Temporal variation in feeding morphology and size-structured population dynamics in fishes

Considerable variation in morphology associated with resource use is a classic example of local adaptation to the environment. We demonstrate that a temporal change in feeding morphology might occur within a population. In a 5-year natural field experiment, we estimated gill raker morphology, resource density and population dynamics of the roach and its competitor, the perch. Despite a variation in density of zooplankton resources and perch across years, no change in roach density was observed. However, gill raker morphology in roach covaried with size structure of the zooplankton resource across years. A laboratory experiment confirmed that gill raker morphology has a great effect on roach foraging efficiency on zooplankton and that there is a functional trade-off with regard to zooplankton foraging. We suggest that the response in gill raker structure is an adaptation to deal with the rapid population dynamics of zooplankton, which are in turn mediated by changes in the size structure of the competing perch.     

The current status and future of commercial embryo transfer in cattle

A commercially viable cattle embryo transfer (ET) industry was established in North America during the early 1970s, approximately 80 years after the first successful embryo transfer was reported in a mammal. Initially, techniques for recovering and transferring cattle embryos were exclusively surgical. However, by the late 1970s, most embryos were recovered and transferred nonsurgically. Successful cryopreservation of embryos was widespread by the early 1980s, followed by the introduction of embryo splitting, in vitro procedures, direct transfer of frozen embryos and sexing of embryos. The wide spread adoption of ethylene glycol as a cryoprotectant has simplified the thaw-transfer procedures for frozen embryos. The number of embryos recovered annually has not grown appreciably over the last 10 years in North America and Europe; however, there has been significant growth of commercial ET in South America. Within North America, ET activity has been relatively constant in Holstein cattle, whereas there has been a large ET increase in the Angus breed and a concomitant ET decrease in some other beef breeds. Although a number of new technologies have been adopted within the ET industry in the last decade, the basic procedure of superovulation of donor cattle has undergone little improvement over the last 20 years. The export-import of frozen cattle embryos has become a well-established industry, governed by specific health regulations. The international movement of embryos is subject to sudden and dramatic disturbances, as exemplified by the 2001 outbreak of foot and mouth disease in Great Britain. It is probable that there will be an increased influence of animal rights issues on the ET industry in the future. Several companies in North America are currently commercially producing cloned cattle. The sexing of bovine semen with the use of flow cytometry is extremely accurate and moderate pregnancy rates in heifers have been achieved in field trials, but sexed semen currently is available in only a few countries and on an extremely limited basis. As of yet, all programs involving the production of transgenic cattle are experimental in nature.     

Assessment of current status and the potential for commercial exploitation of biomass gasification in India

India would seem to present a unique opportunity for large scale commercial exploitation of biomass gasification technology for meeting a variety of energy needs, particularly in the agricultural and rural sector. The combination of favourable parameters includes a clear-cut national commitment, prevailing power shortages and high cost of power, vast geographical expanse, specific applications like irrigation pumping and rural electrification as well as availability of the essential infra-structural base. The country already has more than 250 systems covering a spectrum of power ratings and end use applications and while the overall experience has been favourable, a number of problem areas have already been identified for corrective action. While the paper discusses applications like irrigation pumping, village electrification and pump-set energisation in some detail, other significant applications include captive industrial power generation and MW scale grid-fed power generation coupled to energy plantations on wastelands. Economic viability of the available systems is seen to be acceptable to marginal depending on the assumptions made and perspective chosen i.e., macro national policy perspective vis-à-vis micro, individual user perspective. While the entire situational setting is seen to be quite attractive for deployment of this technology, a number of likely constraints in commercial exploitation are identified and discussed. However, a majority of these can be suitably tackled and the overall perception for commercial exploitation of biomass gasification technology would seem to be quite bright for India.     

Patterns of parasitic infections of fishes in a water body with constant temperature

Patterns of parasitic infections of Schizothorax intermedius in two water bodies of North Tadjikistan (Central Asia), one with constant temperature during the whole year, the other with normal annual seasonal range of temperature fluctuations, have been studied. It has been shown that in the first water body fluctuations in occurrence of the parasites are insignificant and are not under the influence of water temperature.     

