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A Simplified Table for Staging Anuran Embryos and Larvae with Notes on Identification
... The ontogenetic development of anuran amphibians, particularly the species of the family Ranidae, is usually represented by staging tables, among which the tables of Limbaugh and Volpe (1957) and Gosner (1960) are unified. The development of the species of the genus Rana was described in detail only for Rana pipiens (Taylor and Kollros, 1946) and Rana temporaria (Dabagyan and Sleptsova, 1975;Hertwig and Schneider, 1989). ...
... General information on the periods of the main events of the metamorphosis can be taken from some staging tables (Limbaugh and Volpe, 1957;Dabagyan and Sleptsova, 1975;Hertwig and Schneider, 1989), but even so, not all metamorphic events have been timed. Many authors did not use timing in their publications (Gosner, 1960;Taylor and Kollros, 1946;Günther, 1990). ...
... During excursions to the pond, the larvae were periodically captured and observed by placing them in flat white plastic cuvettes, and changes in external morphology, including limb development, tail reduction, and gradual formation of skin texture (Ishchenko, 1978), and changes in shape and position, carefully recorded. In total, 238 larvae and metamorphosing individuals at stages 26 -46 (from limb-bud appearance to complete metamorphosis) were described under natural conditions according to the development table set out by Gosner (1960). Since the researchers often use the development tables with a different number of stages (in particular, for brown frogs), for convenience, we have taken into account also the staging for Rana temporaria (Dabagyan and Sleptsova, 1975;Hertwig and Schneider, 1989) and Rana pipiens (Taylor and Kollros, 1946). ...
For the first time, a description and timing of the development of the main external morphological characteristics of Rana arvalis Nilsson, 1842 is presented, with particular attention to the formation of skin texture. The first signs of texture in the form of dark stripes and spots appeared in tadpole skin at stages G39 – 40. At G41 – 44, the body of the tadpole acquired a typical «frog» position with an orientation of 20 – 30° to the substrate, dorsolateral stripes transformed into folds, and dark spots into tubercles in the caudo-rostral direction. At the end of metamorphosis (G45 – 46), the texture formation was completed on the entire back, and the type of morph (striata, non-striata) was easily determined. The period between the first signs of the appearance of skin texture and its complete formation took 6 – 12 days. The most stable was the interval between the primary protrusion of the forelimbs under the skin and the eruption of the first one (~12 h). The period between the eruption of the first and second forelimbs was the most variable (from an hour to three days). The results obtained highlight the plasticity and problematic nature of the phenomenon of metamorphosis in amphibians.
... Như vậy, hiện nay đơn vị phân loại và dữ liệu hình thái của nòng nọc O. martensii vẫn chưa được cung cấp một cách đầy đủ và chi tiết trong bất kì nghiên cứu nào. Theo Gosner (1960), vòng đời của các loài ếch nhái trải qua 46 giai đoạn phát triển: giai đoạn phôi (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), giai đoạn còn noãn (20)(21)(22)(23)(24)(25), giai đọan nòng nọc (26-41) và giai đoạn con non biến thái thành con trưởng thành (42-46). Ở giai đoạn nòng nọc, chúng tập trung tăng trưởng và hoàn thiện chi sau (giai đoạn 26-40) cho đến khi bắt đầu xuất hiện mầm chi trước (giai đoạn 41) [15][16][17] . ...
... Như vậy, hiện nay đơn vị phân loại và dữ liệu hình thái của nòng nọc O. martensii vẫn chưa được cung cấp một cách đầy đủ và chi tiết trong bất kì nghiên cứu nào. Theo Gosner (1960), vòng đời của các loài ếch nhái trải qua 46 giai đoạn phát triển: giai đoạn phôi (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), giai đoạn còn noãn (20)(21)(22)(23)(24)(25), giai đọan nòng nọc (26-41) và giai đoạn con non biến thái thành con trưởng thành (42-46). Ở giai đoạn nòng nọc, chúng tập trung tăng trưởng và hoàn thiện chi sau (giai đoạn 26-40) cho đến khi bắt đầu xuất hiện mầm chi trước (giai đoạn 41) [15][16][17] . ...
... Theo Gosner (1960), vòng đời của các loài ếch nhái trải qua 46 giai đoạn phát triển: giai đoạn phôi (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19), giai đoạn còn noãn (20)(21)(22)(23)(24)(25), giai đọan nòng nọc (26-41) và giai đoạn con non biến thái thành con trưởng thành (42-46). Ở giai đoạn nòng nọc, chúng tập trung tăng trưởng và hoàn thiện chi sau (giai đoạn 26-40) cho đến khi bắt đầu xuất hiện mầm chi trước (giai đoạn 41) [15][16][17] . Trong nghiên cứu này, chúng tôi tiến hành: (i) Phân loại các mẫu vật nòng nọc của Cóc nước Marten O. martensii thu nhận được ở Cao nguyên Di Linh bằng trình tự gene 16S rRNA (ii) Cung cấp mô tả hình thái nòng nọc giai đoạn 37 một cách chi tiết, và sự thay đổi về hình thái nòng nọc từ giai đoạn 37 đến giai đoạn 41. ...
The tadpole identification can support providing important information on the larval stage of amphibian species, which helps for studying the conservation, ecology, and life history of them. Based on morphological and molecular data, this study accurately identified the tadpoles of Marten's Oriental Frog Occidozyga martensii which had been recorded in the Di Linh Plateau, Lam Dong province. These tadpole specimens were collected in the wet season, July and August 2022. Analyzing the morphology and molecule of the tadpoles, amplifying the 16S rRNA marker by using a pair of primers AH-16S_S and AH-16S_R. Their 16S rRNA sequences matched to those collected at the type locality of O. martensii in Bangkok (Thailand) and closely related to those of O. laevis collected in Philippines. The results provided detailed morphological description of O. martensii tadpoles at stage 37 and the morphological changes from stage 37 to 41, with diagnostic characteristics: upper fin originates far posterior to trunk-tail junction, at approximately 17% of tail length, with black short-stripes in front of eyes and black short-stripe behind mouth, brown belly with many white spots. The tadpole morphology of O. martensii most resembles tadpole of O. laevis when compared with all congeners in genus Occidozyga. O. martensii differs from O. laevis in only having black short-stripes in front of eyes. It is easily confused when identifying these two species by their morphological characteristics. However, the molecular data from this study and previous studies suggested that O. martensii is a different taxon from O. laevis. These results from this study indicated the necessity of molecular methods in the identification of amphibians. The morphological and molecular data of O. martensii tadpole are helpful for the next taxonomic studies and management of Oriental Frog Occidozyga species in the future.
... After finding that tadpoles eat all food items, we fed them a rotation of boiled greens and a mix of meal gels to target an omnivorous diet. Once tadpoles reached Gosner (1960) stages 41-42, we moved them to plastic deli cups consisting of flooded Sphagnum sp. moss, such that they had emergent substrate to haul out (A. ruthveni will drown if not provided with easy haul-out options-unlike glassfrogs, which haul out vertically on aquarium walls). ...
... G A. ruthveni lays individual eggs in a simple capsule (note: two obvious jelly layers visible using brightfield microscopy-additional approaches are required to better examine and count jelly layers). H Hatching occurs at Gosner (1960) stages 18-19, at the onset of a muscular response and a heartbeat). All images were taken of animals in captivity the tank bottom ( Fig. 1, Supp. ...
