Reproductive Isolation with Little Genetic Divergence in Sympatric Populations of Brown Trout (SALMO TRUTTA)

Two reproductively isolated demes of brown trout coexist in a small Swedish mountain lake, Lake Bunnersj?rna. We electrophoretically examined 102 specimens from that lake for 27 enzymes encoded by 54 loci. The two demes are fixed for different alleles at a lactate dehydrogenase locus (LDH-1); statistically significant allele frequency differences at five other loci further support the complete lack of gene flow between these demes. There are significant differences in growth rates between fish in the two demes, but no further morphological differentiation h-s been detected.--In light of these findings, the genetic distance between these populations is surprisingly small (Nei's I = 0.975). These demes represent one of the least genetically divergent, reproductively isolated sympatric pair of vertebrate populations that have been identified. The results are discussed from both an evolutionary and ecological perspective.     

Genetic relationships and reproductive-isolation mechanisms among the Fejervarya limnocharis complex from Indonesia (Java) and other Asian countries

In order to elucidate the genetic relationships and reproductive-isolation mechanisms among the Fejervarya limnocharis complex from Indonesia and other Asian countries, allozyme analyses and crossing experiments were carried out using 208 individuals from 21 localities in eight Asian countries. The allozyme analyses revealed that 17 enzymes examined were controlled by genes at 27 loci, and that 7.9 phenotypes were produced by 5.2 alleles on average. The two species recognized in F. limnocharis sensu lato from Southeast Asia (i.e., F. limnocharis sensu stricto and F. iskandari) were found to occur sympatrically at three localities (Bogor, Cianjur and Malingping), all on Java, Indonesia. Fejervaya iskandari was dominant at each of these localities and showed substantial geographic genetic variation. Laboratory-produced hybrids between F. limnocharis and F. iskandari from Java became underdeveloped and died at the tadpole stage, suggesting that these species are completely isolated by hybrid inviability. Hybrids between topotypic F. limnocharis and the Malaysian and Japanese conspecific populations developed normally to metamorphosis. Likewise, hybrids between topotypic F. iskandari and the Thailand and Bangladesh conspecific populations also showed normal viability throughout larval development. The present allozyme analyses and crossing experiments strongly suggested the presence of two distinct forms, the large type and the small type, in the F. limnocharis complex from Asia, and further subdivision of the large type into the F. limnocharis assemblage and the F. iskandari assemblage. The small type was found in samples from India, Thailand, Bangladesh and Sri Lanka, and included at least three different species. The sample from Pilok, Thailand, was considered to represent an undescribed species.     

Morphology,Molecular Genetics,and Bioacoustics Support Two New Sympatric Xenophrys Toads (Amphibia: Anura: Megophryidae) in Southeast China

Given their recent worldwide declines and extinctions, characterization of species-level diversity is of critical importance for large-scale biodiversity assessments and conservation of amphibians. This task is made difficult by the existence of cryptic species complexes, species groups comprising closely related and morphologically analogous species. The combination of morphology, genetic, and bioacoustic analyses permits robust and accurate species identification. Using these methods, we discovered two undescribed Xenophrys species, namely Xenophrys lini sp. nov. and Xenophrys cheni sp. nov. from the middle range of Luoxiao Mountains, southeast China. These two new species can be reliably distinguished from other known congeners by morphological and morphometric differences, distinctness in male advertisement calls, and substantial genetic distances (>3.6%) based on the mitochondrial 16s and 12s rRNA genes. The two new species, together with X. jinggangensis, are sympatric in the middle range of Luoxiao Mountains but may be isolated altitudinally and ecologically. Our study provides a first step to help resolve previously unrecognized cryptic biodiversity and provides insights into the understanding of Xenophrys diversification in the mountain complexes of southeast China.     

Behavioural Divergence in Allopatric and Sympatric Gerbil Species (Rodentia: Gerbillinae)

