The energetic costs of tail autotomy to reproduction in the lizard Coleonyx brevis (Sauria: Gekkonidae)

Summary Energy reserve utilization and energy budgets were compared in tailed and tailless adult female Coleonyx brevis. Carcass, fat body and caudal energy reserves were used for vitellogenesis; mass and energy content (cal/mg and/or cal/reserve) of each were significantly lower at oviposition than at the initiation of vitellogenesis. Total energy reserves accounted for 53% of the reproductive energy investment in tailed females compared to 29% in tailless females. Tailed females had over twice as many reserve calories for egg production than tailless females. Caudal energy reserves represented 60% of the total reserves of tailed females and were one-third greater than the total energy reserves of tailless females. To produce a clutch of eggs both tailed and tailless females supplemented energy reserves with net metabolizable energy that was available after metabolic costs were paid. Tailless females had a significantly greater rate of food ingestion and more net metabolizable energy available for reproduction than tailed females, yet allocated significantly fewer calories/day to reproduction than tailed females, primarily because of the loss of caudal reserves. Reproductive efforts of tailed and tailless females were equivalent. However, the loss of caudal reserves resulted in the production of eggs that were significantly lower in mass and energy content (cal/mg and cal/egg) than when caudal reserves were used. Results empirically support the hypothesis that reproduction has energetic priority over tail regeneration in short-lived, iteroparous species with a low probability of future reproductive success.     

The influence of changing temperature on the life history of Daphniopsis ephemeralis

We present evidence which suggests that for Daphniopsis ephemeralischanges in water temperature may directly cue changes in sexratio, ephippial and parthenogenetic egg production and indirectlydetermine female body size. Field data suggested that over anannual cycle, a population of D. ephemeralis comprised animalswith three distinct life history phases. The first was madeup of exephippial females which hatched in the fall. They produceda second group made up of large parthenogenetic females whichcould produce more than one overwintering generation. In thespring these parthenogenetic females gave rise to a third lifehistory phase which comprised males and small ephippial females.Field enclosure experiments suggested that the small size ofspring females was not related to predation. Laboratory experimentssuggested that ephippial egg production at small body sizeswas associated with ‘increasing’ temperature. Theseexperiments also suggested that the fall reproductive pattern(parthenogenetic eggs and large body sizes) was associated with‘decreasing’ temperatures. We conclude that directionalityof seasonal temperature change may be the prime factor responsiblefor D. ephemeralis life history changes observed in the field.     

Macronutrient intake affects reproduction of a predatory insect

Prey quality has previously been shown to affect the growth and reproduction of predatory arthropods, however relatively little is known about the specific nutrients responsible for these effects. We tested if the macronutrient content (i.e. lipid and protein) of live prey affected mate attraction, reproductive behavior, egg production and nutrient reserves of adult female praying mantids, Pseudomantis albofimbriata. Females on a high‐protein diet produced more than twice as many eggs as females on a high‐lipid diet despite being fed the same overall biomass of prey. Furthermore, the lipid and protein composition of eggs and the female body was directly related to the diet that females were fed (i.e. high lipid content on the high‐lipid diet). Even more striking was the effect of diet treatment on the number of males attracted to females – only one male was attracted to females on the high‐lipid treatment and 56 males were attracted to females on the high‐protein treatment. Although it is not unexpected that females with more eggs would attract more males, the extreme nature of this difference is certainly surprising because previous studies have shown that females with only a couple of eggs can attract multiple males. Hence, our results suggest that female pheromone production may be affected by the quality/nutritional composition of eggs rather than simply the number of eggs. We found no significant difference in any of the other behaviours measured during mating trials, including the frequency of sexual cannibalism. The positive effects of prey protein content on mate attraction and egg production suggest that praying mantids might be expected to choose more protein‐biased prey in nature or, if prey choice is limited, to have higher reproductive output or population growth in communities dominated by protein‐rich prey.     