人体组成学:历史、现况和未来

目录一、人体组成学的早期研究　 (一 )尸体研究　 (二 )活体测定方法　 (三 )体内外因素对人体组成的影响二、人体组成学研究的现况　 (一 )对人体组成规律的探索　 (二 )对影响人体组成的体内外因素的探讨　 (三 )人体组成的活体测定方法三、人体组成学研究的未来发展人体组成学 (ｈｕｍａｎｂｏｄｙｃｏｍｐｏｓｉｔｉｏｎｓｔｕｄｉｅｓ)是人体生物学的分支之一 ,它主要研究人体内诸多组成成分之间的数量规律 ,体内外各种因素对组分间数量关系的影响 ,以及活体测定人体组分的方法[1] 。人体生物学包含了许多分支 ,如生物化学、细胞学、…     

Addressing water quality in water footprinting: current status,methods and limitations

Purpose

In contrast to water consumption, water pollution has gained less attention in water footprinting so far. Unlike water scarcity impact assessment, on which a consensus has recently been achieved, there is no agreement on how to address water quality deterioration in water footprinting. This paper provides an overview of existing water footprint methods to calculate impacts associated with water pollution and discusses their strengths and limitations using an illustrative example.

Methods

The methods are described and applied to a case study for the wastewater generated in textile processing. The results for two scenarios with different water quality parameters are evaluated against each other and the water scarcity footprint (WSF). Finally, methodological aspects, strengths and limitations of each method are analysed and discussed and recommendations for the methods application are provided.

Results and discussion

Two general impact assessment approaches exist to address water quality in water footprinting: the Water Degradation Footprint (WDF) calculates the impacts associated with the propagation of released pollutants in the environment and their uptake by the population and ecosystem, while the Water Availability Footprint (WAF) quantifies the impacts related to the water deprivation, when polluted water cannot be used. Overall, seven methods to consider water quality in water footprinting were identified, which rely upon one or a combination of WDF, WAF and WSF. Methodological scopes significantly vary regarding the inventory requirements and provided results (a single-score or several impact categories). The case study demonstrated that the methods provide conflicting results concerning which scenario is less harmful with regard to the water pollution.

Conclusions

This paper provides a review of the water pollution assessment methods in water footprinting and analyses their modelling choices and resulting effects on the WF. With regard to the identified inconsistencies, we reveal the urgent need for a guidance for the methods application to provide robust results and allow a consistent evaluation of the water quality in water footprinting.

     

RNA virus evolution, population dynamics, and nutritional status

Trace elements exert a strong influence on immune function. Debilitated humoral and cellular immune responses may impair virus clearance in infected organisms, and favor the generation of virus variants with altered biological properties. The population size in evolving viral quasispecies, as well as increased mutagenesis trigered by oxidative stress, may contribute to altering the outcome of quasispecies evolution in infected hosts. The genetic plasticity of RNA viruses is one of the main obstacles for the control of the diseases they cause and probably a major force in the emergence of new viral pathogens. Recent results suggest links between nutritional deficiencies and the generation of variant viruses, a possibility that is addressed in the present article.     

The role of life history in the relationship between population dynamics and environmental variability in two Mediterranean stream fishes

Chub Squalius torgalensis and nase Chondrostoma lusitanicum , in a Mediterranean stream, showed important differences in life-history traits and population dynamics. Both species reached mean maturity at age 2 years. Chub lived up to age 5 years, spawned in March to June, grew at a maximum rate of 0·59 mm mm⁻¹ year⁻¹ and showed a low reproductive allocation, with fecundity and egg size increasing with body size. Nase lived up to age 4 years, spawned in January to April, grew at a maximum rate of 0·46 mm mm⁻¹ year⁻¹ and showed a high reproductive allocation, with egg size independent of body size. Both chub and nase showed moderate fluctuations in population size during 1991–1998, but differed in factors driving density at age. Density of age 1 year juvenile chub decreased following severe summer droughts and proportionate survival prevailed thereafter. Density of age 2 year adult nase decreased following severe spring floods, but neither environmental nor parental stock effects were detected for juveniles and older fishes. The results illustrated the interplay between life history and environmental variability in driving fish population dynamics, with impacts of both summer droughts and spring floods being contingent on species-specific patterns of spawning and reproductive investment.     

