Evolution Under Dietary Restriction Increases Reproduction at the Cost of Decreased Somatic Growth.

Dietary restriction (DR) is cited as the most reliable means of extending life span in a wide range of taxa, yet the evolutionary basis of the DR effect on life span remains unclear. The resource reallocation hypothesis proposes that the longevity-extending response of DR is adaptive and stems from the reallocation of resources from reproduction to somatic maintenance under food-limited conditions. However, if DR continues for multiple generations, such a response becomes maladaptive, and genotypes with higher fecundity should be selectively favored over genotypes with longer longevity.

Combined Effects of Warming and Imidacloprid on Survival, Reproduction and Population Growth of Brachionus calyciflorus (Rotifera).

Global warming and pesticide contamination are two stressors of high concern, but their combined effects on freshwater biota are controversial. This study investigated the combined effects of warming and imidacloprid (IMI) on survival (measured as life expectancy at hatching), reproduction (net reproductive rate), population growth (intrinsic rate of population increase) and sexual reproduction (proportion of sexual offspring) of Brachionus calyciflorus using a life table experiment. The results showed that compared with controls, treatments with IMI at 50-100 mg/L significantly decreased survival, reproduction and population growth of the rotifers at 20℃.

Effect of chloramphenicol on the life table demography of Brachionus calyciflorus (Rotifera): A multigenerational study.

During the last two decades, there has been increasing concerns about the presence of antibiotics in aquatic environments. Phenicol antibiotics, such as chloramphenicol (CMP), commonly used in the veterinary and aquaculture fields to treat infections, have been often detected in aquatic environments, but scarce ecotoxicity information regarding the effects of CMP on non-target aquatic organisms is available, and multigenerational studies are seldom studied. Here we quantified the demographic responses of Brachionus calyciflorus exposed to sublethal concentrations (0, 5, 10, 30, 50, 70 and 90 mg L) of CMP for three successive generations (P0, F1, and F2).

Rapid adaptation of Brachionus dorcas (Rotifera) to tetracycline antibiotic stress.

Although natural populations can rapidly adapt to selection pressures, the fitness consequences of selection are controversial. In this study, a selection experiment was conducted with replicate populations of Brachionus dorcas that were exposed to two sublethal concentrations (26.8 and 78.

Effects of bromate on life history parameters, swimming speed and antioxidant biomarkers in Brachionus calyciflorus.

The baking industries and disinfection of tap water released a considerable amount of bromate into surface water, which has been reported as a carcinogenic compound to mammals. Rotifers play an important role in freshwater ecosystems and are model organisms to assess environmental contamination. In the present study, the effects of different concentrations (0.

[Effects of ibuprofen concentration on life table demography of Moina macrocopa under different densities of Scenedesmus obliquus].

The cladoceran Moina macrocopa was used as test animal to investigate the effects of ibuprofen concentrations (0, 0.45, 0.9, 1.

[Study on natural population dynamics and spatial distribution pattern of in stored flour].

Objective: To understand the natural population dynamics and spatial distribution of in storage flour, so as to provide an evidence for its prevention and control.

Methods: The samples from five sampling points in Wuhu City were collected monthly from January to December, 2013, and examined and counted for . The dispersion pattern target, Iwao's m*- ̄; regression analysis and Taylor's lg-lg ̄; regression analysis were used for analyzing the spatial distribution pattern of in the storage flour.

Interactive effects of algal level and predator density (Asplanchna sieboldi) on the life-history strategy and morphology of Brachionus calyciflorus.

Predation plays an important role in mediating the coexistence and the community structure of rotifera. In response to predation stresses, prey rotifers develop morphological defenses and change their life-history strategy for the reallocation of energy investment. Yet, how these changes respond to different total energy ingestion remains largely unknown.

Morphological differentiation of Brachionus calyciflorus caused by predation and coal ash pollution.

Different rotifer stains exhibited remarkably morphological differences which could not be eliminated under laboratory conditions. In the present study, we hypothesized that predation pressure and pollution might be two forces driving morphological differentiation of rotifer. To test this hypothesis, rotifers (Brachionus calyciflorus) belonging to two sibling species were collected from three special lakes (with coal ash pollution, high predation pressure or neither) and cultured for more than three months to investigate their potential differentiation in morphology.

Combined Effects of Temperature and the Microcystin MC-LR on the Feeding Behavior of the Rotifer Brachionus calyciflorus.

The aim of this study was to investigate the responses in filtration and grazing rates of five rotifer strains of the species Brachionus calyciflorus under different temperatures and MC-LR concentrations. The results showed that strain identity, MC-LR concentration, temperature, and the interactions of these factors significantly affected both response variables, with the exception of the interaction of strain and MC-LR on the grazing rates. At low MC-LR concentrations and for the control group, the filtration and grazing rates increased with increasing temperature.

[Effects of mercury concentration on life table demography of Moina macrocopa under different Scenedesmus obliquus densities].

In order to compare the chronic toxicity of pollutants to organisms in an aquatic environment under different food densities, the cladoceran Moina macrocopa was used as test animal to investigate the effects of Hg²⁺ concentrations (0, 0.4, 1.1, 1.