... In all six clutches, embryonic development occurred over 30-36 h (with water temps maintained at ~ 22-24 °C) ( Fig. 1F-H). Hatching occurred at Gosner (1960) stages 18-19 (muscular response-heartbeat/gill buds, Fig. 1H). We could not confirm the exact time of oviposition, as eggs are scattered in bouts over several hours. ...
Frogs of the Allophrynidae are an enigmatic family from South America. To date, published information is lacking regarding this group’s reproductive biology and larval morphology. Here, we provide the first detailed description of the reproductive mode, developmental mode, and tadpole morphology for Allophryne ruthveni. We developed a captive breeding and rearing protocol for this species and then conducted a series of observations to describe aspects of its reproductive biology. In captivity, this species exhibits aquatic oviposition, where single eggs are laid ungrouped within a simple jelly capsule and are scattered free in the water column before sinking to develop on benthic substrates. We did not observe parental care nor any parental interactions with eggs post-fertilization. Tadpoles are characterized by an oval body, anteroventral oral disc, a labial tooth row formula of 2(2)/3, and a dextral vent tube. The buccopharyngeal cavity is marked by the presence of two pairs of infralabial papilla and four lingual papillae. Cranial morphology is characterized by the presence of the commissura quadratoorbital. This species possesses an additional slip of the m. rectus cervicis and of the m. levator arcuum branchialium III. We discuss our results in comparison with glassfrogs (Centrolenidae).
... Prior research into NO 3 -N exposure in amphibians has predominantly centered on its disruption of the thyroid axis and resultant thyroid dysfunction, including the depletion of thyroid follicular colloids and reduced thyroid hormone (TH) levels [17][18][19]. It is important to note, however, that the morphogenesis of the amphibian thyroid gland do not occur until around Nieuwkoop and Faber (NF) stage 43 (approximated by Gosner (Gs) stage 23) [20][21][22], and only maternal thyroid hormones function before then [23]. Consequently, we raise two scientific questions here: (1) Does NO 3 -N influence the expression levels of thyroid-related genes during the embryonic stage when the thyroid gland has not undergone morphogenesis? ...
... Body weight and body length of embryos were measured using an analytical balance with 0.1 mg readability and Tesa-Cal Dura-Cal Digital electronic calipers with 0.01 mm precision. Embryos were observed and photographed using a Zeiss Discovery V12 stereoscope equipped with a cannon 7D digital camera, and the embryonic development stage was determined according to the staging criteria proposed by Gosner (1960) [21]. ...
... Body weight and body length of embryos were measured using an analytical balance with 0.1 mg readability and Tesa-Cal Dura-Cal Digital electronic calipers with 0.01 mm precision. Embryos were observed and photographed using a Zeiss Discovery V12 stereoscope equipped with a cannon 7D digital camera, and the embryonic development stage was determined according to the staging criteria proposed by Gosner (1960) [21]. ...
Simple Summary
The ingestion of excessive nitrate can affect the thyroid gland and cause thyroid dysfunction in humans. In the present study, amphibian embryos were exposed to nitrate, thyroxine and methimazole (a thyroid peroxidase inhibitor) during embryonic development to further explore the effects of nitrate on the thyroid. The results showed that nitrate, thyroxine and methimazole inhibited embryo growth and development. Additionally, methimazole and high concentrations of nitrate downregulated the genes related to thyroid morphogenesis and cholesterol metabolism, while upregulating the genes related to inflammation and apoptosis. These suggested that nitrate not only damaged the thyroid gland, but also affected the formation of the thyroid, thus affecting embryonic development.
Abstract
In recent years, nitrate (NO3-N) pollution in water bodies has been increasing due to the excessive use of nitrogen-based fertilizers. Exposure to NO3-N during the development of amphibian embryos may have lasting effects on the growth and development of individuals and even threaten their survival, but the toxicity mechanism of NO3-N in amphibian embryos prior to thyroid morphogenesis remains unclear. In the present study, Bufo gargarizans was selected as the model organism to investigate the toxic effects of 10 mg/L and 100 mg/L NO3-N exposure (N10 and N100) on amphibian embryos using methimazole (MMI) and exogenous thyroxine (T4) as the reference groups. We found that T4, MMI, N10 and N100 inhibited B. gargarizans embryo growth and development, with MMI and N100 showing the earliest and strongest effects. Transcriptome analysis revealed that MMI and NO3-N (especially N100) significantly downregulated genes related to thyroid morphogenesis and cholesterol metabolism, while upregulating genes related to inflammation and apoptosis. Together, these results contribute to a deeper understanding of the complex mechanisms by which NO3-N disrupts B. gargarizans embryonic development, reveal the potential risks of NO3-N pollution to other aquatic organisms, and provide insights into the conservation of a broader ecosystem.
... Tadpoles at stages 35-38 (Gosner 1960) were collected from a temporary pond inside the forest at Estação Biológica de Santa Lúcia, Municipality of Santa Teresa (19 o 56'S, 40 o 35'W), State of Espírito Santo, Brazil, and reared in laboratory. The region of Santa Teresa is located over a mountain ridge, comprised of patches of secondary and undisturbed forests. ...
... Descriptions and measurements are based on six tadpoles in stages 39-40 (Gosner 1960). Tadpoles at stages 35, 36 and 38 were used to corroborate variations in labial tooth row formula. ...
... Tadpole description. Stages 39-40 (Gosner 1960). Mean total length 53.1 (sd = 2.72 mm). ...
The tadpole of Itapotihyla langsdorffii is described and illustrated. Morphological data are compared with available information on tadpoles of casque-headed frogs occurring in the Atlantic Rainforest (genera Aparasphenodon and Trachycephalus), and also with Osteocephalus. The ontogenetic shift in tooth row formula and the great similarity on tadpole external morphology among these genera do not allow the use of the examined larval characters on generic diagnoses. However, we present some juvenile characters which may support the validity of Itapotihyla. The confrontation of the hypotheses concerning oral disk morphology and larval habitat types of the casque-headed tree frogs with the phylogeny of the Lophiohylini indicates that the ancestral larval habitat of this tribe was lentic and that the high number of tooth rows in this clade is not related to larval habitat.
... The control water was tap water that we aged at least 24 h to allow any chlorine to off-gas. We also set aside ten individuals from each population to estimate the initial average mass and developmental stage (Gosner, 1960) of each population. The initial individual masses of the populations ranged from 33 to 64 mg; developmental stages ranged from approximately 26 to 27 (Table 1). ...
... As with the TTD experiment, we set aside ten individuals from each population at the outset of the experiment to quantify the average developmental stage (Gosner, 1960) and mass of the individuals used in the experiment from each population. These initial masses ranged from 62 to 179 mg with development stages ranging from approximately 25 to 28 (Gosner, 1960; Table 1). ...
... As with the TTD experiment, we set aside ten individuals from each population at the outset of the experiment to quantify the average developmental stage (Gosner, 1960) and mass of the individuals used in the experiment from each population. These initial masses ranged from 62 to 179 mg with development stages ranging from approximately 25 to 28 (Gosner, 1960; Table 1). ...
