Mating System Research Articles

Non-Mendelian transmission of X chromosomes: mechanisms and impact on sex ratios and population dynamics in different breeding systems.

The non-Mendelian transmission of sex chromosomes during gametogenesis carries significant implications, influencing sex ratios and shaping evolutionary dynamics. Here we focus on known mechanisms that drive non-Mendelian inheritance of X chromosomes during spermatogenesis and their impact on population dynamics in species with different breeding systems. In Drosophila and mice, X-linked drivers targeting Y-bearing sperm for elimination or limiting their fitness, tend to confer unfavourable effects, prompting the evolution of suppressors to mitigate their impact. This leads to a complex ongoing evolutionary arms race to maintain an equal balance of males and females. However, in certain insects and nematodes with XX/X0 sex determination, the preferential production of X-bearing sperm through atypical meiosis yields wild-type populations with highly skewed sex ratios, suggesting non-Mendelian transmission of the X may offer selective advantages in these species. Indeed, models suggest X-meiotic drivers could bolster population size and persistence under certain conditions, challenging the conventional view of their detrimental effects. Furthering our understanding of the diverse mechanisms and evolutionary consequences of non-Mendelian transmission of X chromosomes will provide insights into genetic inheritance, sex determination, and population dynamics, with implications for fundamental research and practical applications.

Habitat selection interacts with social processes and spatial scale: Conservation implications for a lekking bird

Habitat selection is influenced by landscape composition, resource distribution and social behaviour. Habitat selection is scale-dependent, and the spatial extent and the scale at which processes are measured are therefore of paramount importance. This study focused on the habitat selection of the little bustard (Tetrax tetrax). We developed habitat selection models with the aim of disentangling the relative effects of local habitat parameters (crop), landscape features and social factors (to take into account the exploded lek mating system of this species). We used the SILand package in R, which allows the estimation of simple and interactive effects, using spatially accurate counts of male little bustards over a 1074-km2 study suite (over 11 consecutive years). Local and landscape-scale habitats were taken into account, including agri-environment schemes, allowing a quantitative analysis of these conservation measures. The predictive power of the models that only included local habitat was poor, but including landscape habitats – interacting with local habitat or not – statistically increased the model's predictive power (by 16 %). Adding the social factor further improved model quality (by 14 %). From a conservation perspective, the presence probability of a male increases by about 25 % when the field is managed with an agri-environment scheme. If the habitat around the field is of high quality (50 % of grasslands within a 500-m radius), this probability rises to 0.8, and if a male is already present within 250 m, it reaches 1. This confirms that conservation measures should preferentially target hotspots of male presence (i.e., larger leks).

Experimental evolution suggests rapid assembly of the 'selfing syndrome' from standing variation in Mimulus guttatus.

Ecological and evolutionary changes are likely to occur rapidly when outcrossing populations experience pollinator loss. However, the number and identify of plant traits that will respond to this form of selection, as well as the overall predictability of evolutionary responses, remain unclear. We experimentally evolved 20 large replicate populations of Mimulus guttatus for 10 generations under three treatments: pure outcrossing, mixed mating (10% outcrossing) and pure selfing. These populations were founded from the same genetically diverse and outcrossing natural population. After 10 generations, all measured traits evolved with flower size, phenology, and reproductive traits diverging consistently among mating system treatments. Autogamy increased dramatically in the selfing treatment, but the magnitude of adaptation only becomes clear once inbreeding depression is factored out. Selfing treatment plants evolved reduced stigma-anther separation, and also exhibited declines in flower size and per-flower reproductive capacity. Flower size also declined in selfing populations but this was driven mainly by inbreeding depression and cannot be attributed to adaptation towards the selfing syndrome. Generally, the mixed mating populations evolved trait values intermediate to the fully selfing and outcrossing populations. Overall, our experimental treatments reiterated differences that have been documented in interspecific comparisons between selfing and outcrossing species pairs. Given that such contrasts involve species separated by thousands or even millions of generations, it is noteworthy that large evolutionary responses were obtained from genetic variation segregating within a single natural population.

