Gender underlies the formation of STEM research groups

Research groups are the cornerstone of scientific research, yet little is known about how these groups are formed and how their organization is influenced by the gender of the research group leader. This represents an important gap in our understanding of the processes shaping gender structure within universities and the academic fields they represent. Here, we report the results of an email survey sent to department chairs and discipline‐specific listservs. We received responses from 275 female and 175 male research group leaders. Most respondents were biologists (n = 328) but psychology (n = 27), chemistry (n = 16), physics (n = 32), and mathematics (n = 30) were also relatively well represented. We found that men were self‐reported as overrepresented in research groups in the physical sciences, particularly at later career stages. Within biology, male and female group leaders reported supervising a disproportionate number of same‐gender trainees (students and postdoctoral fellows), particularly early in their careers. These self‐reported patterns were driven primarily by gender‐based differences in the pool of students applying to their research groups, while gender differences in acceptance rates played a seemingly smaller role. We discuss the implications of our results for women continuing into the professoriate and for the recruitment of young scientists into research groups.     

Student‐led field studies of herbivory: Hands‐on experiences for remote (or in‐person) learning

Challenging students to independently design and implement experiments is a powerful way to teach the scientific method while engaging with STEM‐related course material. For ecology and organismal biology, such experiences often take the form of field work. The COVID‐19 pandemic presented formidable challenges for instructors of such courses: How can students conduct any experiments, much less ones of their own design, when they might not even have access to campus? Here we describe a student‐led field project exploring invertebrate herbivory in terrestrial plant systems. Designed to flexibly accommodate student groups working either in‐person, remotely, or both, the project would be suitable for invertebrate biology, plant biology, or general ecology courses at the college or high school level. We describe our implementation in two sections of a sophomore‐level course, provide specific advice based on our experiences, make suggestions for future improvements or adaptations, and provide all the written materials that instructors would need to implement this in their own teaching.     

Sexually differential tolerance to water deficiency of Salix paraplesia—A female‐biased alpine willow

Salicaceae plants are dioecious woody plants. Previous studies have shown that male individuals are more tolerant to water deficiency than females for male‐biased poplars. However, Salix paraplesia is a female‐biased species in nature. It is still unknown whether female willows are more tolerant to drought stress than males. To better understand the sexually different tolerance to water deficiency in willows, a greenhouse experiment combined with a field investigation was conducted, and physiological traits were tested in male and female S. paraplesia under a drought‐stressed condition (50% of soil water capacity). Our field investigation showed that S. paraplesia was a species with female‐biased sex ratio along altitude gradients (2,400 m, 2,600 m and 2,800 m) in their natural habitats. Our results showed that the height growth, biomass accumulation, total chlorophyll pigment content (TChl), and the net photosynthetic rate were higher in female willows than in males at the low and middle altitudes (2,400 m and 2,600 m) rather than at a high altitude (2,800 m) under well‐watered conditions. Under drought‐stressed conditions, the growth, biomass, and photosynthesis were greatly inhibited in both sexes, while females showed higher biomass and TChl content and suffered less negative effects than did males. Particularly, females that originated from a high altitude showed lower leaf relative electrolyte leakage, malondialdehyde content, and less disorder of chloroplast ultrastructures but a higher peroxidase activity (POD) than that of males. Therefore, S. paraplesia females exhibited a better drought tolerance and self‐protective ability than males from high altitude. There is a reason to speculate that the population structure of S. paraplesia at a high altitude would be likely to further female biases with the increased drought intensity in the alpine regions.     

