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836 results for “Toads”
Dynamics behind disjunct distribution, hotspot-edge refugia, and discordant RADseq/mtDNA variability: insights from the Emei mustache toad
<p>Background: The distribution of genetic diversity and the underlying processes are important for conservation planning but are unknown for most species and have not been well studied in many regions. In East Asia, the Sichuan Basin and surrounding mountains constitute an understudied region that exhibits a "ring" of high species richness overlapping the eastern edge of the global biodiversity hotspot Mountains of Southwest China. We examine the distributional history and genetic diversification of the Emei mustache toad <em>Leptobrachium boringii</em> , a typical "ring" element characterized by disjunct ranges in the mountains, by integrating time-calibrated gene tree, genetic variability, individual-level clustering, inference of population splitting and mixing from allele frequencies, and paleoclimatic suitability modeling.</p> <p>Results: The results reveal extensive range dynamics, including secondary contact after long-term isolation via westward dispersal accompanied by variability loss. They allow the proposal of a model that combines recurrent contractions caused by Quaternary climatic changes and some failed expansions under suitable conditions for explaining the shared disjunct distribution pattern. Providing exceptional low-elevation habitats in the hotspot area, the eastern edge harbors both long-term refugial and young immigrant populations. This finding and a synthesis of evidence from other taxa demonstrate that a certain contributor to biodiversity, one that preserves and receives low-elevation elements of the east in this case, can be significant for only a particular part of a hotspot. By clarifying the low variability of these refugial populations, we show that discordant mitochondrial estimates of diversity can be obtained for populations that experienced admixture, which would have unlikely left proportional immigrant alleles for each locus.</p> <p>Conclusions: Dispersal after long-term isolation can explain much of the spatial distribution of genetic diversity in this species, while secondary contact and long-term persistence do not guarantee a large variation. The model for the formation of disjunct ranges may apply to many other taxa isolated in the mountains surrounding the Sichuan Basin. Furthermore, this study provides insights into the heterogeneous nature of hotspots and discordant variability obtained from genome-wide and mitochondrial data.</p>
Supplementary material 4 from: Smart AS, Tingley R, Phillips BL (2020) Estimating the benefit of quarantine: eradicating invasive cane toads from islands. NeoBiota 60: 117-136. https://doi.org/10.3897/neobiota.60.34941
Figure S3. Posterior distributions of the detection probabilities of cane toads on Horan and Indian Islands
Supplementary material 2 from: Smart AS, Tingley R, Phillips BL (2020) Estimating the benefit of quarantine: eradicating invasive cane toads from islands. NeoBiota 60: 117-136. https://doi.org/10.3897/neobiota.60.34941
Figure S1. Estimated density of cane toads on each island using density calculated per km of shoreline, and per km2 of landmass
Morphology and locomotor performance of cane toads, Rhinella marina
<p>As is common in biological invasions, the rate at which cane toads (<i>Rhinella marina</i>) have spread across tropical Australia has accelerated through time. Individuals at the invasion-front travel further than range-core conspecifics, and exhibit distinctive morphologies that may facilitate rapid dispersal. However, the links between these morphological changes and locomotor performance have not been clearly documented. We used raceway trials and high-speed videography to document locomotor traits (e.g. hop distances, heights, velocities, and angles of take-off and landing) of toads from range-core and invasion-front populations. Locomotor performance varied geographically, and this variation in performance was linked to morphological features that have evolved during the toads' Australian invasion. Geographic variation in morphology and locomotor ability was evident not only in wild-caught animals, but also in individuals that had been raised under standardized conditions in captivity. Our data thus support the hypothesis that the cane toad's invasion across Australia has generated rapid evolutionary shifts in dispersal-relevant performance traits, and that these differences in performance are linked to concurrent shifts in morphological traits.</p>
Eye size and investment in frogs and toads correlate with adult habitat, activity pattern and breeding ecology
<p></p><p>Frogs and toads (Amphibia: Anura) display diverse ecologies and behaviours, which are often correlated with visual capacity in other vertebrates. Additionally, anurans exhibit a broad range of relative eye sizes, which have not previously been linked to ecological factors in this group. We measured relative investment in eye size and corneal size for 220 species of anurans representing all 55 currently recognized families and tested whether they were correlated with six natural history traits hypothesized to be associated with the evolution of eye size. Anuran eye size was significantly correlated with habitat, with notable decreases in eye investment among fossorial, subfossorial and aquatic species. Relative eye size was also associated with mating habitat and activity pattern. Compared to other vertebrates, anurans have relatively large eyes for their body size, indicating that vision is probably of high importance. Our study reveals the role that ecology and behaviour may have played in the evolution of anuran visual systems and highlights the usefulness of museum specimens, and importance of broad taxonomic sampling, for interpreting macroecological patterns.</p><p></p>
FIGURE 4 in Advertisement call of two threatened red-bellied-toads Melanophryniscus cambaraensis and M. macrogranulosus (Anura: Bufonidae), from the Atlantic Rainforest, southern Brazil
FIGURE 4. Comparison between populations of parameters selected by PCA (box plot: mean, SD and range).
