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The goals of this study were to test the effects of exogenous hormones and hibernation on breeding behavior and gamete release by boreal toads (Bufo boreas boreas). Each year, a subset of 77 toads was hibernated and then paired with hibernated or nonhibernated mates and treated with luteinizing hormone releasing hormone analogue (LHRHa), human chorionic gonadotropin (hCG), or left untreated. Amplexus and egg and sperm production were recorded. At 1 yr of age, only 19% of pairs exhibited amplexus, and no sperm or eggs were produced. At 2 and 3 yr of age, most male toads treated with LHRHa exhibited amplexus (56.9% and 100%, respectively). Among 2-yr-old males, amplexus was more prevalent (P < 0.05) in those that were hibernated than in those that were nonhibernated (54.0% and 33.3%, respectively), but most males in each group (93.3% and 75%, respectively) produced sperm in response to LHRHa treatment. Only one 2-yr-old and two 3-yr-old females produced eggs. At 4 yr of age, eight females produced eggs, but two died from egg retention. More nonhibernated than hibernated females developed eggs (7 of 10 vs. 1 of 10, P < 0.05). Mean (±SD) weight of female toads producing eggs (58.9 ± 11.9 g) was greater (P < 0.05) than that of nonproducing females (43.6 ± 7.0 g). Similarly, four of seven nonhibernated females (58.8 ± 8.3 g) produced eggs at 5 yr of age. All eggs were produced by females treated once with LHRHa. Number of eggs per female varied (141 to 3307), and development to tadpoles was low (0 to 36.5%), although tadpoles did become toadlets. In conclusion, male and female boreal toads matured at 2 and 4 yr of age, respectively, and heavier females were more likely to produce eggs. To enhance breeding success, males should be hibernated and treated with LHRHa. In contrast, female productivity was enhanced by improving their body condition instead of subjecting them to hibernation prior to LHRHa treatment. 相似文献
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本研究以黑眶蟾蜍(Duttaphrynus melanostictus)为研究对象,通过对比黑眶蟾蜍抱对个体的体长、头长、头宽、眼间距、鼓膜径、耳后腺长、眼径、前臂及手长、前肢长以及后肢长等形态特征,分析雌性黑眶蟾蜍繁殖输出与其体型的关系,探究黑眶蟾蜍两性异形模式及其与雌性生育力的关系;同时通过对配对个体形态学特征的相关性分析探究了黑眶蟾蜍的配对模式。结果表明,黑眶蟾蜍雌性体长和体重显著大于雄体;两性的所有局部形态特征均与体长成正相关;去除体长因素影响后,雄性头长以及后肢长均明显大于雌性,其余局部形态特征两性间则皆无显著差异。雌体的窝卵重、窝卵数均与其体长和体重成正相关关系。雌性成体的前肢长与抱对雄性成体的前肢长之间呈显著正相关,其余形态特征两性间均无相关性。研究表明,生育力选择是导致黑眶蟾蜍两性异形的重要驱动力;黑眶蟾蜍的选型配对模式未表现在个体大小上,而是体现在局部特征(前肢长),这不仅为揭示两栖类配对模式的普遍性提供了参考,还表明对两栖类选型配对的研究应以多个性状为对象。 相似文献
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Andrew R. Blaustein John M. Romansic Joseph M. Kiesecker Audrey C. Hatch 《Diversity & distributions》2003,9(2):123-140
Abstract. As part of an overall ‘biodiversity crisis’, many amphibian populations are in decline throughout the world. Numerous factors have contributed to these declines, including habitat destruction, pathogens, increasing ultraviolet (UV) radiation, introduced non‐native species and contaminants. In this paper we review the contribution of increasing UV radiation and environmental contamination to the global decline of amphibian populations. Both UV radiation and environmental contaminants can affect amphibians at all life stages. Exposure to UV radiation and to certain contaminants can kill amphibians and induce sublethal affects in embryos, larvae and adults. Moreover, UV radiation and contaminants may interact with one another synergistically. Synergistic interactions of UV radiation with contaminants can enhance the detrimental effects of the contaminant and UV radiation. 相似文献
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Jeremy M. Cohen Taegan A. McMahon Chloe Ramsay Elizabeth A. Roznik Erin L. Sauer Scott Bessler David J. Civitello Bryan K. Delius Neal Halstead Sarah A. Knutie Karena H. Nguyen Nicole Ortega Brittany Sears Matthew D. Venesky Suzanne Young Jason R. Rohr 《Ecology letters》2019,22(5):817-825
Global climate change is increasing the frequency of unpredictable weather conditions; however, it remains unclear how species‐level and geographic factors, including body size and latitude, moderate impacts of unusually warm or cool temperatures on disease. Because larger and lower‐latitude hosts generally have slower acclimation times than smaller and higher‐latitude hosts, we hypothesised that their disease susceptibility increases under ‘thermal mismatches’ or differences between baseline climate and the temperature during surveying for disease. Here, we examined how thermal mismatches interact with body size, life stage, habitat, latitude, elevation, phylogeny and International Union for Conservation of Nature (IUCN) conservation status to predict infection prevalence of the chytrid fungus Batrachochytrium dendrobatidis (Bd) in a global analysis of 32 291 amphibian hosts. As hypothesised, we found that the susceptibility of larger hosts and hosts from lower latitudes to Bd was influenced by thermal mismatches. Furthermore, hosts of conservation concern were more susceptible than others following thermal mismatches, suggesting that thermal mismatches might have contributed to recent amphibian declines. 相似文献
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Albert S. Feng Peter M. Narins 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2008,194(2):159-167
The concave-eared torrent frogs (Amolops tormotus) have highly unusual ear morphology--in males the eardrums are embedded deep inside ear cavities. In collaboration with our colleagues we investigated the functional significance of this morphological feature in hearing. Sound recordings in the field showed that males of A. tormotus produce diverse bird-like melodic calls with pronounced frequency modulations and non-linear phenomena (e.g., frequency jumps, different orders of subharmonics, and chaos) that often contain spectral energy in the ultrasonic range. The audible as well as the ultrasonic components of the species call could effectively evoke males' vocal responses, demonstrating that they can hear and respond to ultrasound. Electrophysiological recordings from the auditory midbrain confirmed the ultrasonic hearing capacity of these frogs. The recessed tympana and extremely thin tympanic membranes are adaptations for hearing ultrasound--this sensitivity may have evolved in response to the intense, predominately low-frequency ambient noise from local streams. Finally, results from the isolated laryngeal preparation in euthanized frogs revealed that the origin of call complexity and diversity lies with having a vocal system with nonlinear properties. 相似文献
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2003年7月和2004年1月对海南省黎母山自然保护区两栖动物资源进行了调查,结果表明,该区内有两栖动物1目5科13属25种,全部为东洋界种类,其中华南区成分有15种,华中华南区有10种,分别占黎母山两栖动物总数的60%和40%,海南特有种有7种,具有典型的华南区系成分和热带山地林灌动物群特征。国家Ⅱ级保护动物有虎纹蛙1种;数量优势种有黑眶蟾蜍、小湍蛙、泽蛙、细刺蛙、海南溪树蛙和背条跳树蛙;保护区内两栖动物物种多样性指数为37109,均匀性指数为08321。 相似文献