Biological invasions and the acoustic niche: the effect of bullfrog calls on the acoustic signals of white-banded tree frogs

Invasive species are known to affect native species in a variety of ways, but the effect of acoustic invaders has not been examined previously. We simulated an invasion of the acoustic niche by exposing calling native male white-banded tree frogs (Hypsiboas albomarginatus) to recorded invasive American bullfrog (Lithobates catesbeianus) calls. In response, tree frogs immediately shifted calls to significantly higher frequencies. In the post-stimulus period, they continued to use higher frequencies while also decreasing signal duration. Acoustic signals are the primary basis of mate selection in many anurans, suggesting that such changes could negatively affect the reproductive success of native species. The effects of bullfrog vocalizations on acoustic communities are expected to be especially severe due to their broad frequency band, which masks the calls of multiple species simultaneously.     

Caractères et évolution des enzymes chitinolytiques chez les vertébrés infèrieurs

The activity of chitinases extracted from various organs of different fish, amphibians and reptiles was estimated as a function of pH by using “native” chitin as substrate. Three types of chitinase activity were recorded, suggesting the existence of three different chitinase types: Type 1: (optimum pH; 4.5, no activity at pH 1.0) was found in various organs, such as intestine, pyloric caeca, pancreas, liver, spleen, etc.); Type IIa: (optimum pH; 3.0, weak activity at pH 1.0) was obtained from the gastric mucosa of fish and one species of urodele; Type IIb: (optimum pH; 3.0, strong activity at pH 1.0) was found in the gastric mucosa of reptiles and batrachian anura. Chitinase activity appears to be adapted to the pH of the digestive fluids. A tentative scheme is presented of chitinase evolution among lower vertebrates.     

Activation of a neuralizing factor in amphibian ectoderm

Summary Isolated gastrula ectoderm has no neural-inducing activity and does not differentiate into neural tissues. It has, however, a high neural-inducing capacity, but the inducing factors are present in a masked, inactive form. The inducing factors are partially activated by homogenization and by freezing of the homogenate and are fully activated by treatment with ethanol. The relative distribution of inducing factors in different subcellular fractions changes after treatment with demecolcine and cytochalasin B or after autolytic incubation of the homogenate. The inducing activity of the high-speed supernatant is enhanced under these conditions. The experiments suggest that the activation of neuralizing factor(s) depends on the release from complex structures. Cytoskeletal elements seem to be involved. When early neural plate homogenate was fractionated, the high-speed supernatant showed neural-inducing activity. This is in contrast to the high-speed supernatant from the ectoderm homogenate, which shows no such activity.     

Evolution of the 5 S RNA genes in vertebrates

Summary We have built the phylogenetic tree of Vertebrate 5S RNA using the sequence data of thirteen species belonging to six groups. Evolution of the 5S genes has been very slow in Vertebrates since 90 residues are identical in all 5S RNAs which are presently sequenced.In Amphibians and Teleosts different 5S genes are active in oocytes and in somatic cells. This dual gene system has probably been acquired independently by Amphibians and Teleosts. In Amphibians, the oocyte-type 5S genes have evolved much faster than the somatic-type genes. This is not true in all species since the oocyte-type genes of one Teleost (Tinca tinca) have evolved more slowly than the somatic-type genes.There are in all Vertebrate 5S RNAs five complementary regions which can be base-paired. The sequence data are compatible with the three secondary-structure models that have been proposed for 5S RNA.     

中国肥螈属(两栖纲:蝾螈科)一新种——弓斑肥螈Pachytriton archospotus sp. nov.

本文记述两栖纲蝾螈目蝾螈科一新种,新种具肥螈属(Pachytriton)系列特征,与肥螈属已知2种比较有明显区别.如1)本新种与黑斑肥螈(Pachytriton brevipes)相似,体表具黑色小圆斑,但新种具额鳞弓、上鳃骨直而与后者不同;无斑肥螈(Pachytriti on labiatus)(地模标本)虽具额鳞弓,但上鳃骨明显弯曲,体表无黑色小圆斑;2) 新种吻短,吻长小于眼间距,黑斑肥螈吻长大于眼间距,无斑肥螈吻长大于或等于眼间距, 它们的头型明显不同,虽然三者头长均大于头宽,但头长、吻长、眼间距差异显著;3)繁 殖期新种雄体肛区不明显肿胀,肛裂周边中、后部生殖乳突长,而且多,十分醒目;黑斑肥 螈和无斑肥螈繁殖期肛区明显肿胀膨大,生殖乳突较短、且稀.经统计分析三种肥螈的头体长、头长、头宽、吻长和眼间距存在显著差异     

山东昆嵛山蛙属林蛙群一新种(两栖纲:无尾目:蛙科)

在山东省胶东半岛昆嵛山采集到林蛙类及其蝌蚪标本,与中国林蛙Raha chensinensis具背侧褶弯曲等特征极相似,但有以下主要区别;无声囊,无雄性线,雄性第1指婚垫分2团,蝌蚪唇齿式多为Ⅰ：1-1/Ⅲ,少数为Ⅰ：1-1/Ⅱ：1-1。此蛙与已知林蛙其它种有明显区别,故定为新种,即昆嵛林蛙Rana kunyuensis sp.nov。     

Evolution of reproduction in the Rhacophoridae (Amphibia, Anura)

Rhacophorid treefrogs have different reproductive modes: some go through a tadpole stage and some have direct development, and the adults of some species produce foam nests. Philautus is the only genus characterized by direct development. The production of foam nests has been reported in the genera Polypedates, Rhacophorus, Chiromantis and Chirixalus. Recent molecular studies did not provide a robust hypothesis concerning the origin of these reproductive modes in the Rhacophoridae. In order to better understand the evolution of these reproductive modes, we tried to clarify relationships within this group, using DNA sequencing. Our data set consists in a large number of new sequences (1676 base pairs corresponding to threee genes) for five outgroup ranoids and 48 Rhacophoridae, including 16 undescribed species from Sri Lanka and southern India, and all homologous data available in Genbank. After the inclusion of Philautus from India, our data show that the separation of Philautus into clades does not coincide with their geographic distribution. Our data point to the existence of a clade, including the genera Rhacophorus, Polypedates, Chiromantis and Chirixalus, which confirms the results of Wilkinson et al. (2002) and suggests that the ability to produce foam nests has emerged only once in the Rhacophoridae, as already stated by these authors.