Females In Poor Condition Research Articles

Correction: Polyandry works as bet-hedging in the field cricket Gryllus bimaculatus, even after eliminating females in poor condition that cannot accept remating

Correction: Polyandry works as bet-hedging in the field cricket Gryllus bimaculatus, even after eliminating females in poor condition that cannot accept remating

Female mate choice is affected by male condition but not female condition in an assassin bug

Abstract Sexual selection theory predicts that females prefer males in good condition because mating with them provides more resources such as sperm, ejaculates and nuptial gifts. The female's condition also affects her mating decisions, and condition‐dependent mate choice may allow her to gain more resources from a mate in the context of fluctuating resource availability. We here investigated how female mating decisions and their fitness consequences varied in the assassin bug Amphibolus venator when the conditions of potential mates and/or the females differed (good or poor condition). Females in both good and poor conditions preferred males in good condition, and females that mated with males in good condition produced more eggs with higher hatch rates. This increase in fitness may be attributed to the males in good condition transferring more ejaculate to the females. In contrast, female mate preference, fecundity and hatch rates were not affected by their own condition. This suggests that females do not choose mates according to their own condition in A. venator. However, the females in good condition laid larger eggs than females in poor condition, implying that females in good condition may invest more per egg to improve their reproductive success. To understand the evolution of female mate choice, it is necessary to investigate the effects of the condition of both sexes on female mating decision and their fitness. In A. venator, male condition may affect mate choice more than female condition.

Polyandry works as bet-hedging in the field cricket Gryllus bimaculatus, even after eliminating females in poor condition that cannot accept remating

AbstractAny kind of unpredictability affects female reproduction. In fluctuating environments, the fittest genotype can change between generations, and mating with “unsuitable” males will result in reproductive failure due to their genetic or environmental factors. If females cannot discriminate the quality of mates, monandrous mating with “unsuitable” male may lead to reproductive failure. Bet-hedging polyandry hypothesis suggests that polyandry can spread such risks over multiple males and some empirical studies support this hypothesis. However, no studies have considered the effect of female condition on mating acceptance. Because polyandry accumulates the costs of mating, only high conditioned females could accept multiple mating. In this study, females were assigned to monandry (M), two mating polyandry (2P), or three mating polyandry (3P) treatments. All females were mated with three males. For females assigned to the M treatment, for the second and third matings, we removed spermatophores immediately after transfer. For 2P females, the final spermatophore was removed immediately after transfer. Geometric mean fitness across (pseudo) generations as a long-term fitness index (calculated from the egg fertilization rate and egg hatching rate) significantly increased with the number of undisturbed mates. Therefore, the bet-hedging polyandry hypothesis is again supported after adjusting for the female condition.

Manipulating parental condition affects brood sex ratio, immunocompetence, and early chick mortality in two gull species differing in sexual size dimorphism

AbstractSex allocation theory predicts that parents should adjust their brood sex ratio to maximize fitness returns in relation to parental investment. Adaptive adjustment of sex ratio may be driven by differential costs of rearing sons and daughters or differential benefits of investing limited resources into offspring of different sex. In both cases, possible sex ratio bias should depend on parental condition. For sexually dimorphic birds with males larger than females, sons may be less likely to fledge since they are more vulnerable to food shortages or because they have impaired immunocompetence due to higher testosterone levels. Poor condition females should thus overproduce daughters to minimize possible reproductive failure. We manipulated the number of eggs laid and the amount of food available to laying females to induce differences in the condition in 2 gull species differing in sexual size dimorphism. In the Black-headed Gull (Chroicocephalus ridibundus), sexual size differences are marginal; but in the Mew Gull (Larus canus), males are 11% larger. In both species, females forced to lay an additional egg (presumed in worse condition) overproduced daughters, whereas females receiving supplemental food before laying (presumed improved condition) overproduced sons. This sex ratio skew was larger in Mew Gull, a species with larger size dimorphism. Chick immunocompetence at hatching was unrelated to sex, being higher in broods of fed mothers and lower for chicks hatched from last-laid eggs. Chick survival between hatching and day 5 post-hatch was positively related to their immunocompetence, but chicks from last-laid eggs and males of Mew Gull, the more dimorphic species, survived less well. Results indicate that costs of raising larger sex offspring coupled with parental condition shape brood sex ratio in populations studied. Adaptive brood sex ratio adjustment occurs mostly before egg laying and includes differential sex allocation in eggs depending on the probability of producing a fledged chick.