The increasing salinization of freshwaters is a growing environmental issue as a result of mining, agriculture, climate change, and the application of de‐icing salts in regions that experience ice and snow. Due to narrow osmotic limits, many freshwater species are particularly susceptible to salinization, but it is possible that repeated exposures over time could favor the evolution of increased salt tolerance. Using collected nine populations of larval wood frogs ( Rana sylvatica ) as eggs from ponds and wetlands with close proximity to roads and spanning a wide gradient of salt concentrations. In the first experiment, we used a time‐to‐death experiment to examine the salt tolerance. In a second experiment, we examined whether population differences in salt tolerance were associated with trade‐offs in growth, development, or behavior in the presence of control water or a sublethal salt concentration. We found that populations collected from ponds with low and intermediate salt concentrations exhibited similar tolerance curves over a 96‐h exposure. However, the population from a pond with the highest salt concentration exhibited a much higher tolerance. We also found population differences in growth, development, and activity level among the populations, but these were not associated with population differences in tolerance. In addition, the sublethal concentration of salt had no impact on growth and development, but it did cause a reduction in tadpole activity across the populations. Collectively, these results provide further evidence that some species of freshwater organisms can evolve tolerance to increasing salinization, although it may only occur under relatively high concentrations and without trade‐offs in growth, development, or behavior.
... For larval morphology, we followed a two-dimensional geometric morphometric approach. On a set of 112 photographs/drawings of tadpoles (n = 1 or 2 per species; developmental stages 26-41 [46]), a set of 32 landmarks was defined based on [47] (Supplementary Figure S1). Landmarks were digitized by the same person, and configurations were digitally unbent to correct tail curvature due to fixation artifacts [48]. ...
... To control for the effect of larval developmental stage in shape variation, we performed a Procrustes ANOVA with genus, family, ecomorphological guild, and developmental stage as factors. Gosner developmental stages were collapsed into three categories as follows: limb bud (Stages 26-30), autopodium development (Stages 31-37), and tarsal tubercle differentiation (Stages 38-41) [46], and R 2 and p-values were considered to assess factor relative importance [50]. Other variables known to have a significant effect on tadpole shape, especially at an intraspecific level (e.g., competition, predation) [56,57], were not considered. ...
Phenotypic traits can evolve independently at different stages of ontogeny, optimizing adaptation to distinct ecological contexts and increasing morphological diversity in species with complex life cycles. Given the relative independence resulting from the profound changes induced by metamorphosis, niche occupation and resource utilization in tadpoles may prompt evolutionary responses that do not necessarily affect the adults. Consequently, diversity patterns observed in the larval shape may not necessarily correspond to those found in the adult shape for the same species, a premise that can be tested through the Adaptive Decoupling Hypothesis (ADH). Herein, we investigate the ADH for larval and adult shape differentiation in Neoaustrarana frogs. Neoaustrarana frogs, particularly within the Cycloramphidae family, exhibit remarkable diversity in tadpole morphology, making them an ideal model for studying adaptive decoupling. By analyzing 83 representative species across four families (Alsodidae, Batrachylidae, Cycloramphidae, and Hylodidae), we generate a morphological dataset for both larval and adult forms. We found a low correlation between larval and adult shapes, species with a highly distinct larval shape having relatively similar shape when adults. Larval morphological disparity is not a good predictor for adult morphological disparity within the group, with distinct patterns observed among families. Differences between families are notable in other aspects as well, such as the role of allometric components influencing shape and morphospace occupancy. The larval shape has higher phylogenetic structure than the adult. Evolutionary convergence emerges as a mechanism of diversification for both larval and adult shapes in the early evolution of neoaustraranans, with shape disparity of tadpoles reaching stable levels since the Oligocene. The widest occupation in morphospace involves families associated with dynamically changing environments over geological time. Our findings support the ADH driving phenotypic diversity in Neoaustrarana, underscoring the importance of considering ontogenetic stages in evolutionary studies.
... In addition, some larvae were raised through metamorphosis to confirm species identity by comparing the newly metamorphosed juveniles to adults ( Fig. 1E−F). The stage of development was determined according to Gosner (1960). Voucher specimens were deposited in the Biological Collection of the Instituto Federal de Educação, Ciência e Tecnologia do Piauí -IFPI Campus Pedro II (CBPII). ...
... Tadpole at stage 35(Gosner, 1960; CBPII 113), juvenile, and adult of Dendropsophus soaresi collected in the Pedro II municipality, state of Piauí, northeastern Brasil. (A) Lateral, (B) dorsal, and (C) ventral views; (D) oral disc with structures outlined (black arrows indicate lateroventral gaps); (E) Juvenile; and (F) adult individual (arrow indicates dermal fold on ventral surface of tarsus). ...
Although data from the internal oral anatomy and chondrocranium of anuran larvae can be used to resolve taxonomic questions, there is no information on these characteristics for species of the Dendropsophus marmoratus group. Herein, we provide a complete description of the tadpole of D. soaresi, presenting additional information about the external larval morphology and unpublished data on internal oral anatomy and chondrocranium of specimens collected in the state of Piauí, northeastern Brazil. The measurements and morphological characters were based on 10 tadpoles in stages 35−36. Two tadpoles in stage 36 and one in stage 35 were dissected for analysis of the internal oral anatomy. To describe the chondrocranium, six stage 36 tadpoles were cleared and double-stained. We find small differences concerning the original description of the external morphology, such as body shape, oral disk size, shape and height of the fins, and position of the vent tube. We also present additional information on coloration in life and morphometric details. Similar to other species of the genus, the tadpole of D. soaresi has a reduced number of structures in the buccopharyngeal region, although presenting lingual papillae and a rounded cornified structure in the prenarial arena. Also, D. soaresi presents a set of chondrocranial traits that are not found in other species of the genus and are possible synapomorphies for the D. marmoratus group. This variation highlights the potential of larval morphology as a source of evidence for Dendropsophus systematics. However, additional research on the internal anatomy of Dendropsophus species, especially those of the D. marmoratus group, are essential to clarify the phylogenetic relationships of the genus.
... Bufo castaneoticus. -A typical tadpole in Stage 34 (Gosner, 1960) (MZUSP 68230; original field no. JPC 6796) is 11.5 mm in total length and 4.8 mm in body length (Fig. 4A). ...
... Bufo typhonius.-A typical tadpole in Stage 34 (Gosner, 1960) (MZUSP 68217; original field no. JPC 6713) is 14.4 mm in total length and has a body length of 6.3 mm (Fig. 4B). ...
... For the tadpoles, we had nine replicate tubs for the control and four replicate tubs for each PFAS exposure treatment. We haphazardly assigned 20 tadpoles to each tub (initial mean measurements ± SD; n = 10: mass = 0.121 g ± 0.038 g, snout-vent length (SVL) = 10.12 ± 1.18 mm, Gosner developmental stage = 25.0 ± 0.5; Gosner, 1960). For the snails, we had a single replicate tub for each treatment and randomly assigned 10 individuals to each PFAS treatment tub and 15 snails to the control tub. ...
... To quantify parasite load, we removed the kidneys, pressed them between two glass slides, and counted the number of cysts twice using an inverted scope. Mass, SVL, and Gosner stage (Gosner, 1960) were recorded immediately prior to dissection. ...
Per‐ and polyfluoroalkyl substances (PFAS) are environmental contaminants of growing concern due to their potential negative effects on wildlife and human health. Per‐ and polyfluoroalkyl substances have been shown to alter immune function in various taxa, which could influence the outcomes of host–parasite interactions. To date, studies have focused on the effects of PFAS on host susceptibility to parasites, but no studies have addressed the effects of PFAS on parasites. To address this knowledge gap, we independently manipulated exposure of larval northern leopard frogs ( Rana pipiens ) and parasites (flatworms) via their snail intermediate host to environmentally relevant PFAS concentrations and then conducted trials to assess host susceptibility to infection, parasite infectivity, and parasite longevity after emergence from the host. We found that PFAS exposure to only the host led to no significant change in parasite load, whereas exposure of parasites to a 10‐µg/L mixture of PFAS led to a significant reduction in parasite load in hosts that were not exposed to PFAS. We found that when both host and parasite were exposed to PFAS there was no difference in parasite load. In addition, we found significant differences in parasite longevity post emergence following exposure to PFAS. Although some PFAS‐exposed parasites had greater longevity, this did not necessarily translate into increased infection success, possibly because of impaired movement of the parasite. Our results indicate that exposure to PFAS can potentially impact host–parasite interactions. Environ Toxicol Chem 2024;00:1–10. © 2024 SETAC
... We aerated these containers using an air pump system. We measured their weight and determined their developmental stage according to the Gosner (1960) scale just before and after the experiment. To calculate the relative growth rate (GRr), we used the following formula: ...
