Female Fitness Research Articles

Gene drive-based population suppression in the malaria vector Anopheles stephensi

Gene drives are alleles that can bias the inheritance of specific traits in target populations for the purpose of modification or suppression. Here, we construct a homing suppression drive in the major urban malaria vector Anopheles stephensi targeting the female-specific exon of doublesex, incorporating two gRNAs and a nanos-Cas9 to reduce functional resistance and improve female heterozygote fitness. Our results show that the drive was recessive sterile in both females and males, with various intersex phenotypes in drive homozygotes. Both male and female drive heterozygotes show only moderate drive conversion, indicating that the nanos promoter has lower activity in A. stephensi than in Anopheles gambiae. By amplicon sequencing, we detect a very low level of resistance allele formation. Combination of the homing suppression drive and a vasa-Cas9 line boosts the drive conversion rate of the homing drive to 100%, suggesting the use of similar systems for population suppression in a continuous release strategy with a lower release rate than SIT or fsRIDL techniques. This study contributes valuable insights to the development of more efficient and environmentally friendly pest control tools aimed at disrupting disease transmission.

Temperature-dependent benefits and costs of cytoplasmic male sterility in snail Physa acuta.

Cytoplasmic male sterility (CMS) originates from a mito-nuclear conflict where mitochondrial genes induce male sterility and nuclear genes restore male fertility in hermaphrodites. The first observation of CMS in animals was reported recently in the freshwater snail Physa acuta where it is associated with two extremes divergent mitotypes D and K. The D individuals are male-steriles while male fertility is restored by nuclear genes in K and are found mixed with the most common male-fertile N mitotype in natural populations (i.e. gynodioecy). We compared male and female fitness, growth rate and metabolism between the three mitotypes at two temperatures as this factor influences CMS in gynodioecious plants via alteration of mitochondrial functioning. Temperature did not affect male sterility which depended only on the mitotype and the presence of restorers. Our results provided evidence that CMS is beneficial to female fitness in the absence of restorers while it is costly in their presence, and furthermore driven by body mass, fulfilling a key theoretical condition for the long-term maintenance of gynodioecy. Fitness benefits and costs mediated by differences in body mass are enhanced at cold temperature, suggesting that the system dynamics may vary according to thermal conditions in nature.

Copulation interruption decreases female reproductive success in a false widow spider

Copulation is essential for transferring sperm from males to females in most animals. During copulation, males and females are often static and thus prone to predation or other threats. Its duration should therefore be reduced to minimize costs but sufficient to ensure the fertilization of eggs. Here, we investigated reproductive behavior and success in the false widow spider, Steatoda grossa (Araneae: Theridiidae), when copulation was interrupted after 1, 3, 5, 10, or 20 min or was not experimentally interrupted (control). Copulation duration in this study is defined as the total duration of insertions of male pedipalps into a female’s copulatory openings. In S. grossa, uninterrupted copulations typically last 40 to 60 min. We found that within the first 5 min, copulation interruption negatively affected reproductive success (i.e., number of egg sacs, their total mass, and number of spiderlings), and delayed production of the first egg sac within the first 10 min (in some extreme instances by over 200 days). However, when copulation duration was 10 min or longer, reproductive outcome was unaffected. In the 1-min treatment, the number of egg sacs and their mass varied greatly, which indicates considerable variation among males with respect to the speed and efficiency of sperm transfer. We discuss the costs and benefits of extended copulation duration on female reproduction and on male and female fitness.

Longitudinal Decline of Exercise Capacity in Male and Female Mice.

The population of older adults is exponentially expanding. Alongside aging comes the onset of chronic disease, decline of functional capacity, and reduced quality of life. Thus, this population increase will stress the capacity and financial viability of health and long-term care systems. Developing pre-clinical models for age-related functional decline is imperative to advancing therapies that extend healthspan and prolong independence. Previously in a cross-sectional study, we established a powerful composite scoring system we termed CFAB (comprehensive functional assessment battery). CFAB measures physical function and exercise capacity using well-validated determinants to measure overall motor function, fore-limb strength, four-limb strength/endurance, aerobic capacity, and volitional exercise/activity rate. In the current work, we used CFAB to track cohorts of male and female C57BL/6 mice over the lifespan (measuring CFAB at 6, 12, 18, 24, and 28 months of age). Overall, we found statistically significantly declining function as the mice aged, with some differences between males and females in trajectory and slope. We also determined that body mass changes presented differently between sexes, and tracked body composition (fat percentage, using magnetic resonance imagery) in females. In a subset of mice, we tracked in vivo contractile physiology noting declines in plantar flexor maximum isometric torque. In summary, our data suggest that males and females declined at different rates. We confirmed the efficacy of CFAB to track longitudinal changes in exercise capacity and physical fitness in both males and females, further validating the system to track age-related functional decline.