Genomic signature of successful colonization of Eurasia by the allopolyploid shepherd's purse (Capsella bursa‐pastoris)

Polyploidization is a dominant feature of flowering plant evolution. However, detailed genomic analyses of the interpopulation diversification of polyploids following genome duplication are still in their infancy, mainly because of methodological limits, both in terms of sequencing and computational analyses. The shepherd's purse (Capsella bursa‐pastoris) is one of the most common weed species in the world. It is highly self‐fertilizing, and recent genomic data indicate that it is an allopolyploid, resulting from hybridization between the ancestors of the diploid species Capsella grandiflora and Capsella orientalis. Here, we investigated the genomic diversity of C. bursa‐pastoris, its population structure and demographic history, following allopolyploidization in Eurasia. To that end, we genotyped 261 C. bursa‐pastoris accessions spread across Europe, the Middle East and Asia, using genotyping‐by‐sequencing, leading to a total of 4274 SNPs after quality control. Bayesian clustering analyses revealed three distinct genetic clusters in Eurasia: one cluster grouping samples from Western Europe and Southeastern Siberia, the second one centred on Eastern Asia and the third one in the Middle East. Approximate Bayesian computation (ABC) supported the hypothesis that C. bursa‐pastoris underwent a typical colonization history involving low gene flow among colonizing populations, likely starting from the Middle East towards Europe and followed by successive human‐mediated expansions into Eastern Asia. Altogether, these findings bring new insights into the recent multistage colonization history of the allotetraploid C. bursa‐pastoris and highlight ABC and genotyping‐by‐sequencing data as promising but still challenging tools to infer demographic histories of selfing allopolyploids.     

The differential contributions of herkogamy and dichogamy as mechanisms of avoiding self‐interference in four self‐incompatible Epimedium species

Self‐interference is one of the most important selective forces in shaping floral evolution. Herkogamy and dichogamy both can achieve reductions in the extent of self‐interference, but they may have different roles in minimizing self‐interference in a single species. We used four self‐incompatible Epimedium species to explore the roles of herkogamy and dichogamy in avoiding self‐interference and to test the hypothesis that herkogamy and dichogamy may be separated and become selected preferentially in the taxa. Two species (E. franchetii and E. mikinorii) expressed strong herkogamy and weak protogyny (adichogamy), whereas another two species (E. sutchuenense and E. leptorrhizum) expressed slight herkogamy and partial protandry. Field investigations indicated that there was no physical self‐interference between male function and female function regarding pollen removal and pollen deposition in all species. Self‐pollination (autonomous or facilitated) was greater in species with slight herkogamy than in those with strong herkogamy. Artificial pollination treatments revealed that self‐pollination could reduce outcrossed female fertility in all species, and we found evidence that self‐interference reduced seed set in E. sutchuenense and E. leptorrhizum in the field, but not in E. franchetii and E. mikinorii. These results indicate that well‐developed herkogamy is more effective compared with dichogamy in avoiding self‐interference in the four species. In genus Epimedium, herkogamy instead of dichogamy should be selected preferentially and evolved as an effective mechanism for avoiding self‐interference and might not need to evolve linked with dichogamy.     

Of mudsnails,terrapins, and flukes: Use of trematodes as a field‐based project in parasitology research

We present an exercise for counting trematode cysts on mudsnails that can be implemented as a field‐based project in course work by students or by volunteers. The exercise involves the digenetic trematode Pleurogonius malaclemys, which infects diamondback terrapins (Malaclemys terrapin) as its definitive host, and eastern mudsnails (Tritia obsoleta) as its intermediate host. The trematode forms macroscopic metacercarial cysts on the shells and opercula of the mudsnails, and the life cycle is completed when terrapins ingest the intermediate hosts with cysts. Previous research has suggested that quantifying cysts on mudsnails can be a relatively simple method to estimate terrapin population sizes where terrapins co‐occur with mudsnails. Three non‐professional scientist groups (including students and volunteers) were tested in their estimates of prevalence and intensity data compared to verified cyst counts. Prevalence data were relatively accurate (~76–78%) and reliable (68–89%) across the groups. The intensity of cysts (on shells and opercula of mudsnails) were mostly within 12% of the verified counts (total mean intensity of 1.81–2.97 cysts/parasitized mudsnail) but varied significantly in two cases due to false positives (likely due to sand grains or debris scored as cysts) or negatives (likely due to missed cysts behind the operculum). The exercise can be completed as a lab or series of labs in courses, and data from such projects could be used in terrapin conservation efforts, particularly in helping scientists determine where terrapins occur. We discuss modification of the exercise for other trematode species in regions around the world and hope this expands recognition by the public of the important role of parasites in ecosystems.     