Effects of Multi-metal (Cu, Zn, Cd, Cr, and Mn) Mixtures on the Reproduction of Freshwater Rotifer Brachionus calyciflorus.

In the field, organisms are usually exposed to mixtures of various metals. However, the effects of multi-metal mixtures on growth and reproduction of rotifers remain unknown. In the present study, effects of multi-metal mixtures (Cu, Zn, Cd, Cr, and Mn) on reproduction of the freshwater rotifer Brachionus calyciflorus were assessed by determining various endpoints, including the ratio of ovigerous females to nonovigerous females, the ratio of mictic to amictic females, the mictic rate, the fertilization rate, the population growth rate, and the resting eggs production.

Coal fly ash effluent affects the distributions of Brachionus calyciflorus sibling species.

Fly ash, a coal combustion residue of thermal power plants and a source of multiple pollutants, has been recognized as an environmental hazard all over the world. Although it is known that fly ash effluent affects density, diversity and distribution of rotifers in drainage systems and receiving water bodies, the effect of fly ash effluent on the distributions of highly similar rotifer species remains unknown. In this study, the mtDNA COI genes of 90 individuals in Brachionus calyciflorus complex from Lake Hui (as a fly ash discharge water pond) and other two neighboring lakes (Lake Fengming and Lake Tingtang) were sequenced and analyzed, and the responses in selected life table demographic parameters (life expectancy at hatching, net reproductive rate, intrinsic rate of population increase and proportion of sexual offspring) of different rotifer populations to fly ash effluent were investigated.

Effects of DDT and dicofol on population growth of Brachionus calyciflorus under different algal (Scenedesmus obliquus) densities.

A number of organochlorine pesticides, including DDT and dicofol, used to be important in crop protection and management. Their residues may reach water bodies and eventually affect the non-target organisms such as rotifers. In the present study, we evaluated the effects of DDT (0.

The life-table demographic response of freshwater rotifer Brachionus calyciflorus to multi-metal (Cu, Zn, Cd, Cr, and Mn) mixture interaction.

The effects of multi-metal mixtures on the life-table demography of rotifers are not well known. In this study, the freshwater rotifer Brachionus calyciflorus was exposed to mixture of Cu, Zn, Cd, Cr, and Mn, and the life-table demographic parameters including net reproductive rate, generation time, life expectancy at hatching, and intrinsic rate of population increase were calculated. The results showed that interactions between a given element concentration, except Mn, and the other four elements mixture concentration affected the intrinsic rate of population increase (p < 0.

[Rapid change in structure of Brachionus calyciflorus complex collected from Jiulian Pond and its ecological mechanism].

In order to investigate the rapid variation in the structure of Brachionus calyciflorus complex and the fitness traits of the two sibling species, the rotifers were collected once a week from Jiulian Pond during 16 July and 6 August, their COI genes were sequenced and analyzed, and their fitness parameters (average lifespan, net reproductive rate, intrinsic rate of population increase and proportion of sexual offspring) were calculated at 28 degrees C and 32 degrees C with 1.0 x 10(6), 3.0 x 10(6) and 5.

[Combined toxicity of copper and cadmium to cladoceran Moina marocopa].

In this paper, the 48 h LC50 values of Cu2+, Cd2+ and CU(2+)+Cd2+ (CU2+:Cd2+ = 1:1) to Moina macrocopa were determined by acute toxicity tests, and the effects of different concentrations of Cu2+, Cd2+ and Cu(2+)+Cd2+ on the life table demography of M. macrocopa were studied by life table demography. The 48 h LC50 of Cu2+, Cd2+ and Cu(2+)+Cd2+ to M.

[Effects of water temperature and edible algal density on the population dynamics and sexual reproduction of Moina irrasa].

This paper studied the population dynamics and sexual reproduction of Moina irrasa at different water temperature and edible algal density. The population density of M. irrasa was obviously higher at high than at medium and low densities of edible algae, with the maximum at high edible algal density and 20 degrees C.

Effect of butyl benzyl phthalate on life table-demography of two successive generations of cladoceran Moina macrocopa Straus.

In this study, the acute toxicity of butyl benzyl phthalate (BBP) to freshwater cladoceran Moina macrocopa was tested, and its chronic effects on survival and reproduction of two successive generations of the cladoceran were studied using life-table demographic method. The results showed that the 48-hr LC50 of BBP for M. macrocopa was 3.

[Effects of temperature on Keratella quadrata life table demography and morphometric characteristics].

By the method of individual culture, this paper studied the effects of temperature (10 degrees C, 15 degrees C, 20 degrees C, and 25 degrees C) on the life table demography (net reproductive rate, intrinsic rate of population increase, generation time, average lifespan, and proportion of mictic offspring) and the offspring morphometric characteristics (body length, body width, antero-median spine length, left and right antero-lateral spine lengths, left and right posterior-spine lengths, and posterior spine number) of two posterior-spined, single posterior-spined, and zero posterior-spined morphotypes of Keratella quadrata. All the test life table demographic parameters and offspring morphometric parameters differed with morphotype and temperature, and their responses to elevated temperature differed with morphotype. Temperature had significant effects on the intrinsic rate of population increase, generation time, average lifespan, and the offspring morphometric parameters (P < 0.