Aim: We investigated the relationship between thermal physiology, elevational distribution and thermal stress among nine closely related dendrobatid frogs during their aquatic stage by employing an integrated approach, combining thermal physiology, environmental temperature modelling and predictive assessments of current and future exposure to thermal variation.
Location: Ecuador.
Taxon: Amphibians; Anura, Dendrobatidae, Epipedobates, Hyloxalus.
Methods: We determined the thermal performance curves (TPCs) of larval growth for each species and modelled the thermal variation in contrasting aquatic larval environments for both present and future times. This allowed us to estimate the expected elevational distributions and forecast periods of exposure to stressful temperatures that inhibit larval growth due to elevation and global warming.
Results: We found significant correlations between optimum temperature (Topt), 50% maximum performance temperature (maxB50), 50% minimum performance temperature (minB50) and cold resistance (survival at 9°C) with the current elevational distributions. However, thermal physiology predicted lower than observed distributions for high-elevation dendrobatids and higher than observed maximum elevations for lowland species. Nonetheless, our models predicted that low thermal variability habitats (i.e. streams and deep permanent ponds) can buffer the future temperature increase for all taxa, even when considering the most extreme scenario. In contrast, all species within high thermal variation habitats (open forest temporary ponds) are expected to experience stressful temperatures under present conditions.
Main Conclusions: The findings indicate that thermal physiology may not be a limiting factor for dendrobatid frog species' ranges in this equatorial mountain gradient. Highland species may need to adapt to suboptimal performance, while some lowland species could occupy higher elevations. This study emphasizes the importance of habitat buffering to mitigate thermal stress in the face of climate change for amphibians in tropical mountains.
... Morphometric measurements (in mm, n = 3) of Agalychnis callidryas tadpoles collected in the Refugio Natural Altamira, located in the municipality of Chalán, Sucre department, Colombia (voucher number UPTC-Am-0959). Developmental stages were classified according to the criteria established by Gosner (1960). morphometric measurements of the collected tadpoles at three developmental stages (Table 1). ...
... Morphometric measurements (in mm, n = 3) of Agalychnis callidryas tadpoles collected in the Refugio Natural Altamira, located in the municipality of Chalán, Sucre department, Colombia (voucher number UPTC-Am-0959). Developmental stages were classified according to the criteria established by Gosner (1960). morphometric measurements of the collected tadpoles at three developmental stages (Table 1). ...
... Decreases in immunity were found only in juvenile frogs during the breeding season, while lower fat content and higher lean body content were observed exclusively in adult frogs during the non-breeding season. After hibernation, adult and juvenile frogs appear in paddy fields for breeding and growth, respectively 12,53 . Adult frogs experience explosive energy consumption for reproduction during the breeding season, and juvenile frogs must recover their immunity in a decreased immune state. ...
Gut microbiota impact host physiology, though simultaneous investigations in ectothermic vertebrates are rare. Particularly, amphibians may exhibit more complex interactions between host physiology and the effects of gut microbiota due to the combination of seasonal changes and complex life histories. In this study, we assessed the relationships among food resources, gut bacterial communities, and host physiology in frogs (Phelophylax nigromaculatus), taking into account seasonal and life history variations. We found that food sources were not correlated with physiological parameters but had some relationships with the gut bacterial community. Variations in gut bacterial community and host physiology were influenced by the combined effects of seasonal differences and life history, though mostly driven by seasonal differences. An increase in Firmicutes was associated with higher fat content, reflecting potential fat storage in frogs during the non-breeding season. The increase in Bacteroidetes resulted in lower fat content in adult frogs and decreased immunity in juvenile frogs during the breeding season, demonstrating a direct link. Our results suggest that the gut microbiome may act as a link between food conditions and physiological status, and that the combined effect of seasons and life history could reinforce the relationship between gut microbiota and physiological status in ectothermic animals. While food sources may influence the gut microbiota of ectotherms, we contend that temperature-correlated seasonal variation, which predominately influences most ectotherms, is a significant factor.
... DW (tap water containing Nutrafin Aquaplus, A7928 Hagen®, and Nutrafin Cycle, A7906 Hagen®), and tadpoles were fed ad libitum with store-bought organic spinach softened with boiled DW as well as rabbit food pellets (Hagen®). Tadpoles were housed for approximately 3 weeks until a sufficient number reached at least Gosner developmental stage 25 (Gosner 1960); tadpoles at this stage are known to survive exposure to the trematode and exogenous-CORT doses used here (Belden Content courtesy of Springer Nature, terms of use apply. Rights reserved. ...
Parasites represent a ubiquitous threat for most organisms, requiring potential hosts to invest in a range of strategies to defend against infection—these include both behavioural and physiological mechanisms. Avoidance is an essential first line of defence, but this behaviour may show a trade-off with host investment in physiological immunity. Importantly, while environmental stressors can lead to elevated hormones in vertebrates, such as glucocorticoids, that can reduce physiological immunity in certain contexts, behavioural defences may also be compromised. Here, we investigate anti-parasite behaviour and immune responses against a trematode (flatworm) parasite by larval amphibians (tadpoles) exposed or not to a simulated general stressor in the form of exogenous corticosterone. Tadpoles that were highly active in the presence of the trematode infectious stage (cercariae) had lower infection loads, and parasite loads from tadpoles treated only with dechlorinated water were significantly lower than those exposed to corticosterone or the solvent control. However, treatment did not affect immunity as measured through white blood-cell profiles, and there was no relationship between the latter and anti-parasite behaviour. Our results suggest that a broad range of stressors could increase host susceptibility to infection through altered anti-parasite behaviours if they elevate endogenous glucocorticoids, irrespective of physiological immunity effects. How hosts defend themselves against parasitism in the context of multiple challenges represents an important topic for future research, particularly as the risk posed by infectious diseases is predicted to increase in response to ongoing environmental change.
... Bullfrog tadpoles (N = 90), A. catesbeiana (2.09 ± 0.20 g) (Shaw 1802), at stage 25 of development (Gosner 1960), were sourced from the Santa Rosa frog farm in Santa Bárbara d'Oeste/SP, Brazil (22°4 6′53.0″S, 47°24′17.7″W). ...
This study focused on investigating the water quality in Pirajibú River, a relevant water body that flows through the industrial zone of Sorocaba (São Paulo/Brazil). Due to the limitations of assessing water quality based solely on standard physicochemical tests, an ecotoxicological approach was used to assess biomarker changes in the liver of bullfrog tadpoles (Aquarana catesbeiana). The animals were divided into groups and exposed to water samples collected upstream and downstream of the industrial zone. After 96 hours, the upstream group presented a decrease in the enzymatic activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) and an increase in the activity of catalase (CAT). For the downstream group, while a decreased activity was observed for SOD, an increase in CAT and glutathione S-transferase (GST) activities was stated. A decrease in lipid peroxidation (LPO) levels was observed in the downstream group, and increased carbonyl protein (PCO) levels in the upstream and downstream groups. Integrated Biomarker Response (IBR) revealed GSH and PCO as the most responsive biomarkers, despite no differences were noted between the groups. Regardless of whether the water quality standards of Pirajibú River were following Brazilian environmental legislation, the tadpoles presented high sensitivity when exposed to the water, even for a short period.
