Changes in Heat Resistance of the Muscle and Glycerinated Muscle Fibers of Green Toad (<Emphasis Type="Italic">Bufo viridis complex</Emphasis>)

Heat resistance of muscles and actomyosin proteins was determined at damaging temperatures of 41, 42, and 43°C in three green toad (Bufo viridis complex) populations from different climatic zones of Uzbekistan. The highest muscle and model resistance to these temperatures was revealed in toads living in the warmest plain regions of the country, while the lowest resistance was specific for animals from the piedmont and mountain regions. The variability of heat resistance of the muscle and models was also the highest in toads of the first group. Divergence going in this animal species is proposed.__________Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 3, 2005, pp. 380–384.Original Russian Text Copyright © 2005 by Pashkova, Korotneva, Pasynkova.     

A Light and Electron Microscopic Study of Trypanosoma fallisi N. Sp. in Toads (Bufo americanus) from Algonquin Park, Ontario

Trypanosoma fallisi n. sp. is described from Bufo americanus in Ontario. The parasite was observed in 65 of 94 toads examined. The trypanosomes were pleomorphic with respect to the age of infections, being longer and broader in early infections (during spring and summer) and shorter and more slender during late summer and autumn. They ranged in size from 38–76 μm in body length and 3–8 μm in width, with a free flagellum 6–30 μm long. Epizootiological and experimental evidence suggests that this trypanosome is transmitted to the toads by the leech, Batracobdella picta. Trypanosoma fallisi is morphologically similar to T. bufophlebotomi described in Bufo boreas from California, but geographic isolation, host and vector differences as well as slight morphological differences indicate that speciation has occurred. Similar trypanosomes from Bufo americanus (which were identified as T. bufophlebotomi) in Michigan, are probably T. fallisi. This species shares many ultrastructual features with trypanosomes of other lower vertebrates and also of mammals.     

Polyploidy and deviations in the gonadal morphology of tetraploid toads, Bufo danatensis (Amphibia: Anura: Bufonidae)]

Morphological features of gonads of diploid Bufo viridis and tetraploid B. danatensis from 15 localities of USSR (453 spec.) were investigated. Females with the rudimentary ovaries were found among polyploid toads from south Turkmenia. The toads from Tajikistan having the external features of males usually demonstrated a specific kind of lateral gynandromorphism: a single side testes and rudimentary ovaries (with the normal ovarioles). The observed facts are treated either as a result of hybridization of recent species or as a result of originality of genomes organization.     

RNA and protein content in cells of diploid and tetraploid toads of the Bufo viridis group

Nucleic acids and total protein contents in hepatocytes and erythrocytes of diploid (Bufo viridis, 2n = 22) and tetraploid (B. danatensis, 2n = 44) green toads were measured cytophotometrically. The RNA (table 1) and protein (table 2) contents in the tetraploid cells are twice as much as that in diploid ones. According to these results tetraploidy in green toads may have a recent origin. The relation between structural and functional polyploidization in tetraploid amphibian species is discussed.     

Variability of microsatellites BM224 and Bcal7 in populations of green toads (Bufo viridis complex) differing by nuclear DNA content and ploidy

The variability of microsatellites BM224 and Bcal7 was studied for the first time in three species of the diploid-polyploid complex of Bufo viridis (B. viridis, B. oblongus, and B. pewzowi). The locus Bcal7 was established to be monomorphic in all samples studied. In microsatellite BM224, three allele variants were found. Among tetraploid toads, the western Asiatic species B. oblongus was characterized by one allele only, the eastern B. pewzowi, by the two other alleles. A similar distribution was also revealed in triploid individuals on the borders of range between tetraploid and diploid species. Among the diploid species B. viridis samples, all three allele variants of microsatellite BM224 were observed. Their distribution in the area proved to be geographically determined. In diploid toads, a similarity was revealed between the distribution of microsatellite BM224 alleles and variability of the nuclear DNA content.     

Abundance,richness and composition of lianas in forest communities along an elevation gradient in New Caledonia

Background: Lianas are an abundantand dynamic component of tropical forests, and their abundance ispredicted to increase with global change. A better understandingof factors that explain their distribution is required, especially onoceanic islands for which few data are available.

Aims: Identifythe environmental factors that shape liana communities in NewCaledonian forests

Methods: We studied liana abundance,basal area, richness and climbing modes in 27 forest plots (20m × 20 m) along an elevation gradient (sea level to ca. 1000 ma.s.l.) that covers different forest types and precipitation regimes.