He said, “Why don’t you make me tea in the morning?”: a qualitative study of career building inhibitors and promotors for Japanese female physicians promoted to chief professors in medical schools

There are marked gender disparities in physicians’ academic careers in Japan, and only 4.7% of chief professors in medical departments are women. This qualitative study aimed to identify career-building inhibitors and facilitators for Japanese female physicians who were promoted to the position of chief professor in a medical school. We analyzed interview data obtained during 2019 and 2020 from four Japanese female chief professors in medical schools using Steps for Coding and Theorization. Participants held strong attitudes toward job retention upon graduation, which was previously reported to support career development among women in management positions in large Japanese companies. However, unlike the previous report, our participants did not expect their spouses’ cooperation, and their organizations did not allow for adjustment of working hours or evaluation systems that nurtured women. Other identified disincentives included workplace gender issues, performance jealousy from coworkers, singlism, and glass ceilings. Participants overcame these disincentives through self-directed transfers and career changes. Factors that facilitated career building included the presence of same-sex role models without gender bias, expectations from participants’ fathers, mentoring and sponsorship by male supervisors without gender bias, and early career success. After becoming chief professors, participants were involved in supporting female physicians. They used their own experiences to create an ideal work environment with a sense of fit for females and applied measures to prevent burnout in themselves and their subordinates. The fact that participants continued to promote their careers based on their own abilities offers encouragement for other females.

Reduced fitness of secondary females in a polygynous species: a 32-yr study of Savannah sparrows.

The evolution of mating systems reflects a balance of the often-conflicting interests of males and females. Polygyny, a mating system in which males have multiple mates, presents a fitness benefit to males, but the consequences for females are less clear. Females with polygynous social mates may suffer reduced fitness, especially secondary females who typically receive less male support. We used 32 yr of detailed reproductive data on a population of Savannah sparrows (Passerculus sandwichensis) breeding on Kent Island, NB, Canada, to investigate the effects of females' social mating status on 6 indices of female fitness: survival, clutch size, fledging success, number of fledglings produced per nest and annually, and recruitment of offspring. Secondary females produced fewer fledglings per nest and annually than did monogamous or primary females, and their young were less likely to recruit into the breeding population. Yearling secondary females also had lower survival rates than older secondary females. Combined with higher rates of partial brood loss among secondary females, our results suggest that secondary females are unable to provide enough care to consistently fledge all nestlings in their broods, likely due to reduced male provisioning. Given that the sex ratio of breeders in the population is female-biased, we suggest that polygyny persists despite its fitness costs because some females must mate polygynously to "make the best of a bad situation." Our study demonstrates the value of detailed, long-term population monitoring data for understanding mating systems and using multiple indices of fitness to analyze the costs of polygyny.

Widespread male sterility and trioecy in androdioecious Mercurialis annua: Its distribution, genetic basis, and estimates of morph-specific fitness components.

Angiosperms range in sexual system from hermaphroditism through gynodioecy and androdioecy to dioecy. Trioecy, where females and males coexist with hermaphrodites, is rare. Recently, trioecy was documented in hexaploid populations of the wind-pollinated herb Mercurialis annua in Spain. We surveyed the frequency of males, hermaphrodites, and females in M. annua across its distribution in the Iberian Peninsula, tracked sex-ratio variation in several populations over consecutive generations, and assessed evidence for pollen limitation. In a common garden, we estimated male, female, and hermaphroditic fitness. We used controlled crosses to infer the genetic basis of male sterility. Finally, we compared predictions of a deterministic model with the distribution of observed sex ratios in the field based on our fitness estimates and the inferred genetics of sex determination. Trioecy is widespread in Spanish and Portuguese populations of M. annua. Males are determined by a dominant (Y-linked) allele, and female expression results from the interaction between cytoplasmic male sterility and multiple nuclear male sterility restorers partially linked to the male determiner. Male pollen production is approximately 12 times that of hermaphrodites, while female seed production is less than 1.12 times the observed hermaphroditic levels. The distribution of sex ratios in natural populations conforms with predictions of our deterministic simulations. Our study documents and accounts for a clear case of trioecy in which sex is determined by both maternally and biparentally inherited genes.

