A laboratory study on temperature relations of egg production and development in two related species of carabid beetle.

Egg production and development rates of Centropages typicus (Kroyer) were studied in the laboratory under carying food and temperature conditions. Egg production rates in the laboratory ranged from 0 to 124 eggs female-1 d-1 and increased with food concentration up to a critical food concentration (Pc) above which egg production was constant. Egg production rates were influenced by temperature, with more eggs being produced at 15°C than at 10°C. Thalassiosira weisflogii and Prorocentrum micans were determined to be equally capable of supporting egg production at concentrations above Pc at 15°C. Rate of egg production was independent of adult female size when food and temperature were constant. Egg production rates of freshly captured females ranged from 0 to 188 eggs female-1 d-1 and were higher in April and May than in June or July. Hatching rates of eggs increased with increased temperature; 95% of the eggs at 15°C hatched within 48 h, while only 8% of the eggs at 10°C hatched within 48 h. Development rates, determined at 10°C in excess concentrations of T. weisflogii, were 23.0 d from egg release to copepodid state I, 27.0 d to stage II, 29.5 d to stage III, 32.2 d to stage IV, 38.5 d to stage V and 49 d to adulthood based on the average time required for 50% of the organisms in an experiment to attain a given stage. Adult males were usually observed 2 to 4 d before adult females, and therefore have a slightly faster rate of development. The effects of temperature, food type and food concentration on egg production and the seasonal appearances of diatoms in the New York Bight may account for the observed seasonal cycles in abundance of C. typicus in these coastal waters.

Egg and faecal pellet production rates, and their functional response to food and temperature, were measured for the Antarctic copepod Metridia gerlachei during January 1996. The study area comprised the Gerlache and Bransfield Straits and Drake Passage. The highest rates of “in situ” egg and faecal pellet production were observed in Gerlache stations, coinciding with chlorophyll a concentrations approaching food saturation levels. In the Bransfield and Drake stations, with very low chlorophyll concentrations, the rates of egg production were either very low, or no eggs were produced. Egg production rates, although well correlated with “in situ” chlorophyll values, appeared to be independent of food concentration on a short time-scale (24-h incubations), while the production of faecal pellets was closely related to food abundance in the same experiments. In general, the rates of egg production were low, even at food saturation, with a very high individual variability. Although in the majority of Gerlache stations about 50% of total chlorophyll a corresponded to the phytoplankton size-fraction >10 μm, M. gerlachei feeds preferentially on the <10-μm fraction. Temperature had no clear effects on egg production rate but had a significant effect on pellet production rates, with maximum values at 2.5°C. These features appear to agree with the reproductive strategy attributed to the species, based on a relatively low rate of egg production extended over a long reproductive period.

Measurements of hydrography, water transparency, chlorophyll (Chl)<it>a</it> and egg production rates (EPRs) by females of<it>Calanus marshallae</it> Frost, <it>Calanus pacificus</it> Brodsky, <it>Eucalanus californicus</it> Johnson, <it>Epilabidocera longipedata</it> Sato,<it>Pseudocalanus mimus</it> Frost, <it>Centropages abdominalis</it> Sato, <it>Acartia longiremis</it> Lilljerborg and <it>Paracalanus parvus</it> (Claus) were estimated at weekly intervals between 17 July and 2 September 1997. Production of eggs was determined in 24 h incubations to examine the effects of environmental variability on EPR, to detect the possibility of food limitation of EPR, and to evaluate the hypothesis that growth rates of females are size dependent. During the study, an anomalous downwelling event occurred, possibly in response to the 1997 El Ni&ntilde;o, which allowed us to determine how El Ni&ntilde;o events affect EPRs of coastal copepods. The larger copepods <it>Calanus marshallae, Calanus pacificus</it> and <it>Centropages abdominalis</it> showed the highest egg production and specific growth rates during the period of active upwelling (18 July-13 August, water temperatures 8-13<IMG SRC="/math/deg.gif">C, Chl <it>a</it> concentration 4.7-16.2 <IMG SRC="/math/mu.gif"> l^-1 and water transparency 3-5 m). After 27 August, the 1997-98 El Ni&ntilde;o arrived off Oregon, creating a downwelling situation. Upwelling winds ceased, the thermocline intensified, temperature and transparency increased (to &gt;18&deg;C and 16 m), and Chl<it>a</it> declined to &lt;2 &mgr;g l^-1. Densities of the common coastal species declined greatly as well. <it>Paracalanus parvus</it> became the dominant species, and <it>Eucalanus californicus, Epilabidocera longipedata</it> and <it>Corycaeus anglicus</it> became common in our samples. EPRs for the larger boreal copepods (<it>Calanus</it> and <it>Centropages</it>) declined greatly during El Ni&ntilde;o;; the smaller copepods,<it>Pseudocalanus mimus, A.longiremis</it> and<it>Paracalanus parvus</it>, showed low but relatively constant egg production and specific growth rates during both upwelling and downwelling events. Over the entire study period, only three species produced eggs at its maximum rate (24-28 eggs female^-1 day^-1),<it>Pseudocalanus mimus</it> which averaged 4 eggs day^-1. All other species had EPRs that were two or five times below their maximum EPR. Thus, EPRs were not related to body size, contrary to our expectations. Hatching success was variable among species. Values as low as 20-40% were found for all species at least once during the study period, suggesting that occasionally a substantial portion of egg production may not be viable.

