Interspecific variation in the emetic response of anurans

1. The emetic response of seven species (four genera) of frogs to apomorphine hydrochloride, copper sulfate, antimonyl potassium tartrate and mechanical stimulation at the esophageal orifice was surveyed. Xenopus laevis and Rhacophorus schlegelii were more sensitive to systemically administered apomorphine than were the other species tested.2. The sensitivity of Rana rugosa to apomorphine varied with the season.3. All of the species showed vigorous vomiting behavior after the oral administration of either copper sulfate or antimonyl potassium tartrate.4. Mechanical stimulation also induced vomiting in all species. Although the species differed in sensitivity to the different emetic stimulants, the adaptive significance of this interspecific variation is not known.5. From the stand point of the mechanics for ejecting gastric contents, there is little difference between frogs and mammals.6. Frogs, particularly Xenopus laevis, may be a useful non-mammalian model for studying emesis.     

Interspecific variation in the response of fish to anthropogenic noise

1. Elevated levels of anthropogenic noise, especially those observed through boating activity, can negatively impact fish species, but it remains unclear which species are most affected and which behavioural metrics are best used in assessing fish responses to underwater noise. The effects of boat sounds on freshwater species are of particular interest because freshwater environments are less studied than the marine realm despite comparably high levels of biodiversity.
2. In the current study, we examine the behavioural responses to boat noise in two freshwater species that differ in their hypothesised response to sound inputs: the spottail shiner (Notropis hudsonius), a species with known hearing specialisations, and the bluegill sunfish (Lepomis macrochirus), a species with more generalised hearing capabilities. Fish were presented with boat noise in a laboratory setting, and their swimming, escape and foraging behaviours were assessed to examine differential responses in relation to hypothesised hearing abilities.
3. Both species showed a decrease in general swimming behaviours but an increase in erratic movements in response to boat noise, indicative of stress responses for both species. Despite the similarities in response based on swimming behaviours however, only spottail shiners exhibited true escape responses to the onset of the noise stimulus, suggesting a more extreme reaction in the species with a more refined hearing ability.
4. Taken together, these results show that freshwater fish can respond to increased levels of anthropogenic noise, but that the severity of the response may differ based on auditory structures and therefore presumed hearing ability. The differences seen between behavioural metrics used (swimming vs. escape responses) also demonstrate how care must be taken in choosing a metric when developing exposure guidelines for underwater sound exposures, as different metrics could lead to differential impact assessments.

     

Interspecific variation in the response to low temperature storage in different aphid parasitoids

Cold storage of natural enemies usually involves placing insects under constant subambient temperatures. Even at non-freezing temperatures, a reduction in survival is the norm. Using fluctuating thermal regimes (FTR) instead of constant low temperature (CLT) has shown that mortality due to accumulation of chilling injuries was significantly reduced in Aphidius colemani . Whether this phenomenon can be generalised to other parasitoid species is not known. The aim of this study was to analyse interspecific variation in the ability to tolerate cold storage under CLT (continuous 2°C) versus FTR (daily cycle: 2°C for 22 h and 20°C for 2 h) for various durations (0–20 days). Survival, sex ratio and development of five different Aphidiine parasitoids were analysed: A. colemani , Aphidius ervi , Aphidius matricariae , Ephedrus cerasicola and Praon volucre. A marked interspecific variation in the ability to tolerate cold storage was observed: A. matricariae and A. ervi were most chill tolerant, P. volucre and E. cerasicola had an intermediate chill sensitivity and A. colemani was most chill sensitive. In all species tested, FTR significantly reduced cold-induced mortality. This phenomenon was manifested more in chill-sensitive species as they probably accumulate chilling injuries more rapidly. The sex ratio remained unaffected in all the species. Interspecific variation was also observed in developmental responses to cold storage. Under CLT, time to adult emergence of A. matricariae, A. colemani, A. ervi and P. volucre was temporarily stopped and in E. cerasicola it increased. Under FTR, the short daily intervals at 20°C for 2 h allowed parasitoids to continue development in all the species. Interspecific differences are discussed. This study suggests that positive impact of FTR may apply to a wide range of species.     