Hyperspectral Data Can Differentiate Species and Cultivars of C3 and C4 Turf Despite Measurable Diurnal Variation

The ability to differentiate species is not adequate for modern forage breeding programs. The measurement of persistence is currently a bottleneck in the breeding system that limits the throughput of cultivars to the marketplace and prevents it from being selected as a trait. The use of hyperspectral data obtained through remote sensing offers the potential to reduce guesswork by identifying the distribution of pasture species, but only if such data alone can distinguish the subtle differences within species, i.e., cultivars. The implementation of this technology faces many challenges due to the spectral and temporal variability of species. To understand the spectral variability between and within species groups, differentiation using hyperspectral data from monoculture plots of turf species was utilized. Spectral data were collected over a year using an ASD FieldSpec® and canopy pasture probe (CAPP). The plots consisted of monocultures of various species, and cultivars (a total of 10 plots). Linear discriminant analysis (LDA) was conducted on the full spectrum and reduced band data. This technique successfully differentiated the species with high accuracy (>98%). We demonstrate the potential of hyperspectral data and analysis techniques to accurately separate differences down to cultivar level. We also show that diurnal variation is measurable in the spectra but does not preclude differentiation.

Under the radar: Transcriptomic responses of bed bugs to an entomopathogen, environmental bacteria, and a human pathogen

Bed bugs (Hemiptera: Cimicidae) are widely distributed, obligately blood-feeding insects, but they have never been linked to pathogen transmission in humans. Most other hematophagous insects that frequently bite humans transmit pathogens, and it is unclear why bed bugs do not. One hypothesis is that bed bugs have evolved a highly robust immune system because their mating system, traumatic insemination, exposes females to consistent wounding and bacterial infections. Although this has been proposed, very little is known about the bed bug immune system and how bed bugs respond to microbial challenges introduced by wounding. Similarly, there is little known about how the bed bug immune system responds to human pathogens. Understanding the bed bug immune system could give insight to why bed bugs appear not to transmit disease and under what circumstances they could, while also facilitating biological control efforts involving microbes. To investigate the transcriptomic response of bed bugs to immune challenges, we exposed female bed bugs to three bacterial challenges. 1.) Pseudomonas fluorescens, an entomopathogen known to have harmful effects to bed bugs, 2.) bacteria cultured from a bed bug enclosure (99.9 % Bacillus spp.), likely encountered during traumatic insemination, and 3.) Borrelia duttoni, a human vector-borne pathogen that causes relapsing fever. We compared the transcriptomes of infected bed bugs with uninfected matched controls in a pairwise fashion, focusing on immune-related genes. We found many known antimicrobial effector genes upregulated in response to P. fluorescens and traumatic insemination-associated bacteria, but interestingly, not in response to B. duttoni. In the differentially expressed genes that were shared between experiments, we found significant overlap in the P. fluorescens treatment and the traumatic insemination bacteria treatment, and between the P. fluorescens and B. duttoni treatments, but not between the traumatic insemination bacteria treatment and the B. duttoni treatment. Finally, we identify previously overlooked candidates for future studies of immune function in bed bugs, including a peroxidase-like gene, many putative cuticle-associated genes, a laccase-like gene, and a mucin-like gene. By taking a comprehensive transcriptomic approach, our study is an important step in understanding how bed bugs respond to diverse immune challenges.

Genomic implications of the repeated shift to self-fertilization across a species' geographic distribution.

The ability to self-fertilize often varies among closely related hermaphroditic plant species, though, variation can also exist within species. In the North American Arabidopsis lyrata, the shift from self-incompatibility (SI) to selfing established in multiple regions independently, mostly since recent postglacial range expansion. This has made the species an ideal model for the investigation of the genomic underpinnings of the breakdown of SI and its population genetic consequences. By comparing nearby selfing and outcrossing populations across the entire species' geographic distribution, we investigated variation at the self-incompatibility (S-)locus and across the genome. Furthermore, a diallel crossing experiment on one mixed-mating population was performed to gain insight in the genetics of mating system variation. We confirmed that the breakdown of SI had evolved in several S-locus backgrounds. The diallel suggested the involvement of binuclearly expressed parental genes with dominance relations. Though, the population-level genome-wide association study did not single out clear-cut candidate genes but several regions with one near the S-locus. On the implication side, selfing as compared to outcrossing populations had less than half of the genomic diversity, while the number of runs of homozygosity and their length scaled with the degree of inbreeding. The results highlight that mating system shifts to selfing, its genetic underpinning and the likely negative genomic consequences for evolutionary potential can be strongly interlinked with past range dynamics.