Nutrition during sexual maturation and at the time of mating affects mating behaviour in both sexes of a burying beetle

Theory predicts that the outcome of mating interactions should be influenced by the condition of both males and females. First, females should base their mating decisions on reliable cues about male quality, which are often condition dependent. Second, the costs and/or benefits of being choosy during mating may depend on the female's own condition. Finally, when males divide their time between different mating tactics, investment in alternative mating tactics may depend on male condition. Here we examined the effects of male and female nutritional condition on mating behaviour in the burying beetle Nicrophorus vespilloides. We manipulated male and female nutritional condition either during sexual maturation or at the time of mating and monitored female mate choice and male mating tactics. We found that females in poor condition (i.e. starved either during sexual maturation or at the time of mating) preferred to mate with males in good condition over males that were starved at the time of mating. In contrast, well-fed females showed no such preference. Furthermore, males that were starved during sexual maturation increased their investment in alternative mating tactics by spending more time signalling for females. Our results add to evidence suggesting that females in poor condition bias mating towards males in good condition although it is currently unclear why these females are choosier in this species. Ours is the first study to demonstrate that nutritional condition during sexual maturation can influence mating behaviour, which may have implications for the rate and direction of sexual selection.

Variation in offspring development is driven more by weather and maternal condition than predation risk

Abstract Variation in offspring development is expected to be driven by constraints on resource allocation between growth and maintenance (e.g. thermoregulation). Rapid post‐natal development decreases predation risk to offspring, while inclement weather likely prolongs development. For taxa with parental care, parental behaviour may partially buffer offspring against extrinsic drivers like predation risk and severe weather. Using a 7‐year dataset from an alpine population of horned lark Eremophila alpestris, a ground‐nesting songbird in northern British Columbia, Canada, we investigated multiple potential drivers of variation in the duration of incubation and nestling development. Using path analysis, we evaluated the direct effects of weather, predation risk and parental care on offspring development, as well as indirect developmental “carry‐over” effects of conditions during incubation on the nestling period. Nestling period duration varied by nearly 100% (7–13 days) and incubation duration by 40% (10–14 days). Cold ambient temperatures late in the nestling period prolonged development by 1 day for every 2 days below 10°C, particularly when combined with heavy precipitation. Rapid nestling development was associated with high predation risk, and prolonging development incurred a nest survival cost (–2.3% per day). Females in good condition created nest environments that promoted rapid nestling development periods (average = 8–9 days) compared to poor condition females during harsh, early‐season conditions (10–11 days), indicating parental buffering capabilities against environmental constraints. Fledging age was weakly correlated with incubation duration (r = –0.21) suggesting minimal developmental carry‐over effects. Given high nest predation risk, immediate fitness benefits can be derived by overcoming environmental constraints and reducing development time. While predation risk was influential, inclement weather and maternal condition had stronger effects on variation in offspring development. Addressing multiple drivers of variation in key life‐history traits can provide important context for understanding life‐history theory under changing environmental conditions. A plain language summary is available for this article.

A comprehensive test of the Trivers–Willard hypothesis in pronghorn ( Antilocapra americana )

Abstract The Trivers–Willard hypothesis (TWH) predicts that in a polygynous mating system, when fitness of male offspring is more variable than fitness of female offspring, mothers should invest more heavily in the sex with the highest marginal fitness returns. Females in good condition or high social rank should benefit by investing in sons, and females in poor condition or low social rank should benefit by investing in daughters. Many empirical studies have tested different aspects of the TWH, but no study has tested the assumptions and predictions in a single polygynous species using measures of maternal condition and maternal social rank, while accounting for random effects that can also influence offspring growth and survival. Here, we followed individuals in an isolated population of pronghorn on the National Bison Range, Montana, over multiple generations and tested the assumptions and predictions of the TWH. Pronghorn females who were in good condition or were socially dominant weaned larger fawns that were in better condition, but this advantage did not increase male fawn survival or reproductive success. We detected a slight bias in birth sex ratios according to maternal social rank, but overall we did not detect any adaptive benefit to mothers adopting a sex-biased investment strategy.