The population demography of Betula maximowicziana,a cool‐temperate tree species in Japan,in relation to the last glacial period: its admixture‐like genetic structure is the result of simple population splitting not admixing

Conservation of the local genetic variation and evolutionary integrity of economically and ecologically important trees is a key aspect of studies involving forest genetics, and a population demographic history of the target species provides valuable information for this purpose. Here, the genetic structure of 48 populations of Betula maximowicziana was assessed using 12 expressed sequence tag–simple sequence repeat (EST‐SSR) markers. Genetic diversity was lower in northern populations than southern ones and structure analysis revealed three groups: northern and southern clusters and an admixed group. Eleven more genomic‐SSR loci were added and the demographic history of these three groups was inferred by approximate Bayesian computation (ABC). The ABC revealed that a simple split scenario was much more likely than isolation with admixture, suggesting that the admixture‐like structure detected in this species was due to ancestral polymorphisms. The ABC analysis suggested that the population growth and divergence of the three groups occurred 96 800 (95% CI, 20 500–599 000) and 28 300 (95% CI, 8700–98 400) years ago, respectively. We need to be aware of several sources of uncertainty in the inference such as assumptions about the generation time, overlapping of generations, confidence intervals of the estimated parameters and the assumed model in the ABC. However, the results of the ABC together with the model‐based maps of reconstructed past species distribution and palaeoecological data suggested that the modern genetic structure of B. maximowicziana originated prior to the last glacial maximum (LGM) and that some populations survived in the northern range even during the LGM.     

A novel case of autogamy and cleistogamy in Dendrobium wangliangii: A rare orchid distributed in the dry‐hot valley

Dendrobium wangliangii is an epiphytic orchid distributed in the Jinshajiang dry‐hot valley in Luquan County, Yunnan Province, China. Most Dendrobium spp. typically have a low fruit set, but this orchid shows a higher fruit set under natural conditions despite the lack of effective pollinators. The pollination biology of the critically endangered D. wangliangii was investigated in this study. A fruit set rate of 33.33 ± 4.71% was observed after bagging treatment in 2017 and a high fruit set rate (65.72 ± 4.44% in 2011; 50.79 ± 5.44% in 2017) was observed under natural conditions, indicating that D. wangliangii is characterized by spontaneous self‐pollination. The anther cap blocked the growing pollinium; thus, the pollinium slid down and reached the stigmatic cavity, leading to autogamous self‐pollination. Specifically, 51.50% of 162 unopened flowers (total 257 flowers) of this Dendrobium species under extreme water‐deficit conditions developed into fruits, suggesting the presence of cleistogamy in D. wangliangii. Here, cleistogamy may represent the primary mode of pollination for this orchid. Spontaneous self‐pollination and specific cleistogamous autogamy could represent major adaptions to the drought and pollinator‐scarce habitat in the Jinshajiang dry‐hot valley.     