Male consort behavior is driven by female mate choice and receptive synchrony in Tibetan macaques (Macaca thibetana)

In group-living animals, males’ fighting abilities were usually mediated via dominance rank to sort males into a queue to access fertile females, especially in non-human primates. However, the correlation between male reproductive success and consortship, an alternative high-ranking male reproductive strategy, varies across species, obscuring the adaptive significance of male consort behavior. The priority of access (PoA) model is commonly used to predict male mating/reproductive success based on male dominance rank and female reproductive synchrony. In this study, we aimed to assess the applicability of the PoA model in predicting the distribution of male mating success and consortship, while also identifying the main factors influencing these outcomes in a group of free-ranging Tibetan macaques (Macaca thibetana) at Huangshan, China. Our results showed that (1) the male mating was significantly skewed towards the highest-ranking males, deviating from the expectations set by the PoA model. This departure was attributed to both female mate choice and male consort behavior. Notably, the influence of male rank on mating success decreased as the number of receptive females increased. Additionally, female mate choice became less significant when consorted by males compared to situations when they were not consorted; (2) the observed consort behavior among males was lower than what the PoA model predicted for available receptive days, while high-ranking males exhibited a gradual increase in their consort behavior with the rising number of receptive females. Our results suggests that, in Tibetan macaques, male consort behavior imposed limitations on female mate choice, and mitigated the impact of male dominance rank on male mating success as the number of receptive females grew. We propose that male consort behavior could be driven by female counter-monopoly strategies, and the simultaneous occurrence of consort behavior and opportunistic mating may represent the most effective mating tactic in this promiscuous mating system.

Performance of Provitamin a Maize Hybrids for Yield and Desirable Agronomic Traits

To find improved F1 hybrids for breeding procedures, the heterosis of maize hybrids must be determined. Therefore, to identify prospective hybrids for use in future provitamin A maize breeding systems, this study was carried out to evaluate the amount of standard heterosis for grain yield and related attributes. Fifteen provitamin A maize inbred lines were crossed through the diallel-II design. The resulting Eight four F1 hybrids along with four standard checks (BHQPY545, BH549, BH546, and BH547) were evaluated using RCBD (20 entries) and Alpha-Lattice Design (68 entries) with two replications during 2022/2023 main cropping season at Bako National Maize Research Center. Analysis of variance revealed significant variations for most of the traits indicating the existence of genetic variability. The Standard heterosis assessment noticed significant positive and negative heterosis for the majority of the traits investigated. Cross combinations over BHQPY 545, such as L10 × L3, L10 × L6, and L13×L12, demonstrated the largest proportion of traditional heterosis for grain yield (more than 25% yield advantage). Because BH546 and BH547 are normal maize with grain production potential, the majority of crossings yielded negative and significant results over commercial checks. The highest found heterosis for grain yield and associated factors indicated that maize genotypes' heterotic potential may be beneficial to boost yield. The findings of this study could be valuable for researchers looking to develop high-yielding provitamin A maize hybrids. As a result, possible hybrids might be recommended for commercial usage once the results have been verified by repeating the research over time and across places, as well as incorporating quality attributes analysis data.

The Activity Patterns and Grouping Characteristics of the Remaining Goitered Gazelle (Gazella subgutturosa) in an Isolated Habitat of Western China.

Wildlife activity patterns, which reveal the daily allocation of time and energy, are crucial for understanding survival pressures, adaptive strategies, and behavioral characteristics in different environments. Among ungulates, grouping behavior is a prevalent adaptive trait that reflects the population structure, mating systems, and life history strategies formed over long-term evolutionary processes. This study aimed to elucidate the daily activity patterns and grouping characteristics of the rare goitered gazelle (Gazella subgutturosa) in the Helan Mountains of western China from 2022 to 2023 using camera trap monitoring. With a total of 3869 camera days of effective trapping, we recorded 442 independent detections of goitered gazelles. The results revealed the following: (1) Goitered gazelle is primarily active during the day, showing an activity pattern similar to crepuscular animals, with two activity peaks occurring after dawn and before dusk. (2) Daily activity patterns showed both seasonal and sex differences. In the warm season, morning activity peaks occurred earlier, and afternoon peaks occurred later compared to the cold season. The overlap in daily activity patterns between females and males in the warm season was lower than that in the cold season, and this trend persisted throughout the year. (3) The number of times different types of groups were observed varied significantly, with single males and single females accounting for a larger proportion of all observed groups. There was no significant difference in group size across seasons, with groups typically consisting of 1-2 individuals. Our study provides detailed insights into the temporal ecology and population structure of goitered gazelles in arid and semi-arid ecosystems. This information will guide the identification of future conservation priorities and the development of management plans for the reserve.

