct but not in the cloaca in six out of seven vitellogenic females prior to oviposition. Spermatozoa were found most abundantly between the mucosal folds. In relation to the reproductive status decreased amounts of sperm were present in gravid females compared to pre-ovulatory females. Sperm were absent in females past oviposition. CONCLUSIONS: Our findings indicate short-term oviductal sperm storage in the oviparous Ichthyophis cf. kohtaoensis. We assume that in female caecilians exhibiting high levels of parental investment sperm storage has evolved in order to optimally coordinate reproductive events and to increase fitness.
Introductions of non‐native species can pose serious threats to native populations and ecosystems. However, the impact of introduced species depends on intrinsic characteristics, local habitat ...conditions, and the interaction with native species. Case‐specific management strategies may therefore be required. Using phenotypic characters and molecular markers for species identification, we provide insights into an artificial hybrid zone between two closely related newt species, the native Triturus cristatus and the introduced T. carnifex, near Tübingen, south‐west Germany. Our analyses revealed a central Italian origin of the non‐native T. carnifex and suggested their sustained presence in the study area for at least six years, probably much longer. In some ponds, extensive hybridization with native T. cristatus was detected. However, we found no evidence for a displacement of the native species by its non‐native congener. The gradient from pure T. carnifex to pure T. cristatus currently extends over 7 km. A future expansion of the hybrid zone and swamping of a neighboring T. cristatus meta‐population appears unlikely under the local configuration of breeding ponds. We propose to monitor the hybrid zone using genetic markers for evaluating the direction and speed of gene flow, complemented by capture‐recapture studies to reveal trends in species‐specific population sizes. To protect the native T. cristatus, we recommend practitioners to maintain their habitats, for example, by preventing illegal release of gold fish, by counteracting early drying of the breeding ponds, and by regularly cutting back trees and shrubs along the shoreline.
Closely related non‐native species can affect native congeners by admixture and genetic replacement. We provide a case study, documenting hybridization of non‐native Triturus carnifex with native T. cristatus but no replacement of the native species. A future expansion of the hybrid zone and swamping of a neighbouring T. cristatus meta‐population appears unlikely under the local configuration of breeding ponds.
Tax avoidance among large multinational corporations has considerably increased in recent years, triggering an intense discussion about how to ensure that all pay their ‘fair share’. We propose a ...novel experimental design to incentive-compatibly model the firm-consumer relationship in a consumer goods market. This new paradigm allows us to analyze the effect of increased tax transparency on consumer and firm behavior in a dynamic framework. We find that absent the threat of being directly exposed as a tax avoiding firm, only 26% of the firms decide to pay taxes. Once tax avoiding firms are identifiable in the market, this rate rises to 58%. Providing market participants additionally with information about the social costs of tax avoidance increases the fraction of tax paying firms further to 74%. We observe that these improvements are the consequence of firms proactively deciding to pay taxes. At the highest level of transparency, we further observe that consumers show a stronger proclivity to boycott tax avoiding firms, even if these firms offer cheaper prices.
•We propose a novel, incentive-compatible experimental design for consumer goods markets.•Building on this design, we examine corporate tax avoidance in a dynamic market environment.•Without tax transparency, firms predominantly choose to avoid taxes.•Tax transparency significantly decreases engagement in tax avoidance.•At the highest level of transparency, consumers show a stronger proclivity to boycott tax avoiding firms.
Modern amphibians have an extraordinary diversity of reproductive modes including varieties of oviparity and viviparity. Oviparous and viviparous caecilian amphibians show high degrees of parental ...investment including dermato- and uterotrophy. We examined maternal investment and reproductive biology correlations of the aquatic viviparous caecilian amphibian Typhlonectes natans. Litter sizes ranged from two to ten pups, whereas litter masses averaged around 28% of maternal mass and pups reached up to 43% of the female total length. Maternal size was positively related to litter size and to the average pup body size. Although overall fecundity is reduced in viviparous teresomatan caecilian amphibians, as clutch size is decreased in comparison to oviparous ichthyophiid caecilians, a lower fecundity of viviparous taxa is compensated via uterotrophy leading to an increased offspring size and quality.
This article proposes a novel way to construct an index for economic policy uncertainty that does not depend on language proficiency. We use two specific features of search volume extraction on ...Google Trends, combine policy-relevant search queries, and construct our Google economic policy uncertainty index for nine Eastern European countries-a region in which the construction of other economic policy uncertainty indices would require good language proficiency. We illustratively show that major policy-related events are captured and find that shocks on economic policy uncertainty yield a sizable impact on macroeconomic variables.
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