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Self-fertile Caenorhabditis nematodes carry a surprising number of Medea elements, alleles that act in heterozygous mothers and cause death or developmental delay in offspring that do not inherit them. At some loci, both alleles in a cross operate as independent Medeas , affecting all the homozygous progeny of a selfing heterozygote. The genomic coincidence of Medea elements and ancient, deeply coalescing haplotypes, which pepper the otherwise homogeneous genomes of these animals, raises questions about how these apparent gene-drive elements persist for long periods of time. Here, I investigate how mating system affects the evolution of Medeas , and their paternal-effect counterparts, peels. Despite an intuition that antagonistic alleles should induce balancing selection by killing homozygotes, models show that, under partial selfing, antagonistic elements experience positive frequency dependence: the common allele drives the rare one extinct, even if the rare one is more penetrant. Analytical results for the threshold frequency required for one allele to invade a population show that a very weakly penetrant allele, one whose effects would escape laboratory detection, could nevertheless prevent a much more penetrant allele from invading under high rates of selfing. Ubiquitous weak antagonistic Medeas and peels could then act as localized barriers to gene flow between populations, generating genomic islands of deep coalescence. Analysis of gene expression data, however, suggests that this cannot be the whole story. A complementary explanation is that ordinary ecological balancing selection generates ancient haplotypes on which Medeas can evolve, while high homozygosity in these selfers minimizes the role of gene drive in their evolution. [ABSTRACT FROM AUTHOR]

Background/Objectives: Systems of reproduction differ with respect to the magnitude of neutral genetic diversity maintained in a population. In particular, the partitioning of reproductive organisms into mating types and regular inbreeding have long been recognized as key factors that influence effective population number. Here, a range of reproductive systems are compared with respect to the maintenance of neutral genetic diversity. This study addresses full gonochorism, full hermaphroditism, androdioecy (male and hermaphroditic reproductives), and gynodioecy (female and hermaphroditic reproductives). Methods: Coalescence theory is used to determine the level of diversity maintained under each mating system considered. Results: For each mating system, the nature of the dependence of the level of neutral diversity on inbreeding depression, sex-specific viability, and other factors is described. In particular, the models account for the effects of sex-specific viability on the evolutionarily stable sex ratio and the collective contribution of each mating type (sex) to the offspring generation. Conclusions: Within the context of conservation biology, population genetic and quantitative genetic theory has addressed the determination of the target minimum effective population size. In contrast, this study proposes and explores a summary statistic (a ratio of effective numbers) as a means of characterizing the context in which evolution occurs. [ABSTRACT FROM AUTHOR]

Cannabis (Cannabis sativa) growers seek greater crop uniformity and yield; however, use of vegetatively propagated plants has several drawbacks. There is increased interest in F1 hybrid seed, especially for flower production. Plant growth and performance of inbred lines of the cultivars Wife (WF) and Wilhelmina (WH), produced from one to four rounds of selfing (S1 to S4), and three F1 hybrid lines (WF S1 × WH S1, WF S2 × WH S2, and WF S3 × WH S3) were evaluated. As selfing increased from S1 to S4, within line plant variation did not change substantially for most measures for WF, but variation progressively decreased for plant height, total shoot length and plant dry weight for WH. S4 plants of WH were uniformly diminutive and likely exhibited inbreeding depression. F1 hybrids between WF and WH were larger than WH plants for all measures because WH is photoperiod insensitive (autoflowering) and dwarf. Compared with WF self-lines, F1 WF × WH hybrid lines exhibited greater uniformity, plant dry weight, flower dry weight, and percent cannabidiol and tetrahydrocannabinol. F1 WF × WH hybrid plants were able to achieve similar height and shoot growth to WF self-lines, even though they had a dwarf parent in WH. It is likely that heterosis is responsible for the growth enhancements observed in the F1 WF × WH hybrids. These findings indicate that F1 hybridization can produce uniform, stable, and high-yielding cannabis plants from seed. [ABSTRACT FROM AUTHOR]