Sex drive among the Dark Tetrad

Consisting of Machiavellianism, narcissism, psychopathy, and sadism, the Dark Tetrad of personality have previously been linked to diverse mating strategies. Here, we expand on previous research using two sexuality self-reports: (1) sex drive and (2) pornography use. In Study 1, 779 students completed an online questionnaire that included (a) the Short Dark Tetrad inventory as well as (b) criterion questions about sex drive and pornography use. Based on previous literature, we hypothesized that narcissism and sadism would be independently associated with a composite of the two sexuality items. Multiple regression analyses confirmed this prediction. Males scored higher on all tetrad variables as well as the sexuality variables. In Study 2, a sample of 400 students at a different university replicated this ‘twin peaks’ pattern – even after (a) a 5-month predictor-criterion delay and (b) a control for relationship status. These results speak to debates over the separability of the Dark Tetrad members, and indicate that, in contrast to global sociosexuality, reports of sex drive are highest in narcissistic and sadistic individuals.

How inquilinism shaped breeding systems in a termite host-inquiline relationship.

Social insects have developed a broad diversity of nesting and foraging strategies. One of these, inquilinism, occurs when one species (the inquiline) inhabits the nest built and occupied by another species (the host). Obligatory inquilines must overcome strong constraints upon colony foundation and development, due to limited availability of host colonies. To reveal how inquilinism shapes reproductive strategies in a termite host-inquiline dyad, we carried out a microsatellite marker study on Inquilinitermes inquilinus and its host Constrictotermes cavifrons. The proportion of simple, extended and mixed families was recorded in both species, as well as the presence of neotenics, parthenogenesis and multiple foundations. Most host colonies (95%) were simple families and all were monodomous. By contrast, the inquiline showed a higher proportion of extended (30%) and mixed (5%) families, and frequent neotenics (in 25% of the nests). This results from the simultaneous foundation in host nests of numerous incipient colonies, which, as they grow, may compete, fight, or merge. We also documented the use of parthenogenesis by female-female pairs. In conclusion, the classical monogamous colony pattern of the host species suggests uneventful development of simple foundations dispersed in the environment, in accordance with the wide distribution of their resources. By contrast, the multiple reproductive patterns displayed by the inquiline species reveal strong constraints on foundation sites: founders first concentrate into host nests, then must attempt to outcompete or absorb the neighbouring foundations to gain full control of the resources provided by the host nest.

Mating systems and recombination landscape strongly shape genetic diversity and selection in wheat relatives

Abstract How and why genetic diversity varies among species is a long-standing question in evolutionary biology. Life history traits have been shown to explain a large part of observed diversity. Among them, mating systems have one of the strongest impacts on genetic diversity, with selfing species usually exhibiting much lower diversity than outcrossing relatives. Theory predicts that a high rate of selfing amplifies selection at linked sites, reducing genetic diversity genome-wide, but frequent bottlenecks and rapid population turn-over could also explain low genetic diversity in selfers. However, how linked selection varies with mating systems and whether it is sufficient to explain the observed difference between selfers and outcrossers has never been tested. Here, we used the Aegilops/Triticum grass species, a group characterized by contrasted mating systems (from obligate outcrossing to high selfing) and marked recombination rate variation across the genome, to quantify the effects of mating system and linked selection on patterns of neutral and selected polymorphism. By analyzing phenotypic and transcriptomic data of 13 species, we show that selfing strongly affects genetic diversity and the efficacy of selection by amplifying the intensity of linked selection genome-wide. In particular, signatures of adaptation were only found in the highly recombining regions in outcrossing species. These results bear implications for the evolution of mating systems and, more generally, for our understanding of the fundamental drivers of genetic diversity.