Exploring female fitness app users' motivations and perceptions: A qualitative study.

Women make up nearly 60% of fitness App users and play an important role in the operation and development of these Apps. Despite the widespread adoption of fitness Apps in recent years due to their many physical and mental benefits, the use of Apps tends to be short-term, and user engagement is relatively low. Little is known about the factors that motivate female users to consistently use fitness Apps. This study aimed to study attributes of fitness Apps that are most likely to influence female users during their use of Apps. The means-ends chain theory and the soft-laddering interview technique were used to analyze the attributes that influenced females' perceptions of fitness apps, focusing on the features most likely to provide them with benefits and value. The results of the study indicated that instructiveness, interaction, personalization, ease of use, and convenience were the most important attributes valued by female fitness App users; peer support, entertainment, and exercise adherence were the most important consequences; and health, self-fulfillment, enjoyment of life and sense of achievement were the most important values. The findings provide researchers and management of fitness Apps and women's sports with valuable insights from the means-ends chain theory, as well as suggestions for applying App design and promotion.

Optimal polyandry in fruit flies.

The study of polyandry has received increasing scientific attention with an emphasis on the fitness benefits and costs that females derive from mating with multiple males. There are still gaps in our understanding of how polyandry affects female fitness, however, as many previous studies compared the fitness outcomes of a single mating vs. two or three matings and did not separate the consequences of multiple mating from the costs of sexual harassment. We therefore conducted controlled mating trials with female fruit flies (Drosophila melanogaster) that could mate at either low (every eight days), medium (every four days), or high (every other day) rates while controlling for exposure to harassment from males. We found that female lifetime fitness was highest under the high followed by the medium mating-rate conditions. Moreover, we did not detect reductions in lifespan as a consequence of higher rates of polyandry. Our results demonstrate that even at realistically high rates, polyandry can lead to net fitness benefits for females, which can have major implications for sexual selection. Specifically, we discuss the significance of our findings as they relate to competition and the evolution of secondary sex characteristics in females, and sperm competition amongst males.

Trans regulation of an odorant binding protein by a proto-Y chromosome affects male courtship in house fly.

The male-limited inheritance of Y chromosomes favors alleles that increase male fitness, often at the expense of female fitness. Determining the mechanisms underlying these sexually antagonistic effects is challenging because it can require studying Y-linked alleles while they still segregate as polymorphisms. We used a Y chromosome polymorphism in the house fly, Musca domestica, to address this challenge. Two male determining Y chromosomes (YM and IIIM) segregate as stable polymorphisms in natural populations, and they differentially affect multiple traits, including male courtship performance. We identified differentially expressed genes encoding odorant binding proteins (in the Obp56h family) as candidate agents for the courtship differences. Through network analysis and allele-specific expression measurements, we identified multiple genes on the house fly IIIM chromosome that could serve as trans regulators of Obp56h gene expression. One of those genes is homologous to Drosophila melanogaster CG2120, which encodes a transcription factor that binds near Obp56h. Upregulation of CG2120 in D. melanogaster nervous tissues reduces copulation latency, consistent with this transcription factor acting as a negative regulator of Obp56h expression. The transcription factor gene, which we name speed date, demonstrates a molecular mechanism by which a Y-linked gene can evolve male-beneficial effects.

Sweet mama: affiliative interactions are related to the reproductive success of dominant female Alpine marmots (Marmota marmota)

Sociality is a complex phenomenon, able to influence multiple traits of an individual life history. In group-living mammals, sociality is likely to play a major role in the reproductive success of individuals. Here we investigate how sociality traits are associated to reproductive success in female Alpine marmots (Marmota marmota), a highly social and cooperative breeding ground squirrel distributed in the European Alps. We used social network analysis to calculate sociality metrics and hurdle generalized linear mixed models (hurdle GLMMs) to model the relationship between sociality metrics and reproductive success of individually tagged female Alpine marmots. Our results showed that centrality of a reproductive female within her social group and the number of social partners are positively related to reproductive success, while agonistic behavior was not related with reproduction. Our results highlight the importance of affiliative interactions with other group members in cooperative breeders, suggesting that in such systems female fitness could be more related to social cohesion than to costs of agonistic behaviors to maintain dominance status.

