Clamitans Melanota Research Articles

Larval Growth to Metamorphosis in the Northern Green Frog (Lithobates clamitans melanota) in a South Central Pennsylvania Pond during 2009–2016

Abstract A measure of predictability exists in geographic variation in some of the life history traits of the green frog, Lithobates clamitans. A long breeding and larval transformation season and a small transformation body size of this species in the southern United States give way to opposite patterns farther north. Overwintering of tadpoles occurs northward in its range and eventually typifies many northern populations. Our examination of larval growth and transformation in the northern green frog, L. clamitans melanota, corroborated findings of intermediacy in duration of transformation season (May–August) and mean transformation body size (30 mm) of mid-Atlantic populations. The latter finding may be obscured by metamorphoslings (32 mm) during May–June, presumed to have overwintered and therefore larger than those that transformed in August (29 mm) of the same year they hatched. It remains unknown how often two cohorts emerge within or between years in Pennsylvania. The potential for a warming climate to predispose this species to more frequent within-year transformation of smaller individuals akin to present-day southerly populations should be investigated.

Sex-linked markers in the North American green frog (Rana clamitans) developed using DArTseq provide early insight into sex chromosome evolution.

BackgroundThe extent to which sex reversal is associated with transitions in sex determining systems (XX-XY, ZZ-ZW, etc.) or abnormal sexual differentiation is predominantly unexplored in amphibians. This is in large part because most amphibian taxa have homomorphic sex chromosomes, which has traditionally made it challenging to identify discordance between phenotypic and genetic sex in amphibians, despite all amphibians having a genetic component to sex determination. Recent advances in molecular techniques such as genome complexity reduction and high throughput sequencing present a valuable avenue for furthering our understanding of sex determination in amphibians and other taxa with homomorphic sex chromosomes like many fish and reptiles.ResultsWe use DArTseq as a novel approach to identify sex-linked markers in the North American green frog (Rana clamitans melanota) using lab-reared tadpoles as well as wild-caught adults from seven ponds either in undeveloped, forested habitats or suburban ponds known to be subject to contamination by anthropogenic chemicals. The DArTseq methodology identified 13 sex-linked SNP loci and eight presence-absence loci associated with males, indicating an XX-XY system. Both alleles from a single locus show partial high sequence homology to Dmrt1, a gene linked to sex determination and differentiation throughout Metazoa. Two other loci have sequence similarities to regions of the chimpanzee and human X-chromosome as well as the chicken Z-chromosome. Several loci also show geographic variation in sex-linkage, possibly indicating sex chromosome recombination. While all loci are statistically sex-linked, they show varying degrees of female heterozygosity and male homozygosity, providing further evidence that some markers are on regions of the sex chromosomes undergoing higher rates of recombination and therefore further apart from the putative sex determining locus.ConclusionThe ease of the DArTseq platform provides a useful avenue for future research on sex reversal and sex chromosome evolution in vertebrates, particularly for non-model species with homomorphic or cryptic or nascent sex chromosomes.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3209-x) contains supplementary material, which is available to authorized users.

Seasonal infection rates of Batrachochytrium dendrobatidis in populations of northern green frog Lithobates clamitans melanota tadpoles.

Few studies have documented seasonal variation of Batrachochytrium dendrobatidis (Bd) infection rates in larval amphibians. We identified 4 natural populations of northern green frogs Lithobates clamitans melanota in Pennsylvania (USA) that contained Bd-infected tadpoles during post-wintering collections in May and June, after hibernating tadpoles had overwintered in wetlands. However, we failed to detect infected tadpoles at those wetlands when pre-wintering collections were made in late July through early September. We observed 2 cohorts of tadpoles that appeared to lack Bd-infected individuals in pre-wintering collections, yet contained Bd-infected individuals the following spring. We also observed 4 cohorts of pre-wintering tadpoles that were Bd-free, even though post-wintering tadpoles collected earlier in the year were infected with Bd. Our results suggest that tadpoles either reduce Bd infections during the summer months, and/or infections proliferate sometime prior to (or shortly after) tadpoles emerge from hibernation. It is unlikely that pre-wintering tadpoles were too small to detect Bd zoospores because (1) there was no correlation between Bd zoospore levels and tadpole size or stage, and (2) size was not a significant predictor of infection status. These results suggest that, while sampling larvae can be an effective means of collecting large sample sizes, investigators in our Mid-Atlantic region should conduct sampling by early summer to maximize the chances of detecting Bd. Further research is warranted to determine whether wetland topography and warm, shallow microhabitats within wetlands contribute to a population's ability to drastically reduce Bd prevalence prior to overwintering at ponds.

