Temperature dependence of auditory thresholds in two Central European anurans, Bombina variegata variegata (L.) and Rana ridibunda ridibunda Pall. (Amphibia), and its relation to calling

We recorded multi-unit activity from the torus semicircularis in two European anurans, to test for temperature dependence of the auditory thresholds. In Rana r. ridibunda the entire threshold-vs.-frequency curve shifts downward for a temperature increase from 5° to 15° C; the average increase in sensitivity is 14 dB. In Bombina v. variegata the increase in sensitivity averages 8 dB for a rise in temperature from 12° to 20° C; in addition, the best frequency is shifted by about 150 Hz by this increase in temperature, from 350—400 Hz to 550 Hz. The audiogram of Rana r. ridibunda differs from that of Bombina v. variegata in that it is markedly trimodal; the sensitivity maxima for Rana fall at 300—500 Hz, 750–1000 Hz and 1250–1700 Hz.     

The mating call of hybrids of the fire-bellied toad and yellow-bellied toad (Bombina bombina (L.), Bombina v. variegata (L.), discoglossidae,anura)

Summary Male hybrids obtained by crossing Bombina bombina with Bombina v. variegata displayed calling behavior when treated with hormones at the age of about 12 months. The mating calls of the hybrids are intermediate with respect to rate, duration, inter-call interval, and fundamental frequency between the calls of the two purebred species.     

Effect of temperature upon auditory thresholds in two anuran species,Bombina v. variegata andAlytes o. obstetricans (Amphibia,Discoglossidae)

Summary Because it seemed likely that temperature affects not only the calling mechanism of anurans, but their auditory systems as well, we have measured the thresholds ofBombina variegata variegata andAlytes obstetricans obstetricans at 5°, 12°, 20° and 28°C by recording multiple-unit activity from the torus semicircularis. An increase in temperature from 5° to 28°C shortened the latencies considerably. InBombina v. variegata latencies fell from an average of 32 ms to 13 ms (600 Hz), and inAlytes o. obstetricans from an average of 22 ms to 11 ms (500 Hz). At frequencies below 500 Hz the decrease was still greater. Latency was also dependent on frequency, being shorter with high-frequency tones. At 5°C the auditory neurons ofBombina are rather insensitive and respond irregularly. At 12°C and at 20°C sensitivity is markedly increased. The minimum threshold in males was at 400–500 Hz (49 dB SPL), and that of females was at 450 Hz (47 dB SPL). There was no further increase in sensitivity at 28°C. InAlytes the auditory neurons were fully functional even at 5°C. At this temperature the audiogram had sensitivity maxima at 300, 1,100–1,300 and 1,800 Hz. In both males and females an increase in temperature to 20°C caused an extraordinary increase in sensitivity, primarily in the low-frequency range; the minimum threshold, at 400 Hz, was 44 dB SPL in males and 41 dB SPL in famales. In the intermediate frequency range there was also a marked increase in sensitivity, but not in the high-frequency range, where the best frequency was 1,800 Hz. At 28°C the threshold to low-frequency tones was increased.     

Respiratory metabolism of temperature acclimated Fundulus heteroclitus (L.): Zones of compensation and dependence

The oxygen consumption of temperature acclimated mummichogs, Fundulus heteroclitus (L.) weighing ≈0.1–10.0 g, was measured at 5, 13, 21, and 29 C. Between 13 and 21°C and 21 and 29°C, the values of Q₁₀ were 1.55 and 1.04, respectively, indicating relative thermal independence of respiratory metabolic rate over this 16°C range (Q₁₀ = 1.27). This range encompasses the normal late spring, summer, and early fall range of habitat temperature in Maine estuaries, so that mummichogs are able to grow and reproduce relatively independent of environmental temperature. Between 5 and 13°C, respiratory metabolism is very temperature sensitive (Q₁₀ = 4.42) indicating a substantial reduction of metabolic processes at low temperatures. This enables mummichogs to conserve any metabolic reserves during the coldest months. The regression of log weight-specific oxygen consumption on log body weight was determined at each experimental temperature. All had significantly negative slopes indicating the importance of body size in mummichog respiration.     