... Girinos -Um girino de P. gaigeae procedente de Paranapiacaba, no estagio 37 da tabela de Gosner (1960), tern 26,4 mm de comprimento total (Fig. 6); seu corpo mede 10,3 mm, ocupando aproximadamente 2/5 do comprimento total; visto de cima e de lado, o corpo e aproximadamente oval. Narinas mais proximas do olho que da ponta do focinho; olhos dorso-laterais, pequenos cabendo no espago entre eles e as narinas (1 mm). ...
... We collected two albino L. catesbeianus tadpoles on 15 August 2023 and deposited them at the University of New Mexico's Museum of Southwestern Biology, Albuquerque, New Mexico, USA (MSB:Herp:108532, MSB:Herp:108533). The tadpoles were at developmental stages 34 and 35 (Gosner, 1960), measured 83 and 87 mm in total length, and had a mass of 7.26 and 8.18 g, respectively (calliper to nearest 1 mm and balance to nearest 0.01 g). All albino tadpoles were similar in size and developmental stage to the normally pigmented individuals they were associated with upon collection (Fig. 2). ...
... The environmental conditions in the laboratory were constant, with a natural photoperiod and room temperature of 20°C. After reaching the free-feeding stage (Gosner 25;Gosner, 1960), we pooled all larvae together and randomly selected 208 individuals for the experiment. From this stage, tadpoles were fed ad libitum every second day with the same amount of commercial fish food (one tablet of Tetra TabiMin ® ; Tetra GmbH, per tank). ...
Amphibian larvae inhabiting temporary ponds often exhibit the capacity to accelerate development and undergo metamorphosis in challenging conditions like desiccation. However, not all species exhibit this ability, the yellow-bellied toad (Bombina variegata) is one such example. The underlying mechanisms behind the inability to accelerate development under desiccation remain largely unexplored. The hypothalamic-pituitary-interrenal (HPI) axis and corticosterone (CORT), which act synergistically with thyroid hormone, are thought to facilitate metamorphosis in response to desiccation stress. In this study, we aimed to investigate whether modification in the HPI axis, particularly CORT levels, contributes to the absence of adaptive plasticity in B. variegata under desiccation stress. The study design included four treatments: high water level, high water level with exogenous CORT, low water level, and low water level with metyrapone (a CORT synthesis inhibitor). The main objective was to evaluate the effects of these treatments on whole-body corticosterone levels, life history, morphological traits, and oxidative stress parameters during the prometamorphic and metamorphic climax developmental stages. While low water level had no effect on total corticosterone levels, larval period, body condition index, and metamorphic body shape, it negatively affected metamorph size, mass, and growth rate. Our findings suggest that constant exposure to desiccation stress over generations may have led to modifications in the HPI axis activity in B. variegata, resulting in adaptation to changes in water level, evident through the absence of stress response. Consequently, CORT may not be a relevant stress indicator in desiccation conditions for this species.
... Leptodactylus podicipinus schools had an average of 404 and standard deviation (±) of 173 tadpoles (range = 112-701; N = 14). The schools presented tadpoles of different stages of development (Gosner 1960): seven schools had tadpoles of one recorded for seven minutes. We made behavioural observations to describe schooling features and we registered aggregation time (seconds) using BORIS software (Friard and Gamba 2016). ...
Communication during parental care is important in the context of offspring defence and parent-offspring recognition. In aquatic environments, chemical communication is usually the most effective and plays different roles in parental behaviour in many groups of animals. Attending females of some Neotropical anurans (Leptodactylus) lead entire schools of tadpoles through the water. However, little is known about how attending females communicate with the tadpoles or whether this communication is mother-offspring specific. We therefore conducted behavioural experiments with Leptodactylus podicipinus to address these questions. Initially, we investigated how visual, tactile, and chemical stimuli from attending females affect the aggregation behaviour of tadpoles. Next, we compared the effects of the chemical stimulus from attending females with those from other conspecifics (non-attending females and males) on schooling behaviour. Finally, we tested whether tadpoles preferred to be aggregated next to familiar attending females instead of unfamiliar ones. Our results indicated that only the chemical stimulus from attending females, and not visual or tactile, increased the time that tadpoles remained aggregated. The chemical stimuli from non-attending females and males did not affect tadpoles’ behaviour. However, contrary to our expectations, we did not find a school preference for familiar attending females. Our study is the first showing that chemical stimulus is important for mother-tadpole communication in a Leptodactylus species, playing a crucial role in tadpole aggregation and attraction. Future studies including other species should address the nature of the chemical compounds and their role, if any, in kin recognition in these frogs with aquatic maternal care.
... Nostril nearer eye than tip of snout; distance between nares less than distance between eyes; eyes small, 6% head-body length; mouthparts ventral, in form of large disk; oral disk entire, not emarginate; marginal papillae in single to double row, not interrupted anteriorly; one row of submarginal papillae between anterior tooth row and marginal papillae, two more or less distinct rows of submarginal papillae between posterior tooth row and marginal papillae, scattered submarginal papillae laterally; oral disk width about 40% head-body length; tooth row formula 2/3; jaw moderaly keratinized; spiracle sinistral, midway on side of body; dorsal fin origin just anteriad to body-tail juncture; tail height about equal to body height; tail tip rounded; anal tube dextral, but folded, appearing median in preservative; top of head and body suffused with melanophores, neither uniform nor distinctly mottled; tail fin and musculature mottled; ventral surfaces with scattered melanophores; gut peritoneum black; total length at stage 28 (Gosner, 1960) 25.5 mm; head-body length 39% total length (terminology follows Altig, 1970). ...
... The obtained embryos were kept in shallow plastic containers with 5 L of AS until they reached stage 25. Stages were determined in accordance with Del Conte and Sirlin (1951) and Gosner (1960). ...
... Special emphasis was laid on photographing the oral disc structure of the tadpole, as well as the mottling of the tail and other parts of the animal's anatomy that might be relevant (Figure 2). The specimen had no visible wounds and appeared to be in good general condition, being close to the development of its front legs, stage 41 according to Gosner (1960). After taking the pictures, the individual was released at the same place. ...
... Following the exp eriment, tadp oles' lateral sides were p hotograp hed (Canon 5D mk IV with a 100 mm F2.8 macro lens) to l ater qu antify snout vent length (SVL) a nd cha racterize deve lopm ental s ta ge ( Gosner 1960 ) u sing Im ageJ ( Sc hneider et al . 2012 ). ...
Synopsis
A critical component of animal conservation in a changing world is an understanding of the physiological resilience of animals to different conditions. In many aquatic animals, hypoxia (low environmental oxygen levels) is a regular occurrence, but the likelihood and severity of hypoxia vary across habitats. Fast-flowing, stream-like habitats are never hypoxic, so long as flow is maintained. Do animals from such habitats retain the capacity to survive hypoxic conditions? We use aquatic frog tadpoles to test the effects of natural habitat on performance in hypoxia in an experimental framework, finding that stream-living tadpoles have reduced performance in hypoxia. Tadpoles also vary in lung presence, with some species able to breathe air during hypoxia. We found that among lunged tadpoles, air-breathing rates increase in hypoxia in pond-living species but not stream-living species. Lung presence was also found to influence hypoxia performance, as lungless, stream-living tadpoles were found to be especially vulnerable to hypoxia, while pond-living, lungless tadpoles appeared largely resilient to hypoxia. We consider the ramifications of our findings on conservation outlooks and strategies for frogs and their tadpoles, suggesting that stream-living tadpoles, and especially lungless, stream-living tadpoles, may be particularly at risk to factors that reduce stream flow. Thus, a primary goal for conservation and management of species with stream-living tadpoles should be the maintenance of year-round streamflow, which oxygenates waters and prevents hypoxia.