【Objective】The aim of this study is to utilize the Internal Transcribed Spacer (ITS) region as a molecular marker in identifying newly developed hybrid and selfing offspring banana progeny, thereby laying the foundation for advancements in banana breeding and genetics research.【Method】DNA of parents and their suspected offspring was extracted, then PCR amplifification and Sanger sequencing were conducted, and sequence alignment was performed using software“DNAMAN”and“SnapGene”to analyze the polymorphism of ITS, thereby determining the hybrid and selfing offspring. The plant was classified as a positive plant when the ITS sequence of the suspected offspring plant showed differences at one or more base sites compared with the parent; conversely, if no such differences were found, the plant was determined to be a false positive plant.【Result】The study encompasses three sets of putative progeny derived from cultivated banana crossed with wild banana (‘Guang Fen No. 1’בTian Ye BB No. 1’), selfed offspring of a cultivated variety (‘Fen Za No.1’), and a cross between two wild bananas (‘Musa acuminata No. 1’בMusa acuminata No. 2’). Applying the established banana ITS Sanger sequencing protocol, the notable disparities linked to the ITS sequences of these candidate offspring compared to their parents were identified. Phenotypic observations further confirmed variances in the offspring plants, suggesting they were positive plants. In the hybrid offspring of‘Guang Fen No.1’and ‘Tian Ye BB No.1’, polymorphisms in the“410 bp region”were observed in the ITS Sanger sequencing profiles, accompanied by distinct changes in bunch characteristics. Among four selfed offspring of‘Fen Za No.1’, polymorphic peaks in the“50 bp”and“410 bp regions”were detected, with two lines exhibiting distinctive leaf traits. For the ten seedlings resulting from the‘Musa acuminata No. 1’בMusa acuminata No. 2’cross, significant differences in the sequencing profiles were noted at“115 bp”“431 bp”and“452 bp”relative to their parents. 【Conclusion】The ITS Sanger sequencing approach emerges as a complementary tool to phenotypic assessments and SSR-based identification methods, facilitating rapid, flexible, and convenient material authenticity confirmation in distinguishing banana hybrid or selfed offspring. This methodology aids breeders and researchers in efficiently confirming their materials accuracy in breeding and genetic studies. [ABSTRACT FROM AUTHOR]

The pollination biology of the genus Ophrys has been extensively explored, primarily due to their utilisation of sexual deception to attract pollinators. Typically, members of this genus produce a low number of fruits per individual and are considered obligate crossers. However, instances of self-pollination in Ophrys are not uncommon, although the impact of pollen origin on seed production remains understudied. As a predominantly cross-pollinated genus we hypothesise that self-pollination in Ophrys has a negative effect on seed production. The results of the present work will support decision making for the conservation of the genus. We investigate the consequences of self- and cross-pollination on (a) empty seeds produced and (b) viability of sound seeds for three Ophrys species: Ophrys aesculapii, Ophrys ferrum-equinum, and Ophrys kotschyi native to the East Mediterranean region. Bagged individuals of these species were meticulously hand-pollinated with pollen sourced either from their own flowers or from neighbouring individuals. Significant differences were observed across all three species, both in terms of the number of empty seeds and the viability of the produced seeds, with significantly lower viability and higher number of empty seeds in seed collections from self-pollinated individuals. Despite being self-compatible, the three Ophrys species exhibited notable inbreeding depression, as evidenced by the outcomes of this study. Based on our results the implementation of controlled cross hand-pollination in wild population may contribute in the increase of the reproductive success of Ophrys spp. by increasing the quality and quantity of the produced seeds. [ABSTRACT FROM AUTHOR]

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The temporal separation of male and female flowering—known as dichogamy—is a widespread adaptation across the plant kingdom that increases reproductive success and enhances plant fitness. Differences in timing between male and female flowering can be highly sensitive to environmental variation—and with widespread evidence of shifts in seasonal timing of flowering (i.e., phenology) due to anthropogenic warming—climate change may alter the sequences of male and female flowering for a diversity of taxa around the globe. However, we currently lack a broad understanding of both the extent to which climate change may alter patterns of dichogamy and the potential implications of these shifts for plant reproduction. Here I present evidence that links variation in dichogamy to variation in temperature for a variety of plant taxa. I synthesize the limited number of studies that have investigated shifts in dichogamy specifically in the context of climate change, and detail the physiological, genetic, and developmental factors that control the relative timing of male and female flowering. The literature indicates that dichogamy is highly plastic and sensitive to temperature variation. Plasticity in dichogamy is observed across species with different sexual systems and growth habits, and in both female‐first and male‐first flowering taxa, but at present, no clear patterns of dichogamy shifts related to these associated traits are discernible. Together, these lines of evidence suggest that sequences of male and female flowering are likely to shift with climate change. However, more research is needed to better understand and predict the ecological consequences of shifting patterns of dichogamy in the context of global change. [ABSTRACT FROM AUTHOR]