Temperature dependence of oocyte cleavage in three thermophilically different frogs of the genus Rana

The duration of the mitotic cycle (τ₀) at different temperatures at the time of synchronous cleavage division of oocytes of frogs Rana temporaria L., Rana arvalis Nilss. (= Rana terrestris Andr.) and Rana ridibunda Pall. has been studied. The first species is the least, and the last the most, thermophilic. In the semilogarithmic scale, the dependence of τ₀ on temperature is linear in the middle of the temperature scale, and is limited on both sides by inflexion points. This zone comprises the temperatures at which the larvae develop normally. For R. temporaria these temperatures are between 11–23°C. for R. arvalis 13–24°C and for R. ridibunda 16–27°C. At the midpoints of each zone (17.5, 18.5 and 21.5°C respectively) there is no difference in τ₀ between the species. At the same temperature, however, the mitotic cycle is the shortest for R. temporaria, is somewhat longer for R. arvalis and is the longest for R. ridibunda. The difference in the optimal temperature zones agree with different thermal stabilities of the cells and proteins of these species.     

Effects of different temperatures on the life history of Evania appendigaster L. (Hymenoptera: Evaniidae), a solitary oothecal parasitoid of Periplaneta americana L. (Dictyoptera: Blattidae)

The influence of temperatures on the life parameters of the solitary oothecal parasitoid Evania appendigaster, was investigated in the laboratory. Parasitized oothecae of Periplaneta americana were left to develop under seven constant temperatures: 15, 17, 20, 25, 30, 35, and 40 °C. At the end, we found that: (i) E. appendigaster was able to complete development within the temperature range of 17–34 °C; (ii) mean adult longevity decreased as temperature increased, with the temperature of 40 °C being fatal in a matter of hours; (iii) males lived longer than females between 15 and 30 °C; (iv) adult emergence rate was the highest at 25 °C, and (v) no wasps emerged at 15 or 40 °C. Non-emerged oothecae contained either unhatched eggs or dead larvae. We determined the theoretical lower developmental threshold and thermal constant for the complete development as 12.9 °C and 584.8 day-degrees for males, and 13.1 °C and 588.2 day-degrees for females, respectively. A good balance between faster development, maximum adult longevity and good egg viability was obtained between 25–30 °C, and that would be the best temperature range for rearing E. appendigaster.     

The effect of temperature and body size on digestive efficiency in Fundulus heteroclitus (L.)

The digestive efficiency of temperature acclimated mummichogs, Fundulus heteroclitus (L.), was determined using the amphipod Orchestia grillus Bosc as prey. Experiments were conducted on three size groups of mummichogs (<1 g, 1–3 g, > 3 g) at 5, 13, 21, and 29 °C. No difference was found in digestive efficiency by different sizes of mummichogs. There was, however, a statistically significant difference in efficiency over the range of acclimation temperatures, with the efficiencies being temperature independent from 13 to 29 °C and dropping slightly at 5 °C. From 13 to 29 °C, digestive efficiencies were the maximum possible. Temperatures in this range are normal late spring, summer, and early fall habitat temperatures in Maine estuaries. The ability to maintain a maximum efficiency of digestion over this 16°C temperature range allows mummichogs to get the maximum amount of energy from their prey during the time of year when they are utilizing substantial energy for growth (somatic and gonadal, and for activity (foraging and mating). The digestive efficiency at 5 °C was only about 13.5% less than at 21 and 29 °C. This drop is probably of little ecological or energetic significance, so that mummichogs are actually able to absorb food energy across their alimentary tract relatively independent of acclimation temperature over a 24 °C range.     

Nine new tetranucleotide microsatellite markers for the fire‐bellied toad (Bombina bombina)

We describe nine new polymorphic tetranucleotide microsatellite loci isolated from the fire‐bellied toad (Bombina bombina). The relative yield of new loci was higher than described in previous studies in amphibians: out of 12 loci initially evaluated, nine were polymorphic and amplifying reliably. Number of alleles ranged from four to 10 and observed heterozygosities from 0.47 to 0.91. Seven loci were polymorphic also in Bombina variegata and five in Bombina orientalis. Enrichment protocols yielding long flanking regions potentially overcome difficulties (i.e, low yield of reliable loci relative to number of clones screened) which have been reported in microsatellite development in anurans.     

How can ontogeny help us to understand the morphology of anuran pectoral girdle?