Interspecific variation in the growth response of plants to an elevated ambient CO2 concentration

The effect of a doubling in the atmospheric CO₂ concentration on the growth of vegetative whole plants was investigated. In a compilation of literature sources, the growth stimulation of 156 plant species was found to be on average 37%. This enhancement is small compared to what could be expected on the basis of CO₂-response curves of photosynthesis. The causes for this stimulation being so modest were investigated, partly on the basis of an experiment with 10 wild plant species. Both the source-sink relationship and size constraints on growth can cause the growth-stimulating effect to be transient.Data on the 156 plant species were used to explore interspecific variation in the response of plants to high CO₂. The growth stimulation was larger for C₃ species than for C₄ plants. However the difference in growth stimulation is not as large as expected as C₄ plants also significantly increased in weight (41% for C₃ vs. 22% for C₄). The few investigated CAM species were stimulated less in growth (15%) than the average C₄ species. Within the group of C₃ species, herbaceous crop plants responded more strongly than herbaceous wild species (58%vs. 35%) and potentially fast-growing wild species increased more in weight than slow-growing species (54%vs. 23%). C₃ species capable of symbiosis with N₂-fixing organisms had higher growth stimulations compared to other C₃ species. A common denominator in these 3 groups of more responsive C₃ plants might be their large sink strength. Finally, there was some tendency for herbaceous dicots to show a larger response than monocots. Thus, on the basis of this literature compilation, it is concluded that also within the group of C₃ species differences exist in the growth response to high CO₂.Abbreviations LAR leaf area ratio - LWR leaf weight ratio - NAR net assimilation rate - PS_a rate of photosynthesis per unit leaf area - RGR relative growth rate - RWR root weight ratio - SLA specific leaf area     

Short- and long-term consequences of thermal variation in the larval environment of anurans

1. To survive adverse or unpredictable conditions in the ontogenetic environment, many organisms retain a level of phenotypic plasticity that allows them to meet the challenges of rapidly changing conditions. Larval anurans are widely known for their ability to modify behaviour, morphology and physiological processes during development, making them an ideal model system for studies of environmental effects on phenotypic traits. Although temperature is one of the most important factors influencing the growth, development and metamorphic condition of larval anurans, many studies have failed to include ecologically relevant thermal fluctuations among their treatments. 2. We compared the growth and age at metamorphosis of striped marsh frogs Limnodynastes peronii raised in a diurnally fluctuating thermal regime and a stable regime of the same mean temperature. We then assessed the long-term effects of the larval environment on the morphology and performance of post-metamorphic frogs. 3. Larval L. peronii from the fluctuating treatment were significantly longer throughout development and metamorphosed about 5 days earlier. Frogs from the fluctuating group metamorphosed at a smaller mass and in poorer condition compared with the stable group, and had proportionally shorter legs. 4. Frogs from the fluctuating group showed greater jumping performance at metamorphosis and less degradation in performance during a 10-week dormancy. Treatment differences in performance could not be explained by whole-animal morphological variation, suggesting improved contractile properties of the muscles in the fluctuating group.     

Interspecific variation in the defence secretions of Nasutitermes soldiers

Termite soldiers of the genus Nasutitermes (Isoptera, Termitidae, Nasutitermitinae) eject a viscous, sticky defense secretion composed of non-polar monoterpene hydrocarbons and polyoxygenated diterpenes from the frontal gland. Chemical compositions are described in detail for the East African species, N. kempae and N. infuscatus, and for the Neotropical species N. ephratae. Additional comparisons with the new world species N. costalis, N. rippertii and N. octopilis are presented. The structure of a new monohydroxykempene from N. ephratae is described, and a physicochemical model for the stickiness of the glue is presented. Although the structures of the individual secretion components vary within the genus, the glue-like nature of the secretion remains essentially unchanged. Chemical analysis of soldier defense secretions may be useful in studying the systematic biology of termites.     