Characterization of Gene Expression Endpoints During Postembryonic Development of the Northern Green Frog (Rana clamitans melanota)

Postembryonic development of a larval tadpole into a juvenile frog involves the coordinated action of thyroid hormone (TH) across a diversity of tissues. Changes in the frog transcriptome represent a highly sensitive endpoint in the detection of developmental progression, and for the identification of environmental chemical contaminants that possess endocrine disruptive properties. Unfortunately, in contrast with their vital role as sentinels of environmental change, few gene expression tools currently exist for the majority of native North American frog species. We have isolated seven expressed gene sequences from the Northern green frog (Rana clamitans melanota) that encode proteins associated with TH-mediated postembryonic development and global stress response, and established a quantitative real-time polymerase chain reaction (qPCR) assay. We also obtained three additional species-specific gene sequences that functioned in the normalization of the expression data. Alterations in mRNA abundance profiles were identified in up to eight tissues during R. clamitans postembryonic development, and following exogenous administration of TH to premetamorphic tadpoles. Our results characterize tissue distribution and sensitivity to TH of select mRNA of a common North American frog species and support the potential use of this qPCR assay in identification of the presence of chemical agents in aquatic environments that modulate TH action.

The effect of artificial light on male breeding-season behaviour in green frogs, Rana clamitans melanota

Artificial night lighting (or ecological light pollution) is only now gaining attention as a source of long-term effects on the ecology of both diurnal and nocturnal animals. The limited data available clearly indicate that artificial light can affect physiology and behaviour of animals, leading to ecological consequences at the population, community, and ecosystem levels. Aquatic ecosystems may be particularly vulnerable to such effects, and nocturnally breeding animals such as frogs may be especially affected. To address this potential, we quantify the effects of artificial light on calling and movement behaviour in a rural population of male green frogs ( Rana clamitans melanota (Rafinesque, 1820)) during the breeding season. When exposed to artificial light, frogs produced fewer advertisement calls and moved more frequently than under ambient light conditions. Results clearly demonstrate that male green frog behaviour is affected by the presence of artificial light in a manner that has the potential to reduce recruitment rates and thus affect population dynamics.

The Importance of Spatial Scale for Conservation and Assessment of Anuran Populations in Coastal Wetlands of the Western Great Lakes, USA

Distributions of pond-breeding amphibians may be influenced by habitat factors at different spatial scales. We used anuran calling surveys to investigate the association between 5 anuran species and habitat variables measured within 100, 500, 1000, and 3000 m of sampling points at 63 coastal wetlands along the US shores of Lake Michigan and Lake Huron. Stepwise logistic regression was used to create predictive models for each species at each spatial scale. Our results confirm the view that habitat variables at multiple scales influence frog distributions, but the strength of predictive models was significantly affected by the spatial scale at which habitat variables were derived. Remotely sensed habitat variables within a 3000 m radius were among the most effective predictors of occurrence for American toad (Bufo americanus), eastern gray treefrog (Hyla versicolor), spring peeper (Pseudacris crucifer), and green frog (Rana clamitans melanota). The western chorus frog (Pseudacris triseriata) was predicted most effectively by variables derived within a 500 m radius. For the most part, these anurans exhibited species-specific responses to habitat variables; however the suite of landscape-scale variables associated with urban land use appeared in all species’ regression models. Associations with landscape-scale variables coupled with well-documented habitat needs at local breeding sites suggest that conservation and assessment of frogs and toads in coastal wetlands should consider the influence of habitat variables at multiple spatial scales.