Summary: Plants employ a diversity of reproductive safeguarding strategies to circumvent the challenge of pollen limitation. Focusing on southern African Lachenalia (Asparagaceae: Scilloideae), we test the hypothesis that the evolution of reproductive safeguarding traits (self‐compatibility, autonomous selfing, bird pollination and clonal propagation) is favoured in species occupying conditions of low insect abundance imposed by critically infertile fynbos heathland vegetation and by flowering outside the austral spring insect abundance peak.We trace the evolution of these traits and selective regimes on a dated, multi‐locus phylogeny of Lachenalia and assess their evolutionary associations using ordinary and phylogenetic regression.Ancestral state reconstructions identify an association with non‐fynbos vegetation and spring flowering as ancestral in Lachenalia, the transition to fynbos vegetation and non‐spring flowering taking place multiple times. They also show that self‐compatibility, autofertility, bird pollination and production of multiple clonal offsets have evolved repeatedly.Regression models suggest that bird pollination and self‐compatibility are selected for in fynbos and in non‐spring flowering lineages, with autofertility being positively associated with non‐spring flowering. These patterns support the interpretation of these traits as reproductive safeguarding adaptations under reduced insect pollinator abundance. We find no evidence to support the interpretation of clonal propagation as a reproductive safeguarding strategy. See also the Commentary on this article by Burd, 244: 7–9. [ABSTRACT FROM AUTHOR]

This study describes a compact method for determining joint probabilities of identity-by-state (IBS) within and between loci in populations evolving under genetic drift, crossing-over, mutation, and regular inbreeding (partial self-fertilization). Analogues of classical indices of associations among loci arise as functions of these joint identities. This coalescence-based analysis indicates that multi-locus associations reflect simultaneous coalescence events across loci. Measures of association depend on genetic diversity rather than allelic frequencies, as do linkage disequilibrium and its relatives. Scaled indices designed to show monotonic dependence on rates of crossing-over, inbreeding, and mutation may prove useful for interpreting patterns of genome-scale variation. [ABSTRACT FROM AUTHOR]

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 drivenmainly 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. [ABSTRACT FROM AUTHOR]

Inbreeding depression (ID) is a major selective force during mating system evolution primarily contributed by highly to partially recessive deleterious mutations. Theories suggest that transient genetic association with fitness alleles can be important in affecting the evolution of alleles that modify the selfing rate during its sweep. Nevertheless, empirical tests often focus on the pre- existing genetic association between selfing rate and ID maintained under mutation--selection balance. Therefore, how this standing genetic association is affected by key factors and its impacts on the evolution of selfing remain unclear. I show that as the selection coefficient of deleterious mutations increases, the association between selfing rate and ID declines from positive to negative. These results predict that association between selfing and ID tends to be negative in populations with low selfing rates, while positive in highly selfing populations. Using population genetic and quantitative genetic models, I show that standing genetic associations between selfing rate and fitness alleles can significantly impact the evolution of the mean selfing rate of a population. I present better metrics of population-level ID, which can be calculated based on the correlation coefficient between individual selfing rate and the fitness of selfed and outcrossed offspring. [ABSTRACT FROM AUTHOR]

