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In this work, we performed a biogeographic analysis with Bayesian binary MCMC (BBM) statistical dispersal-vicariance analysis (S-DIVA) and species distribution models (SDM) on three phylogenetically closely related Mediterranean whipsnakes ( Hierophis gemonensis , H. carbonarius , H. viridiflavus ), to investigate the pathways of their geographical diversification and locate putative refugial areas in the last glacial maximum (LGM). Our analysis suggests that the diversification processes between the studied species overall followed an east-west route, from eastern Greece to the Iberian Peninsula and continental France, highlighting a significant role of dispersal and vicariance processes at both inter- and intraspecific levels. In particular, the main lineage-splitting events between H. gemonensis , H. carbonarius and H. viridiflavus coincide with two events of vicariance, involving respectively eastern Greece and eastern Italy, and eastern Italy and western Italy, Iberian Peninsula and continental France. SDM analyses highlight the occurrence of multiple putative glacial refugia in the Balkans, Italy and southern France, which represent well the occurrence of distinct “refugia within refugia” in the main Mediterranean peninsulas. Furthermore, our results suggest how these refugia may have played an important role during the Quaternary climatic oscillations in shaping the current haplotype distribution of European whipsnakes. [ABSTRACT FROM AUTHOR]

Except for polyploidy, parthenogenesis and hybridogenesis, the role of chromosome rearrangements in speciation is still highly debated. This paper highlights an unusual karyotype diversification and a putative case of chromosomal speciation in the endemic Malagasy tomato frogs. The tomato frogs include Dyscophus insularis as well as the sister species D. antongilii and D . guineti , which are characterized by a disjunct distribution and a low genetic divergence, probably due to a recent hybridization. Our results show that the three Dyscophu s species present 2n = 26 biarmed chromosomes, differing in chromatin pattern. Interestingly, both sexes of D . guineti show a heteromorphic chromosome pair 11, with one element larger (11a) than the other (11b) due to the presence of a large terminal tract on the short arm with an euchromatic band enclosed between two heterochromatic bands. This fixed condition reminds that of some newts of the genus Trituru s, but in Dyscophus it probably characterizes the beginning of a cladogenetic process. We hypothesize that in D. guineti the raising of the heteromorphic 11 th chromosome pair followed the hybridization with D. antongilii , originating a post-zygotic barrier and representing a case of sympatric or parapatric chromosomal speciation. This speciation mechanism may also have had important biogeographic consequences, shaping the current disjunct distribution of D . antongilii and D . guineti , so far not sufficiently explained. [ABSTRACT FROM AUTHOR]

Blindsnakes are poorly studied reptiles from the karyological point of view since chromosomal data are only known for eight out of more than 420 species. The present paper shows the results of a karyological study conducted by means of standard and banding staining (Ag-NOR-banding and C-banding plus CMA and DAPI fluorochromes) on three typhlopid species, Madatyphlops arenarius, Xerotyphlops vermicularis and the parthenogenetic blindsnake, Indotyphlops braminus . Madatyphlops arenarius has conserved the primitive snake karyotype of 2n = 36 with 16 biarmed macro- and 20 microchromosomes and NORs on a microchromosome pair. The karyotype of X . vermicularis differed in showing a reduced number of microchromosomes (16) and NORs on the long arms of the third macrochromosome pair. The parthenogenetic I . braminus exhibited a triploid karyotype of 3n = 42 with seven macro- and seven microtriplets and NORs on a microtriplet. Comparison with chromosome data from the available literature suggests that the primitive snake karyotype of 2n = 36 occurred in the common ancestor of Leptotyphlopidae + Typhlopidae and in the common ancestor of Typhlopidae. In the latter family chromosome evolution may well have proceeded towards a decrease in the chromosome number from 2n = 36, 34, 32 until it reached 2n = 28, mainly involving micro- to microchromosome and/or macrochromosome translocations. Furthermore, these chromosome rearrangements occurred independently and repeatedly in the different evolutionary lineages of this family and are partially concordant with phylogenetic relationships. Cytologically identifiable sex chromosomes were not revealed by either standard or C-banding staining. [ABSTRACT FROM AUTHOR]

Karyological studies continue to clarify the evolutionary history of many taxa. We report here on the first chromosome survey of the frog Pseudhymenochirus merlini (Pipidae) in comparison with the related species Hymenochirus boettgeri . In addition to the 2 n = 20 regular (A) chromosomes (eight metacentric and two subtelocentric pairs), H. boettgeri has an accessory B chromosome in about half of the scored karyotypes (2 n = 21). P. merlini showed a karyotype of 2 n = 20 chromosomes, differing from the set of A chromosomes of H . boettgeri by three inversions. Other differences are in the location of the nucleolus organizer regions (NORs), on the 10th chromosome pair in P. merlini instead of the 4th pair in H. boettgeri . Heterochromatin is less abundant in P. merlini , and localized in centromeric and telomeric regions of all chromosomes. The patterns in H. boettgeri resemble those of another pipid species, Silurana tropicalis , as to chromosome number (2 n = 20), morphology, and G-banding patterns. We propose that these characteristics are symplesiomorphic in Pipidae, allowing us to present a scenario for the chromosome evolution in this family. Our results identify a third mechanism of increase in chromosome numbers among pipid frog species, the addition of B chromosomes in Hymenochirus , besides the known processes of polyploidization in Xenopus / Silurana , and centric fission in Pipa . [ABSTRACT FROM AUTHOR]