Field exposure of frog embryos and tadpoles along a pollution gradient in the Fox River and Green Bay ecosystem in Wisconsin, USA

We raised embryos and tadpoles of green frogs (Rana clamitans melanota) and leopard frogs (R. pipiens) in situ along a contamination gradient in the Fox River/Green Bay ecosystem (WI, USA). Differences in exposure were reflected by significant positive regressions between concentrations in sediment and in frogs of polychlorinated biphenyl (PCB) congeners and some heavy metals (Cd, Cr, and Pb), which could have predictive value for estimating exposure of amphibians to contaminants in this ecosystem and, perhaps, in others. On average, non-ortho-substituted coplanar PCBs made up a very small percentage (average, 0.2%) of the PCB congeners in all samples analyzed, with larger fractions accounted for by mono- and di-ortho congeners (average, 19%) and routine congeners (average, 81%). Hatchability of frog embryo batches and anuran species richness at the sites were negatively correlated with level of contamination, but tadpole growth and survival were not. Sediment and tissue levels of PCBs and metals generally were correlated with each other, confounding the association of effects on frogs with any particular contaminant. It is also plausible that high levels of un-ionized ammonia (NH3) reduced hatching success of green frog, but not leopard frog, embryos in the field enclosures. Other environmental factors that were present but unmeasured in the field, such as ultraviolet-B radiation as well as water flow and level fluctuations, might have caused differences in hatching success at the field sites.

Landscape resistance to frog movements

An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments.

Peatlands and green frogs: A relationship regulated by acidity?

:The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.

Drainage Ditches Facilitate Frog Movements in a Hostile Landscape

Ditches are common in landscapes influenced by agricultural, forestry, and peat mining activities, and their value as corridors remains unassessed. Pond-breeding amphibians can encounter hostile environments when moving between breeding, summering, or hibernation sites, and are likely to benefit from the presence of ditches in the landscape. Within a system consisting of ditch networks in bogs mined for peat in eastern New Brunswick, Canada, I quantified the breeding, survival, and movements of green frogs (Rana clamitans melanota) in drainage ditches and also surveyed peat fields. Frogs rarely ventured on peat fields and most individuals frequented drainage ditches containing water, particularly in late summer. Though frogs did not breed in ditches, their survival rate in ditches was high (88%). Ditches did not hinder frog movements, as frogs moved independently of the current. Results indicate that drainage ditches containing water enable some movements between habitats isolated by peat mining, in contrast to peat surfaces, and suggest they function as amphibian movement corridors. Thus, such drainage ditches may mitigate the effects of peat extraction on amphibian populations. At the very least, these structures provide an alternative to hostile peat surfaces. This study highlights that small-scale corridors are potentially valuable in population dynamics.

Cytochrome P450 Activity in Green Frogs (Rana clamitans melanota) Exposed to Water and Sediments in the Fox River and Green Bay, Wisconsin, USA

Cytochrome P450 Activity in Green Frogs (Rana clamitans melanota) Exposed to Water and Sediments in the Fox River and Green Bay, Wisconsin, USA

Impact of lakeshore development on green frog abundance

Many amphibian species exhibit metapopulation spatial dynamics and temporally are faced with local population extinction and re-colonization. These natural population fluctuations can exhibit stochastic effects when human-caused alteration and fragmentation of habitats occur during sensitive life-cycle events. In this study, we explored the effects of shoreline development on adult green frogs Rana clamitans melanota on lakes (n=24) of northern Wisconsin. We estimated green frog abundance using both auditory and direct observation surveys. The immediate shoreline habitat was mapped and placed into a Geographical Information System (GIS) for analysis. Adult green frog populations were significantly lower on lakes with varying degrees of shoreline house and cottage development than lakes with little or no development. A negative linear relationship existed between shoreline development densities and the number of adult green frogs. However, house and cottage densities alone did not directly explain this reduction. Analysis of variance (ANOVA) identified that the amount of suitable habitat, not development density, significantly affected green frog abundance. Therefore, greater development densities significantly decrease breeding habitat quality, resulting in lower adult frog abundance. These and other findings suggest that lakeshore development regulations are not protecting sensitive amphibian species.

Intraerythrocytic development of species of Hepatozoon infecting ranid frogs: evidence for convergence of life cycle characteristics among apicomplexans.