Southern African gerbils comprise 3 genera, each genus represented by morphologically- and ecologically-similar species. All species are monomorphic, with social systems varying from asocial (Desmodillus auricularis) to colonial (Tatera species). This study compares the behaviour patterns of an allopatric species, T. afra, 2 sympatric species, T. leucogaster and T. brantsii, and a species of a different genus, D. auricularis which is sympatric with T. leucogaster and T. brantsii. Interactions between males and females of the same species were staged and quantified in terms of the frequencies of each of 23 behavioural acts. D. auricularis performed 2 acts, namely “sidle” and “fight” which have not been identified in Gerbillurus or Tatera interactions. Sequences of behaviour were similar in all species, and involved females moving away from males, which followed, sniffed the anogenital region and attempted to mount the females. Females responded by presenting, if receptive, or agonistic behaviour such as aggressive or upright postures. Exploration of the terrarium accounted for a large proportion of the behaviour during the 20 min encounter, and watching the opponent also occurred frequently. Discriminant function analysis successfully separated all 4 species on the basis of behaviour frequencies. Individuals were assigned to the correct species with an accuracy of 80%, indicating that each species exhibits species-specific patterns of behaviour. D. auricularis displayed more agonistic and sexual behaviour and less huddling behaviour than any of the Tatera species. The sympatric species-pair, T. leucogaster and T. brantsii, exhibited more significant difference in behaviour than either of the allopatric species-pairs, T. afra and T. brantsii, and T. afra and T. leucogaster. Divergence in behaviour patterns has occurred in allopatric species, but divergence is more marked in species which are sympatric. It is not known whether divergence between T. leucogaster and T. brantsii occurred during a period of allopatry, or whether divergence has occurred due to selection against hybrids in sympatry.     

Morpha striata in the members of the genus Rana (Amphibia, Anura), the reasons of adaptability to environmental changes

Under investigation is a complex of inherited physiological properties of the morpha striata (a monogenous dominant mutation) in two species of the genus Rana. Insufficient effectiveness of the potassium-sodium pump responsible for the skin transport in amphibians had lead to formation of a number of compensative physiological mechanisms in this morpha. The yearlings of the morpha striata are characterized by highly dynamic hemopoetic system playing important role in individual adaptations to unstable environments. Such a high level of metabolism in the morpha striata promotes rising of adaptive potential of the nervous system due to decrease of the excitability threshold, but causes shortening the life span. Therefore, physiological differences correlated with polymorph structure of the close species can be of crucial importance in their adaptations under existence in the natural and artificial geochemical anomalies and in anthropogenically disturbed ecosystems.     

Patterns of DNase sensitivity in the chromosomes of Rana perezi (Amphibia: Anura).

We have analyzed the patterns of DNase I/nick translation in the chromosomes of Rana perezi. The results show a nonuniform DNase sensitivity in different chromosome domains; the hypersensitivity appears to be concentrated at both the NOR and the distal regions. The resemblance to the situation in mammals, where active genes are DNase I hypersensitive, is discussed.     

Allozyme variation among Rana balcanica,R. levantina,and R. ridibunda (Amphibia: Anura)1

The allozyme variation among water frogs of the species R. balcanica, R. levantina and R. ridibunda, all formerly considered as one species (R. ridibunda Pallas, 1771), was studied using horizontal starch gel electrophoresis. Blood samples (N # 63) of frogs were collected from five populations in Greece and Israel. Samples (N = 9) of the hybrid frog R. esculenta collected from a locality in Germany were used as an outgroup for phylogenetic analyses. Fifteen enzymes controlled by twenty presumptive loci were identified. Thirteen loci were polymorphic within or among the studied populations. Genetic differentiation among the species was considerably greater than among populations of the same species. Even at Nestos River where R. ridibunda and R. balcanica occur in the same habitats, individuals could be assigned to either species due to characteristic differences of the genotypes (GPI1). This indicates reproductive isolation among these species. The reconstruction of phylogenetic relationships among the three species based on the allozyme data corroborated the model presented on the basis of bioacoustic data: R. ridibunda and R. balcanica (Nei's genetic distance D = 0.0820) are sibling species pertaining to an Eurasian lineage, whereas R. levantina (distance to the European species D = 0.1780 - 0.1955) together with R. perezi represent an independent afroasian lineage.     

Genetic Variation in Some Populations of the Golden-Striped Salamander, Chioglossa lusitanica (Amphibia: Urodela), in Portugal

Genetic variation in the golden-striped salamander (Chioglossa lusitanica) was assessed in 231 individuals from four Portuguese populations by means of horizontal starch gel electrophoresis and isoelectric focusing. Three of 19 enzyme systems, representing 21 presumptive loci, were found to be polymorphic: phosphoglucomutase 1 (PGM1), peptidase B (PEPB), and peptidase D (PEPD). The observed average heterozygosity in Chioglossa lusitanica (0.027) is significantly lower than that observed for other amphibians, either urodeles or salamandrids. Differences in allele frequencies and the presence of private alleles are indicative of a high degree of population differentiation. PEPD, in particular, seems to be a diagnostic locus separating the southernmost population studied from the others.     