FIGURE 1 in Advertisement call of two threatened red-bellied-toads Melanophryniscus cambaraensis and M. macrogranulosus (Anura: Bufonidae), from the Atlantic Rainforest, southern Brazil
FIGURE 1. Data collection of Melanophryniscus cambaraensis, in FLONA SFP (1) and M. macrogranulosus, in Garapiá (2) and Morro da Gruta (3) in Rio Grande do Sul, south Brazil.
FIGURE 3 in Advertisement call of two threatened red-bellied-toads Melanophryniscus cambaraensis and M. macrogranulosus (Anura: Bufonidae), from the Atlantic Rainforest, southern Brazil
FIGURE 3. Oscillogram and spectrogram of Melanophryniscus cambaraensis call from FLONA SFP (A - FZ 9093) and a close view of the call (B); and a close view of the call of M. macrogranulosus from Garapiá (C – FZ9102) and from Morro da Gruta (D – FZ 9113). In each figure we show call part A (single pulses) and B (pulsed trill) of the call.
Morphology of parotoid glands in cane toads
<p>If optimal investment in anti-predator defences depends on predation risk, invading new regions (and thus, encountering different predators) may favour shifts in that investment. Cane toads offer an ideal system to test this prediction: expensive anti-predator toxins are stored mainly in parotoid glands whose dimensions are easy to measure, and toad invasions have changed the suites of predators they encounter. Although plasticity may influence parotoid morphology, comparisons between parents and progeny revealed that gland dimensions were highly heritable. That heritability supports the plausibility of an evolved basis to variation in gland dimensions. Measurements of 3,779 adult toads show that females have larger glands than males, invasive populations have larger glands than in the native-range, and that parotoid sexual size dimorphism varies strongly among invaded areas. Geographic variation in parotoid morphology may be driven by predation risk to both adult toads and offspring (provisioned with toxins by their mother), with toxins allocated to eggs exacerbating the risk of cannibalism but reducing the risk of interspecific predation. Investment into chemical defences has evolved rapidly during the cane toad's international diaspora, consistent with the hypothesis that organisms flexibly adjust resource allocation to anti-predator tactics in response to novel challenges.</p>
Data from: Phenotypic divergence of the common toad (Bufo bufo) along an altitudinal gradient: evidence for local adaptation
Variation in the environment can induce different patterns of genetic and phenotypic differentiation among populations. Both neutral processes and selection can influence phenotypic differentiation. Altitudinal phenotypic variation is of particular interest in disentangling the interplay between neutral processes and selection in the dynamics of local adaptation processes but remains little explored. We conducted a common garden experiment to study the phenotypic divergence in larval life-history traits among nine populations of the common toad (Bufo bufo) along an altitudinal gradient in France. We further used correlation among population pairwise estimates of quantitative trait (QST) and neutral genetic divergence (FST from neutral microsatellite markers), as well as altitudinal difference, to estimate the relative role of divergent selection and neutral genetic processes in phenotypic divergence. We provided evidence for a neutral genetic differentiation resulting from both isolation by distance and difference in altitude. We found evidence for phenotypic divergence along the altitudinal gradient (faster development, lower growth rate and smaller metamorphic size). The correlation between pairwise QSTs–FSTs and altitude differences suggested that this phenotypic differentiation was most likely driven by altitude-mediated selection rather than by neutral genetic processes. Moreover, we found different divergence patterns for larval traits, suggesting that different selective agents may act on these traits and/or selection on one trait may constrain the evolution on another through genetic correlation. Our study highlighted the need to design more integrative studies on the common toad to unravel the underlying processes of phenotypic divergence and its selective agents in the context of environmental clines.