Results: We inventoried 992 lianas belonging to 71 species. The abundance and basal area decreased logarithmically withincreasing elevation while species richness tended to peak at midelevations.Twining lianas were the most abundant and species-richfunctional group. We found no clear relationship between climbingmodes and forest structure.

Conclusions: Our results show thatliana abundance decreases with increasing elevation in responseto lower precipitation in seasonal dry forest. At high elevation (600–1000 m a.s.l.), climbing secondary hemi-epiphytes replace lianasprobably as a result of climate-based niche differentiation. Variationof species richness along the gradient could not be explained byprecipitation or by forest structural parameters.     

Genome size rather than content might affect call properties in toads of three ploidy levels (Anura: Bufonidae: Bufo viridis subgroup)

In vertebrates, genome size has been shown to correlate with nuclear and cell sizes, and influences phenotypic features, such as brain complexity. In three different anuran families, advertisement calls of polyploids exhibit longer notes and intervals than diploids, and difference in cellular dimensions have been hypothesized to cause these modifications. We investigated this phenomenon in green toads (Bufo viridis subgroup) of three ploidy levels, in a different call type (release calls) that may evolve independently from advertisement calls, examining 1205 calls, from ten species, subspecies, and hybrid forms. Significant differences between pulse rates of six diploid and four polyploid (3n, 4n) green toad forms across a range of temperatures from 7 to 27 °C were found. Laboratory data supported differences in pulse rates of triploids vs. tetraploids, but failed to reach significance when including field recordings. This study supports the idea that genome size, irrespective of call type, phylogenetic context, and geographical background, might affect call properties in anurans and suggests a common principle governing this relationship. The nuclear‐cell size ratio, affected by genome size, seems the most plausible explanation. However, we cannot rule out hypotheses under which call‐influencing genes from an unexamined diploid ancestral species might also affect call properties in the hybrid‐origin polyploids. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 584–590.     

Molecules and models indicate diverging evolutionary effects from parallel altitudinal range shifts in two mountain Ringlet butterflies

Quaternary climatic oscillations caused severe range expansions and retractions of European biota. During the cold phases, most species shifted to lower latitudes and altitudes, and expanded their distribution range northwards and to higher elevations during the warmer interglacial phases. These range shifts produced contrasting distribution dynamics, forming geographically restricted distribution patterns but also panmictic distributions, strongly dependent on the ecologic demands of the species. The two closely related butterfly species Erebia ottomana Herrich‐Schäffer, 1847 and Erebia cassioides (Reiner & Hohenwarth, 1792) show subalpine and alpine distribution settings, respectively. Erebia ottomana is found up to the treeline (1400–2400 m a.s.l.), whereas E. cassioides reaches much higher elevations (from about 1800 m a.s.l. in the Retezat Mountains, in Romania, to 2800 m a.s.l.). Thus, both species cover diverging climatic niches, and thus might also have been distributed differently during the cold glacial stages. Individuals of these two species were sampled over the mountain areas of the Balkan Peninsula and genetically analysed using allozyme electrophoresis. Additionally, we performed species distribution models (SDMs) to simulate the distribution patterns of both species in the past (i.e. during the Last Glacial Maximum and the Atlanticum). Our genetic data show contrasting structures, with comparatively low genetic differentiation but high genetic diversity found in E. ottomana, and with stronger genetic differentiation and a lower level of genetic diversity, including many endemic alleles, occurring restricted to single mountain massifs in E. cassioides. The SDMs support a downhill shift during glacial periods, especially for E. ottomana, with possible interconnection among mountain regions. We conclude that during the cold glacial phases, both species are assumed to shift downhill, but persisted at different elevations, with E. ottomana reaching the foothills and spreading over major parts of the Balkan Peninsula. In contrast, E. cassioides (the truly alpine species) survived in the foothills, but did not reach and spread over lowland areas. This more widespread distribution at the Balkan Peninsula of E. ottomana compared with E. cassioides is strongly supported by our distribution models. As a consequence, long‐term geographic restriction to distinct mountain massifs in E. cassioides versus panmixia in E. ottomana produced two contrasting evolutionary scenarios. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 112 , 569–583.     