Influence of Mating Systems on Trait Associations in Segregating Populations of Maize (Zea mays L.) Double Cross

In the present challenging scenario of climate change, it is essential to breed maize cultivars that withstand stress especially abiotic stresses in a broader sense. Diversification of existing germplasm is invariable to harness the actual potential of maize hybrids which are bred for specific agroecosystems. Double crosses interact less with environment compared to single crosses and their broad parentage enables better performance under varied situations of cultivation. In the present study, impact of mating systems ie., self pollination, sib mating and open pollination was studied in a high yielding double cross of maize so as to identify robust and diverse recombinants. The double cross, (BML-32 x BML-6) x (BML-10 x BML-7) was imposed with the three types of mating systems for three consecutive seasons and the resultant S3 (F4) populations were evaluated for trait interrelationssips. It was observed that sib mating established stronger and highest number of positive correlations with seven and twelve additional positive correlations than self and open pollinations respectively among the yield and its attributing traits in its progenies. Therefore deploying sib mating cycles during line development may result in more effective selection processes. Results of path analysis, however, did not significantly vary with the mating type though sib mating showed lowest residual effect.

Production system analysis and breeding practices of indigenous goats in North Wollo zone, Amhara region, Ethiopia

ABSTRACT This study describes the goat production system and breeding practices in selected districts of North Wollo zone, Ethiopia. Data were collected from 180 respondents through a semi-structured questionnaire and group discussions. Descriptive and GLM procedures were employed for data analysis. A mixed crop-livestock production system was the main production system in the area. The mean number of goats per household is 9.66 and they are mainly kept for cash income and meat consumption. The flock structure of indigenous goats consisted of a large number of female goats. Natural pasture and crop residue were the major feed resources in the dry and wet seasons, with an overall mean of 37.53% and 54.26%, respectively. Feed shortage, diseases, and drought were the major constraints for goat production. Most goat owners (97.1%) practiced an uncontrolled mating system. Most farmers (88.93%) reported selecting breeding goats to be a parent for the next generation. Body conformation and coat colour were the preferred traits for the selection of goats. The current level of goat management and breeding methods would not significantly enhance goats’ productivity and profitability. Therefore, designing management and genetic improvement programmes would be vital to improving the productivity of indigenous goats.

Precision breeding in agriculture and food systems in the United Kingdom.

In recent years there have been major advances in precision breeding technologies, such as gene editing, that offer promising solutions to revolutionise global crop production and tackle the pressing issues in food systems. The UK has leading expertise in genomics, and research is already taking place to develop crops with improved resilience to climate change, resistance to disease and less reliance on chemical inputs. In March 2023, the Genetic Technology (Precision Breeding) Act received Royal Assent and passed into UK law. It provides a framework from which to build more proportionate regulations for plants and animals made using genetic technologies which contain genetic changes that could also arise through traditional breeding-known as 'Precision Bred Organisms'. New legislation and the utilization of UK world-leading research could help to enhance the efficiency of breeding systems and enable the development of plants and animals that are healthier, better for the environment and more resilient to climate change.

Efficient breeding system of infertile Niemann-Pick disease type C model mice by in vitro fertilization and embryo transfer.

Niemann-Pick disease type C (NPC) is a lethal genetic disease with mutations in NPC1 or NPC2 gene. Npc1-deficient (Npc1-/-) mice have been used as a model for NPC pathogenesis to develop novel therapies for NPC. However, Npc1-/- mice are infertile; thus, securing sufficient numbers for translational research is difficult. Hence, we attempted reproductive engineering techniques such as in vitro fertilization (IVF) and sperm cryopreservation. For the first time, we succeeded in producing fertilized oocytes via IVF using male and female Npc1-/- mice. Fertilized oocytes were also obtained via IVF using cryopreserved sperm from Npc1-/- mice. The obtained fertilized oocytes normally developed into live pups via embryo transfer, and they eventually exhibited NPC pathogenesis. These findings are useful for generating an efficient breeding system that overcomes the reproductive challenges of Npc1-/- mice and will contribute to developing novel therapeutic methods using NPC model mice.

Manipulating hormones to mitigate trade-offs in crops.