Liking the good guys: amplifying local adaptation via the evolution of condition-dependent mate choice.

Local adaptation can be strengthened through a diversity of mechanisms that reduce gene flow between contrasting environments. Recent work revealed that mate choice could enhance local adaptation when females preferentially mate with locally adapted males and that such female preferences readily evolve, but the opposing effects of recombination, migration and costs of female preferences remain relatively unexplored. To investigate these effects, we develop a two-patch model with two genes, one influencing an ecological trait and one influencing female preferences, where both male signals and female preferences are allowed to depend on the match between an individual's ecological trait and the local environment (condition). Because trait variation is limited when migration is rare and the benefits of preferential mating are short-lived when migration is frequent, we find that female preferences for males in high condition spread most rapidly with intermediate levels of migration. Surprisingly, we find that preferences for locally adapted males spread fastest with higher recombination rates, which contrasts with earlier studies. This is because a stronger preference allele for locally adapted males can only get uncoupled from maladapted ecological alleles following migration through recombination. The effects of migration and recombination depend strongly on the condition of the males being chosen by females, but only weakly on the condition of the females doing the choosing, except when it comes to the costs of preference. Although costs always impede the spread of female preferences for locally adapted males, the impact is substantially lessened if costs are borne primarily by females in poor condition. The abundance of empirical examples of condition-dependent mate choice combined with our theoretical results suggests that the evolution of mate choice could commonly facilitate local adaptation in nature.

Sexual signals for the colour‐blind: cryptic female mantids signal quality through brightness

Summary Cryptic coloration may evolve in response to selective pressure imposed by predators, yet effective intraspecific communication may require some level of detectability. This creates a tension between the benefits of sexually selected visual traits and the predatory costs imposed by greater conspicuousness, and little is known about how this tension may be ameliorated in highly cryptic species. We explore these competing demands in the false garden mantid Pseudomantis albofimbriata, a colour‐blind and seemingly cryptic insect. We use reflectance spectrometry and receptor‐noise modelling to characterize the conspicuousness of mantid body regions in the visual systems of mates (mantids), as well as potential predators (birds) and prey (bees). We then use condition manipulation and conspecific choice tests to further explore the colour traits of interest. Based on visual modelling, we find that male mantids are inconspicuous to conspecifics, prey and predators – that is, they are chromatically and achromatically cryptic. In contrast, female mantids are chromatically cryptic to all potential receivers, but their abdomens are achromatically conspicuous. Our food manipulation experiment shows that females in good condition (and therefore with more eggs) have brighter abdomens than females in poor condition. Choice assays show male mantids are consistently attracted to females bearing brighter abdomens. Our results reveal brightness‐mediated sexual signalling in a colour‐blind and classically cryptic insect. By communicating in the only visual channel available to them, female mantids are conspicuously signalling their quality to mates, while potentially minimizing their conspicuousness to predators and prey. Furthermore, by signalling with only a single body region, female mantids are apparently using coincident disruptive coloration to further decrease detectability to potential eavesdroppers. Our data reveal a novel example of the way in which the trade‐off between sexual selection for conspicuousness and natural selection for crypsis may be mediated in a visual signalling system. Such signals may be common in apparently cryptic species, and this study once again demonstrates the importance of analysing visual signals beyond the capacity of human vision.

Reproductive life-history strategies in lake whitefish (Coregonus clupeaformis) from the Laurentian Great Lakes

Recent food-web changes in the Laurentian Great Lakes are affecting energy and nutrient allocation to lake whitefish (Coregonus clupeaformis) with potential downstream effects on egg condition and recruitment. We tested whether egg condition was conserved or varied with maternal condition in eight stocks from Lakes Erie, Michigan, and Superior. Egg condition was conserved across stocks based on (i) a lack of correlation between females and eggs for total lipid, DHA, and other essential fatty acids; (ii) higher levels of energy and long-chain polyunsaturated fatty acids (LC-PUFA) in eggs compared with females; and (iii) no among-stock differences for those same variables in eggs. Females from northern Lake Michigan generally made the greatest trade-offs between egg size and fecundity. Highly fecund females provisioned less lipid, but more n-3 LC-PUFA to their eggs. A lack of stock-level patterns in energy and nutrient allocation suggests that trade-offs occur at the level of individual females and that females in poor condition make greater trade-offs among egg size and fecundity, total lipids, and n-3 LC-PUFA than females in good condition.

