Male Reproductive Investment Research Articles

Reproductive endocrinology of zoo-housed aardwolves

Knowledge regarding the relationship between endocrine parameters and reproductive activity can offer important insights into how social and environmental factors influence the reproductive success of mammals. Although components of both the physical and social environment affect endocrine regulation of reproduction, less is understood about the potential role of interactions between different endocrine axes on reproductive activity. We evaluated temporal patterns of reproductive and adrenocortical steroids in two male and three female aardwolves (Proteles cristata) housed in captivity at Brookfield Zoo, Chicago, IL, USA. We found seasonal variation in faecal androgens, estrogens, and progestagens, which provide support for previous observations of the aardwolf as a seasonal breeder. However, the timing of peak endocrine activity did not correspond to observations from wild populations. Our interpretation is that this discrepancy is caused by photoperiodic regulation of reproductive activity. We found a positive relationship between faecal androgens and faecal glucocorticoid metabolites in males and a positive relationship between faecal estrogens and faecal glucocorticoid metabolites in females when housed with conspecifics but not when housed alone. We also found a positive but asymptotic relationship between faecal progestagens and faecal glucocorticoid metabolites. We argue that these observations indicate a potential effect of reproductive endocrine activity on the hypothalamic–pituitary–adrenal axis, which could result in interesting physiological trade-offs in male reproductive tactics and female pre-partum maternal investment because of the negative effects of long-term glucocorticoid elevation on reproductive performance. Finally, our results suggest that social and environmental factors interact in regulating many aspects of endocrine fluctuations in this mostly solitary species.

Age‐dependent trade‐offs between immunity and male, but not female, reproduction

Immune function is costly and must be traded off against other life-history traits, such as gamete production. Studies of immune trade-offs typically focus on adult individuals, yet the juvenile stage can be a highly protracted period when reproductive resources are acquired and immune challenges are ubiquitous. Trade-offs during development are likely to be important, yet no studies have considered changes in adult responses to immune challenges imposed at different stages of juvenile development. By manipulating the timing of a bacterial immune challenge to the larvae of the cotton bollworm moth, we examined potential trade-offs between investment into immunity at different stages of juvenile development (early or late) and subsequent adult reproductive investment into sperm or egg production. Our data reveal an age-dependent trade-off between juvenile immune function and adult male reproductive investment. Activation of the immune response during late development resulted in a reduced allocation of resources to eupyrene (fertilizing) sperm production. Immune activation from the injection procedure itself (irrespective of whether individuals were injected with an immune elicitor or a control solution) also caused reproductive trade-offs; males injected early in development produced fewer apyrene (nonfertilizing) sperm. Contrary to many other studies, our study demonstrates these immune trade-offs under ad libitum nutritional conditions. No trade-offs were observed between female immune activation and adult reproductive investment. We suggest the differences in trade-offs observed between male sperm types and the absence of reproductive trade-offs in females may be the result of ontogenetic differences in gamete production in this species. Our data reveal developmental windows when trade-offs between immune function and gametic investment are made, and highlight the importance of considering multiple developmental periods when making inferences regarding the fundamental trade-offs expected between immune function and reproduction.

Effect of larval food stress on male adult behaviour, morphology and reproductive investment in the butterfly Pararge aegeria

Males of several animals increase their reproductive success by territorial behaviour. In butterflies, males may defend a territory (i.e., territorial perching tactic), but this is assumed to be an energetically costly way to locate mates. Limitations of the energy budget may affect fight performance, and may, consequently, force males to adopt an alternative non-territorial searching behaviour (i.e., patrolling tactic) to maximize reproductive success. In this study, we tested to what extent behavioural tactics adopted by adult males of the butterfly Pararge aegeria (L.) were affected by the nutritional conditions during the larval stage. We compared the occurrence of territorial versus patrolling behaviour, lipid mass, flight muscle ratio, metabolic rate and spermatophore production of low quality males that were reared as a larva on drought-stressed host plants and control, high quality males. Low quality males were less likely to adopt the territorial perching tactic and emerged as adults with lower lipid mass than high quality males, but they were able to restore their lipid mass through adult feeding (and perhaps the breakdown of flight muscles). Host plant quality also affected spermatophore size. Independent of the larval food treatment, territorial perching males metabolised more lipids than non-territorial males, produced larger spermatophores and copulated for longer than males adopting non-territorial behaviour. We discuss the results relative to the co-existence of the behavioural tactics (perching and patrolling).