... The model organism used in the present study was the green toad, Bufotes viridis (Anura: Bufonidae), during its embryonic , hatchling (G.S. 20-25), and early larval (G.S. 26-30) stages (Gosner 1960). Six clutches of green toad eggs (G.S. 3-6) were collected from Sarb-e Barnj (34° 28′ 19′′ N; 47° 22′ 42′′ E) in Kermanshah Province, Iran, on May 1 (n = 3) and 12 (n = 3), 2022. ...
The toxicity of aluminum oxide (Al2O3), copper oxide (CuO), iron oxide (Fe3O4), nickel oxide (NiO), zinc oxide (ZnO), and titanium dioxide (TiO2) nanoparticles (NPs) on amphibians and their interaction with high temperatures, remain unknown. In this study, we investigated the survival, developmental, behavioral, and histological reactions of Bufotes viridis embryos and larvae exposed to different NPs for a duration of 10 days, using lethal concentrations (LC25%, LC50%, and LC75% mg/L) under both ambient (AT: 18 °C) and high (HT: 21 °C) temperatures. Based on LC, NiONPs > ZnONPs > CuONPs > Al2O3NPs > TiO2NPs > Fe3O4NPs showed the highest mortality at AT. A similar pattern was observed at HT, although mortality occurred at lower concentrations and Fe3O4NPs were more toxic than TiO2NPs. The results indicated that increasing concentrations of NPs significantly reduced hatching rates, except for TiO2NPs. Survival rates decreased, abnormality rates increased, and developmental processes slowed down, particularly for NiONPs and ZnONPs, under HT conditions. However, exposure to low concentrations of Fe3O4NPs for up to 7 days, CuONPs for up to 72 h, and NiO, ZnONPs, and TiO2NPs for up to 96 h did not have a negative impact on survival compared with the control group under AT. In behavioral tests with larvae, NPs generally induced hypoactivity at AT and hyperactivity at HT. Histological findings revealed liver and internal gill tissue lesions, and an increase in the number of melanomacrophage centers at HT. These results suggest that global warming may exacerbate the toxicity of metal oxide NPs to amphibians, emphasizing the need for further research and conservation efforts in this context.
... The eggs were then transported to the laboratory, where they developed at an ambient temperature of approximately 20 • C under a natural sunlight photoperiod. The experiments started when tadpoles were able to swim freely, at developmental stage 25 according to Gosner [26]. ...
... Premetamorphic larvae (Gosner stages, (Gosner, 1960) were collected from a natural free-pesticides pond , situated in a natural floodplain of the Paraná River (31°36′ 50.6″ S, 60° 35′ 52.9″W), Santa Fe, Argentina. ...
... One site was situated at a high altitude (25.29745ºN, 91.58512ºE; elevation 1424 m; Fig. 1 To assess the environmental conditions influencing development, various physicochemical parameters of water were recorded at each site using specialized instruments, including temperature, pH, dissolved oxygen, and free carbon dioxide, during each observation period. The staging of embryos followed the criteria outlined by Gosner in 1960 [7]. Specifically, ten early embryonic Gosner stages (Gosner stage 1, 5, 10, 14, 15, 16, 17, 18, 19, and 20) were considered for analysis across four clutches observed annually at each site. ...
The study investigated the embryonic development of Hyla annectans Jerdon, a frog species, at high and low altitude breeding sites of Meghalaya, North East India. Results revealed significant differences in the duration of embryonic development and hatching between the two altitudes. Embryos at low altitude sites exhibited a faster development, hatching approximately four days earlier than those at high altitude sites. Early embryonic stages displayed similar characteristics in size between the two sites, but distinct differences emerged during later stages, notably in stages associated with heart development, muscular response, and gill circulation. Furthermore, metamorphosis completion varied between altitudes, with a shorter duration observed at low altitude compared to high altitude. Environmental conditions, particularly water properties, also differed significantly between the two sites. Water temperature and free carbon dioxide levels were higher at low altitude, while pH and dissolved oxygen levels were higher at high altitude. These findings suggest a potential influence of altitudinal gradients as environmental factors on embryonic development in H. annectans.
... Special emphasis was laid on photographing the oral disc structure of the tadpole, as well as the mottling of the tail and other parts of the animal's anatomy that might be relevant (Figure 2). The specimen had no visible wounds and appeared to be in good general condition, being close to the development of its front legs, stage 41 according to Gosner (1960). After taking the pictures, the individual was released at the same place. ...
... According to Gosner stages (GSs) [17], tadpole stages 0-20 are called the embryonic stage, stages 21-24 are the outer gill stage, and stage 25 is the tadpole stage, where they can swim freely for feeding. In stage 26, the hind legs begin to develop until the tail disappears completely at stage 46, marking the completion of metamorphosis. ...
Metamorphosis is a crucial process in the life cycle of Rana (Aquarana) catesbeiana. R. catesbeiana tadpoles, in their short larval period, possess a high survival rate and also a highly competitive ability in the amphibious stage. In actual seed production, the economic traits of larval period and metamorphosis rate are used as quantifiable indicators of quality for individuals and populations, respectively. However, studies of these economic traits in larval cultivation and production are still lacking. In this study, we constructed 40 full-sib families of R. catesbeiana and measured the weight and metamorphosis rate of tadpoles at different developmental stages. Subsequently, we calculated the phenotypic and genetic association between weight and metamorphosis rate in tadpoles and assessed the heritability of these two traits. The heritabilities of weight at three developmental stages were all higher than 0.40 and decreased with advancement of the developmental stage; the heritability of the metamorphosis rate was 0.18 ± 0.20, a moderate level. Correlation analysis of weight and metamorphosis rate at each developmental stage in each tadpole family showed that weight at stages 25-I, 25-II, and 25-III was significantly correlated at the phenotypic level but non-significantly at the genetic level. The metamorphosis rate was only moderately associated with stage 25-III weight (0.38, p < 0.05). The results of this study confirm the importance and transportability of tadpole weight in actual seed production and provide basic data and a potentially optimized direction for the selective breeding of high-metamorphosis-rate bullfrogs.
... One hundred and fifty O. americanus tadpoles in Gosner stages 26-30 (Gosner, 1960) were collected from a pond at the Federal University of Santa Maria (Santa Maria, RS, Brazil) and transported to the laboratory. Tadpoles were housed in plastic tanks (25 cm in length, 15 cm in width, and 10 cm in height) filled with dechlorinated water to a depth of 6 cm in a density of 50 tadpoles per tank until the day before the experiments. ...