Condition Dependent and Infection Dependent Mate Preferences in Women: Preferences for Healthy Appearing Men are Associated with General Condition and Measures of Infection

Condition dependent mate choice in females, whereby condition or attractiveness influences preferences for markers of male quality, is seen both in non-humans and humans. There are several possible explanations for such effects. For example, in previous studies of fish it has been postulated that females in poor condition have energetic constraints limiting their choosiness. In this article, preferences for healthy facial appearance were measured in women and related to measures of condition. Questions were associated with two factors: a factor reflecting general health and condition (related to self-ratings of attractiveness, health, and physical fitness) and a factor reflecting experience of and current state of infection (colds per year and current cold). General health and condition were positively related to preferences for healthy appearance in male faces, in line with previously seen condition dependent preferences. However, the measure of current and previous infection was also positively related to preferences for healthy appearance in male faces. While these two findings appear to conflict, in fact, they may reflect different mechanisms at work. Previous explanations, such as competitiveness for mates and/or energetic constraints may explain general condition dependent preferences. In terms of avoiding contagion, however, those most at risk may benefit most from increased attraction to healthy partners: “infection dependent” mate preferences. In this way, general condition may be positively related to preferences for male quality but infection or experience of infection, while associated with a lowering of condition, may also be positively associated with preferences for male quality.

Sub‐lethal effects of monoterpenes on reproduction by mountain pine beetles

Abstract Plant defences may negatively affect the oviposition behaviour of insect herbivores. We exposed adult female mountain pine beetles Dendroctonus ponderosae (Hopkins) to monoterpene vapours and assessed their subsequent oviposition in lodgepole pine Pinus contorta. Exposure to 31.25 and 125 p.p.m. of α‐pinene and limonene for 24 h did not affect the survival or establishment of oviposition galleries compared with controls. Females had fewer, smaller eggs and therefore lower cumulative reproduction after exposure to 125 p.p.m. compared with the other treatments. Limonene negatively affected oviposition more than did α‐pinene. Female body condition, a measure of energetic state, influenced the responses (i.e. significant interactions between condition and monoterpene concentration). With exposure to 31.25 p.p.m., females in better condition tended to have fewer, larger eggs, whereas females in poorer condition tended to have more, smaller eggs, compared with controls. Overall, reproductive investment declined with body condition when exposed to monoterpenes. Egg size and number increased with female body size. The findings of the present study may indicate the toxic effects of monoterpenes or may be a result of females choosing not to invest in adverse environments depending on body condition. In either case, reduced reproduction when exposed to high plant defences may be increasingly important as climate change affects plant defences.

Maternal condition determines birth date and growth of newborn bear cubs

The number, size, and survival of bear cubs emerging from winter dens depend on maternal condition prior to entering the den. We hypothesized that delayed implantation provides flexibility in timing of birth such that pregnant females are able to track environmental or body conditions long after conception to optimize reproductive output in a changing environment. We tested the hypotheses that causative links between maternal condition and size of newly emerging brown bear (Ursus arctos) cubs were females in superior condition give birth earlier and, thereby, lactate longer in the den than females in poorer condition; and females in superior condition produce more milk or higher quality milk, which accelerates cub growth relative to females in poorer condition. No brown bear with a body fat content 20% produced cubs even though breeding occurred. Brown bears that were fat gave birth earlier than those that were lean. Cubs nursing from fat mothers grew faster than those nursing from lean mothers. The combination of an earlier birth date and faster growth by cubs produced from fat mothers increased mass of brown bear and polar bear (U. maritimus) twins at den emergence by 330– 360 g for each unit increase in percent maternal body fat content when entering hibernation.

Mortality Patterns and the Cost of Reproduction in a Northern Population of Ratsnakes, Elaphe obsoleta

Abstract A recent study of Ratsnakes (Elaphe obsoleta) in Texas found that adult mortality was higher for females than males, consistent with the cost of reproduction in snakes being higher for females. To determine whether the same pattern prevailed in a northern population of Ratsnakes, we used data collected using radio-telemetry to test several predictions of the cost-of-reproduction hypothesis. Contrary to there being a cost to reproduction, mortality rates did not differ between juvenile and adult snakes and, contrary to females having a higher cost of reproduction, mortality rates among adults did not differ between males and females. The only evidence consistent with reproduction increasing mortality risk was higher winter mortality for females in poor condition following egg laying. Mortality did not vary with activity but increased with time spent basking, although group differences in basking were not sufficient to produce differences in mortality. High risk of winter mortality in this populati...