Premise: Evolution of cross‐pollination efficiency depends on the genetic variation of flower traits, the pollen vector, and flower trait matching between pollen donors and recipients. Trait matching has been almost unexplored among nonheterostylous species, and we examined whether the match of anther length in pollen donors and stigma length in pollen recipients influences the efficiency of cross‐pollination. To explore potential constraints for evolutionary response, we also quantified genetic variation and covariation among sepal length, petal length and width, stamen length, style length, and herkogamy. Methods: We created 58 experimental arrays of Turnera velutina that varied in the extent of mismatch in the position of anthers and stigmas between single‐flowered plants. Genetic variation and correlations among flower traits were estimated under greenhouse conditions. Results: Style length, but not herkogamy, influenced the efficiency of cross‐pollination. Plants with stamen length that matched the style length of other plants were more efficient pollen donors, whereas those with the style protruding above the stamens of other plants were more efficient pollen recipients. Significant broad‐sense heritability (0.22 > hB2 < 0.42) and moderate genetic correlations (0.33 > r < 0.85) among floral traits were detected. Conclusions: Our results demonstrated that anther‐stigma mismatch between flowers contributed to variation in the efficiency of cross‐pollination. The genetic correlations between stamen length and other floral traits suggests that any change in cross‐pollination efficiency would be driven by changes in style rather than in stamen length. [ABSTRACT FROM AUTHOR]

Asexual seed reproduction, apomixis, is a relatively rare reproductive strategy in angiosperms. Its rarity is probably due to evolutionary constraints that require full and synchronous expression of all the steps that modify the ancestral sexual pathway. Therefore, the documentation of any new occurrence of apomixis, especially in taxonomic groups with no previous report, should be based on thorough and solid evidence. Here, we correct the report of suggested apomictic reproduction in two endemic hexaploid species of Senecio from Australia. Based on either excess or deficiency of expected heterozygosity across loci, over-representation of several multilocus genotypes, and segregation analysis assessed using microsatellite markers, it was suggested that apomixis together with selfing could explain the observed patterns of genetic variation in perennial S. macrocarpus and annual S. squarrosus. We used flow cytometric seed screening analyses to verify the mode of reproduction of several widespread multilocus genotypes that are considered to be apomictic. These analyses revealed that all seed progeny arose by the sexual pathway, as they exhibited a constant 3:2 endosperm to embryo ploidy ratio, typical of double fertilization of a reduced embryo sac by two reduced sperm cells. Therefore, both species reproduce sexually. We suggest that the unusual genetic patterns in both allopolyploids are caused by originally low variation in the parental species, which probably also reproduce by selfing, disomic inheritance and probably also the presence of null alleles. We call for a more careful and critical interpretation of the patterns obtained, taking into account all aspects related to apomictic reproduction. [ABSTRACT FROM AUTHOR]

Exploring the genetic diversity and reproductive strategies of Paspalum species is essential for advancing forage grass improvement. We compared morpho-phenological, molecular, and genotypic variation in five tetraploid Paspalum species with contrasting mating systems and reproductive modes. Contrary to previous findings, selfing (Paspalum regnellii and P. urvillei) and outcrossing (P. durifolium and P. ionanthum) species exhibited similar phenotypic diversity patterns, with low intrapopulation variability and no morphological differentiation among populations. The apomictic species (P. intermedium) exhibited low intrapopulation phenotypic variation but high population differentiation, indicative of genetic drift and local adaptation. Outcrossing species showed greater intrapopulation genotypic variation than selfing species, which displayed a high population structure due to restricted pollen migration. The apomictic species exhibited the lowest intrapopulation molecular diversity, forming uniclonal populations with high interpopulation differentiation, highlighting the fixation of distinct gene pools via apomixis. This is the first report about genetic diversity in populations of sexual allopolyploid species of Paspalum. Population structure in these allotetraploid Paspalum species is primarily shaped by how reproductive modes, mating systems, and geographic distribution influence gene flow via pollen and seeds. Our findings contribute significantly to the conservation and genetic improvement of forage grasses, particularly for developing cultivars with enhanced adaptability and productivity.