Producing extra eggs does not deplete macronutrient reserves in European Starlings Sturnus vulgaris

Recent studies have suggested that the size of avian clutches may be determined in part by the costs of egg production, which are thought to involve the depletion of endogenous nutrient reserves. I tested the hypothesis that producing extra eggs would deplete protein and lipid reserves in a passerine species, the European Starling Sturnus vulgaris . The first three eggs of clutches were removed on the days they were laid to induce females to lay extra eggs. Females responded to this manipulation by laying, on average, 1.3 eggs more than controls. However, based on the distribution of clutch sizes, it appears that some females responded to the removal of three eggs by producing more than one extra egg, whereas others responded by laying no extra eggs or by deserting. In unmanipulated females, the lean dry mass of the flight muscles and total body lipid were found to decline throughout breeding, an observation which is often interpreted as evidence that egg production depletes endogenous reserves. However, females experimentally induced to produce an extra egg did not have reduced stores of protein or lipid at clutch completion. No effect was observed in starlings even though this study had substantial (80%) power to detect a change in protein reserves of the same magnitude as that observed in a previous study of gulls. The decrease in flight muscle mass that has frequently been observed during breeding in passerines may not be due simply to mobilization of endogenous protein reserves.     

Foraging behaviour and diet of an ectothermic herbivore: Testudo horsfieldi

Herbivorous vertebrates of arid regions are frequently faced with inadequate food quality, quantity or both. The time and energy devoted to foraging is vital to balancing their energy budgets. For desert ectotherms, a low metabolism should be advantageous, reducing their total energy requirement, but extreme ambient temperatures can strongly constrain these animals' activity periods. We provide the first data on the activity budgets, foraging behaviour and diet of a highly abundant, desert-dwelling, herbivorous ectotherm, the steppe tortoise Testudo horsfieldi . Extreme climatic conditions of Central Asia limit steppe tortoise's activity to only three months per year. They remain inactive most of their "active season" (90%), and spend very little time foraging (<15 min per day). This suggests that steppe tortoises can satisfy their energy requirements with modest feeding efforts. Interestingly, steppe tortoises avoid feeding on grass species and feed mostly on plant species that are usually highly toxic to mammals. This result suggests that steppe tortoises and ungulates do not compete for food.     

Translocation as a conservation tool for Agassiz's desert tortoises: Survivorship,reproduction, and movements

We translocated 120 Agassiz's desert tortoises to 5 sites in Nevada and Utah to evaluate the effects of translocation on tortoise survivorship, reproduction, and habitat use. Translocation sites included several elevations, and extended to sites with vegetation assemblages not typically associated with desert tortoises in order to explore the possibility of moving animals to upper elevation areas. We measured survivorship, reproduction, and movements of translocated and resident animals at each site. Survivorship was not significantly different between translocated and resident animals within and among sites, and survivorship was greater overall during non-drought years. The number of eggs produced by tortoises was similar for translocated and resident females, but differed among sites. Animals translocated to atypical habitat generally moved until they reached vegetation communities more typical of desert tortoise habitat. Even within typical tortoise habitat, tortoises tended to move greater distances in the first year after translocation than did residents, but their movements in the second or third year after translocation were indistinguishable from those of resident tortoises. Our data show that tortoises translocated into typical Mojave desert scrub habitats perform well; however, the large first-year movements of translocated tortoises have important management implications. Projects that employ translocations must consider how much area will be needed to contain translocated tortoises and whether roads need fencing to prevent the loss of animals. © 2012 The Wildlife Society.     

Nutritional implications for sexual cannibalism in a sexually dimorphic orb web spider

Models predicting mechanisms driving sexual cannibalism in spiders with sexual size dimorphism (SSD) often assume that spiders use post‐copulatory food to channel nutrients into eggs and fecundity is altered through changes in clutch size or egg mass. I tested these assumptions using an orb web spider with extreme SSD, Argiope keyserlingi. I fed mated female spiders prey of either high protein‐low energy or low protein‐high energy composition. I measured egg energy density; a measure of the relative volumes of yolk and albumen. I predicted that if A. keyserlingi increase their egg energy density upon feeding on prey of a specific nutrient composition, they could enhance their fecundity by investing in more energy dense eggs. However, if the egg energy densities are dissimilar to their post‐copulatory prey they must be drawing energy from their somatic reserves to invest in eggs. In a further experiment I allowed female spiders to mate with and cannibalize males to determine if cannibalism induces similar effects on egg energy density. Male spider protein energy ratio was measured and found to resemble the high protein‐low energy prey. I found disagreement between the composition of post‐copulatory food and eggs in both experiments. Additionally, spiders fed high protein‐low energy prey lost weight indicating that they draw on their energy reserves to invest in eggs. I thus concluded that spiders that feed on high protein‐low energy prey or on males increase their egg energy density and, possibly, fecundity. However, the nutrient content of the prey or males cannot provide for investment in eggs. The energy invested in eggs is drawn from somatic reserves, probably induced by an as yet undescribed physiological trigger.     