Interspecific variation in the visual pigments of deep-sea fishes

Summary Visual pigments in the rods of 38 species of deep-sea fish were examined by microspectrophotometry. 33 species were found to have a single rhodopsin with a wavelength of maximum absorbance ( _max) in the range 470–495 nm. Such visual pigments have absorbance maxima close to the wavelengths of maximum spectral transmission of oceanic water. 5 species, however, did not conform to this pattern and visual pigments were found with _max values ranging from 451 nm to 539 nm. In 4 of these species two visual pigments were found located in two types of rod. Some 2-pigment species which have unusual red sensitivity, also have red-emitting photophores. These species have both rhodopsin and porphyropsin pigments in their retinae, which was confirmed by HPLC, and the two pigments are apparently located in separate rods in the same retinal area. In deep-sea fishes the occurrence of unusual visual pigments seems to be correlated with aspects of the species' depth ranges. In addition to ecological influences we present evidence, in the form of _max spectral clustering, that indicates the degree of molecular constraint imposed on the evolution of visual pigments in the deep-sea.     

Auditory processing in anurans.

Anurans (frogs and toads) represent an example of peripheral specialization of the auditory systems. Their inner ear contains two distinct auditory organs: the amphibian papilla and the basilar papilla. Each organ is tuned to different species-specific frequency ranges. Because of this peripheral specialization, anurans offer an excellent opportunity to explore neural decoding of complex sounds in the central auditory system.     

The inhibitory effect of halothane on the emetic response in the ferret

Emesis and nausea are often associated with anaesthesia and continue to be a common clinical problem. Past clinical studies have demonstrated that halothane produces a higher incidence of vomiting compared with other anaesthetics, but some investigators have described an antiemetic effect. The purpose of this study was to investigate the effects of various doses of halothane on the emetic response in the decerebrate ferret. Following a control emetic response, a maximum of six increasing cumulative concentrations of halothane were delivered. At the end of each delivery period, the supradiaphragmatic vagal communicating branch, which has been shown to reproducibly elicit vomiting, was electrically stimulated and the emetic response was monitored. An increase in halothane concentration produced a marked depression of tongue, abdominal muscle, and diaphragm EMG activity as well as a decrease in central venous pressure. Licking, a prodromal response comparable to nausea in the human, appeared to be most sensitive. An increase in latency of the emetic response occurred as the concentration of halothane was increased. All phases of the response were observed at concentrations below 0.6 vol% halothane. At 0.6 vol% halothane, 75% of the animals vomited. At higher concentrations, the emetic response was completely abolished. One hour post-halothane, all latencies had returned to near control values. The methods utilized in this study provided a model that was not complicated by a large number of variables usually present in clinical studies. These data demonstrate that halothane exerts an inhibitory, concentration-dependent, and reversible effect on the emetic response in the ferret and provide further support that halothane alone does not possess emetic properties at clinical properties at clinical concentrations.     

Interspecific variation in growth of British pigeons Columbidae

Growth patterns of nestling Collared Doves Streptopetia decaocto , Woodpigeons Columba palumbus , Feral Pigeons C. livia and Stock Doves C. oenas , in Britain were compared. Open-nesting Collared Doves and Woodpigeons left the nest at about 60% of adult weight, hole-nesting Stock Doves at adult weight, and partial hole-nesting Feral Pigeons at an intermediate stage. Other species of pigeons and doves studied to date also fit this pattern. Stock Dove nestlings reared in nest-boxes reached heavier weights and left the nest later than those in more exposed sites. These results were correlated with differential predation pressure on open- versus hole-nesting birds.     

Patterns of molecular variation. I. Interspecific comparisons of electromorphs in the Drosophila mulleri complex

The average mobility of electromorphs at an enzyme locus in a single population was defined as the weighted average mobility of the electromorphs in that population, where the electromorph frequencies are the weights. A derivative distance measure was defined whose taxonomic utility was determined in the Drosophila mulleri species complex. Most of the variation in this metric was at the interspecific level, primarily among clusters of sibling species. The electromorphs of some loci were equally and regularly spaced, while those of other loci were less regular in their spacing. Overall, these minor perturbations from regular spacing did not noticeably detract from the taxonomic utility of average mobility, and cluster analysis yielded the same taxonomic relationships as more conventional nonmolecular treatments. On the other hand, electromorph spacing may be related to functional constraints on the enzyme molecules. Some possible implications of the results for the modes of selection during evolution of the different enzymes are discussed.Supported by NSF Grant 22770, AEC Contract AT-(40-1)-4023, and NIH Career Development Award GM 47350-05 to R.H.R.     