Immunological sex differences in socially promiscuous African ground squirrels.

Differences in how males and females respond to foreign antigens are common across taxa. Such sexual differences in the immune system are predicted to be greater in species with high promiscuity and sociality as these factors increase the likelihood of disease transmission. Intense sperm competition is thought to further this sexual dichotomy as increased investment in spermatogenesis likely incurs additional immunological costs. Xerus inauris, a ground squirrel found throughout southern Africa, is extremely social and promiscuous with one of the highest male reproductive investments among rodents. These life-history attributes suggest males and females should demonstrate a large dichotomy in immunity. Contrary to our prediction, we found no difference in spleen mass between the sexes. However, we did find significant biases in leukocyte types and red blood cell counts, possibly reflecting responses to parasite types. Among males, we predicted greater investments in spermatogenesis would result in reduced immunological investments. We found a negative association between testes and spleen size and a positive relationship between testes and number of lice suggesting trade-offs in reproductive investment possibly due to the costs associated with spermatogenesis and immunity. We suggest when measuring sexual differences in immunity it is important to consider the effects of reproductive pressures, parasite types, and life history costs.

Singing activity stimulates partner reproductive investment rather than increasing paternity success in zebra finches

Song is used as a signal in sexual selection in a wide range of taxa. In birds, males of many species continue to sing after pair formation. It has been suggested that a high song output after pair formation might serve to attract extra-pair females and to minimise their own partner’s interest in extra-pair copulations. A non-exclusive alternative function that has received only scant attention is that the amount of song might stimulate the own female’s investment into eggs in a quantitative way. We address these hypotheses in a captive population of zebra finches, Taeniopygia guttata, by relating male undirected song output (i.e. non-courtship song) to male egg siring success and female reproductive investment in two different set-ups. When allowed to breed in aviaries, males with the highest song output were no more attractive than others to females in an analysis of 4,294 extra-pair courtships involving 164 different males, and they also did not sire more offspring (both trends were against the expectation). When breeding in cages with two different partners subsequently, females produced larger eggs with more orange yolks when paired to a male with a high song output. These findings suggest that singing activity in paired zebra finch males might primarily function to stimulate the partner and not to attract extra-pair females.

Tissue‐dependent changes in oxidative damage with male reproductive effort in house mice

Summary1. Investment in reproduction is anticipated to be costly and can decrease survival or future reproductive success. For males, substantial reproductive costs may be accrued when competing for mates, particularly when individuals need to invest heavily in the production of sexual signals to attract females. On a proximate level, increased male signalling effort can cause somatic damage because of oxidative stress, although this has been demonstrated only in species with visual sexual signals.2. We tested whether reproductive effort (comprising reproduction, aggression and scent signalling) is associated with increased oxidative stress in male house mice (Mus musculus domesticus). Sexual signalling in this species involves the production and deposition of scent signals containing a high concentration of protein around a defended territory. Male reproductive investment was manipulated by housing males alone, with a female or with a female and in the vicinity of competitors.3. Males breeding in the vicinity of competitors invested the most in olfactory signalling as well as having regular aggressive interactions with other males. These males tended to show greater oxidative damage to lipids in the gastrocnemius muscle but no other indication of increased oxidative stress. Instead, lipid oxidation was lower in the serum and liver of reproductive males compared with those housed alone.4. Our results highlight that oxidative stress does not always occur simply as a function of increasing reproductive effort. The lack of a consistent increase in oxidative damage could be due to adaptive regulation of antioxidants and/or a consequence of the scent signalling system of house mice, which differs considerably from the visual signalling of birds previously examined in this context.

Male reproductive investment relative to age and flight behaviour in the monandrous butterfly Pararge aegeria