Solar ultraviolet-B (UVB) radiation has increased due to stratospheric ozone depletion, climate and ecosystem changes and is a driver of amphibian population declines. Photoenzymatic repair (PER) is a critical mechanism for limiting UVB lethality in amphibian larvae. However, the link between PER and the UVB-induced effects remains understudied through long-term investigations in vivo. Here, we assessed how larval PER determines the lethal and sublethal effects induced by environmentally relevant acute UVB exposure until the juvenile phase in the Neotropical frog Odontophrynus americanus. We conducted laboratory-based controlled experiments in which tadpoles were or were not exposed to UVB and subsequently were exposed to light (for PER activation) or dark treatments. Results showed that the rates of mortality and apoptosis observed in post-UVB dark treatment are effectively limited in
post-UVB light treatment, indicating PER (and not dark repair, i.e. nucleotide excision repair) is critical to limit the immediate genotoxic impact of UVB-induced pyrimidine dimers. Nonetheless, even tadpoles that survived UVB exposure using PER showed sublethal complications that extended to the juvenile phase. Tadpole responses included alterations in morphology, chromosomal instability, increased skin susceptibility to fungal proliferation, as well as increased generation of reactive oxygen species. The short-term effects were carried over to later stages of life because metamorphosis time increased and juveniles were smaller. No body abnormalities were visualized in tadpoles, metamorphs, and juveniles, suggesting that O. americanus is UVB-resistant concerning these responses. This study reveals that even frog species equipped with an effective PER are not immune to carry-over effects from early UVB exposure, which are of great ecological relevance as late metamorphosis and smaller juveniles may impact individual performance and adult recruitment to breeding. Future ecological risk assessments and conservation and management efforts for amphibian species should exercise caution when linking PER effectiveness to UVB resistance.
... The larval developmental stage was determined according to Gosner (1960). The following morphometric measurements were taken with a micrometer coupled to a stereomicroscope from 10 tadpoles at stages 35 (n = 7) and 41 (n = 3): total length (TL), body length (BL), tail length (TAL), maximum tail height (MTH), tail muscle height (TMH), tail muscle width (TMW), inter-nostril distance (IND) and interorbital distance (IOD) (Altig and McDiarmid 1999); body height (BH), body width at spiracle level (BW), eye-nostril distance (END), eye diameter (ED) and oral-disc width (ODW) (Lavilla and Scrocchi 1986); body width at eye level (HW) (Lima et al. 2015); and vent-tube length (VTL) (Lins et al. 2018). ...
By using integrative taxonomy, we describe a new species of terrestrial foam-nesting frog of the genus Adenomera from white-sand forests of the Rio Negro Sustainable Development Reserve, Central Amazonia, Brazil. Within the A. andreae clade, the new species belongs to the A. simonstuarti complex where it is sister to the lineage from the lower Juruá River. The new species is assigned to the genus Adenomera by having adult SVL smaller than 34.1 mm, by its lack of fringing and webbing between toes and by the absence of spines on the thumb of adult males. It differs from other Adenomera by the following combination of characters: antebrachial tubercle absent; toe tips flattened or slightly flattened, with visible expansions; nearly solid, dark-coloured stripe on underside of forearm; single-note advertisement call; notes formed by 11–21 incomplete pulses; call duration varying between 100 and 199 ms; fundamental frequency 1,765–2,239 Hz; dominant frequency 3,448–4,349 Hz; and endotrophic tadpoles with spiracle present and labial teeth absent. Over the last decade, we have inventoried many permanent sampling modules in ombrophilous forests in the Manaus Region and in the Purus-Madeira interfluve, but the new species was found only in the white-sand forest from West Negro-Solimões Interfluve. Adenomera sp. nov. may be endemic to, or at least a specialist in, this environment.
The timing and size of metamorphosis are crucial for the future fitness of organisms with complex life cycles, such as amphibians. In some amphibian species, a portion of tadpoles will metamorphose in their natal year whereas others from the same cohort overwinter as tadpoles. Low temperature and food availability were previously assumed to be the underlying reasons; however, the factors influencing the decision to overwinter as tadpoles or metamorphose in the natal year have not been extensively studied. This study investigated these factors by conducting laboratory‐rearing experiments on Babina subaspera tadpoles. The tadpoles were individually reared under controlled temperature and light conditions that simulated five different growing seasons (i.e., the start month) observed in the field. Four different food quantity levels were set to induce different growth rates, which were measured individually. The results revealed that 33 tadpoles metamorphosed within their natal year, whereas 52 tadpoles were overwintered as tadpoles and metamorphosed the following spring. The size at metamorphosis was larger in tadpoles that metamorphosed after winter than in those that metamorphosed before winter. Whether tadpoles metamorphosed before or after winter was influenced by the individual growth rate and growing season. Tadpoles with slower growth rates were more likely to metamorphose after winter, possibly because slower growth prevented them from reaching the critical size threshold required for metamorphosis before winter. The threshold for the occurrence of larval overwintering varied with the growing season; tadpoles that spawned later in the year were more likely to overwinter, even with a high growth rate. The results suggested that slow‐growing B. subaspera tadpoles with insufficient time until the onset of winter would gain a higher fitness by metamorphosing after winter. This would be advantageous due to the tadpoles' potentially high survival rate during dormancy as well as their larger size at metamorphosis in the following year.
The article presents the results of studies of the effect of acidic (4.0, 5.0) and alkaline (9.0) pH values on cytomorphological parameters of erythrocytes of Rana macrocnemis tadpoles. The negative effect of pH 4.0 on the cytomorphological features of erythrocytes is shown, expressed in a decrease in their geometric parameters (area, volume), which leads to a deterioration of their function. Changes in the linear and geometric parameters of tadpole blood cells when exposed to pH 5.0 and 9.0 in both series of the experiment allow us to judge their focus on improving the efficiency of oxygen transport, that is, they are compensatory in nature.
Titulo en ingles: Preliminary list of anuran larvae in ponds and temporary pools of tropical savanna in times high rainfall season, Yopal, Casanare.RESUMEN: Se realizó el inventario preliminar de anuros en estado larval, sobre 144 lotes colectados en dos esteros semipermanentes y cuatro charcos temporarios, en sabana inundable y de desborde de la altillanura en el municipio de Yopal, Casanare (05° 21' 31''N 072º 13' 16''W, 214 msnm), durante la época de alta precipitación (mayo, junio y julio) de 2008. Se registraron cinco Familias de anuros con diez Géneros y trece Especies. La Familia Hylidae, presento siete especies que corresponden al 53,84 % de la riqueza con preferencias de hábitat acuático; junto a la Familia Leptodactylidae con tres especies (23,07 %), siendo estos los grupos dominantes en los esteros semipermanente y charcos temporales, respectivamente. La riqueza registrada en el estudio representa el 59,09 % del total de la herpeto-fauna con desarrollo indirecto conocida para Casanare y el 28,26 % de la Orinoquia colombiana. En los dos esteros tropicales se registro el mayor número de especies de anuros en etapa larval, comparado con lo observado en los charcos de lluvia temporarios (a excepción de uno de estos).Palabras clave: Anuro fauna, renacuajos, esteros semipermanentes, charcos, Orinoquía.ABSTRACT: A preliminary report of tadpoles of anura, on the 144 lot in the two semipermanent tropical ponds and four rain temporally pond, in flooded savanna and overflow in the high plains of the municipality of Yopal-Casanare municipality, department of Casanare (05° 21' 31''N 072º 13' 16''W, 214 msnm). This collect was in temporally high rain (may, june and july) of 2008. The fauna consisted of five family of frogs reported with ten genus and thirteen species. The Hylidae family, preset seven species, this is correponded the 53,84 % of abundance with preferece of habitat pond lentic; the family Leptodactylidae have three species (23,07 %). This are group are more dominate in semipermanent tropical ponds and temporally pond, respectively. This abundance report in this articule represent the 59,09 % of totaly of anura with indirect develop know from Casanare and the 28,26 % of Orinoquia colombian. In two tropical ponds are report the more number of species of tadpoles, with relation the tadpoles present in rain pond.Key words: Anura, tadpoles, semipermanent tropical ponds, temporally pond, Orinoquía.