Bi-parental hybrids (BPHs) are recommended cocoa planting materials in Ghana and other West African countries. However, the inability to produce enough BPHs to meet farmers' demand makes it almost impossible to avoid open-pollinated families (OPF) in the supply chain. To study the effects of OPF on cocoa production, parentage analysis, vigor, and precocity of seven BPHs generated from a 4 × 2 North Carolina II (NC II) incomplete mating design were compared with eight OPFs. The 15 cocoa progenies together with two checks of Guiana (GU) origin were evaluated in a randomized complete block design with four replications across five contrasting locations for stem diameter increment (SDI) and number of pods per tree (NP). Parentage analyses at 75 single nucleotide polymorphism (SNP) loci of leave samples from the 17 progenies revealed that the BPHs were of the appropriate female and male parents, while the OPF had varying number of male parents. The pollination effect (bi-parental vs open-pollinated progenies) was not significantly different for both traits, but the BPH was relatively better and surpassed on average the OPF by 3.5% for SDI and 7.8% for NP. Crosses involving GU 144/ C, T63/967, and T65/238 as females in both the OPF and BPH showed predominantly higher performance than those with PA 7 and T79/501 for both traits. Among the promising female parents, GU 144/C is the only one that is not in the seed gardens and could be added to parental clones currently used in producing cocoa varieties in the seed garden. [ABSTRACT FROM AUTHOR]

Premise of research. Reinforcement is the process through which prezygotic reproductive barriers evolve in sympatry owing to selection against hybridization between co-occurring, closely related species. The role of self-fertilization in reinforcement and reproductive isolation is uncertain, in part because its efficiency as a barrier against heterospecific mating can depend on the timing of autonomous selfing. Methodology. To investigate whether increased autonomous selfing has evolved as a mechanism for reinforcement, we compared Phlox cuspidata populations across their native Texas range using both estimates of genetic diversity and experimental manipulation with morphological measurements. Specifically, we investigated patterns of variation in floral traits and timing of selfing between individuals from allopatric populations of P. cuspidata and from populations sympatric with the closely related species Phlox drummondii. Pivotal results. We infer intermediate rates of selfing across field-collected individuals with no significant difference between allopatric and sympatric populations. Among greenhouse-grown plants, we find no differences in timing of selfing or other floral traits, including anther dehiscence timing, anther-stigma distance, autonomous selfing rate, and self-seed count, between allopatric and sympatric populations. However, our statistical analyses indicate that P. cuspidata individuals sympatric with P. drummondii seem to have generally larger flowers compared with allopatric individuals. Conclusions. Despite strong evidence of costly hybridization with P. drummondii , we find no evidence of trait divergence due to reinforcement in P. cuspidata. Although we document nearly complete autonomous self-seed set in the greenhouse, estimates of selfing rates from genetic data imply that realized selfing is much lower in nature, suggesting an opportunity for reinforcing selection to act on this trait. [ABSTRACT FROM AUTHOR]

Background and Aims Despite chromosomal evolution being one of the major drivers of diversification in plants, we do not yet have a clear view of how new chromosome rearrangements become fixed within populations, which is a crucial step forward for understanding chromosomal speciation. Methods In this study, we test the role of genetic drift in the establishment of new chromosomal variants in the context of hybrid dysfunction models of chromosomal speciation. We genotyped 178 individuals from seven populations (plus 25 seeds from one population) across the geographical range of Carex helodes (Cyperaceae). We also characterized karyotype geographical patterns of the species across its distribution range. For one of the populations, we performed a detailed study of the fine-scale, local spatial distribution of its individuals and their genotypes and karyotypes. Key Results Synergistically, phylogeographical and karyotypic evidence revealed two main genetic groups: southwestern Iberian Peninsula vs. northwestern African populations; and within Europe our results suggest a west-to-east expansion with signals of genetic bottlenecks. Additionally, we inferred a pattern of descending dysploidy, plausibly as a result of a west-to-east process of post-glacial colonization in Europe. Conclusions Our results give experimental support to the role of geographical isolation, drift and inbreeding in the establishment of new karyotypes, which is key in the speciation models of hybrid dysfunction. [ABSTRACT FROM AUTHOR]