Male reproductive investment may signify a considerable cost to male insects that produce sperm packages or spermatophores. Male butterflies allocate much of their active time budget to mate location, and they may adopt different behavioural strategies to do so. In the speckled wood butterfly (Pararge aegeria L.), males adopt either a territorial wait-and-fight strategy (territorial perching) or a fly-and-search strategy in wider areas (patrolling). In this study, we analysed the impact of male age, male size and male behaviour (i.e. behavioural strategies and levels of activity) on spermatophore investment (i.e. spermatophore mass, number of eupyrene sperm bundles). As predicted, reproductive investment increased with male age and size. Nevertheless, the increase of spermatophore mass with age and the number of eupyrene sperm bundles (i.e. fertile sperm) was stronger in low-activity males compared to active flying males. This suggests that flight activity has a negative impact on male reproductive investment. However, males that were forced to fly in the laboratory produced more eupyrene sperm bundles than resting males. We discuss the potential effects of male–male competition and predation risk on current versus future male reproduction. Males adopting different mate-locating strategies (perching and patrolling) in outdoor cages did not differ in spermatophore traits as was predicted from their very different flight performances. Copulations of territorial perching males took somewhat longer than copulations with non-perching males. There was a significant family effect of spermatophore size and of the expression of male mate-locating strategies suggesting heritable variation. Female traits (i.e. age and size) did not strongly affect spermatophore production. We discuss the results relative to both ultimate and proximate explanations of the complex relationships between butterfly activity, behavioural strategies, age and spermatophore production.

Mortality risk affects mating decisions in the spider Nephila clavipes

Risk assessment is a fundamental component of any decision-making process, including mate choice. For males, one element of risk that is rarely considered is that a female mate may not survive to offspring independence, resulting in total reproductive failure. This element of risk could be particularly important in short-lived species where all individuals, regardless of condition, attempt to reproduce, and developing mature eggs is a time and energetically expensive process during which females are at risk of predation, starvation, and disease. I evaluate whether males use female survival probability as a mate choice criterion in the golden orb-web spider Nephila clavipes by assessing how male reproductive investment changes depending on female proximity to oviposition. Using a field experiment and a controlled mating experiment, I show that males mate at higher frequencies, transfer more sperm, and father more offspring in the first clutch when mated with nonvirgin females close to oviposition compared with younger nonvirgin females. Furthermore, females close to oviposition have a lower probability of mortality prior to egg deposition compared with virgin females and young nonvirgin adult females. These findings support the hypothesis that males invest more reproductive effort as a female approaches oviposition, possibly because these females are a low-risk mating investment. Copyright 2011, Oxford University Press.

A physiological marker for quantifying differential reproductive investment between the sexes in Yellow-legged gulls ( Larus michahellis)

Asymmetry between males and females in the energy they invest initially in reproduction has resulted in the evolution of differing reproductive strategies (caring females vs. competitive males). However, parental care in many birds is shared by both sexes suggesting that male energy expenditure in agonistic behaviors and courtship feeding might compensate female costs of clutch production. Here, we tested the hypothesis that initial investment in reproduction by both sexes in the Yellow-legged Gull ( Larus michahellis), a species with biparental care, is similar from a physiological perspective. In this income breeder, female and male reproductive investment during early breeding can be ultimately related to muscular activity (local foraging effort required for clutch production in females and courtship feeding and agonistic behaviors in the case of males). Thus, we evaluated sex-specific patterns of creatine kinase (CK, IU/L) levels in plasma, an indicator of physical effort associated with muscular activity dependent behaviors, through incubation as a reflection of the physiological response of both sexes to the reproductive investment they made up to clutch completion. Raw levels of CK were related to plasma levels of total proteins (TP, g/dL) to account for the differential physiological state of individuals when sampled (i.e. differential dehydratation). Female costs of clutch production were associated with post-laying levels of CK/TP. We grouped females according to their relative investment in clutch production: < 15.8%, 15.8 to 17.3% and > 17.3% of field metabolic rate; which showed increasing values of CK/TP (24.6, 53.1 and 66.0 IU/g, respectively). Moreover, we found similar CK/TP trends throughout incubation for both sexes (CK/TP = 50.2− [3.3 × days from laying]) suggesting similar physiological responses to reproductive effort and, therefore, analogous sex-specific initial investment. Thus, male investment in agonistic behaviors and courtship feeding apparently equaled female investment in clutch production. The use of CK measurements is revealed as a useful approach to investigating overall investment in reproduction for both sexes, providing further insights into our comprehension of reproductive strategies in seabirds.