Mother traits and offspring sex in two threatened gazelle species in captivity

Since threatened species are generally incapable of surviving in their natural environments, ex situ conservation programs are required to preserve them from total extinction. Captive breeding provides the tool to rear sustained populations. Knowledge about biology of such species is critical for managing such breeding programmes. In this paper, we look at the sex variation in calves surviving to 30 days in captive populations of two endangered polygynous gazelles, Gazella cuvieri and Gazella dama mhorr. We examined which of the following mother traits may affect sex allocation: her age; experience; and inbreeding coefficient. Because twins are quite common in Cuvier's gazelle, we also analyse whether offspring sex is mediated by litter size in this gazelle. In both species the overall sex ratio did not differ from unity at the age of 30 days. These results support the suggestion that for a given population to be in equilibrium, a 1:1 calf sex ratio is to be expected, with females in good condition producing sons and females in poor condition producing daughters. We also found that offspring sex is not significantly related to the same mother traits in the two gazelles studied. Cuvier's gazelle findings showed that only maternal inbreeding influenced offspring sex, the less inbred the mother the higher the probability of producing sons. In contrast, none of the maternal traits studied were related to offspring sex in Mohor gazelle. Two nonexclusive explanations are given to justify differences observed between these two species; one relates to a probable differential cost of producing either sex; the other refers to the actual homozygosis level in captive populations of each species. For Cuvier's gazelle litter size has no effect on offspring sex when the sex of the littermate is taken into account. This result fits predictions derived from Trivers–Willard model: mother in good conditions (less inbred) produce the sex with higher fitness returns (i.e., male), no matter if born at single or twins brood. Many variables are likely to affect progeny sex ratio. We have presently examined only a few. But our results might be of interest in management decisions and conservation programs such as reintroductions.

Responses to increased costs of activity during incubation in a songbird with female-only incubation: does feather colour signal coping ability?

Individuals differ in their ability to cope with energetically demanding situations while caring for the current brood, and they can signal this ability by their colouration. We examined the impact of handicapping (clipping of wing and tail feathers) on an energetically demanding care behaviour (incubation) in female Great Tits (Parus major). We hypothesised that the intensity of carotenoid-based breast feather colouration signals the ability to cope with impaired flight ability and the consequent increased energetic demands. If this is the case, females with more intensely coloured feathers should cope better with the handicap compared with less intensely coloured females, i.e. the impact of handicapping on mass loss and nest attentiveness should be negatively correlated with colouration. Handicapped females lost more weight than control females but did not decrease nest attentiveness to a greater extent, suggesting that females take the costs of handicapping on themselves. Females in poor condition were more severely influenced by handicapping. Intensity of female breast feather colouration did not correlate with either change in nest attentiveness or body mass loss during incubation. Intensity of breast feather colouration therefore does not appear to signal female ability to cope with this energetically demanding situation during incubation.

Only females in poor condition display a clear preference and prefer males with an average badge

BackgroundFemale condition-dependent variation in mate preference may have important evolutionary implications, not only within the same population but also among populations. There are few experiments, however, on how condition and/or genotype influences female mate preferences. The black throat patch of the male house sparrow, Passer domesticus, is an intensively studied plumage trait. It is often referred to as a 'badge of status' and seems to be involved in female mate choice, but differences exist among populations. Between-population variation in mate preference may occur for condition-dependent mate preferences. We tested the hypothesis that female preference may vary with female quality (body condition). Therefore, we measured female preference for badge size using an aviary two-choice test in which females were presented with two males that had different sizes of badges (enlarged or averaged).ResultsOverall we did not find a female preference for enlarged or average badges, but low-quality females spent more time near average badge males. Conversely, high-quality females did not show a clear preference.ConclusionsCollectively, these results indicate that female preference varies with female quality. Differences in female condition are causes of within-population variation in mating preferences. To our knowledge, our results provide one of the first experimental evidences that variation in preference for a male ornament is associated with female condition. In our study, however, only females of low condition displayed a clear mate preference. Differences observed among populations could be partly explained by differences in female condition.