This perspective article offers a meditation on F S T and other quantities developed by Sewall Wright to describe the population structure, defined as any departure from reproduction through random union of gametes. Concepts related to the F -statistics draw from studies of the partitioning of variation, identity coefficients, and diversity measures. Relationships between the first two approaches have recently been clarified and unified. This essay addresses the third pillar of the discussion: Nei's G S T and related measures. A hierarchy of probabilities of identity-by-state provides a description of the relationships among levels of a structured population with respect to genetic diversity. Explicit expressions for the identity-by-state probabilities are determined for models of structured populations undergoing regular inbreeding and recurrent mutation. Levels of genetic diversity within and between subpopulations reflect mutation as well as migration. Accordingly, indices of the population structure are inherently locus-specific, contrary to the intentions of Wright. Some implications of this locus-specificity are explored. [ABSTRACT FROM AUTHOR]

To improve our understanding of the selfing of G. lingzhi basidiospore monokaryons and increase the efficiency of breeding excellent strains, 52 basidiospore monokaryons were isolated from a commercial G. lingzhi strain (laboratory number P). A severe partial segregation was observed using the chi-square test, the growth rate of the monokaryotic strains was normally distributed, and colonies exhibited 5 forms. The genetic diversity of the monokaryotic strains was further demonstrated by intersimple sequence repeat (ISSR) analysis, and the similarity coefficient was in the range of 0.49–1, which was consistent with the genotype classification results. In total, 14 AxBx monokaryotic strains were randomly selected for selfing with the 1 AyBy strain when the similarity coefficient was 0.76, and a total of 14 offspring were obtained via selfing, all of which were incompatible with their parents. The traits of the selfing progenies were diverse. The mycelial growth rate, fruiting body yield, and polysaccharide, triterpene, and sterol contents were the main indices. According to the membership function value, 71.43% of the selfing progeny were super parent, and the A88 strain with the best comprehensive traits was selected. These findings prove that ISSR molecular marker-assisted breeding reduces blindness, greatly reduces workload, and improves work efficiency. [ABSTRACT FROM AUTHOR]

Theory predicts that organisms should diversify their offspring when faced with a stressful environment. This prediction has received empirical support across diverse groups of organisms and stressors. For example, when encountered by Caenorhabditis elegans during early development, food limitation (a common environmental stressor) induces the nematodes to arrest in a developmental stage called dauer and to increase their propensity to outcross when they are subsequently provided with food and enabled to develop to maturity. Here we tested whether food limitation first encountered during late development/early adulthood can also induce increased outcrossing propensity in C. elegans. Previously well‐fed C. elegans increased their propensity to outcross when challenged with food limitation during the final larval stage of development and into early adulthood, relative to continuously well‐fed (control) nematodes. Our results thus support previous research demonstrating that the stress of food limitation can induce increased outcrossing propensity in C. elegans. Furthermore, our results expand on previous work by showing that food limitation can still increase outcrossing propensity even when it is not encountered until late development, and this can occur independently of the developmental and gene expression changes associated with dauer. Caenorhabditis elegans increase their propensity to outcross in response to food limitation encountered during late development. [ABSTRACT FROM AUTHOR]

Potato genetic improvement begins with crossing cultivars or breeding clones which often have complementary characteristics for producing heritable variation in segregating offspring, in which phenotypic selection is used thereafter across various vegetative generations (Ti). The aim of this research was to determine whether tetrasomic genomic best linear unbiased predictors (GBLUPs) may facilitate selecting for tuber yield across early Ti within and across breeding sites in inbred (S1) and hybrid (F1) tetraploid potato offspring. This research used 858 breeding clones for a T1 trial at Umeå (Norrland, 63°49′30″ N 20°15′50″ E) in 2021, as well as 829 and 671 clones from the breeding population for T2 trials during 2022 at Umeå and Helgegården (Skåne, 56°01′46″ N 14°09′24″ E), respectively, along with their parents (S0) and check cultivars. The S1 and F1 were derived from selfing and crossing four S0. The experimental layout was an augmented design of four-plant plots across testing sites, where breeding clones were non-replicated, and the parents and cultivars were placed in all blocks between the former. The genomic prediction abilities (r) for tuber weight per plant were 0.5944 and 0.6776 in T2 at Helgegården and Umeå, respectively, when T1 at Umeå was used as the training population. On average, r was larger in inbred than in hybrid offspring at both breeding sites. The r was also estimated using multi-environment data (involving at least one S1 and one F1) for T2 performance at both breeding sites. The r was strongly influenced by the genotype in both S1 and F1 offspring irrespective of the breeding site. [ABSTRACT FROM AUTHOR]

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.