Acoustic Experience Shapes Alternative Mating Tactics and Reproductive Investment in Male Field Crickets

Developmental plasticity allows juvenile animals to assess environmental cues and adaptively shape behavioral and morphological traits to maximize fitness in their adult environment. Sexual signals are particularly conspicuous cues, making them likely candidates for mediating such responses. Plasticity in male reproductive traits is a common phenomenon, but empirical evidence for signal-mediated plasticity in males is lacking. We tested whether experience of acoustic sexual signals during juvenile stages influences the development of three adult traits in the continuously breeding field cricket Teleogryllus oceanicus: male mating tactics, reproductive investment, and condition. All three traits were affected by juvenile acoustic experience. Males of this species produce a long-range calling song to attract receptive females, but they can also behave as satellites by parasitizing other males' calls. Males reared in an environment mimicking a population with many calling males were less likely to exhibit satellite behavior, invested more in reproductive tissues, and attained higher condition than males reared in a silent environment. These results contrast with other studies and demonstrate how the effects of juvenile social experience on adult male morphology, reproductive investment, and behavior may subsequently influence sexual selection and phenotypic evolution.

Testosterone, physical activity, and somatic outcomes among Filipino males

Testosterone (T) facilitates male investment in reproduction in part through its anabolic effects on skeletal muscle. Traits like muscle and strength are energetically costly but are believed to enhance competitive ability in humans and other mammals. However, there are limited data on relationships between T and somatic outcomes in lean, non-western populations. We evaluate relationships between waking and pre-bed salivary T and adiposity, fat-free mass (FFM), arm muscle area (AMA), and grip strength (GS) in a large, population-based birth cohort of young adult Filipino males (20.8-22.6 years, n = 872). Data were collected as part of the Cebu Longitudinal Health and Nutrition Survey. Neither waking nor evening T predicted FFM, AMA, or GS. However, there were borderline or significant interactions between T and basketball playing (the most common team sport) and weight lifting as predictors of outcomes: higher waking T predicted higher FFM (activity x T interaction P < 0.01), AMA (interaction P < 0.1), and GS (interaction P < 0.02) among frequent basketball players, and GS (interaction P < 0.09) among the smaller sample of weight lifters. In contrast to clinical studies, but consistent with findings in several subsistence-level populations, T was positively related to adiposity in these lean young males, suggesting that energy status might regulate circulating T. Our findings support a role of the prewaking rise in T as a determinant of energetic allocation to lean mass and strength in the context of repeated muscular use and support the hypothesized role of T as a mediator of investment in costly somatic traits in human males.

No consistent female preference for higher crown UV reflectance in Blue Tits Cyanistes caeruleus: a mate choice experiment

Although male UV structural plumage coloration can indicate male quality (e.g. Keyser & Hill 2000) and female reproductive investment strategies (e.g. Sheldon et al. 1999, Griffith et al. 2003), unambiguous evidence that such plumage is a direct target of female choice is still lacking. A straightforward way of testing this is by conducting controlled mate choice experiments that exclude confounding factors such as male–male competition or territory quality. The first experiments on the role of structural colours in mate choice used UV-blocking windows (e.g. Bennett et al. 1996, Hunt et al. 1999), thereby completely removing male UV reflectance. A better approach is to vary UV reflectance within the natural range under natural light conditions. Only two such mate choice experiments have been undertaken to date (Ballentine & Hill 2003, Liu et al. 2007). In neither study did females show a preference for more UV-ornamented males. In the present study, we manipulated crown reflectance of first-year male Blue Tits Cyanistes caeruleus to test the hypothesis that females prefer males with a higher crown UV reflectance, as predicted by patterns of sex allocation, paternity and female parental investment in this species (Johnsen et al. 2005, Delhey et al. 2007a,b). In a mate choice experiment, females were offered a choice of two males (matched for yellow breast colour), one with a UV-reduced crown reflectance and one control-manipulated male. The results indicated that female preference was inconsistent and may be context-dependent

Effect of food addition on the reproductive intensity and timing of both sexes of an intertidal crab

Males and females of most animals time reproduction and synchronize their reproduc- tive activity to maximize lifetime fitness. When food is abundant, however, the 2 sexes may time investments in reproduction differently due to sexual differences in how energy limits reproductive success. Many intertidal animals have reproductive cycles with semilunar or lunar periods timed to coincide with a certain phase of the tidal amplitude cycle when offspring survive best. Given an opti- mal time to breed, well-fed females may increase their investment in offspring but not change when they breed, while males may invest more both before and after the mating peak. We explored this possibility by feeding a mixed-sex population of the fiddler crab Uca terpsichores in field enclosures over 2 sequential trials of 1 mo each. Food addition increased male courtship intensity, particularly in the latter part of the semilunar reproductive cycles, but did not change the peak days of reproductive activity. Food addition had no consistent effects on female mate-searching intensity or reproductive timing during either month-long trial. These results suggest that female reproductive cycles and their timing do not result from semilunar variation in food. However, since females breed at most once a month, the trials may not have been of sufficient duration to reveal an effect of food on female repro- ductive investment. Previous studies suggest that semilunar variation in predation on larvae is the most important factor regulating reproductive timing by both sexes. Our results indicate that addi- tional food also influences the schedule of male reproductive investment.