Background
Anuran metamorphosis, which is driven by thyroid hormone (TH)-mediated processes, orchestrates intricate morphological and functional transformations for the transition from aquatic tadpoles to terrestrial life, providing a valuable model for studying organ functionalization, remodeling, and regression. Larva-specific organ regression is one of the most striking phenomena observed during the anuran metamorphic climax. While previous studies extensively analyzed the regression mechanisms of the tail, the molecular processes governing gill resorption remain elusive.
Results
We employed Microhyla fissipes as a model, and utilized a comprehensive approach involving histological analysis, transmission electron microscopy, and transcriptomics to unravel gill development and resorption. The pro-metamorphic stages revealed highly developed gill structures, emphasizing their crucial role as the primary respiratory organ for tadpoles. The transcriptomic analysis highlighted the upregulation of genes associated with enhanced respiratory efficiency, such as hemoglobin and mucins. However, as metamorphosis progressed, gill filaments underwent shrinkage, decreases in blood vessel density, and structural changes that signified a decline in respiratory function. The molecular mechanisms driving gill resorption involved the TH pathway—in particular, the upregulation of thyroid hormone receptor (TR) β, genes associated with the tumor necrosis factor pathway and matrix metalloproteinases. Two distinct pathways orchestrate gill resorption, involving apoptosis directly induced by TH and cell death through the degradation of the extracellular matrix. In addition, metabolic reorganization during metamorphosis is a complex process, with tadpoles adapting their feeding behavior and mobilizing energy storage organs. The gills, which were previously overlooked, have been unveiled as potential energy storage organs that undergo metabolic reorganization. The transcriptomic analysis revealed dynamic changes in metabolism-related genes, indicating decreased protein synthesis and energy production and enhanced substrate transport and metabolism during metamorphic climax.
Conclusion
This study sheds light on the structural, molecular, and metabolic dynamics during gill development and resorption in M. fissipes. The findings deepen our understanding of the intricate mechanisms governing organ regression and underscore the pivotal role of the gills in facilitating the transition from aquatic to terrestrial habitats.
Infanticide is widespread across the animal kingdom. However, the physiological mechanisms underlying infanticide versus care or neglect are relatively unexplored. Here, we identified salient environmental and physiological antecedents of care and infanticide in the mimic poison frog ( Ranitomeya imitator ), a biparental and monogamous amphibian in which female parents feed their tadpoles with unfertilized eggs. Specifically, we explored potential environmental cues by evaluating changes in the frequency of food provisioning and tadpole mortality after cross-fostering tadpoles within and between morphs and displacing tadpoles within the terraria of their parents. After analyzing trophic egg deposition and observing tadpole mortality in the latter condition, we concluded that changes to offspring location reduce care and increase infanticide. Following this observation, we investigated whether steroid hormones relate to infanticide in an unfamiliar, resource-limited setting. Infanticidal behavior towards fertilized eggs and hatchlings included cannibalism and was associated with lower testosterone concentrations upon displacement to the new environment, while corticosterone concentrations did not correlate with infanticide at any sampling event. Ratios of testosterone to corticosterone were overall lower in infanticidal individuals. Overall, these findings support earlier investigations of environmental cues for offspring-directed behavior in poison frogs, while offering a novel perspective on temporal endocrine correlates of infanticide.
Highlights
Offspring location drives parental decisions of care vs. infanticide.
In novel territories, adults cannibalize conspecific, unrelated young.
Lower circulating T in novel territory is associated with infanticide.
Infanticidal adults exhibit lower T/CORT ratios.
For adult anuran amphibians, the kidney and urinary bladder play important osmoregulatory roles through water reabsorption. In the present study, we have examined ontogenetic expression of aquaporins, i.e., AQP2, AQPamU (AQP6ub, AQPa2U), and AQP3, in these organs using the Japanese tree frog, Dryophytes japonicus. Immunohistochemistry using the metamorphosing larvae at stages 40-43 localized AQP2 protein to the collecting ducts in the dorsal zone of the mesonephric kidney. At prometamorphic stages 40 and 41, labelling of AQP2 protein was observed in the apical/ subapical regions of the collecting duct cells. At climax stages 42 and 43, labels for AQP2 and AQP3 became observed in the apical/subapical regions and basolateral membrane of the collecting duct cells, respectively, as seen in the adults. As for the urinary bladder, immuno-positive labels for AQPamU were localized to the apical/subapical regions of granular cells in the mucosal epithelium at stages 40-43. On the other hand, AQP3 immunoreactivity was hardly observed in the urinary bladder at stage 40, and weakly appeared in many granular cells at stage 41. Thereafter, labels for AQP3 became evident along the basolateral membrane of granular cells at stages 42 and 43, together with AQPamU in the apical/subapical regions. These results suggest that the kidney and urinary bladder might be capable of water reabsorption, via AQP2, AQPamU, and AQP3, at stage 42, contributing to the acclimation of the tree frogs to terrestrial environments.
Living with a diverse array of predators provides a significant challenge for prey to learn and retain information about each predator they encounter. Consequently, some prey respond to novel predators because they have previous experience with a perceptually similar predator species, a phenomenon known as generalization of predator recognition. However, it remains unknown whether prey can generalize learned responses across ontogenetic stages of predators. Using wood frog tadpole (Lithobates sylvaticus) prey, we conducted two experiments to explore the extent of predator generalization of different life stages of two different predators: (1) predacious diving beetles (Dytiscus sp.) and (2) tiger salamanders (Ambystoma mavortium). In both experiments, we used chemical alarm cues (i.e., injured conspecific cues) to condition tadpoles to recognize the odor of either the larval or adult stage of the predator as risky. One day later, we tested tadpoles with either the larval or adult predator odor to determine whether they generalized their learned responses to the other life stages of the predator. Tadpoles generalized between larval and adult beetle odors but failed to generalize between larval and adult salamander odors. These results suggest that the odor of some predator species changes during metamorphosis to an extent that reduces their recognisability by prey. This “predator identity reset” increases the number of threats to which prey need to attend.
Genomes are heterogeneous during the early stages of speciation, with small ‘islands’ of DNA appearing to reflect strong adaptive differences, surrounded by vast seas of relative homogeneity. As species diverge, secondary contact zones between them can act as an interface and selectively filter through advantageous alleles of hybrid origin. Such introgression is another important adaptive process, one that allows beneficial mosaics of recombinant DNA (‘rivers’) to flow from one species into another. Although genomic islands of divergence appear to be associated with reproductive isolation, and genomic rivers form by adaptive introgression, it is unknown whether islands and rivers tend to be the same or different loci. We examined three replicate secondary contact zones for the Yosemite toad ( Anaxyrus canorus ) using two genomic data sets and a morphometric data set to answer the questions: (1) How predictably different are islands and rivers, both in terms of genomic location and gene function? (2) Are the adaptive genetic trait loci underlying tadpole growth and development reliably islands, rivers or neither? We found that island and river loci have significant overlap within a contact zone, suggesting that some loci are first islands, and later are predictably converted into rivers. However, gene ontology enrichment analysis showed strong overlap in gene function unique to all island loci, suggesting predictability in overall gene pathways for islands. Genome‐wide association study outliers for tadpole development included LPIN3, a lipid metabolism gene potentially involved in climate change adaptation, that is island‐like for all three contact zones, but also appears to be introgressing (as a river) across one zone. Taken together, our results suggest that adaptive divergence and introgression may be more complementary forces than currently appreciated.
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