The relative frequency of sexual versus asexual reproduction governs the distribution of genetic diversity within and among populations. Most studies on the consequences of reproductive variation focus on the mating system (i.e., selfing vs. outcrossing) of diploid‐dominant taxa (e.g., angiosperms), often ignoring asexual reproduction. Although reproductive systems are hypothesized to be correlated with life‐cycle types, variation in the relative rates of sexual and asexual reproduction remains poorly characterized across eukaryotes. This is particularly true among the three major lineages of macroalgae (green, brown, and red). The Rhodophyta are particularly interesting, as many taxa have complex haploid–diploid life cycles that influence genetic structure. Though most marine reds have separate sexes, we show that freshwater red macroalgae exhibit patterns of switching between monoicy and dioicy in sister taxa that rival those recently shown in brown macroalgae and in angiosperms. We advocate for the investigation of reproductive system evolution using freshwater reds, as this will expand the life‐cycle types for which these data exist, enabling comparative analyses broadly across eukaryotes. Unlike their marine cousins, species in the Batrachospermales have macroscopic gametophytes attached to filamentous, often microscopic sporophytes. While asexual reproduction through monospores may occur in all freshwater reds, the Compsopogonales are thought to be exclusively asexual. Understanding the evolutionary consequences of selfing and asexual reproduction will aid in our understanding of the evolutionary ecology of all algae and of eukaryotic evolution generally. [ABSTRACT FROM AUTHOR]

The evolution of reproductive mode is expected to have profound impacts on the genetic composition of populations. At the same time, ecological interactions can generate close associations among species, which can in turn generate a high degree of overlap in their spatial distributions. Caenorhabditis elegans is a hermaphroditic nematode that has enabled extensive advances in developmental genetics. Caenorhabditis inopinata , the sister species of C. elegans , is a gonochoristic nematode that thrives in figs and obligately disperses on fig wasps. Here, we describe patterns of genomic diversity in C. inopinata. We performed RAD-seq on individual worms isolated from the field across three Okinawan island populations. C. inopinata is about five times more diverse than C. elegans. Additionally, C. inopinata harbors greater differences in diversity among functional genomic regions (such as between genic and intergenic sequences) than C. elegans. Conversely, C. elegans harbors greater differences in diversity between high-recombining chromosome arms and low-recombining chromosome centers than C. inopinata. F ST is low among island population pairs, and clear population structure could not be easily detected among islands, suggesting frequent migration of wasps between islands. These patterns of population differentiation appear comparable with those previously reported in its fig wasp vector. These results confirm many theoretical population genetic predictions regarding the evolution of reproductive mode and suggest C. inopinata population dynamics may be driven by wasp dispersal. This work sets the stage for future evolutionary genomic studies aimed at understanding the evolution of sex as well as the evolution of ecological interactions. [ABSTRACT FROM AUTHOR]

Premise of research. The maintenance of mixed selfing and outcrossing is an enduring mystery in evolutionary biology. Cleistogamy, in which individuals produce both potentially outcrossing chasmogamous (CH) and obligately selfing cleistogamous (CL) flowers, provides an ideal framework in which to study the evolutionary forces maintaining mixed mating. Despite their promise for providing insight into mating system evolution, few studies of cleistogamous species have comprehensively investigated the relative costs and benefits of CL selfing. Methodology. We quantified the necessary components to calculate the relative energetic cost of reproduction of each flower type—CH and CL—in a greenhouse study using three populations of the perennial Ruellia humilis Nutt (Acanthaceae). These components included flower dry mass, fertility (i.e., fruit set), seed mass per fruit, and number of seeds per fruit. We also measured pollen-ovule ratios for both flower types as another measure of relative energetic investment. Last, we tracked phenology of the two flower types and used the proportion of CH flowers to estimate maximum potential outcrossing rates. Pivotal results. We found that the energetic cost of reproduction via CL flowers was four to 10 times lower than that of reproduction via CH flowers. This energetic economy derived both from the reduced mass and from the increased fertility of CL flowers. Pollen-ovule ratios in CL flowers were one-third to one-half those of CH flowers, providing additional support for their energetic economy. Maximum potential outcrossing rates in these populations based on CH flower production were between 43% and 61%, but CH flowers can autogamously self at rates between 33% and 75%. Conclusions. These results suggest that selection should favor only CL flowers due to their greater energetic economy. Additional work in this species demonstrates that neither inbreeding depression nor heterosis can provide an advantage strong enough to overcome the energetic benefits of CL reproduction. Further research on the developmental genetics of the two flower types and potential genetic constraints on the loss of CH flowers is needed. [ABSTRACT FROM AUTHOR]