Endemic gypsophytes composition delimitated by soil properties and altitude: From calciphytes to halophytes in the south–central Alborz Ranges

Specialized plant species have long served as geobotanical tools for locating mines and ores. Despite their importance, not much research has been dedicated to studying the ecology of endemic specialized plant species, such as those of gypsum or calcareous habitats. Here we describe and analyze the occurence of endemic plant species in gypsum habitats of the south–central Alborz Ranges (Semnan), Iran, in relation to altitude and soil properties. Ecological data and soil samples were collected from 120 plots along along an altitudinal gradient correlated with differences in soil properties. Forty seven plant species, including 6 species endemic to the Semnan area and 20 species endemic to Iran, were identified. The occurrence of the species were analyzed using canonical correspondence (CCA) and detrended correspondence Analysis (DCA), and based on the results the species were categorized as gypsophytes G₁ (1600–2245 m a.s.l.), calciphytes (1500–1700 m a.s.l.), gypsophytes G₂ (1300–1600 m a.s.l.) and halophytes (1100–1300 m a.s.l.). Gypsum content, elevation and salinity (Na content) were identified as the environmental factors having the largest effects on vegetation compositon. Endemic Semnan plant species included Astragalus fridae, Euphorbia gypsicola and Gypsophila mucronifolia at higher altitudes, and Astragalus semnanensis, Centaurea lachnopus and Nepeta eremokosmos at lower altitude gypsic soils. More frequent Iranian endemic plant species included Moltkia gypsaceae at higher altitudes, Echinops nizvanus and Acantholimon cymosum at lower altitude gypsic soils, Astragalus glaucacanthos, A. podolobus and A. microcephalus occurring mainly in calcic carbonate soil, and halophyte species such as Artemisia sieberi dominating at lower altitudes with more saline–alkaline soil.     

First report of a green toad (Bufo viridis sensu lato) in the Early Pleistocene of Spain: Palaeobiogeographical and palaeoecological implications

For the first time unequivocal fossil remains of a green toad (Bufo viridis s.l.) are described in the Iberian Peninsula. The fossils come from the Cueva Victoria site, a late Early Pleistocene (ca. 1.1–1.2 Ma) karstic filling in semi-arid southeastern Spain (Murcia region). By extension, other remains from two other Early Pleistocene Spanish localities, Barranco León D (ca. 1.3 Ma) and Almenara-Casablanca 3 (ca. 1.1 Ma), are cautiously attributed to the group B. viridis. The B. viridis group was previously reported with some uncertainty to the west of its current distribution area in Western Europe (Spain and France) in the Pliocene (Bufo cf. viridis) and less probably in the Early Miocene (Bufo aff. viridis). Since no osteological differences have been established between the recently described extant species of B. viridis s.l. (e.g. Bufo balearicus, Bufo siculus, Bufo boulengeri, B. viridis sensu stricto and Bufo variabilis) no precise palaeobiogeographical relationships can be drawn for the Spanish fossils. However, the occurrence of a third species of bufonid toad during the Pleistocene in the South of the Iberian Peninsula raises some interesting ecological questions in relation to the local disappearance of the green toad, which can be hypothetically linked to the intensification of the Pleistocene glacial/interglacial climate dynamic or to probable competition with another toad, Bufo calamita.     

Effects of the ecological conditions on morphological variations of the green toad, Bufo viridis, in Turkey

Ten populations of the green toad, Bufo viridis, from three areas having different climatic regimes were compared. Multivariate analyses of morphological characteristics revealed three distinct populations of green toads: the first group inhabiting the lowland and humid localities was characterized by a small body size, the second group occurred at higher altitudes and in desert areas had a significantly larger body size, while the third group from the Mediterranean localities was characterized by a large tympanum, a longer tarsus and short first toes. Interestingly, the specimens from Giresun Island were clustered with the second group with a similar pattern of body size. Differences in the morphological characteristics among populations were positively associated with ecological conditions, and not with geographic distance. Some characteristics previously used for taxonomic purposes in B. viridis were shown to be associated with local climatic conditions.     

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.     

Biological traits are correlated with elevational distribution range of eastern Tibetan herbaceous species

Plants that share the same habitat often exhibit similar biological traits. As climatic conditions change with increasing elevation, biological traits are expected to vary among plant species with temperate endemic, alpine endemic, or widespread elevational distributions. On a northeast Tibetan flora including temperate (1,850–2,800 m a.s.l.), subalpine (2,800–3,400 m a.s.l.), and alpine (3,400–4,150 m a.s.l.) vegetations, we analyzed patterns of change for ten traits of 326 annual and perennial herbaceous species using both univariate and multivariate analyses. The traits selected for this study fit in different groups, i.e., traits related to light competition, photosynthesis, reproduction, defense, and dispersal. We found that plant shape (plant height and leaf distribution along stem) and leaf traits (specific leaf area and leaf area) were significant predictors of plants’ elevational distributions, suggesting an important role for a trade-off between light competition and biomass costs in support structures, and between photosynthetic efficiency and leaf defense. Moreover, species with a broad distribution had significantly higher seed germination and shorter first germination time, as compared to species with narrow distributions, which indicates that rapid regeneration may be crucial for widespread species. However, dispersal-related traits may not be the main factor in shaping plants’ elevational distribution because no significant difference was detected in wind- and animal-dispersal ability. In addition, annual species potentially may have different strategies and adaptive mechanisms because we detected no differences in trait related to the elevational distributions.     