Sperm depletion and mate choice of the crab spider, Ebrechtella tricuspidata (Fahricius)

Abstract Mounting evidence suggests that male sperm may be gradually depleted after consecutive matings, resulting in the decline of female reproductive output in insect species. It is predicted that females may employ adaptive strategies to avoid the sperm-depleted males, such as mating multiply with different males and/or discriminating against previously mated males (MMs). Similarly, males may exhibit adaptive behaviors toward females varying in mating status. However, in spiders with males lacking primary copulatory organs and their pedipalps modified to transfer sperm, there are few studies on male mating potential and previous mating experience on their subsequent mate choice. In this study, we used a polyandrous crab spider, Ebrechtella tricuspidata, a sit-and-wait predator with female-biased sex ratio as a model system to ascertain whether 1) male mating experiences influence female reproductive fitness; 2) females respond differently to males varying in mating status; and 3) males respond differently to females varying in mating status. Our results showed that female fecundity was independent of male mating experiences, but female fertility markedly declined with the increase of male previous mating experiences in the first eggsac. Counter to our predictions, females preferred to choose and mate with the larger males, regardless of their mating status. In contrast, male mating status influenced their mating preference toward females. Virgin males did not show any preference between virgin and mated females; however, MMs were more likely to prefer the virgin females over the mated ones. Overall, our results indicated that female choice depended primarily on male relative size rather than male mating status, whereas male choice depended on female mating status. Depending on the investigation of reproductive dynamics and mate choice in E. tricuspidata, the study will provide valuable insights into the adaptive behaviors of both males and females exhibiting toward mates varying in mating status.

Learning to handle flowers increases pollen collection for bees but does not affect pollination success for plants

Abstract Cooperation and conflict are common in plant–pollinator interactions. Flowering plants often entice pollinators to visit by offering floral food rewards, thereby facilitating pollination. However, pollinators such as bees can learn to improve their collection of floral rewards (such as pollen), changing how they interact with the flower’s reproductive organs, which together could reduce pollination success. Consequently, complex flowers that slow pollinator learning might benefit the plant. Yet how pollinator learning and flower complexity interact to affect pollination success is unknown. We therefore asked how differences in complexity of 4 flower types (Phacelia campanularia, Exacum affine, Solanum elaeagnifolium, and Erythranthe guttata) affected learning by pollen-foraging generalist bumble bees (Bombus impatiens) and how learning affected pollen collection and pollen deposition on these flowers. We found that bees generally learned how to efficiently handle more complex flower types more slowly. Bees that required more visits to become efficient foragers collected less pollen, with no effect on pollen deposition. Except for the simplest flower type, learning also involved development of motor routines unique to each flower type. Experienced bees overall collected more pollen, but individual differences in motor routines did not affect pollen collection. Conversely, individual differences in motor routines affected pollen deposition, but there was no overall effect of experience. Thus, even though learning overall benefits the bee, it does not alter female (and potentially male) fitness benefits for the plant. We discuss potential reasons for these patterns and consequences for bee behavior and flower evolution.

High-intensity interval training vs. yoga in improving binge eating and physical fitness in inactive young females