Breeding systems in Cyrtanthus (Amaryllidaceae): variation in self‐sterility and potential for ovule discounting

• Breeding systems of plants determine their reliance on pollinators and ability to produce seeds following self‐pollination. Self‐sterility, where ovules that are penetrated by self‐pollen tubes that do not develop into seeds, is usually considered to represent either a system of late‐acting self‐incompatibility or strong early inbreeding depression. Importantly, it can lead to impaired female function through ovule or seed discounting when stigmas receive mixtures of self and cross pollen, unless cross pollen is able to reach the ovary ahead of self pollen (‘prepotency’). Self‐sterility associated with ovule penetration by self‐pollen tubes appears to be widespread among the Amaryllidaceae.
• We tested for self‐sterility in three Cyrtanthus species – C. contractus, C. ventricosus and C. mackenii – by means of controlled hand‐pollination experiments. To determine the growth rates and frequency of ovule penetration by self‐ versus cross‐pollen tubes, we used fluorescence microscopy to examine flowers of C. contractus harvested 24, 48 and 72 h after pollination, in conjunction with a novel method of processing these images digitally. To test the potential for ovule discounting (loss of cross‐fertilisation opportunities when ovules are disabled by self‐pollination), we pollinated flowers of C. contractus and C. mackenii with mixtures of self‐ and cross pollen.
• We recorded full self‐sterility for C. contractus and C. ventricosus, and partial self‐sterility for C. mackenii. In C. contractus, we found no differences in the growth rates of self‐ and cross‐pollen tubes, nor in the proportions of ovules penetrated by self‐ and cross‐pollen tubes. In this species, seed set was depressed (relative to cross‐pollinated controls) when flowers received a mixture of self and cross pollen, but this was not the case for C. mackenii.
• These results reveal variation in breeding systems among Cyrtanthus species and highlight the potential for gender conflict in self‐sterile species in which ovules are penetrated and disabled by pollen tubes from self pollen.

     

Dual influence of terrestrial and marine historical processes on the phylogeography of the Brazilian intertidal red alga Gracilaria caudata

In this study, we explored how past terrestrial and marine climate changes have interacted to shape the phylogeographic patterns of the intertidal red seaweed Gracilaria caudata, an economically important species exploited for agar production in the Brazilian north‐east. Seven sites were sampled along the north‐east tropical and south‐east sub‐tropical Brazilian coast. The genetic diversity and structure of G. caudata was inferred using a combination of mitochondrial (COI and cox2‐3), chloroplast (rbcL) and 15 nuclear microsatellite markers. A remarkable congruence between nuclear, mitochondrial and chloroplast data revealed clear separation between the north‐east (from 03° S to 08° S) and the south‐east (from 20° S to 23° S) coast of Brazil. These two clades differ in their demographic histories, with signatures of recent demographic expansions in the north‐east and divergent populations in the south‐east, suggesting the maintenance of several refugia during the last glacial maximum due to sea‐level rise and fall. The Bahia region (around 12° S) occupies an intermediate position between both clades. Microsatellites and mtDNA markers showed additional levels of genetic structure within each sampled site located south of Bahia. The separation between the two main groups in G. caudata is likely recent, probably occurring during the Quaternary glacial cycles. The genetic breaks are concordant with (i) those separating terrestrial refugia, (ii) major river outflows and (iii) frontiers between tropical and subtropical regions. Taken together with previously published eco‐physiological studies that showed differences in the physiological performance of the strains from distinct locations, these results suggest that the divergent clades in G. caudata correspond to distinct ecotypes in the process of incipient speciation and thus should be considered for the management policy of this commercially important species.     

A molecular analysis of African lion (Panthera leo) mating structure and extra‐group paternity in Etosha National Park

The recent incorporation of molecular methods into analyses of social and mating systems has provided evidence that mating patterns often differ from those predicted by group social organization. Based on field studies and paternity analyses at a limited number of sites, African lions are predicted to exhibit a strict within‐pride mating system. Extra‐group paternity has not been previously reported in African lions; however, observations of extra‐group associations among lions inhabiting Etosha National Park in Namibia suggest deviation from the predicted within‐pride mating pattern. We analysed variation in 14 microsatellite loci in a population of 164 African lions in Etosha National Park. Genetic analysis was coupled with demographic and observational data to examine pride structure, relatedness and extra‐group paternity (EGP). EGP was found to occur in 57% of prides where paternity was analysed (n = 7), and the overall rate of EGP in this population was 41% (n = 34). Group sex ratio had a significant effect on the occurrence of EGP (P < 0.05), indicating that variation in pride‐level social structure may explain intergroup variation in EGP. Prides with a lower male‐to‐female ratio were significantly more likely to experience EGP in this population. The results of this study challenge the current models of African lion mating systems and provide evidence that social structure may not reflect breeding structure in some social mammals.     