Summary statementAddressing trait coupling due to gene pleiotropy presents challenges in conventional breeding system. However, targeted hormonal manipulation and precise genetic engineering designs hold promise to alleviate trade‐offs and unlock the potential of crops for multiple desirable traits.

Bat mating systems-A review and recategorisation.

Mating systems, influenced by the social and ecological environment and individual attributes, are fundamental components of animal social organisation, impacting behaviour, animal distribution, ecosystem processes, individual reproductive success, and population dynamics. Bats are of particular interest for studies of mating systems as they are thought to exhibit a greater diversity in mating systems than any other mammalian order, and thus make great models for improving our fundamental understanding of causes and consequences of social organisation. Here, we review the current knowledge of bat mating systems. Our analyses show that research on bat mating systems has not kept pace with research on bats in general and that traditional typologies do not accommodate the mating system of several species. Therefore, we propose an alternative, functional framework to categorise mating systems of bats and by extension of other taxa. We argue that mating systems can be classified according to a male reproductive skew continuum, with an increasing skew from monogamy to true lekking. We include an additional category of lek-like mating system along the continuum to account for previous trans-categorical cases that have the appearance of resource defence but are functionally akin to a lek. The new framework has a total of seven categories: promiscuity, monogamy, female defence polygyny, resource defence polygyny, a lek-like mating system, exploded classical lek, and clustered classical lek. Applying this framework to bats reveals that lek mating systems are more prevalent in bats than previously recognised. It is our aim that this review and the proposed framework provide a greater understanding of bat mating systems particularly and provoke research into the factors that shape mating systems across animal taxa more generally.

Population genetic structure in a self-compatible hermaphroditic snail is driven by drift independently of its contemporary mating system.

Genetic drift, gene flow, and natural selection commonly influence population genetic diversity. In populations of self-compatible hermaphrodites, the mating system (e.g., self-fertilization) further reduces individual heterozygosity. Furthermore, selfing, as a form of inbreeding, significantly impacts genetic drift by reducing effective population size (N e). This can potentially accelerate genetic drift, particularly in small populations where self-fertilization is likely during founder events. To investigate the roles of genetic drift and contemporary mating system in populations of the freshwater snail Lymnaea stagnalis, we examined their effective population sizes (N e) and Tajima's D values, which reflect genetic drift over extended time periods, as well as estimates of within-population selfing rates and pairwise relatedness reflecting contemporary mating system. We used 4054 SNP markers obtained using restriction site associated DNA (RAD) sequencing from individuals in five snail populations originating from geographically closely located ponds. We found strong population genetic structure and differences in genetic diversity among populations. Covariation between genetic diversity and N e estimates and Tajima's D values suggested drift being an important determinant of genetic diversity and structure in these populations. However, this effect was independent of the contemporary mating system, as indicated by the similarity of selfing rates and relatedness estimates among populations. Thus, founder events (possibly including historical inbreeding) and/or drift due to small sizes of L. stagnalis populations are likely to explain their genetic structure and limit within-population genetic diversity.

Inbreeding avoidance, competition and natal dispersal in a pair-living, genetically monogamous mammal, Azara's owl monkey (Aotus azarae).

Natal dispersal is an important life-history stage influencing individual fitness, social dynamics of groups and population structure. Understanding factors influencing dispersal is essential for evaluating explanations for the evolution and maintenance of social organization, including parental care and mating systems. The social and mating systems of Azara's owl monkeys (Aotus azarae) are infrequent among mammals; these primates are pair-living, serially and genetically monogamous and both sexes directly care for offspring. To evaluate the role that competition and inbreeding avoidance play in shaping dispersal patterns, we used 25 years of demographic and genetic data to examine how variation in timing of natal dispersal is related to social (adult replacements, step-parents, births and group size) and ecological factors (seasonal abundance of resources) in a wild population of A. azarae in Formosa, Argentina. We found that all males and females dispersed from their natal groups, but subadults delayed dispersal when a step-parent of the opposite sex joined the group, indicating that they may perceive these step-parents as potential mates. Dispersal was more probable when resource conditions were better, regardless of age. Overall, agonistic conflict over food and potential mates with adults in the natal group, as well as inbreeding avoidance, contribute to regulating dispersal.