Yoga is effective in binge eating disorder (BED) treatment, but it does not seem effective enough to improve low physical fitness. In contrast, high-intensity interval training (HIIT) is effective in improving physical fitness but has never been studied in the context of BED. In the study, 47 young inactive females with mild to moderate BED were recruited and randomly assigned to a HIIT group (HIIT), a Yoga group (YG), or a control group (CG; age, 19.47 ± 0.74, 19.69 ± 0.874, and 19.44 ± 0.63 years; BMI, 21.07 ± 1.66, 21.95 ± 2.67, and 20.68 ± 2.61 kg/m2, respectively). The intervention groups participated in 8-week specific exercises, while the CG maintained their usual daily activity. Before and after the training, participants were evaluated for BED using the binge eating scale (BES) and for physical fitness. The obtained data were compared within groups and between groups, and a correlation analysis between BES and physical fitness parameters was performed. After the training, the YG presented significant improvements in BES (− 20.25%, p = 0.006, ηp2 = 0.408), fat mass (FM, − 3.13%, p = 0.033, ηp2 = 0.269), and maximal oxygen consumption (VO2max, 11.51%, p = 0.000, ηp2 = 0.601), whereas the HIIT showed significant improvements in body weight (BW, − 1.78%, p = 0.006, ηp2 = 0.433), FM (− 3.94%, p = 0.033, ηp2 = 0.285), and BMI (− 1.80%, p = 0.006, ηp2 = 0.428), but not in BES. Comparisons between groups revealed that both HIIT and YG had significantly higher VO2max levels than CG (HIIT 12.82%, p = 0.006, ηp2 = 0.088; YG: 11.90%, p = 0.009, ηp2 = 0.088) with no difference between HIIT and YG. Additionally, YG presented significantly lower BES than both HIIT (15.45%, p = 0.02, ηp2 = 0.03) and CG (11.91%, p = 0.022, ηp2 = 0.03). In conclusion, Yoga is an effective treatment for BED, but HIIT is not, despite its high efficacy in improving physical fitness.

Interacting phenotypic plasticities: do male and female responses to the sociosexual environment interact to determine fitness?

Socially induced plasticity in reproductive effort is a widely documented phenomenon. However, few empirical studies have examined how male and female plastic responses to the social environment might interact in determining fitness outcomes. In field crickets, Teleogryllus oceanicus, males respond to rival songs by increasing expenditure on seminal fluid proteins that enhance competitive fertilization success at the cost of reduced embryo survival. It remains unknown whether plastic responses in females could moderate the effects of male competitiveness on offspring performance. Here, we used a fully factorial design to explore the interacting effects on fitness of male and female plasticity to the sociosexual environment. We found that female crickets exposed to male songs increased the number of eggs produced during early life reproduction, which came at the cost of reduced offspring size. There was evidence, albeit weak, that interacting effects of male and female sociosexual environments contributed to variation in the hatching success of eggs laid by females. Lifetime offspring production was unaffected by the sociosexual environments to which upstream male and female plastic responses were made. Our data offer a rare test of the theoretical expectation that male and female plasticities should interact in their effects on female fitness.

Pollinator response to yellow UV-patterned versus white UV-patternless flower dimorphism in Anemone palmata.

Flower colour polymorphisms are uncommon but widespread among angiosperms and can be maintained by a variety of balancing selection mechanisms. Anemone palmata is mostly yellow-flowered, but white-flowered plants coexist in some populations. We analysed the distribution of colour morphs of A. palmata across its range. We also characterised their colours and compared their vegetative and sexual reproductive traits, pollinator attention and fitness. The range of A. palmata is limited to the Western Mediterranean, while white-flowered plants are restricted to Portugal and SW Spain, where they occur at low proportions. Yellow flowers have a characteristic UV pattern, with a UV-absorbing centre and UV-reflecting periphery, which is absent in the white morph. Colour features of both morphs were highly delineated, making it easy for pollinators to distinguish them. Both morphs were protogynous, with the same duration of sexual stages, and the main floral traits related to pollinator attraction, apart from flower colour, were similar. Hymenoptera and Diptera were the main pollinators, showing preference for the yellow morph, clear partitioning of pollinator groups between the two colour morphs and a marked constancy to flower colour during foraging. Both morphs combined clonal propagation with sexual reproduction, but sexual reproductive potential was lower in white-flowered plants. Finally, female fitness was higher in the yellow morph. Pollinator partitioning and colour constancy could maintain this polymorphism, despite the lower visitation rate and fitness of white-flowered plants, which could facilitate their clonal propagation.