Altitudinal Distribution of Ammonia-Oxidizing Archaea and Bacteria in Alpine Grassland Soils Along the South-Facing Slope of Nyqentangula Mountains,Central Tibetan Plateau

Nitrogen is a major limiting nutrient for the net primary production of terrestrial ecosystems, especially on sentinel alpine ecosystem. Ammonia oxidation is the first and rate-limiting step on nitrification process and is thus crucial to nitrogen cycle. To decipher climatic influence on ammonia oxidizers, their communities were characterized by qPCR and clone sequencing by targeting amoA genes (encoding the alpha subunit of ammonia mono-oxygenase) in soils from 7 sites over an 800 m elevation transect (4400–5200 m a.s.l.), based on “space-to-time substitution” strategy, on a steppe-meadow ecosystem located on the central Tibetan Plateau (TP). Archaeal amoA abundance outnumbered bacterial amoA abundance at lower altitude (<4800 m a.s.l.), but bacterial amoA abundance was greater in surface soils at higher altitude (≥4800 m a.s.l.). Archaeal amoA abundance decreased with altitude in surface soil, while its abundance stayed relatively stable and was mostly greater than bacterial amoA abundance in subsurface soils. Conversely, bacterial amoA abundance gradually increased with altitude at all three soil depths. Statistical analysis indicated that altitude-dependent factors, in particular pH and precipitation, had a profound effect on the abundance and community of ammonia-oxidizing bacteria, but only on the community composition of ammonia-oxidizing archaea along the altitudinal gradient. These findings imply that the shifts in the relative abundance and/or community structure of ammonia-oxidizing bacteria and archaea may result from the precipitation variation along the altitudinal gradient. Thus, we speculate that altitude-related factors (mainly precipitation variation combing changed pH), would play a vital role in affecting nitrification process on this alpine grassland ecosystem located at semi-arid area on TP.     

Rapid expansion of the cane toad (Bufo marinus) invasion front in tropical Australia

Abstract Cane toads (Bufo marinus) are large toxic anurans that have spread through much of tropical Australia since their introduction in 1935. Our surveys of the location of the toad invasion front in 2001 to 2005, and radiotracking of toads at the front near Darwin in 2005, reveal much faster westwards expansion than was recorded in earlier stages of toad invasion through Queensland. Since reaching the wet‐dry tropics of the Northern Territory, the toads have progressed an average of approximately 55 km year⁻¹ (mean rate of advance 264 m night⁻¹ along a frequently monitored 55‐km road transect during the wet season of 2004–2005). Radiotracking suggests that this displacement is due to rapid locomotion by free‐ranging toads rather than human‐assisted dispersal; individual toads frequently moved >200 m in a single night. One radiotracked toad moved >21 800 m in a 30‐day period; the fastest rate of movement yet recorded for any anuran. Daily displacements of radiotracked toads varied with time and local weather conditions, and were highest early in the wet season on warm, wet and windy nights. The accelerated rate of expansion of the front may reflect either, or both: (i) evolved changes in toads or (ii) that toads have now entered an environment more favourable to spread. This accelerated rate of expansion means that toads will reach the Western Australian border and their maximal range in northern Australia sooner than previously predicted.     

Shoot growth and seasonal changes of nonstructural carbohydrate concentrations at the upper and lower distribution limits of three conifers

Nonstructural carbohydrate (NSC) concentration in plant organs is an indicator of a balance between carbon sources (i.e., photosynthesis) and sinks (i.e., growth). Understanding how NSC concentrations change with altitude would help determine altitudinal changes in plant growth. This study compared shoot growth and seasonal changes in NSC concentrations of current-year and 1-year-old needles and branch woods between the upper and lower distribution limits of subalpine conifers Abies veitchii (1600–2000 m a.s.l.), A. mariesii (2000–2400 m a.s.l.), and Pinus pumila (2400–2800 m a.s.l.) in Japan. The lengths of 1-year-old shoots were shorter at the upper distribution limits for the three species, and concentrations and branch woods were all high in spring but decreased toward summer, increasing from summer to autumn. No clear difference was found for either parameter between upper and lower distribution limits for each species. Therefore, this study suggests that growth reduction at the upper distribution limits is due to reduction of both sink and source activities, with similar degrees for each species. However, further studies of sink and source activities, such as temperature-dependent photosynthesis and growth traits, are necessary to reveal clearly the cause of this growth reduction in high altitudes.     