Strobilurins represent the most widely used class of fungicides nowadays andare considered relatively non-toxic to mammals and birds but highly toxic to aquatic biota. Dimoxystrobin is one of the novel strobilurins, recently included in the 3rd Watch List of the European Commission as available data indicate that it could pose a significant risk to aquatic species. As yet, the number of studies explicitly assessing the impact of this fungicide on terrestrial and aquatic species is extremely low, and the toxic effects of dimoxystrobin on fish have not been reported. Here we investigate for the first time the alterations induced by two environmentally relevant and very low concentrations of dimoxystrobin (6.56 and 13.13 μg/L) in the fish gills. morphological, morphometric, ultrastructural, and functional alterations have been evaluated using zebrafish as a model species. We demonstrated that even short-term exposure (96 h) to dimoxystrobin alters fish gills reducing the surface available for gas exchange and inducing severe alterations encompassing three reaction patterns: circulatory disturbance and both regressive and progressive changes. Furthermore, we revealed that this fungicide impairs the expression of key enzymes involved in osmotic and acid-base regulation (Na+/K+-ATPase and AQP3) and the defensive response against oxidative stress (SOD and CAT). The information presented here highlights the importance of combining data from different analytical methods for evaluating the toxic potential of currently used and new agrochemical compounds. Our results will also contribute to the discussion on the suitability of mandatory ecotoxicological tests on vertebrates before the introduction on the market of new compounds. [Display omitted] • Low dimoxystrobin doses induce structural and ultrastructural alterations in zebrafish gills. • The frequency and severity of injuries increased with increasing dose. • Dimoxystrobin affect gills function through Na+/K+-ATPase and AQP3 downregulation. • Dimoxystrobin induces a defensive response against oxidative stress. [ABSTRACT FROM AUTHOR]

Heavy metal contamination is recognized worldwide as a serious threat to human health and wildlife, and reducing their emissions is a priority of international and EU actions. Due to its persistence, high bioaccumulation tendency, and toxicity properties, lead (Pb) is one of the heavy metals of greatest concern. Even at low concentrations, lead induces various clinical and subclinical conditions in both humans and animals, and it has been included in the priority list of hazardous substances. In the present study, we used zebrafish's early stages as a model, given their well-acknowledged predictive value in the risk assessment of chemicals. This study was designed to investigate the morphological and morphometric alterations induced by Pb during zebrafish's early development and disclose the putative effects stage- and/or dose-dependent. We examined injuries induced by two environmentally relevant and extremely low concentrations of Pb (2.5 μg/L and 5 μg/L) during two exposure windows: early (between 1 and 7 dpf) and late (between 2 and 8 dpf). We clearly demonstrated that the incidence and severity of morphological abnormalities increased with increasing Pb dose and exposure time in both early and late-exposed groups. Furthermore, we revealed that malformation severity was significantly higher in the early exposed group than in the late exposure group at all exposure times and for both tested doses, thus highlighting the high sensitivity of zebrafish during the initial stages of development. The information presented in this paper emphasizes the effectiveness of morphological biomarkers in unveiling threatening situations and supports the role of zebrafish embryos and larvae in risk assessment and environmental monitoring. [Display omitted] • Low Pb doses induce morphological alterations in developing zebrafish. • Abnormalities appear after short-term exposure in all experimental groups. • The frequency and severity of injuries increased with increasing dose and time. • The degree of injuries is higher in early-exposed animals. • Specific target organ alterations depend on dose/stage. [ABSTRACT FROM AUTHOR]

• We identified the 2nd chromosome pair in C. chamaeleon as the XX/XY sex chromosomes. • NOR loci were located on the 2nd chromosome pair and C-bands on centromeric regions. • Our results evidenced a propensity of chromosome pairs 2 and 3 for rearrangements. • Multiple ITSs in the karyotype of C. chamaeleon may suggest past chromosome fusions. • We identified several truncated TEs, highly interspersed in the species' genome. Chameleons display high karyological diversity in chromosome number (from 2n = 20 to 62), morphology, heterochromatin distribution and location of specific chromosomal markers, making them unique study models in evolutionary cytogenetics. However, most available cytogenetic data are limited to the description of the chromosome number and morphology. Concerning sex chromosomes, our knowledge is limited to ZZ/ZW and Z1Z1Z2Z2/Z1Z2W systems in the genus Furcifer and the isolation of sex-linked, male-specific, sequences in Chamaeleo calyptratus , but the putative XY chromosomes have still to be identified in Chamaeleo and the conservation of male heterogamety in the genus needs confirmation from other species. In this study we performed a molecular and a cytogenetic analysis on C. chamaeleon , using standard, banding methods and molecular cytogenetics to provide a throughout karyological characterization of the species and to identify and locate the putative XY chromosomes. We confirm that the chromosome formula of the species is 2n = 24, with 12 metacentric macrochromosomes, 12 microchromosomes and NORs on the second chromosome pair. Heterochromatin was detected as weak C-bands on centromeric regions, differently from what was previously reported for C. calyptratus. Fluorescence in situ hybridization (FISH) showed the occurrence of interspersed telomeric signals on most macrochromosomes, suggesting that ancient chromosome fusions may have led to a reduction of the chromosome number. Using a combination of molecular and FISH analyses, we proved that male specific Restriction site-Associated DNA sequences (RADseq) isolated in C. calyptratus are conserved in C. chamaeleon and located the putative XY chromosomes on the second chromosome pair. We also identified different transposable elements in the focal taxa, which are highly interspersed on most chromosome pairs. [ABSTRACT FROM AUTHOR]