Morphology and cell population kinetics of primary spermatogonia in the frog (Rana esculenta) (Amphibia: Anura)

Two morphologically distinct primary spermatogonial cell types were observed in the frog testis and distinguished on the basis of nuclear characteristics. They have been designated the pale and dark types of primary spermatogonia. On the basis of a kinetic analysis, it is proposed that the pale spermatogonia possess the faculty of self-renewal as well as that of forming dark spermatogonia; they are thus bipotential stem cells comparable to the undifferentiated type of mammalian spermatogonia. The dark spermatogonia, in contrast, are committed to a single pathway, i.e. to form secondary sperrnatogonia, and can be defined as differentiated or committed elements of the primary spermatogonial population. The number of stem cell spermatogonia and differentiated spermatogonia vary according to the period of the year, as does the rate of turnover of stem cells, with nearly 60–90% of cells temporarily out of the cell cycle at any given time. It is indicated that the spermatogonial population represents a 'cell renewal system' in a steady state for appreciably long periods of time, however, changing with season in as far as the magnitude of yield of spermatogonial cells is concerned. This implies that an equality should exist between the rate at which stem cells enter cell-cycling and the rate at which daughter cells change their morphological identity.     

A New Species of the Asian Toad Genus Megophrys sensu lato(Amphibia: Anura: Megophryidae) from Guizhou Province,China

We describe a new species of the genus Megophrys sensu lato from Guizhou Province, China. Molecular phylogenetic analyses based on mitochondrial DNA and nuclear DNA sequences all strongly supported the new species as an independent lineage in Megophrys(Panophrys) clade. The new species is distinguished from its congeners by a combination of the following morphological characteristics:(1) small body size with SVL 38.8 mm in male and SVL 42.3 mm in female;(2) vomerine teeth absent;(3) tongue not notched behind;(4) a small horn-like tubercle at the edge of each upper eyelid;(5) tympanum distinctly visible, rounded;(6) two metacarpal tubercles in hand;(7) relative finger lengths: II I V III;(8) toes with rudimentary webbing at bases;(9) heels overlapping when thighs are positioned at right angles to the body;(10) tibiotarsal articulation reaching the level between tympanum to eye when leg stretched forward;(11) an internal single subgular vocal sac in male;(12) in breeding male, the nuptial pads with black nuptial spines on the dorsal bases of the first and second fingers.     

Heterochronies in the cranial development of Asian tree frogs (Amphibia: Anura: Rhacophoridae) with different life histories

The development of bony skull was studied in four species of Asian tree frogs (Rhacophoridae) with different life histories: biphasic development with free larval stage and direct development. In biphasic rhacophorids the sequence of the appearance of cranial bones generally followed the generalized pattern of craniogenesis, which was described for most studied anurans. In contrast, direct-developing species displayed some heterochronies in the formation of skull bones, namely, the accelerated formation of the anlagen of jaw and suspensorium bones. The obtained results support that the embryonization in amphibians is regularly accompanied by a heterochronic repatterning of craniogenesis, rather similar in different phyletic groups.     

Taxonomic Revision of Raorchestes menglaensis(Kou,1990)(Amphibia:Anura),with Descriptions of Two New Species from Yunnan,China

Raorchestes is a group of Bush frogs mainly distributed in South and Southeast Asia that are poorly recognized by morphological criteria.We recognize the true R...     

Morphological differentiation among populations of Rhinella marina (Amphibia: Anura) in western Mexico

Conspecific populations inhabiting different environments may exhibit morphological differences, potentially reflecting differential local adaptation. In anuran amphibians, morphology of the pelvis and hindlimbs may often experience strong selection due to effects on locomotion. In this study, we used the cane toad Rhinella marina to test the hypothesis that populations experiencing a higher abundance of predators should suffer higher mortality rates and exhibit morphological traits associated with enhanced locomotor performance (narrower pelvis and head, longer pelvis and hindlimbs, shorter presacral vertebral column). We investigated inter-population variation in survival rate, abundance of predators, and body shape across five populations in rivers in western Mexico. We conducted (1) mark-recapture experiments to calculate survival rates, (2) linear transects with point counts to estimate abundance of predatory spiders, snakes, and birds, and (3) geometric morphometric analyses to investigate body shape variation. We found significant differences among populations in survival rates, abundance of predators, and body shape. However, these three variables were not necessarily inter-related. Increased predator abundance did not result in decreased survival rates, suggesting other causes of mortality affect these populations. While some morphological differences supported our predictions (trend for longer pelvis, shorter presacral vertebral column, and narrower head in sites with increased abundance of spiders and snakes), other aspects of morphology did not. We discuss alternative explanations for the lack of clear associations between predation, survival, and morphology.     