Influence of female nutritional status on mating dynamics in a sexually cannibalistic praying mantid

The classical paradigm of sexual selection is that of advertising males and choosy females; however, male mate choice may be more common than previously thought. Unlike visual and acoustic cues, females rather than males usually emit long-distance chemical signals for mate attraction, thus providing an excellent opportunity to examine male mate choice further. Here, I used the sexually cannibalistic praying mantid Pseudomantis albofimbriata to determine the effect of female body condition on male mate choice via chemical cues in a natural scenario. Female body condition is positively correlated with fecundity and negatively correlated with the propensity to cannibalize in this system, so I predicted strong male mate choice for good-condition females to maximize male reproductive fitness. Results of field-based choice tests showed differential male attraction to good-condition females: all males were found on the cages of good-condition females and none on those of poor-condition females. In a second series of choice tests conducted in large field enclosures, I found that some poor-condition females attracted males in the absence of good-condition females, and that these females had significantly more eggs in their ovaries than the unattractive poor-condition females. Furthermore, when egg number was controlled but female body condition varied, males no longer had a significant preference for good-condition females. I therefore propose that the male preference for fecund females is a result of egg-bearing females producing a greater quantity/quality of pheromone than egg-free females, and that chemical cues are likely to be an honest indicator of female fecundity in this system.

Multimodal mate assessment by male praying mantids in a sexually cannibalistic mating system

The traditional view of sexual selection has been that of competing males and choosy females; however, more recently it has been recognized that males mayexhibit mate choice when females vary in quality and when males suffer costs associated with mating. Sexually cannibalistic mating systems provide an opportunitytoexaminemalematechoicefurther:thehighcostspotentiallyinvolvedinthematingprocess for males, as well as variation in female quality, predict male mate choice. We used the praying mantid Pseudomantis albo! mbriata to determine the effect of female body condition on male mate choice in a system with frequent precopulatory sexual cannibalism. Female body condition is positively correlated with fecundity and negatively correlated with the propensity to cannibalize, so we predicted males would strongly prefer females in good condition to maximize their reproductive potential. Results of our simultaneouschoicetestsshowedthatmalesusechemicalandvisualcuesformatelocationandassessment,and that theycan use eitherof these sensory modalities to distinguish and choose between females differing in body condition, with a signi! cant preference for good-condition females. However, surprisingly, males rarely rejected poor-condition females in the more ecologically relevant scenario of only one immediate potential mate and both sensory modes available to them, which may be explained by the strong scramble competition known for praying mantid systems. These results show that even when female quality varies and the cost of mating for males is substantial, male mate rejection does not always evolve. Crown Copyright ! 2010. Published on behalf of The Association for the Study of Animal Behaviour by Elsevier Ltd. All rights reserved.

Conditional sex allocation in the Red Mason bee, Osmia rufa

Trivers' and Willard's hypothesis that natural selection favors sex allocation in relation to maternal condition assumes iteropary. Though this assumption is not met in most solitary Aculeata, the reproductive life span of semelparous females may be divided into discrete successive cycles by the risk of open-cell parasitism. Females can avoid losing their investment to parasites attacking the open cell only by limiting the provision time for each cell. The restriction of time available for the investment in a single progeny irrespective of the condition of the female leads to de facto iteropary. Moreover, in Hymenoptera, there are no costs for sex allocation due to the haplodiploid mode of sex determination. In sexually size dimorphic species, females in poor condition are predicted to invest in the smaller sex and vice versa. The resulting prediction of a conditional sex allocation in solitary Aculeata was tested in the Red Mason bee, Osmia rufa (Osmia bicornis), a stem or hole-nesting, polylectic, univoltine megachilid bee. Body size is a key component of condition in females of nest-constructing solitary bees. Large females collect the same amount of pollen and nectar in a shorter time than small ones and should suffer less from parasitism. We found that small females dealt with their handicap of a low provisioning performance by shifting the sex ratio toward sons (the smaller sex) and by reducing the body size of daughters. Large females, however, shifted their offspring sex ratio toward daughters, the sex that depends more on body size in its reproductive value. The sex ratio in the population met the expected Fisherian sex ratio. Although females allocated their investment in the sexes according to their body mass, the population-level investment was balanced.