The ontogenetic development of the pectoral girdle in seven anuran species (Xenopus laevis, Discoglossus pictus, Bombina bombina, Bombina variegata, Pelobates fuscus, Bufo bufo and Rana dalmatina) was studied using cleared and stained specimens. The epicoracoid cartilage was found to develop in two different ways resulting in an arciferal or firmisternal type of the pectoral girdle. In the arciferal one, the epicoracoid originates from a medial prolongation of the procoracoid cartilage and broadly overlaps its counter part during further development. In the firmisternal pectoral girdle, the epicoracoids are formed by the widened cartilaginous medial edges of the coracoids that fuse together along the midline. Polarization of ontogenetic characters shows, that omosternum evolves inside Anura, and the type of sternum occurring in basal Anura seems to be an apomorphy of all Batrachia. The sternal elements have a single or paired rudiment, their development is connected with M. rectus abdominis or a zonal area and they remain cartilaginous or ossify during postmetamorphic development. An occurrence of omosternum in Barbourula busuangensis was described for the first time.     

Retinoic acid homeostasis regulates meiotic entry in developing anuran gonads and in Bidder’s organ through Raldh2 and Cyp26b1 proteins

The vitamin A (retinol) and its metabolites such as retinoic acid (RA) affect vertebrate gametogenesis. The level of RA in cells relies on the balance between its synthesis and degradation. The sex-dependent equilibrium is reached in different ways in various species. It is known that RA induces meiosis in developing gonads in mouse, chicken and urodel amphibians, but its role in anuran amphibians has not been studied. Here we show in six anuran species (Xenopus laevis, Bombina bombina, Hyla arborea, Bufo viridis, Rana arvalis and Rana temporaria) that cultured undifferentiated gonads were insensitive to RA treatment, but the RA induced ectopic meiosis in cultured larval testes. In larval testes of all studied species, the exogenous RA induced leptotene phase of I meiotic prophase in gonia, but only in H. arborea and B. viridis gonia progressed to zygotene phase. In the cultured developing ovaries, exogenous RA led to increase in the number of oocytes as compared to the control. Inhibition of either RA synthesis or RA-receptors prevented meiotic entry in larval gonads of all species. Exogenous RA rescued this inhibitory effect demonstrating that the balance in RA homeostasis plays a key role in meiotic entry in anuran gonads. The localization of two enzymes, Raldh2 and Cyp26b1, which antagonistically control RA levels and whose abundance suggests the sites of RA synthesis and degradation respectively, showed two distinct expression patterns specific for (i) X. laevis, H. arborea, R. arvalis, R. temporaria and (ii) B. bombina, B. viridis. Thus, RA, in correlation with specific expression patterns of Raldh2 and Cyp26b, induces meiosis during gonad development in anurans. In addition, in B. viridis, RA signalling seems important for development of the Bidder’s organ containing oocytes both in males and females.     

Hybridization between the fire-bellied toads Bombina bombina and Bombina variegata in the karst regions of Slovakia and Hungary: morphological and allozyme evidence

Geographic variability and genetic interactions in the contact zone between the fire-bellied toads, Bombina bombina and B. variegata, were studied using analysis of morphological and genetic variation in sixteen samples from the Slovak Karst and Aggtelek Karst regions. Genotype frequencies at four marker loci (Ldh-1, Mdh-1, Adk, Hem) demonstrate the existence of a hybrid zone with highly variable population structures. While some samples appear to represent panmictic hybrid populations, other samples are very heterogeneous. Pure individuals of both species occurred together with hybrids at one site. Habitat segregation among genetically differentiated demes probably causes this heterogeneity of population structures. Increased frequencies of the allele Ldh-1^M, which is present in low proportion in B. bombina south of the contact zone, were found in some hybrid populations.     

Genetic Differentiation Among Peripheral Populations of Bombina bombina from Thrace and Anatolia: An Allozyme Analysis

Genetic structures of Bombina bombina populations, located as peripheral isolates in Turkish Thrace and northwestern Anatolia, were analyzed by polyacrylamide gel electrophoresis using 20 allozyme loci, to investigate the populations’ current genetic variation and possible colonization history. Significant genetic variability was detected in most of the loci and all populations. Allozyme pairwise F _ST matrices and distribution of allele frequencies indicate their very close genetic relationships and relatively recent formation. Mean genetic distance values between Thracian and Anatolian populations indicate a Middle or Upper Pleistocene lineage separation before the formation of the Bosporus as an isolating geographic barrier. All the samples show substantial heterozygosity excess, and there was statistically significant evidence of recent bottlenecks. The extent and patterns of genetic divergence indicate that the Anatolian and Thracian populations have probably experienced bottlenecks, and incipient speciation may have occurred in Anatolian populations of B. bombina.     