Effect of body size and sugar meals on oviposition of the yellow fever mosquito,Aedes aegypti (Diptera: Culicidae)

The effects of dietary sugar and body size on the oviposition of Ae. aegypti were studied under laboratory conditions. In female mosquitoes provided with sugar, the start of maximum fecundity was significantly delayed and the oviposition period was longer than in females provided with water. The peak of oviposition was also delayed in sugar‐fed females. Large females oviposited more eggs per day than small females at maximum fecundity and during eight days of observations. Large females also visited significantly more water‐containing cups in their cages per day than small females at maximum fecundity. During the eight days of observations, large females and sugar‐fed females visited more water‐containing cups in their cages than water‐fed small females. Both large females and sugar‐fed females oviposited their eggs at sites higher above the water line than water‐fed small females. These results suggested that large and sugar‐fed female Ae. aegypti mosquitoes had more energy reserves and oviposited their eggs at higher sites, which would lead to a time lag in hatching.     

Artificial miniaturization causes eggs laid by crowd-reared (gregarious) desert locusts to produce green (solitarious) offspring in the desert locust, Schistocerca gregaria

The mechanism underlying the phase-dependent polyphenism in hatchling body coloration was studied by testing for a possible causal relationship with egg size in the desert locust, Schistocerca gregaria. Crowd-reared (gregarious) females typically produce large, black offspring, whereas females reared in isolation (solitarious) deposit small, green offspring. We first tested for possible genetic differences in the role of egg foam by washing or separating eggs from two strains of locust. No solitarizing effect was found in either of the strains tested, supporting a previous finding, using another laboratory strain, to show that the hatchling body coloration and size are pre-determined in the ovary of the mother and no egg foam factor is involved in the control of the hatchling body coloration. Topical application of fenoxycarb, a juvenile hormone analog (JHA), and implantation of extra corpora allata (CA), taken from Locusta migratoria, caused gregarious female adults of S. gregaria to produce small eggs. Some eggs laid by CA-implanted females produced green hatchlings. All large eggs chosen among those deposited by gregarious females produced black hatchlings. When eggs were either kept on dry filter paper at nearly saturated relative humidity during embryogenesis or pricked with a needle so that some egg yolk was squeezed out, some produced small, green hatchlings. These results suggested that the amount of egg yolk or the availability of yolk material may determine the body coloration of hatchlings.     

Quantifying the costs and benefits of parental care in female treehoppers

Parental protection of eggs represents one of the most basicforms of parental care. Theory suggests that even such basicparental investment represents a trade-off between current offspringsurvival and future reproductive success. However, few studieshave quantified the underlying costs and benefits of parentalcare for marked individuals across an entire lifetime. I markedand followed 370 females of Publilia concava (Hemiptera: Membracidae)that exhibited a range of guarding durations for their firstclutch. Greater hatching success was correlated with longerguarding durations, and a removal experiment verified that femalepresence was responsible for a twofold increase in hatchingsuccess. On the other hand, females that remained to guard eggshad a lower number and size of future broods, suggesting thatparental care may reduce lifetime fecundity. Marked femalesexhibited a bimodal distribution of guarding durations, reflectingthe extreme tactics of immediate abandonment or remaining throughhatching. Estimates of lifetime number of nymphs produced byfemales that abandon eggs early versus guard eggs through hatchingrevealed roughly equivalent levels of fitness. I discuss theconditions under which we might expect a female to adopt eachof the alternative tactics, given the costs and benefits ofparental care that were quantified in this study.     