A comparative study between outcomes of an in‐person versus online introductory field course

The COVID‐19 pandemic has disrupted many standard approaches to STEM education. Particularly impacted were field courses, which rely on specific natural spaces often accessed through shared vehicles. As in‐person field courses have been found to be particularly impactful for undergraduate student success in the sciences, we aimed to compare and understand what factors may have been lost or gained during the conversion of an introductory field course to an online format. Using a mixed methods approach comparing data from online and in‐person field‐course offerings, we found that while community building was lost in the online format, online participants reported increased self‐efficacy in research and observation skills and connection to their local space. The online field course additionally provided positive mental health breaks for students who described the time outside as a much‐needed respite. We maintain that through intentional design, online field courses can provide participants with similar outcomes to in‐person field courses.     

Efficacy of aqueous and oil formulations of a specific Metarhizium anisopliae isolate against Aphis craccivora Koch, 1854 (Hemiptera: Aphididae) under field conditions

Cowpea (Vigna unguiculata) production is constrained by biotic and abiotic factors, among which Cowpea aphid (Aphis craccivora) is ranked a key insect pest that severely limits its potential for provision of food and nutritional security to millions of people in sub‐Saharan Africa. The use of entomopathogenic fungi for A. craccivora management has been recently demonstrated at laboratory and field levels as alternative to synthetic insecticides, but with low adoption in Africa. This study assessed the efficacy of aqueous and oil formulations of Metarhizium anisopliae ICIPE 62 against A. craccivora under field conditions. Metarhizium anisopliae formulations and a commonly used insecticide Duduthrin^® were applied using knapsack sprayers with target output of 350 L/ha. Data on aphid infestation levels were collected weekly. ICIPE 62 efficacy in inducing mortality was also assessed 24 hr post‐treatment coupled with mycosis test. Further, leaf and grain yields were determined. After six weeks post‐treatment in the wet season, there was no significant reduction in aphid density in fungus‐treated plots compared to control and Duduthrin^®‐treated plots. However, in the dry season six weeks after applying the treatments, oil formulation spray resulted low aphid density compared to control and Duduthrin^®‐treated plots. ICIPE 62 formulations did not negatively affect the natural enemies’ population. Leaf yield from the various treatments did not differ significantly in the wet season, but the two fungal formulations recorded higher yields in dry season compared to other treatments. Grain yields in wet and dry seasons were lower in control and Duduthrin^®‐treated plots compared to both ICIPE 62 formulations. This study showed that both M. anisopliae ICIPE 62 formulations are effective in suppressing A. craccivora population under field conditions without adverse effects on its beneficial insects. The study also revealed that efficacy of fungal‐based biopesticides is highly dependent on environmental conditions.     

Native insect herbivory overwhelms context dependence to limit complex invasion dynamics of exotic weeds

Understanding the role of consumers in density‐dependent plant population dynamics is a long‐standing goal in ecology. However, the generality of herbivory effects across heterogeneous landscapes is poorly understood due to the pervasive influence of context‐dependence. We tested effects of native insect herbivory on the population dynamics of an exotic thistle, Cirsium vulgare, in a field experiment replicated across eight sites in eastern Nebraska. Using hierarchical Bayesian analysis and density‐dependent population models, we found potential for explosive low‐density population growth (λ > 5) and complex density fluctuations under herbivore exclusion. However, herbivore access drove population decline (λ < 1), suppressing complex fluctuations. While plant–herbivore interaction outcomes are famously context‐dependent, we demonstrated that herbivores suppress potentially invasive populations throughout our study region, and this qualitative outcome is insensitive to environmental context. Our novel use of Bayesian demographic modelling shows that native insect herbivores consistently prevent hard‐to‐predict fluctuations of weeds in environments otherwise susceptible to invasion.     