Fitness parameters of Plutella xylostella (L.) (Lepidoptera; Plutellidae) at four constant temperatures by using age-stage,two-sex life tables

Different temperature zones have significant impact on the population dynamics of Plutella xylostella. Effective management of P. xylostella requires the knowledge of temperature tolerance by different life stages. In the current study, fitness parameters of diamondback moth were reported by using age-stage, two-sex life table traits at four constant temperatures (15, 20, 25 and 30 °C). The life cycle of P. xylostella was significantly longer at 15 °C. The 20 °C level of temperature was found optimal for fecundity, gross reproductive rate (51.74 offspring) and net reproductive rate (44.35 offspring per individual). The adult pre-oviposition period was statistically at par at all four level of temperatures. However, the survival was maximum at 20 °C as compared to other three temperature ranges. Based on the current study, it was concluded that temperature has a great role in population build-up of P. xylostella and effective management tactics should be applied to prevent significant damage to cabbage and other cruciferous crops when the temperature in the field is near 20 °C.     

Vasoactive intestinal polypeptide (VIP)-like immunoreactivity in anuran intestine

Summary Immunocytochemical and radioimmunological techniques with region specific antisera have been used to identify a vasoactive intestinal polypeptide-like material in the anuran intestine. Seven species of Anura were investigated: Bombina bombina, Alytes obstetricans, Rana temporaria, Rana esculenta, Hyla arborea, Hyla crepitans and Bufo bufo.In five of the species (A. obstetricans, R. temporaria, H. arborea, H. crepitans and B. bufo) vasoactive intestinal polypeptide-like immunoreactive mucosal endocrine cells and nerve fibres in all layers of the gut wall, were detected by both immunofluorescence and peroxidase-antiperoxidase methods. In the other two species, R. esculenta and B. bombina, no mucosal endocrine cells were detected although the vasoactive intestinal polypeptide-immunoreactive nerve fibres were plentiful.Radioimmunoassay showed the presence of significant amounts of vasoactive intestinal polypeptide-immunoreactivity in intestinal extracts from all species. The highest quantities were present in those anurans with both immunostained cells and nerves. Gel permeation chromatography showed that most of the vasoactive intestinal polypeptide-like peptide eluted in a position identical to that of natural mammalian (porcine) vasoactive intestinal polypeptide.The results indicate that a vasoactive intestinal polypeptide-like peptide is well represented in the Anura and that it is immunologically very similar to the mammalian peptide.Part of this work was presented at the European Society of Comparative Endocrinology, 1979; see Buchan et al. 1980a     

Temperature and auditory thresholds: Bioacoustic studies of the frogsRana r. ridibunda,Hyla a. arborea andHyla a. savignyi (Anura,amphibia)

Summary The auditory thresholds of three frogs-two subspecies of the genusHyla (H. a. arborea, H. a. savignyi) and one of the genusRana (R. r. ridibunda)—were measured at 5°, 12°, 20° and 28°C, by recording multi-unit activity from the torus semicircularis. In the tree frogs, the upper limit of the audible range is 7,000 Hz. At 5°C the best frequency is 3,000 Hz; the threshold (expressed in dB SPL in all cases) at this frequency is 49 dB (males) and 43 dB (females) forH. a. arborea and 42 dB (males) and 48 dB (females) forH. a. savignyi. At 12°C the thresholds are lower, and they are lower still at 20°, reaching a minimum, at 3,000 Hz, of 42 dB (males) and 38 dB (females) forH. a. arborea and 41 dB (males) and 40 dB (females) forH. a. savignyi. At frequencies of 1,000 Hz and lower, thresholds are high at 5°C; in part of this range they are considerably lowered at 20°C, whereas at 28°C there is a reduction in sensitivity to most frequencies inH. a. arborea, amounting to more than 10 dB in the males.H. a. savignyi differs in this regard; at 28° sensitivity is no less than at lower temperatures, and in fact is greater in the range 1,000–1,400 Hz. The audible range ofR. r. ridibunda is more restricted than that of the tree frogs, but it is more sensitive within this range. The highest frequency is 4,500 Hz. At 5°C the thresholds of the males are lowest at 500–600 Hz (42 dB) and 1,400–1,900 Hz (ca. 39 dB). The best frequencies of the females are 700 Hz (38 dB) and 1,400 Hz (36 dB). At 12°C the thresholds at 300 Hz and 1,000 Hz are markedly lowered, by 10–18 dB. The thresholds of the females at 20°C are still lower over almost the entire audible range, whereas in the males only part of the range is affected. This difference persists at 28°C, the threshold curve of the males being slightly raised, while that of the females is unchanged. Latencies are dependent upon temperature and sound pressure. With a rise in temperature from 5° to 20°C the latency falls by ca. 8 ms. An increase in sound pressure from 5 dB to 30 dB SPL shortens the latency by ca. 10 ms. These changes were found in all the frogs studied.     