Tactile stimuli perceived by the antennae cause the isolated females to produce gregarious offspring in the desert locust, Schistocerca gregaria

Maternal determination of progeny body size and coloration in the desert locust, Schistocerca gregaria, depends on the crowding conditions experienced during the short sensitive period that occurs two to six days before the deposition of the egg pod. Solitarious (isolated-reared) females produce relatively small eggs that yield solitarious green hatchlings but, females that are exposed to crowded conditions during the sensitive period, produce larger eggs that yield the dark-colored hatchlings characteristic of gregarious forms. The present study aimed to determine the stimuli influencing the maternal determination of progeny characteristics as well as the site at which such stimuli are perceived. By exposing isolated female adults to various combinations of visual, olfactory and tactile stimuli from a crowd of other adults, we found that no crowding effects could be elicited without tactile stimulation. Coating of various body surfaces with nail polish followed by exposure to crowding stimulation suggested that female adults perceive crowding stimuli with their antennae. This finding was supported by another experiment in which the antennae were either removed or covered with wax before the isolated females were exposed to crowded conditions. Neither serotonin nor an antagonist of its receptor affected the density-dependent maternal determination of progeny characteristics when injected into isolated or crowded female adults.     

Quantitative seasonal changes in the protein, lipid and energy content of the carcass, ovaries and liver of adult female plaice, Pleuronectes platessa L.

A detailed study was made of the seasonal changes in energy reserves in adult female plaice, Pleuronectes platessa L. The weights of lipid, protein, glycogen and ash in the carcass, liver and ovaries were measured in females approximately 35 cm long on ten occasions during one year. These data were converted to data for a'real'growing female by using a growth curve to take account of increasing length during the year. Growth of the whole body and of the body components was assumed to be isometric.
Plaice show a marked seasonal cycle of body weight and energy content. A six year old female plaice of 330 g, 32.6 cm long and with an energy content of 406 kcal in May, assimilates 560 kcal before December when it ceases to feed. Of this, 234 kcal is used to produce eggs, 159 kcal is used for metabolism during starvation, and the remainder 167 kcal, is used in growth. There is an increase in length to 35.9 cm and in weight to 462 g over the year. From December until March, when plaice do not feed but grow large ovaries, 40% of the protein in the body is utilised, 33% is devoted to egg production and 7% is metabolised to provide energy; 64% of the lipid is used, only 14% being used for egg production but 50% is metabolised for energy. Lipid supplies 75% of the energy for metabolism and so forms the major reserve; 42% of the energy assimilated during the year is devoted to reproduction. The main source of lipid and protein reserves is the carcass.     

稻虱缨小蜂的寄主选择性和适宜性

稻虱缨小蜂Anagrus nilaparvatae Pang &Wang对白背飞虱Sogatella furcifera(HO· rvath)卵龄无明显的寄生选择性,但在新鲜寄主中的发育历期较短,育出的蜂体较大,生殖力较高,而羽化 率和雌雄性比则不受寄主卵龄的影响。在白背飞虱和褐飞虱Nilaparvata lugens (Stal)卵共存时,稻虱缨小蜂明显选择褐飞虱。稻虱缨小蜂在褐飞虱卵中的发育显著地比在白背飞虱卵中的慢;褐飞虱卵育出的 蜂的初羽化成虫怀卵量显著高于白背飞虱卯育出的,虫体大小也类似,且虫体越大,生殖力越高。从白背飞虱卵育出的蜂供给白背飞虱卵(W→W)时,产卵量低于其它育蜂寄主和供给产卵寄主组合(w→B、B→B、B→W)的,其内禀增长力rm较其余者小25%。本文还讨论了应用适宜性指数来综合衡量寄主的适宜性。     

Influences of sex, size, and symmetry on ejaculate expenditure in a moth

Although sperm fundamentally function to fertilize eggs, forcesarising from both sexes select for optimal ejaculate composition.Sperm competition is one recognized agent in the evolution ofsperm and ejaculate structure. Few studies, however, have examinedhow female factors influence ejaculate structure, despite somebehavioral evidence for male mate choice. Male Plodia interpunctella(Lepidoptera, Pyralidae) accrue all resources for reproductionas larvae. Adults emerge with a limited sperm complement andare therefore under intense selection to optimize gamete allocation.I detected no effect of male body weight on ejaculate size.However, female reproductive potential (ovary masses) was dictatedby body weight In addition, heavier females had greater spermathecalvolumes, but there was no such relationship with bursal size.Finally, heavier females showed a higher mating frequency. Ifound that mating males were sensitive to female size and producedlarger ejaculates when mating with heavier females. Males mayejaculate more sperm into larger females either because it paysthem to "spend" more reproductive resources on matings thatprovide greater reproductive potential, or because heavier (longerlived and more attractive) females mate more frequently andhave larger spermathecal volumes. Alternatively, females maycontrol spermatophore formation and "accept" an appropriateejaculate to maximize fertility. Males may therefore be alsoselected to ejaculate more sperm into larger females to counteractgreater risks of sperm competition associated with heavier females.There was no association between male or female femur asymmetryand ejaculate size. P.interpunctella may be selected to exercisemodulation of ejaculate size because males invest paternally,sperm for the single reproductive episode are limited, and femalefecundity and mating pattern vary between individuals and areassociated with body weight. More obvious variability in malereproductive behavior and choice may therefore be paralleledat the cryptic gametic level by plasticity in ejaculate allocation.     