The Association between Weight Perception and BMI among High School Students

Objective: To assess the association between weight perception and BMI among a large, diverse sample of adolescents. This study used both measured and self‐reported height and weight to calculate BMI. Research Methods and Procedures: A convenience sample of students (n = 2032) in grades 9 through 12 completed a questionnaire assessing demographic characteristics, self‐reported height and weight, and body weight perception. These students were then weighed and had their height measured using a standard protocol. Results: Using BMI calculated from measured height and weight, 1.5% of students were classified as underweight or at risk for underweight, 51.2% of students were normal weight, and 47.4% were overweight or at risk for overweight. Among this same sample of students, however, 34.8% perceived themselves as underweight, 42.9% perceived themselves as about the right weight, and 22.3% perceived themselves as overweight. Even when using BMI calculated from self‐reported height and weight, >20% of students who were overweight or at risk for overweight perceived themselves as underweight. Discussion: Because perception of overweight is a key determinant of adolescent nutritional habits and weight management, many students who are overweight or at risk for overweight but who do not perceive themselves as such are unlikely to engage in weight control practices. Increasing awareness of medical definitions of overweight might improve accuracy of weight perceptions and lead to healthier eating and increased physical activity.     

Microtopography‐induced transient waterlogging affects switchgrass (Alamo) growth in the lower coastal plain of North Carolina,USA

Very limited information is currently available on growth responses of switchgrass (lowland cultivars) to transient waterlogging in lowland or poorly drained areas. This study investigated impacts of microtopography‐induced transient waterlogging on switchgrass (Alamo cultivar) growth, represented by leaf‐level gas exchange and biomass yield, in an established experimental field located in the Atlantic coastal plain of North Carolina, USA. Intensive leaf‐level gas exchange measurements were conducted on switchgrass at paired spots with distinct elevations in three sub‐blocks. Aboveground biomass was randomly collected across the study field to explore the potential impacts of the transient waterlogging on biomass yield. The sum of excess water (SEW) was calculated based on measured instantaneous water table depth to generalize the relationship between biomass yield and intensity of transient waterlogging. Results showed significant (P ≤ 0.0001) treatment effects on leaf‐level gas exchange, characterized by evident reduction in both CO₂ assimilation rate and stomatal conductance when water table was at or near the soil surface at low positions. Negative impacts of transient waterlogging on leaf‐level gas exchange became more evident with the increasing of elevation differences between paired subplots. Stomatal closure was found to be the main mechanism responsible for the decline of net assimilation under transient waterlogging. Aboveground biomass yields of switchgrass showed relatively high spatial variability and were positively and linearly correlated with microtopography (represented by elevation in the analysis) (P < 0.03, R² > 0.77). Further analysis showed that biomass yields were negatively correlated with SEW (P < 0.001, R² > 0.6) with an exponential relationship. Results of this study strongly demonstrated transient waterlogging could negatively affect switchgrass growth by suppressing leaf‐level gas exchange rates and ultimately reducing biomass yield. Findings from this study have critical implications for evaluating the economic viability of growing switchgrass on marginal lands that are subject to transient waterlogging stresses.     