THE QUANTITATIVE GENETICS AND COEVOLUTION OF MALE AND FEMALE REPRODUCTIVE TRAITS

Studies of experimental sexual selection have tested the effect of variation in the intensity of sexual selection on male investment in reproduction, particularly sperm. However, in several species, including Drosophila pseudoobscura, no sperm response to experimental evolution has occurred. Here, we take a quantitative genetics approach to examine whether genetic constraints explain the limited evolutionary response. We quantified direct and indirect genetic variation, and genetic correlations within and between the sexes, in experimental populations of D. pseudoobscura. We found that sperm number may be limited by low heritability and evolvability whereas sperm quality (length) has moderate V(A) and CV(A) but does not evolve. Likewise, the female reproductive tract, suggested to drive the evolution of sperm, did not respond to experimental sexual selection even though there was sufficient genetic variation. The lack of genetic correlations between the sexes supports the opportunity for sexual conflict over investment in sperm by males and their storage by females. Our results suggest no absolute constraint arising from a lack of direct or indirect genetic variation or patterns of genetic covariation. These patterns show why responses to experimental evolution are hard to predict, and why research on genetic variation underlying interacting reproductive traits is needed.

Seminal fluid protein depletion and replenishment in the fruit fly, Drosophila melanogaster: an ELISA-based method for tracking individual ejaculates.

In many species, seminal fluid proteins (SFPs) affect female post-mating behavioral patterns, including sperm storage, egg laying, feeding, and remating. Yet, few studies have investigated the patterns of allocation, depletion, and replenishment of SFPs in male animals, despite the importance of these proteins to male and female reproductive success. To investigate such SFP dynamics, it is necessary to have a sensitive method for quantifying SFP levels in males and mated females. We developed such a method by adapting the enzyme-linked immunosorbent assay (ELISA) using anti-SFP antibodies. Here, we first use two Drosophila melanogaster SFPs (ovulin and sex peptide) to demonstrate that ELISAs provide accurate measures of SFP levels. We find that, consistent with previous data from Western blotting or immunofluorescence studies, levels of both ovulin and sex peptide decline in the mated female with time since mating, but they do so at different rates. We then use ELISAs to show that males become depleted of SFPs with repeated matings, but that previously mated males are able to transfer "virgin" levels of SFPs after 3 days of sexual inactivity. Finally, we demonstrate that ELISAs can detect SFPs from wild-caught D. melanogaster males and, thus, potentially can be used to track mating patterns in the wild. This method of measuring SFP dynamics can be used in a wide range of species to address questions related to male reproductive investment, female mating history, and variation in female post-mating behavioral changes.

Ritualized combat as an indicator of intrasexual selection effects on male life history evolution

Trade-offs between survival, growth, current reproduction, and future reproduction influence life history evolution, leading to adaptive timing of investment in various strategies. If engagement in costly intrasexual contests to gain better access to mates is an important form of male reproductive investment, then the expression of characters that promote success in this process should be influenced by their fitness effects across the lifespan. To test this prediction, the ages at which human (Homo sapiens) males exhibit the greatest investment in morphological, behavioral, and physiological characters associated with intrasexual competition was estimated by examining the ages at which males succeed in a form of ritualized combat. The average age of international boxing champions was in the latter half of the twenties, and titles were held for about 2 years on average. Thus, peak investment in traits that enhance intrasexual competition abilities appears to coincide with ages at which males have highest reproductive success. Additionally, larger males reached peak probability of success in this ritualized combat at ages about 2.6 years greater than smaller males. Because body size is highly heritable and there is strong positive assortative mating relative to this character among humans, this may indicate a polymorphic set of reproductive strategies produced through maintenance of coadapted gene complexes.