Land-based foraging by polar bears reveals sexual conflict outside mating season

According to sexual selection theory, the sexes are faced with opposing evolutionary goals. Male fitness benefits from access to females, whereas female fitness is constrained by food resources and safety for themselves and their offspring. Particularly in large solitary carnivores, such as polar bears (Ursus maritimus), these divergent goals can potentially lead to conflict between the sexes. Outside the mating season, when polar bears are on the move across vast distances, the consequences of such conflict can become apparent when individuals arrive at the same food source. To investigate interrelationships between the sexes, we observed successive polar bears visiting a bird breeding colony to feed on clutches of eggs. We found that males succeeded females more frequently and more closely than expected by chance. Moreover, when males were closer to conspecifics, they walked faster, spent less time in the colony and ingested less food. In contrast, female foraging performance was not associated with proximity to other bears. Irrespective of proximity, females generally spent short periods in the colony and ingested fewer clutches than males. Our results suggest that in polar bears, there is a trade-off between the benefits of food intake and the opportunities (in males) and risks (in females) posed by encountering conspecifics.

Introduction to the Symposium: An Integrative Look at Whole-organism Trade-offs from the Female-centered Perspective of Biology.

Trade-offs during reproduction have long been a central focus within biology and much of the foundational work within life history evolution has focused on females, as the fitness of females is more easily quantified for use in theoretical models. However, in many regards, the field of organismal biology has deviated from this early focus on females, particularly as it relates to the nuances and dynamic nature of female reproduction. Regardless, at the organismal level, reproduction is thought to trade-off with other simultaneously occurring processes. Recent papers have sought to outline the issues with our current understanding of whole-organism trade-offs, though the field as a whole has not come to a consensus on what trade-offs mean to a reproducing female. To rectify this important gap in how trade-offs are discussed in organismal biology as well as confusion about what constitutes a trade-off, our overarching goal of this symposium was to discuss trade-offs from an integrative perspective that places female reproduction at the center. By answering what trade-offs are and what they mean to reproducing females, what has been neglected in the context of whole-organism physiology, and how maternal effects fit within this framework, our group of speakers and their associated papers will crystalize nuances of measuring and determining presence (if any) of trade-offs in reproducing females in a range of taxa and subfields.

Breeding phenology drives variation in reproductive output, reproductive costs and offspring fitness in a viviparous ectotherm.

Phenological advances are a widespread response to global warming and can contribute to determine the climate vulnerability of organisms, particularly in ectothermic species which are highly dependent on ambient temperatures to complete their life cycle. Yet, the relative contribution of breeding dates and temperature conditions during gestation on fitness of females and their offspring is poorly documented in reptiles. Here, we exposed females of the common lizard Zootoca vivipara to contrasting thermal scenarios (cold versus hot treatment) during gestation and quantified effects of parturition dates and thermal treatment on life-history traits of females and their offspring for one year. Overall, our results suggest that parturition date has a greater impact than thermal conditions during gestation on life history strategies. In particular, we found positive effects of an earlier parturition date on juvenile survival, growth and recruitment suggesting that environmental dependent selection and/or differences in parental quality between early and late breeders underlie seasonal changes in offspring fitness. Yet, an earlier parturition date compromised the energetic condition of gravid females, which suggests the existence of a mother-offspring conflict regarding the optimisation of parturition dates. While numerous studies focused on the direct effects of alterations in incubation temperatures on reptile life-history traits, our results highlight the importance of considering the role of breeding phenology in assessing the short- and long-term effects of thermal developmental plasticity.

Growth and reproductive toxicity of bisphenol A in Oikopleura dioica at environmentally relevant concentrations

Bisphenol A (BPA), a known endocrine disruptor, is ubiquitous in various aquatic environments. Appendicularians are among the most abundant mesozooplankton populations and occupy a crucial niche in marine ecosystems. However, no toxicological data are available concerning the effects of BPA on this functional group. In this study, an evaluation of the toxicity of environmentally relevant levels of BPA (2.5–150 μg/L) on the appendicularian Oikopleura dioica, including its morphology and transcriptome, was conducted. Our results demonstrated the high sensitivity of O. dioica to BPA, with a LC50 of 142 μg/L. Exposure to 125 μg/L BPA significantly inhibited the somatic growth, gonadal development and reproduction of individuals, whereas exposure to an environmentally safe concentration (2.5 μg/L) affected female fecundity and fitness as well as male gene expression. The results of the transcriptomic analysis suggest that males were more sensitive to BPA stress at the molecular level. BPA exposure not only led to abnormal secretion of digestive enzymes and phospholipase A2, affecting the function of the digestive system and arachidonic acid but also significantly down-regulated the expression of mRNAs related to enzymes involved in carbohydrate and energy metabolism in males. These findings suggest that the current safe environmental concentrations may not be safe.