Omnivory in the calanoid copepod Temora longicornis: feeding, egg production and egg hatching rates

This study of the carabid beetle Notiophilus biguttatus F. concerns whether in poikilotherms, a negative relationship between reproduction and survival may arise as a special case of the negative relationship between metabolic rate and longevity. We therefore carried out an experiment in which we varied food intake rate by means of prey supply (the springtail Orchesella cincta (Linne)) and temperature. The data allowed us to establish relationships between the rate of oxygen consumption and rate of egg production for the different temperature regimes. In a second experiment we chose three temperature/feeding regimes at which we established survival and egg production for a good two years. With one regime, rates of metabolism, egg production and consumption were high due to an ad lib. supply of prey plus a relatively high temperature; for the other two regimes the rates were low, food intake rate being reduced either by food supply or by temperature. Median and maximum survival time were shortest in the high expenditure group (51 weeks and 114 weeks respectively) and longest in the group with limited food supply (median survival time 117 weeks). Using the relations between rate of oxygen consumption and rate of egg production we estimated total oxygen consumed in the three groups. These estimates did not differ in the two groups kept with excess prey at different temperatures; it was however, much higher in the group with restricted prey supply. We conclude that in this species survival is negatively related to rates of egg production and metabolism, with the relationship seeming to depend on whether the rates are manipulated by temperature or by food supply.

The rates of egg production of individually reared females of Centropages typicus have been observed from the moulting C5-adult to death under constant conditions of food (10 000 cells mh1 of Hymenomonas elongatd) and temperature (15 and 20°C). Preliminary experiments showed that virgin females could produce unfecunded eggs, but that the distinctive spines of the eggs of Ctypicus were only obtained after fecundation occurred. High and continuous egg production needs several matings, and the following experiments were run with a couple. In all experiments, both males and females fed and produced faecal pellets. The females show a high variability in spawning life periods, in spawning rhythms, in daily rates and, consequently, in cumulated numbers of eggs spawned during their life. The highest daily rates of egg production were obtained in the first half of the female's life, and were as high at 20°C as at 15°C. Nevertheless, the females survived longer at 15°C than at 20°C, and finally produced 47.6% more eggs during their whole life at 15°C than at 20°C, which can be partially due to the difference in size (almost 10% bigger at 15°C than at 20°C). The production of faecal pellets occurred during the whole of life and was more regular than egg production, with a maximum daily rate in the first part of life, and showed a decrease until death. The decline in daily egg production with age was parallel to the decrease in daily faecal pellet production. The daily pro- duction of faecal pellets was higher at 15°C than at 20°C. At 20°C, a good correlation was observed between the total egg production per female and the total faecal pellet production per female. The individual-based egg production rates of our experiments have been compared with rates obtained in different conditions by several authors, and were lower than in other published studies, probably due to the food offered. We emphasize the difficulties of comparing results which have been obtained for the entire life of the females with those based on daily egg production. The total egg production of a female is an important parameter in regard to the population dynamics because it fixes the maximal rate of losses (mortality plus dispersion) for which a population can continue to develop.