Intraerythrocytic development of the adeleorin apicomplexans Hepatozoon clamatae and Hepatozoon catesbianae were investigated in the bullfrog, Rana catesbeiana, the green frog, Rana clamitans melanota, and the Northern leopard frog, Rana pipiens. Merozoites emerging from hepatic meronts penetrated erythrocytes and underwent 1-3 rounds of binary fission to produce 2-8 merozoites. Following their release from infected erythrocytes, individual merozoites entered new cells and transformed into gamonts. Although this is the first report of intraerythrocytic development for a fully described species of Hepatozoon, a phylogenetic reanalysis of 11 species of Hepatozoon, 6 species representative of the 5 other hemogregarine taxa, 2 species of dactylosomatids, and 2 species of piroplasms, indicates that asexual reproduction of parasites within blood cells of vertebrates has arisen at least 3 times in the apicomplexan lineage that includes adeleorins and piroplasms. This method of asexual development, which is also observed in species of hemospororin genera such as Plasmodium, is discussed in the context of the evolution of apicomplexan life cycles. In addition to supporting the paraphyly of the genus Hepatozoon determined in an earlier study, this phylogenetic analysis featured a monophyletic group, consisting of the sister taxa Hemolivia and Karyolysus, that was the sister group to a clade consisting of the more derived hemogregarines, the dactylosomatids, and the piroplasms.

The Distribution of Anurans in Two River Systems of a Coastal Plain Watershed

The Distribution of Anurans in Two River Systems of a Coastal Plain Watershed

Acid Water Anuran Pond Communities along a Regional Forest to Agro-Urban Ecotone

iables in 14 acid water ponds located within drainage areas that displayed a range of agricultural and developed land use cover in the New Jersey Pinelands (Pine Barrens). Species were classified as those restricted to the Pinelands (Pine Barrens species: Hyla andersonii and Rana virgatipes), those with a wide-ranging distribution in southern New Jersey (wide-ranging species: Pseudacris crucifer crucifer, Bufofowleri, Rana sphenocephala utricularius, and Rana clamitans melanota), and those normally unable to enter the Pinelands except in habitats disturbed by human activities (border-entrant species: Hyla versicolor, Pseudacris kalmi, Acris crepitans crepitans, and Rana sylvatica). The frequency of occurrence of Pine Barrens and wide-ranging species was greater than that of any border-entrant species. Detrended correspondence analysis revealed an adult community gradient associated with geographic position where border-entrant species were heard only at ponds located along the transition between forested and disturbed landscapes. Principal component analysis revealed a primary environmental gradient of increasing pH and emergent herbaceous vegetation cover and decreasing specific conductance and floating vegetation cover and contrasted natural and artificial (borrow pits) pond types. Floating vegetation cover and specific conductance were lower and pH was higher in artificial versus natural ponds. Larval recruitment occurred for all species except the four border entrants and B. fowleri. Larval species richness was directly related to emergent herbaceous vegetation cover and inversely related to specific conductance. Our results suggest that landscape patterns influence the distribution of adult anurans, whereas pond chemistry may limit recruitment.

Phylogenetic relationships among Hepatozoon species from snakes, frogs and mosquitoes of Ontario, Canada, determined by ITS-1 nucleotide sequences and life-cycle, morphological and developmental characteristics

The molecular biological characteristics of Hepatozoon species infecting various species of snakes, frogs and mosquitoes were investigated by determining the nucleotide sequences of the first internal transcribed spacer region. A phylogenetic analysis was performed on seven isolates of Hepatozoon infecting snakes, including Hepatozoon sipedon and four morphologically similar but not identical forms, and two isolates of Hepatozoon catesbianae infecting Green frogs ( Rana clamitans melanota). This analysis, which utilised data from first internal transcribed spacer nucleotide sequences, morphological and morphometric features of gamonts, oocysts and sporocysts, and previously determined life-cycle and host-specificity characteristics, revealed that H. sipedon is a polymorphic species with a wide host and geographic range. Four synapomorphies, including two nucleotide substitutions and two morphological character state changes, supported a monophyletic group of six isolates of H. sipedon from the central region of Ontario which was the sister group for an isolate (HW1) from the southern part of the province. Based on the results of this study, an evaluation of which criteria are useful for describing species of Hepatozoon is presented, with the intent of curtailing the practice of naming species based on morphological features of gamonts or on incomplete life-cycle data.