Data from: Temporal population genetic instability in range edge Western Toads, Anaxyrus boreas
In this article, we address the temporal stability of population genetic structure in a range-edge population that is undergoing continual, short-distance colonization events. We sampled western toad, Anaxyrus boreas, breeding populations over 2 seasons near their northern range limit in southeast Alaska. We sampled 20 ponds each during the summers of 2008 and 2009, with 14 ponds sampled in both summers. We found considerable turnover in the population genetic relationships among ponds in those 2 seasons, as well as biologically meaningful genetic differentiation between years within some ponds. We found relatively consistent relationships between major population centers, whereas the relationships between the central ponds and smaller, outlying populations differed year to year. This finding indicates that multiple years of genetic sampling may be important for understanding the genetic landscape of some populations.
Data from: Population admixture and high larval viability among urban toads
<p>In terms of evolutionary biology, a population admixture of more than two distinct lineages may lead to strengthened genetic variation through hybridization. However, a population admixture arising from artificial secondary contact poses significant problems in conservation biology. In urban Tokyo, a population admixture has emerged from two lineages of Japanese common toad: native Bufo japonicus formosus and nonnative B. japonicus japonicus, of which the latter was introduced in the early 20th century. To evaluate the degree of genetic disturbance in the admixed population of these two subspecies, we analyzed genotypes of toads distributed within and outside Tokyo by assessing mtDNA and seven microsatellite loci. We found that the introduced B. japonicus japonicus genotype dominates six local populations in the Tokyo admixture zone and was clearly derived from past introgressive hybridization between the two subspecies. These observations were supported by morphological assessments. Furthermore, the average larval survival rate in Tokyo was significantly higher than that outside Tokyo, suggesting that the temporary contribution of introduced toads occurred through introgression. The fitness of toads in urban Tokyo may thus be increasing with the assistance of nonnative individuals.</p>
Data from: Origin and genome evolution of polyploid green toads in Central Asia: evidence from microsatellite markers
Polyploidization, which is expected to trigger major genomic reorganizations, occurs much less commonly in animals than in plants, possibly because of constraints imposed by sex-determination systems. We investigated the origins and consequences of allopolyploidization in Palearctic green toads (Bufo viridis subgroup) from Central Asia, with three ploidy levels and different modes of genome transmission (sexual versus clonal), to (i) establish a topology for the reticulate phylogeny in a species-rich radiation involving several closely related lineages and (ii) explore processes of genomic reorganization that may follow polyploidization. Sibship analyses based on 30 cross-amplifying microsatellite markers substantiated the maternal origins and revealed the paternal origins and relationships of subgenomes in allopolyploids. Analyses of the synteny of linkage groups identified three markers affected by translocation events, which occurred only within the paternally inherited subgenomes of allopolyploid toads and exclusively affected the linkage group that determines sex in several diploid species of the green toad radiation. Recombination rates did not differ between diploid and polyploid toad species, and were overall much reduced in males, independent of linkage group and ploidy levels. Clonally transmitted subgenomes in allotriploid toads provided support for strong genetic drift, presumably resulting from recombination arrest. The Palearctic green toad radiation seems to offer unique opportunities to investigate the consequences of polyploidization and clonal transmission on the dynamics of genomes in vertebrates.
Data from: The advertisement call of the toad Rhinella humboldti (Bufonidae)
Despite important advances in understanding phylogenetic relationships among anurans (Frost et al. 2006; Pyron & Wiens, 2011), many uncertainties persist regarding phylogenetic affinities and taxonomic limits. The male advertisement call offers numerous opportunities to find diagnostic characters and is therefore useful for anuran species delimitation (Gerhardt & Huber, 2002; Grant et al. 2006). Thirteen species are recognized within the Rhinella granulosa group (Narvaes & Rodrigues, 2009; Sanabria et al. 2010) although it is possible that R. dorbignyi and R. fernandezae being conspecifics (Guerra et al. 2011, page 36). The advertisement call has been described for nine species of the granulosa group: Rhinella granulosa, R. bergi, R. major, R. azarai, R. fernandezae, R. dorbignyi, R. merianae, R. centralis and R. pygmaea (Köhler et al. 1997; Guerra et al. 2011; São-Pedro et al. 2011; Ribeiro de Carvalho et al. 2013). Some information regarding call features are available for R. humboldti from populations of Guyana (Lescure & Marty, 2000); however, there are no associated data of male body size, sample size, and call traits such as pulse number per notes, note duration, etc. Here we provide a formal description of the advertisement call of R. humboldti using call recordings obtained in a population in Colombia, South America.