RAD‐seq linkage mapping and patterns of segregation distortion in sedges: meiosis as a driver of karyotypic evolution in organisms with holocentric chromosomes

Meiotic drive, the class of meiotic mechanisms that drive unequal segregation of alleles among gametes, may be an important force in karyotype evolution. Its role in holocentric organisms, whose chromosomes lack localized centromeres, is poorly understood. We crossed two individuals of Carex scoparia (Cyperaceae) with different chromosome numbers (2n = 33^II = 66 × 2n = 32^II = 64) to obtain F1 individuals, which we then self‐pollinated to obtain second‐generation (F2) crosses. RAD‐seq was performed for 191 individuals (including the parents, five F1 individuals and 184 F2 individuals). Our F2 linkage map based on stringent editing of the RAD‐seq data set yielded 32 linkage groups. In the final map, 865 loci were located on a linkage map of 3966.99 cM (linkage groups ranged from 24.39 to 193.31 cM in length and contained 5–51 loci each). Three linkage groups exhibit more loci under segregation distortion than expected by chance; within linkage groups, loci exhibiting segregation distortion are clustered. This finding implicates meiotic drive in the segregation of chromosome variants, suggesting that selection of chromosome variants in meiosis may contribute to the establishment and fixation of chromosome variants in Carex, which is renowned for high chromosomal and species diversity. This is an important finding as previous studies demonstrate that chromosome divergence may play a key role in differentiation and speciation in Carex.     

Populations at risk: conservation genetics of kangaroo mice (Microdipodops) of the Great Basin Desert

The Great Basin Desert of western North America has experienced frequent habitat alterations due to a complex biogeographic history and recent anthropogenic impacts, with the more recent alterations likely resulting in the decline of native fauna and flora. Dark (Microdipodops megacephalus) and pallid (M. pallidus) kangaroo mice are ecological specialists found within the Great Basin Desert and are potentially ideal organisms for assessing ecosystem health and inferring the biogeographic history of this vulnerable region. Herein, newly acquired nuclear‐encoded microsatellite loci were utilized to assess patterns of variation within and among spatially discrete groups of kangaroo mice and to evaluate gene flow, demographic trends, and genetic integrity. Results confirm that there are at least three genetically distinct units within M. megacephalus and two such units within M. pallidus. The three units of M. megacephalus appear to have different demographic histories, with effectively no gene flow among them since their divergence. Similarly, the two units of M. pallidus also appear to have experienced different demographic histories, with effectively no gene exchange. Contemporary effective population sizes of all groups within Microdipodops appear to be low (<500), suggesting that each genetic lineage may have difficulty coping with changing environmental pressures and hence may be at risk of extirpation. Results of this study indicate that each Microdipodops group should be recognized, and therefore managed, as a separate unit in an effort to conserve these highly specialized taxa that contribute to the diversity of the Great Basin Desert ecosystem.     

Fitness of reciprocal F1 hybrids between Rhinanthus minor and Rhinanthus major under controlled conditions and in the field

The performance of first‐generation hybrids determines to a large extent the long‐term outcome of hybridization in natural populations. F₁ hybrids can facilitate further gene flow between the two parental species, especially in animal‐pollinated flowering plants. We studied the performance of reciprocal F₁ hybrids between Rhinanthus minor and R. major, two hemiparasitic, annual, self‐compatible plant species, from seed germination to seed production under controlled conditions and in the field. We sowed seeds with known ancestry outdoors before winter and followed the complete life cycle until plant death in July the following season. Germination under laboratory conditions was much lower for the F₁ hybrid formed on R. major compared with the reciprocal hybrid formed on R. minor, and this confirmed previous results from similar experiments. However, this difference was not found under field conditions, which seems to indicate that the experimental conditions used for germination in the laboratory are not representative for the germination behaviour of the hybrids under more natural conditions. The earlier interpretation that F₁ hybrid seeds formed on R. major face intrinsic genetic incompatibilities therefore appears to be incorrect. Both F₁ hybrids performed at least as well as and sometimes better than R. minor, which had a higher fitness than R. major in one of the two years in the greenhouse and in the field transplant experiment. The high fitness of the F₁ hybrids confirms findings from naturally mixed populations, where F₁ hybrids appear in the first year after the two species meet, which leads to extensive advanced‐hybrid formation and introgression in subsequent generations.