Intersexual differences in energy expenditure of Anolis carolinensis lizards during breeding and postbreeding seasons

Although the amount of energy that males and females invest in reproduction is an integral component of theories explaining the evolution of particular mating strategies, few studies have actually determined the amount of energy that each sex allocates to reproduction. We compared how energy is expended by male and female Anolis carolinensis lizards during both the breeding and postbreeding seasons. We used laboratory respirometry to determine resting metabolic rates (RMRs) of inactive, freshly captured lizards and the doubly labeled water technique to determine field metabolic rates (FMRs) of free-ranging lizards. Both RMRs and FMRs were influenced by body mass but not by sex. Season did not influence FMRs; however, RMRs of both sexes increased approximately 40% from the breeding to the postbreeding season. The seasonal increase in RMRs was attributed to a postreproductive increase in feeding rate and specific dynamic action. We used RMRs, FMRs, and thermal profiles of lizards to calculate energy budgets for breeding and postbreeding seasons. Energy budgets partitioned daily field energy (DFE; calculated from FMRs) into daily activity energy (DAE) and daily resting energy (DRE; calculated from RMRs). Energy expended for reproduction was estimated as DAE during the breeding season plus egg production (for females). Despite males having 40% greater body mass, females expended 46% more energy for reproduction than did males (906 and 619 J/d, respectively). Total metabolizable energy (TME=DFE+egg production for females) expended during the breeding season was similar for males and females (1,280 and 1,365 J/d, respectively). Although TME of females decreased 44% from the breeding to the postbreeding season (1,365 vs. 766 J/d), TME of males was similar during both seasons (1,280 vs. 1,245 J/d). There were both seasonal and sexual differences in DRE and DAE. Compared with most lizards from semiarid/desert habitats, A. carolinensis in a temperate habitat expends more total energy during the breeding season, allocates more energy to eggs, and appears to have more total energy available for reproduction.     

Temperature affects male and female potential reproductive rates differently in the sex-role reversed pipefish, Syngnathus typhle

The differences in potential reproductive rate between the sexescan be used to predict the operational sex ratio and the patternsand intensity of mating competition and hence sexual selectionin a population. This article describes how one environmentalcomponent, temperature, affects potential reproductive ratesof the two sexes in the paternally brooding, sex-role reversedpipefish (Syngnathus typhle). Males brooded embryos much longer(on average 58 days) in cold water (about 10°C) than inwarmer water (35 days at about 15°C). As a consequence,the potential reproductive rate (number of eggs brooded perday) of males was significantly higher in warm water. In females,however, potential reproductive rate, i.e., number of eggs producedper day given an unlimited access to mates, was not significantlydifferent between temperatures. In both sexes, potential reproductiverate was positively related to body size. At both temperatures,females had the potential to reproduce faster than males. Asa result, the operational sex ratio will become female biasedand sex-roles reversed, as is the case in this species. Sincetemperature differently influenced the potential reproductiverates of males and females, with the sexual difference largerat lower temperatures, more intense female-female competitionis predicted at low temperatures.     