Data from: Genomewide scan for adaptive differentiation along altitudinal gradient in the Andrew's toad Bufo andrewsi
Recent studies of humans, dogs and rodents have started to discover the genetic underpinnings of high altitude adaptations, yet amphibians have received little attention in this respect. To identify possible signatures of adaptation to altitude, we performed a genome scan of 15 557 single nucleotide polymorphisms (SNPs) obtained with restriction site-associated DNA sequencing of pooled samples from 11 populations of Andrew's toad (Bufo andrewsi) from the edge of the Tibetan Plateau, spanning an altitudinal gradient from 1690 to 2768 m.a.s.l. We discovered significant geographic differentiation among all sites, with an average FST = 0.023 across all SNPs. Apart from clear patterns of isolation by distance, we discovered numerous outlier SNPs showing strong associations with variation in altitude (1394 SNPs), average annual temperature (1859 SNPs) or both (1051 SNPs). Levels and patterns of genetic differentiation in these SNPs were consistent with the hypothesis that they have been subject to directional selection and reflect adaptation to altitudinal variation among the study sites. Genes with footprints of selection were significantly enriched in binding and metabolic processes. Several genes potentially related to high altitude adaptation were identified, although the identity and functional significance of most genomic targets of selection remain unknown. In general, the results provide genomic support for results of earlier common garden and low coverage genetic studies that have uncovered substantial adaptive differentiation along altitudinal and latitudinal gradients in amphibians.
Data from: Behavioural tactics used by invasive cane toads (Rhinella marina) to exploit apiaries in Australia
Behavioural flexibility plays a key role in facilitating the ability of invasive species to exploit anthropogenically-created resources. In Australia, invasive cane toads (Rhinella marina) often gather around commercial beehives (apiaries), whereas native frogs do not. To document how toads use this resource, we spool-tracked cane toads in areas containing beehives and in adjacent natural habitat without beehives, conducted standardized observations of toad feeding behaviour, and ran prey-manipulation trials to compare the responses of cane toads versus native frogs to honeybees as potential prey. Toads feeding around beehives travelled shorter distances per night, and hence used different microhabitats, than did toads from nearby control sites without beehives. The toads consumed live bees from the hive entrance (rather than dead bees from the ground), often climbing on top of one another to gain access to the hive entrance. Prey manipulation trials confirm that bee movement is the critical stimulus that elicits the toads' feeding response; and in standardized trials, native frogs consumed bees less frequently than did toads. In summary, cane toads flexibly modify their movements, foraging behaviour and dietary composition to exploit the nutritional opportunities created by commercial beehives, whereas native anurans do not.
Data from: Development of nuclear microsatellite loci and mitochondrial single nucleotide polymorphisms for the natterjack toad, Bufo (Epidalea) calamita (Bufonidae), using next generation sequencing and Competitive Allele Specific PCR (KASPar)
Amphibians are undergoing a major decline worldwide and the steady increase in the number of threatened species in this particular taxa highlights the need for conservation genetics studies using high-quality molecular markers. The natterjack toad, Bufo (Epidalea) calamita, is a vulnerable pioneering species confined to specialized habitats in Western Europe. To provide efficient and cost-effective genetic resources for conservation biologists, we developed and characterized 22 new nuclear microsatellite markers using next-generation sequencing. We also used sequence data acquired from Sanger sequencing to develop the first mitochondrial markers for KASPar assay genotyping. Genetic polymorphism was then analyzed for 95 toads sampled from 5 populations in France. For polymorphic microsatellite loci, number of alleles and expected heterozygosity ranged from 2 to 14 and from 0.035 to 0.720, respectively. No significant departures from panmixia were observed (mean multilocus F IS = −0.015) and population differentiation was substantial (mean multilocus F ST = 0.222, P < 0.001). From a set of 18 mitochondrial SNPs located in the 16S and D-loop region, we further developed a fast and cost-effective SNP genotyping method based on competitive allele-specific PCR amplification (KASPar). The combination of allelic states for these mitochondrial DNA SNP markers yielded 10 different haplotypes, ranging from 2 to 5 within populations. Populations were highly differentiated (G ST = 0.407, P < 0.001). These new genetic resources will facilitate future parentage, population genetics and phylogeographical studies and will be useful for both evolutionary and conservation concerns, especially for the set-up of management strategies and the definition of distinct evolutionary significant units.