Mutational effects and population dynamics during viral adaptation challenge current models

Adaptation in haploid organisms has been extensively modeled but little tested. Using a microvirid bacteriophage (ID11), we conducted serial passage adaptations at two bottleneck sizes (10(4) and 10(6)), followed by fitness assays and whole-genome sequencing of 631 individual isolates. Extensive genetic variation was observed including 22 beneficial, several nearly neutral, and several deleterious mutations. In the three large bottleneck lines, up to eight different haplotypes were observed in samples of 23 genomes from the final time point. The small bottleneck lines were less diverse. The small bottleneck lines appeared to operate near the transition between isolated selective sweeps and conditions of complex dynamics (e.g., clonal interference). The large bottleneck lines exhibited extensive interference and less stochasticity, with multiple beneficial mutations establishing on a variety of backgrounds. Several leapfrog events occurred. The distribution of first-step adaptive mutations differed significantly from the distribution of second-steps, and a surprisingly large number of second-step beneficial mutations were observed on a highly fit first-step background. Furthermore, few first-step mutations appeared as second-steps and second-steps had substantially smaller selection coefficients. Collectively, the results indicate that the fitness landscape falls between the extremes of smooth and fully uncorrelated, violating the assumptions of many current mutational landscape models.     

An examination of the population dynamics of syngnathid fishes within Tampa Bay,Florida,USA

<正> Seagrass ecosystems worldwide have been declining, leading to a decrease in associated fish populations, especiallythose with low mobility such as syngnathids (pipefish and seahorses). This two-year pilot study investigated seasonal patterns indensity, growth, site fidelity, and population dynamics of Tampa Bay (FL) syngnathid fishes at a site adjacent to two marinas underconstruction. Using a modified mark-recapture technique, fish were collected periodically from three closely located sites thatvaried in seagrass species (Thalassia spp., Syringodium spp., and mixed-grass sites) and their distance from open water, but hadconsistent physical/chemical environmental characteristics. Fish were marked, photographed for body size and gender measurements,and released the same day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicatinga large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter andlate summer. Spatially, syngnathid densities were highest closest to the mouth of the bay and lowest near the shoreline. Sevenspecies of syngnathid fishes were observed, and species-specific patterns of seagrass use emerged during the study. However,only two species, Syngnathus scovelli and Hippocampus zosterae, were observed at high frequencies. For these two species, bodysize decreased across the study period, but while S. scovelli's population density decreased, H. zosterae's increased. Across six ofthe seven species, population size declined over the course of this preliminary study; however, seasonal shifts were impossible todistinguish from potential anthropogenic effects of construction     

An examination of the population dynamics of syngnathid fishes within Tampa Bay, Florida, USA

Seagrass ecosystems worldwide have been declining, leading to a decrease in associated fish populations, especially those with low mobility such as syngnathids (pipefish and seahorses). This two-year pilot study investigated seasonal patterns in density, growth, site fidelity, and population dynamics of Tampa Bay (FL) syngnathid fishes at a site adjacent to two marinas under construction. Using a modified mark-recapture technique, fish were collected periodically from three closely located sites that varied in seagrass species (Thalassia spp., Syringodium spp., and mixed-grass sites) and their distance from open water, but had consistent physical/chemical environmental characteristics. Fish were marked, photographed for body size and gender measurements, and released the same day at the capture site. Of the 5695 individuals surveyed, 49 individuals were recaptured, indicating a large, flexible population. Population density peaks were observed in July of both years, with low densities in late winter and late summer. Spatially, syngnathid densities were highest closest to the mouth of the bay and lowest near the shoreline. Seven species of syngnathid fishes were observed, and species-specific patterns of seagrass use emerged during the study. However, only two species, Syngnathus scovelli and Hippocampus zosterae, were observed at high frequencies. For these two species, body size decreased across the study period, but while S. scovelli's population density decreased, H. zosterae's increased. Across six of the seven species, population size declined over the course of this preliminary study; however, seasonal shifts were impossible to distinguish from potential anthropogenic effects of construction [Current Zoology 56 (1): 118-133 2010].     