Female egg dumping and the effect of sex ratio on male egg carrying in a coreid bug

Phyllomorpha laciniata Vill (Heteroptera, Coreidae) is uniqueamong terrestrial insects in that females glue eggs on the backsof other conspecifics. Egg carrying byP. laciniatamales haspreviously been considered as paternal care. We explored femaleoviposition with respect to previous mating experience of femalesand tested whether sex ratio affects male egg-carrying. Thehypothesis that male egg-carrying is a form of paternal carepredicts that a male should always accept eggs after matingwith a female. However, if male egg-carrying is a form of postcopulatorymate guarding rather than paternal care, egg carrying shouldincrease in the presence of other males. When two couples wereplaced together, females laid eggs on the backs of all individualsenclosed, including the backs of other females. However, whena female was accompanied by 2 males, 22 out of 26 females ovipositedon their mating partner. Thus, sexual competition rather thanpaternity alone, affects a male's eagerness to carry eggs. However,even if males sometimes carry their own eggs, females lay eggson the backs of all conspecifics they can easily acquire. Thus,egg carrying in P. laciniata is partially voluntary and partiallythe result of female egg dumping     

Nonreciprocal gonadal dysgenesis in hybrids of the chironomid midgeChironomus thummi. IV. Behavior of a female-specific protein,probably a vitellogenin

Using denaturing SDS-polyacrylamide gel electrophoresis, a protein with a subunit MW of about 148,000 daltons could be detected in the fat body of females of the reciprocal hybrids of Chironomus thummi thummi and Chironomus thummi piger, which is not present in males. This protein is presumably a vitellogenin and can be found in both hybrids during the late fourth-instar larval stage until eclosion of the adults, i.e., in early vitellogenesis. After eclosion, the reciprocal hybrids behave differently concerning the 148-kd protein. In females of the piger female x thummi male cross, which are fertile and produce yolky eggs, the 148-kd protein disappears from the fat body immediately after eclosion. In females of the reciprocal cross (thummi female x piger male) which are affected by gonadal dysgenesis and in which the oocytes only rarely contain yolk, the 148-kd protein is still present in the fat body of the adult up to 50 hr after eclosion until the fat body degrades. It is concluded that the inability of the sterile thummi female x piger male females to produce yolky eggs is caused by an impaired uptake of the presumed 148-kd vitellogenin into oocytes and not by a defective vitellogenesis. The impaired vitellogenin deposition into oocytes is taken as another aberrant trait of gonadal dysgenesis of the thummi female x piger male hybrids.     

State-dependent vertical distribution of the carnivore copepod Pareuchaeta norvegica

We explored the impact of body condition on vertical distributionof the carnivore copepod Pareuchaeta norvegica. Individualssampled in the upper part of the water column had lower dryweight and slightly shorter prosome than individuals sampleddeeper. Non-ovigerous females occurred higher in the water columnthan ovigerous females. Our results suggest that ovigerous femalesand individuals with large energy reserves to a large extentprioritize predator avoidance in deep water versus feeding inthe upper part of the water column compared to non-ovigerousfemales and individuals with low energy reserves. Adult femalescollected closest to the surface were less pigmented than thosefound deeper. This, however, proved to be a quickly adjustabletrait depending on prevailing light conditions.     

Adult female desert locusts require contact chemicals and light for progeny gregarization

Crowding causes many organisms to express phenotypic plasticity in various traits. Phase polyphenism in desert locusts represents one extreme example in which a solitary form (solitarious phase) turns into a gregarious form (gregarious phase) in response to crowding. Conspicuous differences in body size and colour occur even in hatchlings. The phase‐specific differences in hatchling characteristics are caused by the tactile stimuli perceived by the antennae of their mother. However, the nature of the tactile stimuli and the mechanism by which the perceived stimuli are processed as a gregarizing signal remain unknown. To explore this problem, the antennae of solitarious adult females of the desert locust Schistocerca gregaria are touched with the bodies of conspecific locusts at different physiological stages and those of other species. The results suggest that a cuticular chemical factor at a specific developmental stage of conspecific locusts causes the solitarious females to produce large eggs that give rise to black hatchlings characteristic of gregarious forms (progeny gregarization), and that this or a similar compound occurs in other acridids, crickets and cockroaches but not in beetles. The involvement of a chemical substance is also supported by hexane extracts of cuticular surfaces of locusts that induce the same effects. Interestingly, crowding induces such gregarizing effects only when the female receives the appropriate stimulus in the presence of light. Solitarious female S. gregaria with their head capsule coated with phosphorescent paint exhibit progeny gregarization in response to crowding and light pulses in darkness, whereas those treated in the same way without light pulses fail to do so.