Data from: Evidence toads may modulate landing preparation without predicting impact time
Within anurans (frogs and toads), cane toads (Bufo marinus) perform particularly controlled landings in which the forelimbs are exclusively used to decelerate and stabilize the body after impact. Here we explore how toads achieve dynamic stability across a wide range of landing conditions. Specifically, we suggest that torques during landing could be reduced by aligning forelimbs with the body's instantaneous velocity vector at impact (impact angle). To test whether toad forelimb orientation varies with landing conditions, we used high-speed video to collect forelimb and body kinematic data from six animals hopping off platforms of different heights (0, 5 and 9 cm). We found that toads do align forelimbs with the impact angle. Further, toads align forelimbs with the instantaneous velocity vector well before landing and then track its changes until touchdown. This suggests that toads may be prepared to land well before they hit the ground rather than preparing for impact at a specific moment, and that they may use a motor control strategy that allows them to perform controlled landings without the need to predict impact time.
Data from: Conquering the world in leaps and bounds: hopping locomotion in toads is actually bounding
1.While most frogs maximize jump distance as an escape behavior, toads have traded jump distance for endurance with a strategy of hopping repeatedly. This strategy has enabled toads to expand across the continents as one of the most diverse groups of anurans. Multiple studies have revealed physiological endurance adaptations for sustained hopping in toads, however, the kinematics of their sequential hopping behavior, per se, has not been studied. 2.We compared kinematics and forces of single hops and multiple hopping sequences and quantified field performance of hopping behaviors in free ranging toads of three species and discovered a novel aspect of locomotion adaptation that adds another facet to their exceptional terrestrial locomotor abilities. 3.We found that bouts of repeated hopping are actually a series of bounding strides where toads rotate on their hands and then land on their extended their feet and jump again without stopping. In addition, free-ranging toads appear to use bounding locomotion more frequently than single hops. Bounding in toads has the advantage of maintaining velocity and producing longer jump distances. In comparison to single hops, cyclic bounding steps reduce energy expenditure and appear to provide limb loading dynamics better suited for potential cycling of elastic energy from stride to stride than would be possible with repeated single hops. 4.This is the first case of the common use of a bounding gait outside of mammals. Bounding adds a key terrestrial locomotor trait to the toad's phenotype that may help explain their history of global expansion and the challenges to modern faunas as introduced toads rapidly invade new ecosystems today.
Data from: Para-allopatry in hybridizing fire-bellied toads (Bombina bombina and B. variegata): inference from transcriptome-wide coalescence analyses
Ancient origins, profound ecological divergence, and extensive hybridization make the fire-bellied toads Bombina bombina and B. variegata (Anura: Bombinatoridae) an intriguing test case of ecological speciation. Previous modeling has proposed that the narrow Bombina hybrid zones represent strong barriers to neutral introgression. We test this prediction by inferring the rate of gene exchange between pure populations on either side of the intensively studied Kraków transect. We developed a method to extract high confidence sets of orthologous genes from de novo transcriptome assemblies, fitted a range of divergence models to these data and assessed their relative support with analytic likelihood calculations. There was clear evidence for postdivergence gene flow, but, as expected, no perceptible signal of recent introgression via the nearby hybrid zone. The analysis of two additional Bombina taxa (B. v. scabra and B. orientalis) validated our parameter estimates against a larger set of prior expectations. Despite substantial cumulative introgression over millions of years, adaptive divergence of the hybridizing taxa is essentially unaffected by their lack of reproductive isolation. Extended distribution ranges also buffer them against small-scale environmental perturbations that have been shown to reverse the speciation process in other, more recent ecotypes.
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Allen Brain Atlas
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