黑眶蟾蜍、黑斑蛙、中国雨蛙不同地理居群的染色体多样性

本文研究温州地区的黑眶蟾蜍、黑斑蛙、中国雨蛙的核型,分析了三个地理居群的黑星期五蟾蜍、四个地理居群的黑斑蛙、三个地理居群的中国雨蛙核型。结果表明不同地理居群的同种蛙有相同的染色体数和核型模式。黑星期五蟾蜍为2n＝22,NF＝44,核模式6＋5;黑斑蛙为2n=26,NF=52,核模式5＋8;中国雨蛙为2n＝24,NF＝48,核模式6＋6。但同一种蛙的不同地理居群之间在SM数目和顺序、次缢痕或随体的位置等有所不同。说明不同地理居群的同种蛙的染色体具有丰富的多样性。     

Multiscale determinants of tree frog (Hyla arborea L.) calling ponds in western Switzerland

A tree frog (Hyla arborea L., 1758) metapopulation in western Switzerland was studied during spring 2001. All potential calling ponds in an area of 350km² were searched for tree frog calling males. Twenty-nine out of 111 ponds sheltered between 1 and 250 callers. Most ponds were occupied by less than 12 males. Pond parameters were measured at three different levels using field analysis and a Geographical Information System (GIS). The first level was water chemistry and pond-associated measures. The second level was the surrounding land use in a 30m buffer around the pond. The third level consisted of landscape indices on a broader scale (up to 2km). Logistic regression was applied to identify parameters that can predict the presence of calling males in a pond. Response variable was the presence or absence of callers. Four significant parameters allowed us to explain about 40% of the total deviance of the observed occupational pattern. Urbanization around the pond had a highly negative impact on the probability of presence of calling males. Hours of direct sunlight on the pond was positively correlated with callers. Higher water conductivity was associated with a lesser probability of species presence. Finally, the further the closest two-lane road, the higher the probability of callers presence. Our results show that presence or absence of callers is influenced by factors acting at various geographical scales.     

A molecular perspective on the phylogeny of the Hyla pulchella species group (Anura, Hylidae)

A molecular phylogenetic analysis of the Hyla pulchella species group was performed to test its monophyly, explore the interrelationships of its species, and evaluate the validity of the taxa that were considered subspecies of H. pulchella. Approximately 2.8 kb from the mitochondrial genes 12s, tRNA valine, 16s, and Cytochrome b were sequenced. The analysis included 50 terminals representing 10 of the 14-15 species currently recognized in the H. pulchella group, including samples from several localities for some taxa, several outgroups, as well as two species previously suspected to be related with the group (Hyla guentheri and Hyla bischoffi). The results show that the H. pulchella and Hyla circumdata groups are distantly related, and, therefore, should be recognized as separate groups. As currently defined, the H. pulchella group is paraphyletic with respect to the Hyla polytaenia group; therefore, we recognize the Hyla polytaenia clade in the H. pulchella group. Two subspecies of H. pulchella recognized by some authors are considered full species including Hyla pulchella riojana because it is only distantly related to H. pulchella, and Hyla pulchella cordobae because molecular and non-molecular evidence suggests that it is specifically distinct. With the inclusion of the H. polytaenia clade, H. guentheri, and H. bischoffi, and the recognition of the two former subspecies of H. pulchella as distinct species, the H. pulchella group now comprises 25 described species. All representatives of the H. pulchella group with an Andean distribution are monophyletic and nested within a clade from the Atlantic forest from south-southeastern Brazil/northeastern Argentina, and Cerrado gallery forest from central Brazil.     

Recombination is suppressed and variability reduced in a nascent Y chromosome

Several hypotheses have been elaborated to account for the evolutionary decay commonly observed in full-fledged Y chromosomes. Enhanced drift, background selection and selective sweeps, which are expected to result from reduced recombination, may all share responsibilities in the initial decay of proto-Y chromosomes, but little empirical information has been gathered so far. Here we take advantage of three markers that amplify on both of the morphologically undifferentiated sex chromosomes of the European tree frog (Hyla arborea) to show that recombination is suppressed in males (the heterogametic sex) but not in females. Accordingly, genetic variability is reduced on the Y, but in a way that can be accounted for by merely the number of chromosome copies per breeding pair, without the need to invoke background selection or selective sweeps.     