Temperature and immobility reaction in Rana temporaria

Experiments were conducted on two groups of Rana temporaria acclimatized to 7°C and to 14°C. Two hours prior to the experiments the animals were divided into six groups of 40 subjects each and placed in containers at temperatures of 5°, 10°, 15°, 20°, 25° and 30°C. Frogs remained immobile for a shorter time in temperatures which differed little from those of acclimatization. It was concluded that the body temperature interferes with the duration of the immobility reaction.     

Eight new microsatellite loci for the critically endangered fire‐bellied toad Bombina bombina and their cross‐species applicability among anurans

We describe eight new microsatellite loci for the critically endangered fire‐bellied toad, Bombina bombina. Seven of them are polymorphic with two to seven alleles per locus, an expected heterozygosity between 0.41 and 0.8, and an observed heterozygosity between 0.27 and 0.7. The yield of new loci was relatively low, presumably due to mildly repetitive sequence motifs in microsatellite flanking regions. As typical for anurans, cross‐species amplification was limited (here, to congeners Bombina orientalis and Bombina variegata). Combining these new loci with those already available provides a reasonable number of loci for population studies and pedigree analysis in Bombina.     

Effect of temperature on the embryonic development of the plaice, Pleuronectes Platessa L. (teleostei)

In normalyears, eggs and prolarvae of the plaice (Pleuronectes platessa L.) in the southern North Sea develop within the temperature range 6.0–8.5 °C, although the water may at times be some degrees colder or warmer than this. The effect of temperature, t °C, on the embryonic development time, D days, has been investigated within the tolerated range 2.8–10.5 °C. Various models to express the observed curvilinear relationship between t and D have been considered, that giving the closest fit to the data being (t−t₀)(D−D₀) = k or $\text{D =}\text{k}\text{(t−t}{}_0\text{)+D}{}_0$. A method is given for the calculation of constants k, D₀, and t₀. The relationship may also be expressed by the equation D = a(t−t₀)^b where a and b are constants, but t₀ must in this case be found by iteration. At investigated temperatures in the range 4.1–10.5 °C the smallest eggs in a batch from a single source hatched first. Within the tolerated range, hatching prolarvae were substantially smaller at 10.5 °C than at the other temperatures. During the period of prolarval yolk utilization, growth is slower at the high temperatures, so that median temperatures of 6.5–8.0 °C are most efficient in terms of the relationship between growth in length and yolk utilization. Toward the end of the yolk-sac phase, the rate of yolk utilization declines unless a suitable external food source (e.g., Artemia nauplii) is provided.     

Metabolic uniformity over the environmental temperature range in Brachionus plicatilis (rotifera)

Organisms inhabiting small water bodies frequently encounter radical, short-term fluctuations in temperature. The population of Brachionus plicatilis that was used in this study encounters temperature changes as great as 12°C in 24 hours. In this paper we describe the metabolic response to temperature change in this eurythermal rotifer population. Metabolism was determined over the environmental range (15°C to 32°C) in intervals of 2°C. Utilization of such narrow temperature intervals allowed us to approximate the instantaneous Q₁₀, which we define as the Q₁₀ over an infinitely small temperature interval. Our results show the existence of a plateau in the curve of respiration against temperature (Q₁₀ > 1) over the range 20–28°C. The plateau is bounded on either side by temperature ranges over which metabolism is temperature sensitive (Q₁₀ values from 3.4 to 4.8). It is significant that the plateau occurs over the environmental temperature range for the major portion of the growing season. This population is thus programmed to hold a constant (preferred?) metabolic rate in spite of diel temperature fluctuations when the environment is otherwise favorable.