Measurements of hydrography, chlorophyll, moulting rates of juvenile copepods and egg production rates of adult female copepods were made at eight stations along a transect across the Skagerrak. The goals of the study were to determine (i) if there were correlations between spatial variations in hydrography, phytoplankton and copepod production rates, (ii) if copepod egg production rates were correlated with juvenile growth rates, and (iii) if there was evidence of food-niche separation among co-occumng female copepods The 200 km wide Skagerrak had a stratified water column in the center and a mixed water column along the margins. Such spatial variations should lead to a dominance of small phytoplankton cells in the center and large cells along the margins; however, during our study blooms of Gyrodinium aureolum and Ceratium (three species) masked any locally driven differences in cell size: 50% of chla was >11 μm, 5% in the 11–50 μm fraction and 45% <50 μm. averaged for all stations. Chlorophyll ranged from 0.2 to 2.5 μg l −1 at most depths and stations. Specific growth rates of copepods averaged 0.10 day −1 for adult females and 0.27 day −1 for juveniles The latter is similar to maximum rates known from laboratory studies, thus were probably not food-limited. Egg production rates were food-limited with the degree of limitation varying among species: 75% of maximum for Centropages typicus , 50% for Calanus finmarchicus , 30% for Paracalanus parvus and 15% for Acartia longiremis and Temora longicornis . The degree of limitation was unrelated to female body size suggesting food-niche separation among adults. Copepod production, summed over all species, ranged from 3 to 8 mg carbon m −3 day −1 and averaged 4.6 mg carbon m −1 day −1 . Egg production accounted for 25% of the total.

Body size is an indicator of fitness in fruit flies (Diptera: Tephritidae), with larger males and females having increased mating success and egg production, respectively. Based on laboratory studies, the larval diet and its nutritional composition are considered the most important factors influencing juvenile growth and subsequent adult body size. However, a very limited literature is less clear on the importance of larval diet as an adult size modifier of wild fruit flies. Bactrocera tryoni (Froggatt) is a polyphagous species with larvae feeding within the fruit of over 200 plant species. To test the impact of larval host on adult size in wild individuals of this species, we collected naturally infested fruit from the field and then reared out adults in the laboratory. The wing length and dry body weight of emergent flies were measured. Linear mixed models were used to analyse the difference in size depending on fruit type, larval density, sex and their interactions. Separate measurements of body size, wing length and dry body weight were significantly influenced by the larval host fruit collected from the field. However, only 7% and 24% of the variation of the wing discal–medial cell length and dry body weight, respectively, could be explained by larval host fruit type with high individual body size variation both within and between host fruit types. Fruit protein content was positively correlated, and water content negatively correlated, to wing discal–medial cell length. Unexpectedly, the parameters of wing length and dry body weight were only weakly correlated with each other. The results support the large body of laboratory‐based fruit fly diet work, which identifies protein as a key component of the larval diet, but do not support a general assumption that larval host is the key driver of adult body size variation in wild frugivorous tephritids. Rather, and in agreement with a small number of laboratory‐based trials, the importance of larval diet to adult fitness appears to become less important as the larval feeding environment becomes more complex.

1. Temperature‐induced egg size variation and its effects on successive life stages in the carabid beetle Notiophilus biguttatus were examined. 2. In the laboratory, across temperature regimes, egg size and number were inversely related; number of eggs and total egg mass were higher, but egg size was smaller at high temperatures. 3. Food intake rate was shown not to be involved in the temperature effect on egg size. 4. Within the higher temperature regimes, among females, egg size was negatively correlated with number of eggs and with total egg mass. 5. Data on egg mortality and egg development time did not explain why at low temperature eggs were larger than at high temperature. 6. Larvae hatching from eggs produced at a low temperature were heavier than larvae from eggs produced at a high temperature, irrespective of temperature during development. 7. In a prolonged outdoor experiment (January – July), encompassing the main breeding period of N. biguttatus , egg size decreased and both egg production rate and total egg mass increased in the course of the experiment. 8. In the field, an effect of seasonal change in temperature on adult body size was found; teneral beetles that had their juvenile period early in the season were larger than those that had their juvenile period later in the season. 9. The results of the study suggest a mechanistic explanation in which the egg size response to temperature follows from a difference in temperature sensitivity between two processes in oogenesis; adaptiveness of the temperature response was not clarified.