Interspecific variation in leaf wax of Dudleya

The distribution of the pentacylic triterpenoids, β-amyrin acetate and taraxerone, in the glaucous epicuticular wax of Dudleya subgenus Dudleya is correlated with both the geographic distribution and corolla tube length of a particular species. This is significant in a genus with many systematic problems.     

Interspecific variation of sperm morphology in the Australian rodent genus Zyzomys

The sperm head morphology and tail length of two species of Australian rock rats, Zyzomys argurus and Zyzomys pedunculatus, are presented. In Z. argurus the sperm head has an apical hook together with two ventral processes extending from the upper concave surface that are largely composed of cytoskeletal material, and the sperm tail is about 135 µm in length. By contrast, in Z. pedunculatus the sperm head is paddle‐shaped with the nucleus capped by an acrosome that has a large apical segment and is surrounded by a thin layer of cytoskeletal material, and the sperm tail is only around 85 µm in length. Since the structure of the spermatozoon of Z. argurus is similar to that of most of the old endemic Australian rodents it is presumed to be the ancestral condition within the Zyzomys genus with that of Z. pedunculatus being highly derived and showing convergence with the sperm structure in some other orders of mammals.     

Ecological wood anatomy of NepaleseRhododendron (Ericaceae). 1. Interspecific variation

The relationship of selected wood anatomical characters of NepaleseRhododendron with stem diameter, plant height, altitude, and plant form was investigated. We studied one to three specimens each of 26 species: five species each of trees and subtrees I, three species of subtrees II, and 13 species of shrubs. Multiple regression analysis and actual distribution of character values show that pore characters and multiseriate ray ratio have a stronger correlation with stem diameter than altitude; that pore density, vessel element length, fiber-tracheid length, and multiseriate ray density and width are equally related to altitude and stem diameter, or to altitude and plant height; and that bar number, and multiseriate ray area and height have a stronger connection with altitude. Among the characters, average pore area is most strongly correlated with stem diameter and increases exponentially as diameter increases. For wood structure of NepaleseRhododendron, 17 to 63 % of the variation is affected by non-anatomical factors. The general trends in wood structure of NepaleseRhododendron show that trees and subtrees form one continuous unit whereas shrubs form another that often has wider ranges of variation.     

Interspecific and progeny relationships in the genus Stylosanthes inferred from chloroplast DNA sequence variation.

The chloroplast trnL (UAA) intron and trnL (UAA)-trnF (GAA) intergenic spacer region have been sequenced from 37 samples, 36 of which representing 19 Stylosanthes species and one from the related genus Zornia. The DNA sequences were used to study phylogenetic relationships in the tropical forage legume genus Stylosanthes, by means of parsimony analysis using the heuristic search method of the computer program PAUP. The resulting cladograms divide Stylosanthes into four separate clades. Within the clades, species are poorly resolved owing to low sequence divergence. Small intra-specific chloroplast DNA variation is observed in S. humilis, S. scabra and the species complex S. guianensis. Variation between S. humilis populations is considered to be geographically structured. The overall results agree well with previously established inter-specific relationships and provide evidence for the genetic origin of the alloploid species S. hamata, S. scabra, S. ingrata, S. sympodialis, S. subsericea, S. capitata and S. fruticosa. This understanding of evolutionary relationships in Stylosanthes, in combination with biogeographical concepts provides a way of discerning isolated habitats in Central and South America, which may therefore contribute to strategies of plant collecting.     

Interspecific variation in tephritid fruit fly larvae surface hydrocarbons

Hydrocarbons extracted from seven species of tephritid fruit fly larvae were analyzed using capillary column gas-liquid chromatography and gas-liquid chromatography/mass spectrometry. Interspecific variation in hydrocarbon patterns was evaluated using both classical and nonparametric discriminant analysis for four of the seven Anastrepha taxa; A. acris, A. Fraterculus, A. suspensa and A. obliqua. Three of the four taxa, excluding A. acris, were correctly classified using a linear discriminant model at 72–83% and a nonparametric kernel density discriminant model at 87–92%. © 1993 Wiley-Liss. Inc.