The species composition and seasonal dynamics of infusorian species from fishes in the bodies of water in the Minusinsk depression

The infusoria fauna was examined in 495 specimens of 9 fish species living in different water basins of the Minusinsk depression. Data on host associations and location of all found infusoria species are given.     

The electrolyte content of the body of insects, ascidians, fishes, amphibians and mammals and its dynamics in ontogeny

In animals in which sodium is a predominant cation of the blood serum or haemolymph (rat, newt Triturus vulgaris, sturgeon Acipenser güldenst?dti, herring Clupea pallasi, ascidian Goniocarpa rustica), its content in the body amounts up to a half of the total bulk of electrolytes; in insects with potassium type of the haemolymph, the share of sodium is equal to 6.4%. In animals of the same species, total electrolyte content (sodium, potassium, calcium, magnesium) and the relationship between separate ions were found to be remarkably constant. During ontogenetic development of the sturgeon and herring, as well as in rat embryos beginning from the 15th day of gestation, the ratio between separate cations exhibits significant conservatism.     

Life history strategies affect climate based spatial synchrony in population dynamics of West African freshwater fishes

Spatial synchrony in species abundance is a general phenomenon that has been found in populations representing virtually all major taxa. Dispersal among populations and synchronous stochastic effects (the so called "Moran effect") are the mechanisms most likely to explain such synchrony patterns. Very few studies have related the degree of spatial synchrony to the biological characteristics of species. Here we present a case where specific predictions can be made to relate river fish species characteristics and synchrony determined exclusively by a Moran effect through the expected sensitivity of species to the regional component of environmental stochasticity. By analyzing 23-year time series of abundance estimates in two isolated localities we show that species associated with synchronized reproduction during the wet season, high fecundity, small egg size and high gonado-somatic index (the so called "periodic" strategy) have a higher degree of spatial synchrony in population dynamics than species associated with the opposite traits (the so called "equilibrium" strategy). This is supported by significant relationships (P values <0.01) between species traits and the levels of synchrony after removing taxonomical relatedness. Spatial synchrony computed from summed annual total catches by groups of species, separated into strategy types also showed a significantly higher degree of synchrony for the periodic (r=0.83) than the equilibrium (r=0.46) group. Regional hydrological variability is likely to be partly responsible for the observed synchrony pattern and a regional discharge index showed better relationships with the periodic group, supporting the expected differential effect of regional environmental correlation on population dynamics.     

Permian–Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end‐Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian–Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian–Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, ‘Palaeopterygii’, ‘Subholostei’, Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end‐Guadalupian crisis is not evident from our data, but ‘palaeopterygians’ experienced a significant body size increase across the Guadalupian–Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian–Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, ‘palaeopterygians’, ‘subholosteans’) and a second one during the Middle Triassic (‘subholosteans’, neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle–Late Permian, resulted in a profound change within global fish communities, from chondrichthyan‐rich faunas of the Permo‐Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events.     

Correlated evolution of body and fin morphology in the cichlid fishes

Body and fin shapes are chief determinants of swimming performance in fishes. Different configurations of body and fin shapes can suit different locomotor specializations. The success of any configuration is dependent upon the hydrodynamic interactions between body and fins. Despite the importance of body–fin interactions for swimming, there are few data indicating whether body and fin configurations evolve in concert, or whether these structures vary independently. The cichlid fishes are a diverse family whose well‐studied phylogenetic relationships make them ideal for the study of macroevolution of ecomorphology. This study measured body, and caudal and median fin morphology from radiographs of 131 cichlid genera, using morphometrics and phylogenetic comparative methods to determine whether these traits exhibit correlated evolution. Partial least squares canonical analysis revealed that body, caudal fin, dorsal fin, and anal fin shapes all exhibited strong correlated evolution consistent with locomotor ecomorphology. Major patterns included the evolution of deep body profiles with long fins, suggestive of maneuvering specialization; and the evolution of narrow, elongate caudal peduncles with concave tails, a combination that characterizes economical cruisers. These results demonstrate that body shape evolution does not occur independently of other traits, but among a suite of other morphological changes that augment locomotor specialization.     