Intraspecific variation in testis asymmetry in birds: evidence for naturally occurring compensation

In many taxa, the left and right testes often differ in size. The compensation hypothesis states that one testis of the pair serves as a 'back-up' for any reduced function in the other and provides a mechanism to explain intraspecific variation in degree and direction of gonad asymmetry. Although testis asymmetry is common in birds, evidence for natural testis compensation is unknown. Using a novel quantitative approach that can be applied to any bilateral organ or structure, we show that testis compensation occurs naturally in birds and can be complete when one testis fails to develop. Owing to a recurrent risk of testis impairment and an evolutionary trade-off between natural and sexual selections acting on the arrangement of internal organs in species with abdominal and/or seasonal testes, compensation adds an important, but neglected, dimension to measures of male reproductive investment.

Large spermatophores reduce female receptivity and increase male paternity success in the almond moth, Cadra cautella

The size of a male's reproductive investment may have profound consequences for female mating frequency and male fitness. Male ejaculate size may affect female fecundity and fertility, while large ejaculates may confer an advantage for males in both avoiding and engaging in sperm competition. We explored experimentally the effect of male ejaculate size on female receptivity and male fertilization success, in the largely monandrous almond moth. Females received either a large or small first spermatophore, and were then given the opportunity to remate with another male that also provided a large or small ejaculate. We examined the effect of spermatophore size on female postmating receptivity, likelihood of remating and reproductive output. For males, we examined the effect that spermatophore size and mating order had on subsequent paternity success. Females that received a small first ejaculate were both more likely to remate (with mated males) and remated sooner than females that received a large first ejaculate. Furthermore, females that remated were also more likely to commence calling behaviour following their first mating, but there were no effects of spermatophore size on female reproductive output. For a male, however, if his female remated, the size of the spermatophore he transferred had important fitness consequences. Second-mating males suffered a paternity cost when competing against a rival that provided a large spermatophore. We propose that the enlarged spermatophore transferred by virgin males explains the low remating rate in this species, and may suggest a more polyandrous past for the almond moth, potentially shaped by sexual conflict.

Sexual conflict over the duration of copulation in Drosophila montana: why is longer better?

BackgroundConflicts of interest between the sexes are increasingly recognized as an engine driving the (co-)evolution of reproductive traits. The reproductive behaviour of Drosophila montana suggests the occurrence of sexual conflict over the duration of copulation. During the last stages of copulation, females vigorously attempt to dislodge the mounting male, while males struggle to maintain genital contact and often successfully extend copulations far beyond the females' preferred duration.ResultsBy preventing female resistance, we show that females make a substantial contribution towards shortening copulations. We staged matings under different sex ratio conditions, and provide evidence that copulation duration is a form of male reproductive investment that responds to the perceived intensity of sperm competition as predicted by game theoretical models. Further, we investigated potential benefits to persistent males, and costs to females coerced into longer matings. While males did not benefit in terms of increased progeny production by protracting copulation, female remating was delayed after long first copulations.ConclusionCopulation time is a trait subject to sexual conflict. Mating durations exceeding female optima serve males as a form of 'extended mate guarding': by inducing mating refractoriness in the female, a male extends the time over which its sperm is exclusively used to sire progeny and reduces the likelihood of the female being reinseminated by a competitor.

The Effect of Diet Quality and Wing Morph on Male and Female Reproductive Investment in a Nuptial Feeding Ground Cricket

A common approach in the study of life-history trade-off evolution is to manipulate the nutrient content of diets during the life of an individual in order observe how the acquisition of resources influences the relationship between reproduction, lifespan and other life-history parameters such as dispersal. Here, we manipulate the quality of diet that replicate laboratory populations received as a thorough test of how diet quality influences the life-history trade-offs associated with reproductive investment in a nuptial feeding Australian ground cricket (Pteronemobius sp.). In this species, both males and females make significant contributions to the production of offspring, as males provide a nuptial gift by allowing females to chew on a modified tibial spur during copulation and feed directing on their haemolymph. Individuals also have two distinct wing morphs, a short-winged flightless morph and a long-winged morph that has the ability to disperse. By manipulating the quality of diet over seven generations, we found that the reproductive investment of males and females were affected differently by the diet quality treatment and wing morph of the individual. We discuss the broader implications of these findings including the differences in how males and females balance current and future reproductive effort in nuptial feeding insects, the changing nature of sexual selection when diets vary, and how the life-history trade-offs associated with the ability to disperse are expected to differ among populations.