Anuran Development, Density and Diversity in Relation to Agricultural Activity in the Holland River Watershed, Ontario, Canada (1990–1992)

Significantly lower anuran species diversity and density was recorded in a vegetable growing area relative to upstream and downstream sites in the Holland River watershed, Ontario, Canada. Egg hatching success and tadpole deformity rates of American toads (Bufo americanus americanus), green frogs (Rana clamitans melanota) and northern leopard frogs (Rana pipiens) eggs in water from field sites and control water were assessed. Compared to the control and the upstream site, the total abnormality rate (unhatched eggs plus deformed tadpoles) was higher for American toads in water from the agricultural and downstream sites. Total abnormality was higher in green frog eggs in water from the agricultural site and a downstream site. Trace concentrations of organophosphorus pesticides were detected most often in agricultural zone water and sediments than in upstream and downstream sites. Organochlorine pesticide residues, especially in agricultural zone samples, exceeded the no effect level guidelines for the protection of aquatic life. Ammonia, phosphorus, particulates, BOD and TKN were highest in the agricultural zone. Significant correlations between these parameters and anuran development suggest nutrient run-off as a causal or contributing factor in lower anuran diversity, density and reproductive success of American toads and green frogs in the site dominated by agriculture.

The Life History and Host Specificity of Hepatozoon clamatae (Apicomplexa: Adeleorina) and ITS-1 Nucleotide Sequence Variation of Hepatozoon Species of Frogs and Mosquitoes from Ontario

The life cycle of an intraerythrocytic hemogregarine, Hepatozoon clamatae, was studied in green frogs (Rana clamitans melanota), bullfrogs (Rana catesbeiana), northern leopard frogs (Rana pipiens), and in the mosquito, Culex territans. Gametogenesis, fertilization, and sporogony occurred within cells of the Malpighian tubules of laboratory-reared Cx. territans that had fed on naturally infected frogs. Mature oocysts containing hundreds of sporocysts were observed in mosquitoes 30 days postfeeding. Each sporocyst enclosed 4 sporozoites. Merozoites appeared in the peripheral circulation of laboratory-reared bullfrogs, green frogs and leopard frogs that had been fed sporocysts 35-70 days previously. Attempts to infect American toads (Bufo americanus) and blue-spotted salamanders (Ambystoma laterale) were not successful. Gamonts of this parasite induced nuclear fragmentation or segmentation in host erythrocytes. The life cycle, morphological, and morphometric features of H. clamatae are compared with H. catesbianae, a similar species that also infects ranids. Nucleotide sequence analysis of the internal transcribed spacer region (ITS-1) of these sympatric species revealed that only 6 nucleotide sites of the 129 base pairs of this region were variable among 4 isolates of H. clamatae and 2 isolates of H. catesbianae. A redescription of H. clamatae is presented based on data from this study and from the original description by Stebbins in 1905.

Habitats préférentiels d'amphibiens ranidés dans des lacs oligotrophes du Bouclier laurentien, Québec

From a study of riparian habitat structure and a quantitive distribution survey of bullfrog, Rana catesbeiana, mink frog, Rana septentrionalis, and green frog, Rana clamitans melanota, in 31 oligotrophic lakes, we looked for, among 18 physiographic parameters, those that could best explain the spatial organisation of the ranid community. The three species cohabitated in 18 lakes, the mink frog and the green frog in 10 lakes without bullfrog, and the bullfrog alone in 3 lakes. These frogs preferentially occupied (i) habitats with medium or high density of emergent vegetation, (ii) areas with extensive floating aquatic vegetation, (iii) muddy and silty areas, and (iv) especially for the green frog, shrubby habitats with ericaceae. Substrates had a poor explicative value. In lakes devoid of bullfrogs, the mink frogs and green frogs were more frequently abundant and showed a more even distribution in the different habitats than when they were sympatric with bullfrogs. A Spearman's rank correlation analysis confirmed the similarity of habitat preferences between the three species and the poor capacity of the habitat structure to predict the ranid community composition.

The effect of pH on Bullfrog, Rana catesbeiana, and Green Frog, Rana clamitans melanota, tadpoles

The effect of pH on Bullfrog, Rana catesbeiana, and Green Frog, Rana clamitans melanota, tadpoles