Genetic relationships among Korean brown frog species (Anura,Ranidae), with special reference to evolutionary divergences between two allied species Rana dybowskii and R. huanrenensis

Allozyme analysis for 41 populations of brown frog species, Rana dybowskii, R. huanrenensis, and R. amurensis from Korea and three reference species (Chinese R. chensinensis and Japanese R. dybowskii and R. tsushimensis), were performed to clarify taxonomic status of Korean brown frogs. The level of average genetic differentiation (Nei's D) among local populations of each species in Korea was very low (D<0.01 2) and Korean and Japanese R. dybowskii also showed conspecific level of differentiation (D=0.070). Whereas, much larger, discrete genetic differences were detected in the interspecific comparisons (D>0.370). In the genetic relationships among five species examined, the 24 chromosome brown frogs (R. dybowskii, R. huanrenensis, and R. chensinensis) did not form a monophyletic group. Rana dybowskii with the chromosome number of 2n=24 was grouped together with R. amurensis with the chromosome number of 2n=26. The hypothesis of reversal change from 24 to 26 in Korean R. amurensis seems to better explain the phylogenetic relationships of east Asian brown frogs than the assumption of parallel reduction in chromosome number from 2n=26 to 24 in R. dybowskii and in the common ancestor of R. huanrenensis and R. chensinensis. The genetic, morphological, and reproductive divergences between Korean R. dybowskii and R. huanrenensis were compared.     

Call Characteristics of Two Sympatric and Morphologically Similar Tree Frogs Species,Polypedates megacephalus and Polypedates mutus(Anura: Rhacophoridae), from Hainan,China

Anuran calls are usually species-specific and therefore valued as a tool for species identification. Call characteristics are a potential honest signal in sexual selection because they often reflect male body size. Polypedates megacephalus and P. mutus are two sympatric and morphologically similar tree frogs, but it remains unknown whether their calls are associated with body size. In this study, we compared call characteristics of these two species and investigated any potential relationships with body size. We found that P. megacephalus, males produced six call types which consisting of three distinct notes, while P. mutus males produced five types consisting of two types of notes. Dominant frequency, note duration, pulse duration, and call duration exhibited significant interspecific differences. In P. megacephalus, one note exhibited a dominant frequency that was negatively correlated with body mass, snout-vent length, head length, and head width. In P. mutus, the duration of one note type was positively correlated with body mass and head width. These differences in call characteristics may play an important role in interspecific recognition. Additionally, because interspecific acoustic variation reflects body size, calls may be relevant for sexual selection. Taken together, our results confirmed that calls are a valid tool for distinguishing between the two tree-frog species in the field.     

The Species and Size Composition of Tropical Freshwater Zooplankton with Special Reference to the Oriental Region (South East Asia)

A contrast between temperate and tropical Cladocera, Copepoda and Rotifera zooplankton fauna shows a markedly different size composition and species diversity. There are fewer species, and these are generally smaller in the tropics than in either the North or South Temperate Zones. Larger species of the genera Daphnia and Simocephalus are relatively rare in the tropics, while members of Eurycerus and Saycia are absent. Members of the families Holopedidae, Leptodoridae and Polyphemidae increase in abundance toward the temperate regions. Two small cyclopoid copepods are common in tropical zooplankton, while many of the common larger species of other regions are absent or very rare. The chief rotifer components are Keratella tropica and species of Brachionus.     

Reevaluation of the Holotype of Odorrana schmackeri Boettger,1892(Amphibia:Anura:Ranidae)and Characterization of One Cryptic Species in O.schmackeri sensu lato through Integrative Approaches

The Odorrana schmackeri sensu lato is a group of cascade frogs that are widely distributed in southern China.However,their taxonomy has long been unresolved and...     

Karyotype study of Rana camerani and comparisons with the other 26-chromosome European brown frog species (Amphibia, Anura).

The results of a detailed morphological and morphometrical chromosome analysis of Rana camerani (2n = 26) are described. It was established that the karyotype of this species consisted of three homologous pairs of large metacentrics, two homologous pairs of large submetacentrics, three homologous pairs of small metacentrics, two homologous pairs of small submetacentrics, and three homologous pairs of small subtelocentrics. Morphologically discernible sex chromosomes were not found. The similarity and peculiarities in the R. camerani karyotype and those of R. temporaria, R. dalmatina and R. graeca are discussed. This comparative karyotype analysis has suggested the possibility for developing a general chromosomal formula, by means of which these 26-chromosome species could be characterized.