Abstract. Food demands of the predatory carabid Notiophilus biguttatus F. and their fulfilment were studied in the laboratory and field. In the laboratory, larval consumption, growth, adult body size and egg production were established for different regimes of temperature and food, the springtail Orchesella cincta. Temperature strongly influenced feeding rate of larvae and adults and consequently growth and oviposition rates. Accordingly, growth rate and ovi‐position rate increased with prey supply. Prey supply also had an effect on fat content, but the number of ripe eggs in the ovaries was related neither to temperature nor to prey supply. Adult body size was affected by temperature during the larval period but more so by food supply. Dissection of field fresh females showed them to bear eggs for the whole year, except in late winter/early spring and in July. Fat content was low in spring and, from July on, high in summer and autumn. Survivorship during starvation differed widely between samples and seemed to be related to reproductive status rather than to fat content. Samples of beetles and springtails from eleven pine plantations revealed for the beetles significant differences in fat content and body size, the latter ranging between the maximum and minimum value obtained in the laboratory. Conclusions about food limitation based on body size and fat content were not corroborated by a relationship of these indices with springtail density.

CCEIII: Persistent functional relationships between copepod egg production rates and food concentration through anomalously warm conditions in the California Current Ecosystem

1. The variation of body size and egg production between individuals of a laboratory population ofDrosophila melanogaster has been examined. Estimates of genetic and environmental contributions to the phenotypic variation have been derivedby comparing the variability of the flies of the wild population with that of genetically uniform flies from crosses between inbred lines reared under similar favourable conditions. Apparently about 50 % of the variance of body size and about 60 % of the variance of egg production is attributable to genetic segregation. 2. From the results of two-way selection for body size and also egg production, the heritability of the two characters is estimated as respectively 0.43 and 0.18, suggesting that most of the genetic variation in body size behaves as additive in the statistical sense, while non-additive effects predominate in the variability of egg production. 3. There is a clear-cut phenotypic correlation between size and egg production among the individuals of the wild population and this is mostly genetic in origin. Selection for large and small size leads to comparatively little change in egg production. A series of different genotypes, each represented by a number of genetically identical individuals; were prepared by combining haploid sets of chromosomes from the wild population with a haploid set from an inbred line—and these provided no evidence of genetic correlation between size and egg production. Hence the genetic correlation in the wild stock is essentially non-additive in behaviour. 4. Gene-environment interaction has been demonstrated for both egg production and body size by comparing estimates of variance and heritability on the live medium with those found on a synthetic medium which permits normal growth. It is suggested that gene-environment interaction will be particularly important under the suboptimal condition in which the population usually lives. 5. Reduction of the body size of genetically uniform flies by varying the nutrition of the larvae leads to a proportional reduction in the rate at which eggs are laid. 6. The variability of development time has also been examined in preliminary experiments which indicate that about half the variance is genetic in origin. Under favourable conditions there is a high correlation between length of development and body size, while egg production tends to be negatively correlated, suggesting that egg production and growth rate are genetically associated. 7. The results are discussed in relation to the stability of average body size in. the population and the ease with which selection either way leads to striking change. There are strong indications that the apparently continuous variation of attributes such as size or egg production are heterogeneous with respect to the effects on physiology and development which contribute to the final variation, while the relative contribution of different sorts of effect may vary according to environmental conditions.