Chytridiomycosis Widespread in Anurans of Northeastern United States

ABSTRACT An emerging disease of amphibians caused by the chytrid fungus Batrachochytrium dendrobatidis has been associated with morbidity, mortality, and extinction of species. Typically, researchers have detected B. dendrobatidis only when examining amphibians for causes of mortalities; few data exist on infection rates where mortalities are lacking. During May-September 2000–2002 we obtained amphibian specimens killed by vehicles and others collected at remote off-road sites throughout Maine, USA, and from federal lands in 5 states in the Northeast. We detected infected specimens, mostly green frogs (Rana clamitans), at 5 of 7 national wildlife refuges, a federal waterfowl production area, and Acadia National Park. Seven of 9 species, including all Ranidae species, were infected throughout Maine; rates ranged from 14.6% in American toads (Bufo americanus) to 25.7% in northern leopard frogs (Rana pipiens). We did not detect any infections in 50 eastern gray tree frogs (Hyla versicolor) or 21 spring peepers (Pseudacris crucifer). Species that hibernate in terrestrial habitats seem to have lower rates of infection than species that hibernate in aquatic habitats. Infections peaked in spring and autumn and were associated with air temperatures optimal for B. dendrobatidis growth. The relatively high infection rates among species without documented die-offs suggest that either losses have occurred undetected, that the fungus is endemic and species have attained a level of resistance to infections becoming lethal, or that climatic conditions of the Northeast have a role in preventing infections from being lethal. Data on prevalence and distribution of this chytrid fungus in the Northeast may be useful in modeling its origins and predicting long-term ecosystem effects involving anurans.     

Variation of microsatellites BM224 and Bcal7 in populations of green toads (Bufo viridis complex) with various nuclear DNA content and ploidy

We studied variation of microsatellites BM224 and Bcal7 in three species of the Bufo viridis diploid-polyploid complex. We found that locus Bcal7 in all examined samples was monomorphic. Three alleles of microsatellite BM224 were found. Among tetraploid toads, the western species B. oblongus had only one allele variant, whereas the eastern species B. pewzowi had two other alleles. Similar distribution of alleles was observed in triploid specimens, collected in the area borders of tetraploid and diploid species. Among samples of diploid toad B. viridis, we found all three allele variants of microsatellite BM224. Their distribution was geographically determined. A comparison of allele distribution with genome size variation in diploid toads showed very similar patterns.     

A VERTEBRATE REPRODUCTIVE SYSTEM INVOLVING THREE PLOIDY LEVELS: HYBRID ORIGIN OF TRIPLOIDS IN A CONTACT ZONE OF DIPLOID AND TETRAPLOID PALEARCTIC GREEN TOADS (BUFO VIRIDIS SUBGROUP)*

The rise and consequences of polyploidy in vertebrates, whose origin was associated with genome duplications, may be best studied in natural diploid and polyploid populations. In a diploid/tetraploid (2n/4n) geographic contact zone of Palearctic green toads in northern Kyrgyzstan, we examine 4ns and triploids (3n) of unknown genetic composition and origins. Using mitochondrial and nuclear sequence, and nuclear microsatellite markers in 84 individuals, we show that 4n (Bufo pewzowi) are allopolyploids, with a geographically proximate 2n species (B. turanensis) being their maternal ancestor and their paternal ancestor as yet unidentified. Local 3n forms arise through hybridization. Adult 3n mature males (B. turanensis mtDNA) have 2n mothers and 4n fathers, but seem distinguishable by nuclear profiles from partly aneuploid 3n tadpoles (with B. pewzowi mtDNA). These observations suggest multiple pathways to the formation of triploids in the contact zone, involving both reciprocal origins. To explain the phenomena in the system, we favor a hypothesis where 3n males (with B. turanensis mtDNA) backcross with 4n and 2n females. Together with previous studies of a separately evolved, sexually reproducing 3n lineage, these observations reveal complex reproductive interactions among toads of different ploidy levels and multiple pathways to the evolution of polyploid lineages.