Interspecific differences in molecular weights of skeletal myosin,actin, troponin C and tropomyosin in the frogs <Emphasis Type="Italic">Hyla japonica</Emphasis> and <Emphasis Type="Italic">Xenopus tropicalis</Emphasis>

Molecular weights of the skeletal muscle myosin, actin, troponin C and tropomyosin were compared in two frog species, Hyla japonica and Xenopus tropicalis, by SDS-PAGE and Western blot. Polyclonal antibody was produced using H. japonica skeletal muscle as the antigen. Polyclonal antibodies to nematode (Caenorhabditis elegans), mold slime (Physarum polycephalum), crab (Pagurus japonicus) and chicken skeletal muscle were also used. In H. japonica, the molecular weights of skeletal myosin, actin, troponin C and tropomyosin were 230, 42, 19 and 38 kDa, respectively, by using anti-C. elegans paramyosin, anti-P. polycephalum actin, anti-crab troponin C and anti-chicken gizzard tropomyosin antibodies. Molecular weights of the same proteins in X. tropicalis detected by the same antibodies were 230, 43, 20 and 40 kDa, respectively. In total, 29 protein bands were detected in H. japonica skeletal muscle and 24 bands in X. tropicalis by SDS-PAGE. The results revealed interspecific differences in molecular weights of selected skeletal muscle proteins and in the total skeletal muscle protein profiles between the two frog species.     

Phylogeography of the canyon treefrog, Hyla arenicolor (Cope) based on mitochondrial DNA sequence data

Patterns of phylogeography and gene flow were examined in the canyon treefrog, Hyla arenicolor. A total of 973 bp of mitochondrial cytochrome b sequence data were obtained for 65 individuals from 53 populations, yielding 50 unique haplotypes. Interpopulation sequence variation ranged from 0 to 13.7%. Phylogenetic analysis revealed three deeply divergent mtDNA lineages. These three Clades were mapped onto geography and found to represent completely concordant, nonoverlapping, geographical regions. Levels of sequence divergence between the three Clades were equal to or greater than published levels of divergence found in other vertebrate species and genera. Furthermore, one Clade of H. arenicolor was found to be more closely related to the outgroup H. eximia than to other H. arenicolor, suggesting that the taxonomy of this species may require revision.     

Relationship of Endangered Amphibians to Landscape Disturbance

Abstract: We examined the density of 2 endangered amphibians, natterjack toads (Bufo calamita) and yellow-bellied toads (Bombina variegata), in 150 breeding pools at each of 2 military training areas in the German state of Bavaria. We selected pools to ensure a wide range of observable ground disturbance resulting from military vehicular traffic during cross-country maneuvers. Both species exhibited significant affinity for pools with high levels of ground disturbance. Natterjack toads preferred pools with 80–100% ground disturbance; yellow-bellied toads preferentially occupied pools with 40–100% ground disturbance. Pools occupied by the target species were characterized by higher levels of bare ground and minimal vegetation. Among other observed amphibians, European edible frogs (Rana esculenta) preferred pools with ≤60% ground disturbance, less bare ground, more vegetative cover, and disturbance >2 years old. Common tree frogs (Hyla arborea), smooth newts (Triturus vulgaris), and alpine newts (T. alpestris) showed no preference for level of disturbance; densities were correlated to parameters apparently unrelated to disturbance. The habitat mosaic created by the heterogeneous nature of military training disturbance may help explain the high biodiversity that often characterizes military training areas. Preservation of native biodiversity is dependent on maintaining an appropriate disturbance regime that, in turn, maintains a habitat mosaic conducive to the presence of native species adapted to a broad disturbance—succession continuum. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):738–744; 2008)