Ecological and site historical aspects of N dynamics and current N status in temperate forests

Ecological developments during Holocene age and high atmospheric depositions since industrialization have changed the N dynamics of temperate forest ecosystems. A number of different parameters are used to indicate whether the forests are N‐saturated or not, most common among them is the occurrence of nitrates in the seepage water below the rooting zone. The use of different definitions to describe N saturation implies that the N status of ecosystems is not always appropriately assessed. Data on N dynamics from 53 different German forests were used to classify various development states of forest ecosystems according to the forest ecosystem theory proposed by Ulrich for which N balances of input – (output plus plant N increment) were used. Those systems where N output equals N input minus plant N increment are described as (quasi‐) Steady State Type. Those forests where N output does not equal N input minus plant N increment as in a ‘transient state.’ Forests of the transient state may lose nitrogen from the soil (Degradation Type) or gain nitrogen [e.g., from atmospheric depositions (Accumulation Type)]. Forest ecosystems may occur in four different N states: (a) (quasi‐) Steady State Type with mull type humus, (b) Degradation Type with mull type humus, (c) Accumulation Type with moder type humus, and (d) (quasi‐) Steady State Type with moder type humus. Forests with the (quasi‐) steady state with mull type humus in the forest floor (n= 8) have high‐soil pH values, high N retention by plant increment, high N contents in the mineral soils, and have not undergone large changes in the N status. Forests of the Degradation Type lose nitrogen from the mineral soil (currently degradation is occurring on one site). Most forests that have moder or mor type humus and low‐soil pH values, and low N contents in the mineral soil have gone through the transient state of organic matter loss in the mineral soils. They accumulate organic matter in the forest floor (accumulation phase, currently 21 sites are accumulating 6–21 kg N ha^?1 yr^?1) or have reached a new (quasi‐) steady state with moder/mor type humus (n= 15). N retention in the accumulation phase has significantly increased in soil with N deposition (r²= 0.38), soil acidity (considering thickness of the forest floor as indices of soil acidity, r²= 0.43) and acid deposition (sulfate deposition, r²= 0.39). Retention of N (4–20 kg N ha^?1 yr^?1) by trees decreased and of soils increased with a decrease in the availability of base cations indicating the important role of trees for N retention in less acid soils and those of soils in more acid soils. Ecosystem theory could be successfully applied on the current data to understand the dynamics of N in temperate forest ecosystems.     

Spatial variation in water loss predicts terrestrial salamander distribution and population dynamics

Many patterns observed in ecology, such as species richness, life history variation, habitat use, and distribution, have physiological underpinnings. For many ectothermic organisms, temperature relationships shape these patterns, but for terrestrial amphibians, water balance may supersede temperature as the most critical physiologically limiting factor. Many amphibian species have little resistance to water loss, which restricts them to moist microhabitats, and may significantly affect foraging, dispersal, and courtship. Using plaster models as surrogates for terrestrial plethodontid salamanders (Plethodon albagula), we measured water loss under ecologically relevant field conditions to estimate the duration of surface activity time across the landscape. Surface activity time was significantly affected by topography, solar exposure, canopy cover, maximum air temperature, and time since rain. Spatially, surface activity times were highest in ravine habitats and lowest on ridges. Surface activity time was a significant predictor of salamander abundance, as well as a predictor of successful recruitment; the probability of a juvenile salamander occupying an area with high surface activity time was two times greater than an area with limited predicted surface activity. Our results suggest that survival, recruitment, or both are demographic processes that are affected by water loss and the ability of salamanders to be surface-active. Results from our study extend our understanding of plethodontid salamander ecology, emphasize the limitations imposed by their unique physiology, and highlight the importance of water loss to spatial population dynamics. These findings are timely for understanding the effects that fluctuating temperature and moisture conditions predicted for future climates will have on plethodontid salamanders.     

Population dynamics in cladoceran zooplankton in the presence and absence of fishes

The pattern of annual changes in zooplankton composition andabundance was investigated in Lake Mikolajskie and in a small,artificial pond. Changes in the cladoceran abundance in thelake do not accord with the competitive exclusion principle,which appears to occur in the pond. In the lake, though notin the pond, fish predation on zooplankton seems to weaken interspecificcompetition sufficiently to allow related cladocerans to achievetheir highest levels of abundance simultaneously.