The present experiment was conducted to determine the extent the performance of young laying hen was affected by dietary crude protein (CP) and metabolizable energy (ME) levels, preceeding a series of experiment to determine the requirement of each essential amino acid.Seven hundred twenty pullets of a commercial strain were housed two birds per cage in an open convention-ventilated laying house and fed twelve diets ad libitum from 150 to 255 days of age. Three replicate (240 birds per replicate) were involved. Mean daily temperature ranged from 15° to 25°C during the experimental period. Experiment had a 4×3 factorial arrangement of treatment with four levels of CP and three levels of ME.The diets were formulated for methionine, lysine and tryptophan to reach 85, 95, 105 or 115% of the NRC recommendations and contained graded levels of dietary ME (2, 700, 2850 and 3, 000 kcal/kg).Significant diet differences for feed intake, egg production, egg weight, egg mass, body weight gain and feed conversion ratio were noted. Increasing the dietary energy resulted in reduced feed intake and a general tendency to increase energy intake. But feed consumption was not affected by dietary CP levels. Increasing the protein level of the diet resulted in increased protein intake but had no effect on energy intake. Throughout the whole experimental periods, egg production increased with increasing CP levels. The egg production rate was not affected by ME level till 192 days of age, but it tended to decrease with increasing ME level after that age. Egg weight increased with age on all diets. It increased with increasing CP level until 234 days of age, but was not affected by ME level throughout all experimental period. Since egg weight increased with age on all diets and egg production rate increased with increasing CP levels, egg mass also increased with age and by CP levels in the similar way as egg weight and production rate. As protein and energy levels increased, efficiency of feed utilization increased.The present study showed that the CP level which maximized hen performance was 14.5% or more across all ME levels and on the protein requirements of laying hens indicated that for maximum production of about 90%, hens required about 18 grams of protein per day. Present experiment also have suggested that in a moderate environmental temperature (from 15° to 25°C) ME levels of 2, 700-2, 850 kcal per kg diet might give economical results. The daily energy requirement of the hens for maximum production of about 90% ranged from approximately 310 to 330 kcal ME per day.

The Cyclops sp. responses of life history traits (growth, development, and reproduction) to food conditions from oligotrophic Lake Toya were analyzed by rearing animals individually under four food regimes:three densities of the alga Cryptomonas tetrapyrenoidosa and nauplii of the calanoid copepod Eurytemora affinis as prey in an algal suspension. Cyclops sp. grew successfully from newborn nauplii to adults when algal density was ≥4 × 103 cells ml‐1 . Development time was shorter and body length larger in the high‐density (H) treatment (4 × 104 cells ml‐1 ) than in medium‐density (M) treatment (4 × 103 cells ml−1) until the early copepodite stages. In late copepodite stages, females tended to grow more slowly but tended to be larger in the M treatment than in the H treatment. However, stage‐specific growth rates were similar among treatments during development, suggesting a trade‐off between body size and development time. Although the egg production rate was higher in the M treatment than in the H treatment, it depended on female body size regardless of the food regime. Furthermore, the weight‐specific egg production rate was the same among treatments, indicating egg production was not affected by the algal concentrations tested. Addition of copepod prey influenced neither postembryonic development time nor body size, and egg production rates were comparable to those reared with an algal diet. These results reveal that even older copepodites and adults, which are generally thought to be predacious, do not necessarily require animal prey for growth and reproduction, and that Cyclops sp. can complete its life cycle on an algal diet alone. For female Cyclops sp., reduction of algal density resulted in slow development and large body size, which might be an adaptation to the oligotrophic environment, the original habitat of the copepod.

The majority of animal species have complex life cycles, in which larval stages may have very different morphologies and ecologies relative to adults. Anurans (frogs) provide a particularly striking example. However, the extent to which larval and adult morphologies (e.g. body size) are correlated among species has not been broadly tested in any major group. Recent studies have suggested that larval and adult morphology are evolutionarily decoupled in frogs, but focused within families and did not compare the evolution of body sizes. Here, we test for correlated evolution of adult and larval body size across 542 species from 42 families, including most families with a tadpole stage. We find strong phylogenetic signal in larval and adult body sizes, and find that both traits are significantly and positively related across frogs. However, this relationship varies dramatically among clades, from strongly positive to weakly negative. Furthermore, rates of evolution for both variables are largely decoupled among clades. Thus, some clades have high rates of adult body-size evolution but low rates in tadpole body size (and vice versa). Overall, we show for the first time that body sizes are generally related between adult and larval stages across a major group, even as evolutionary rates of larval and adult size are largely decoupled among species and clades.