To investigate the deflection, maximum stress, maximum strain, and failure of pavement joints of conventional and remix concrete pavement models. Nine model pavement slab specimens has been cast and statically loaded using hydraulic jack, load cell on loading frame assembly. Two concrete mix design grades and three concrete remixing procedures were chosen and fixed. This work checks the effect of remix concrete on rigid pavements, taking into account time lag (t in hr.) of Concrete (THC) and the blend ratio (r). The methods were a regular mixed with traditional procedures and a remix mixture with selfing and crossing methods. The results of a 3D finite element analysis with ANSYS simulation are compared to experimental trials. By adding a higher graded fresh concrete to the old and partially set concrete, there is improvement in the compressive strength, quality of the concrete, and modulus subgrade reaction, according to this study.

Introduction: Monoecy is usually interpreted as an important evolutionary route of the plant sexual system from hermaphroditism to dioecy. This floral mechanism can effectively reduce self-interference during the reproductive process, and the services provided by pollinators may play an essential role in monoecious species; however, relevant research is still lacking. Thus, we aimed to determine whether monoecious plants could effectively avoid selfinterference and promote the evolution of monoecy under the service of pollinators. Methods: Here, we successfully performed manipulation experiments to test self-compatibility, pollinator behavior, and self-interference between male and female functions in Akebia trifoliata, a typical monoecious species. Results: We demonstrated that experimental self-pollination did not yield any fruit, and supplemental pollination significantly increased fruit set and fruit weight compared to natural pollination, suggesting that this species is completely selfincompatible and experiences strong pollen limitation. Simultaneous self- and cross-pollination and self-pollination prior to cross-pollination significantly reduced reproductive fitness, but self-pollination after cross-pollination did not, indicating self-interference in this plant. Moreover, both male flower probing preference and switching modes within inflorescences by pollinators successfully reinforced self-interference and were also responsible for decreasing reproductive fitness in A. trifoliata. Discussion: In summary, pollinator-mediated self-interference significantly reduced selfing, providing potential dynamics for the maintenance and evolution of monoecy. [ABSTRACT FROM AUTHOR]

Premise: What maintains mixed mating is an evolutionary enigma. Cleistogamy—the production of both potentially outcrossing chasmogamous and obligately selfing cleistogamous flowers on the same individual plant—is an excellent system to study the costs of selfing. Inbreeding depression can prevent the evolution of greater selfing within populations, and heterosis in crosses between populations may further tip the balance in favor of outcrossing. Few empirical estimates of inbreeding depression and heterosis in the same system exist for cleistogamous species. Methods: We investigate the potential costs of selfing by quantifying inbreeding depression and heterosis in three populations of the cleistogamous perennial Ruellia humilis Nutt (Acanthaceae). We performed three types of hand‐pollinations—self, outcross‐within, and outcross‐between populations—and measured seed number, germination, total flower production, and estimated cumulative fitness for the resulting progeny in a greenhouse experiment. Results: We found moderate inbreeding depression for cumulative fitness (<30%) in two populations, but outbreeding depression for crosses within a third population (–26%). For between‐population crosses, there was weak to modest heterosis (11–47%) in two of the population combinations, but modest to strong outbreeding depression (–21 to –71%) in the other four combinations. Conclusions: Neither inbreeding depression nor heterosis was of sufficient magnitude to explain the continued production of chasmogamous flowers given the relative energetic advantage of cleistogamous flowers previously estimated for these populations. Outbreeding depression either within or between populations makes the maintenance of chasmogamous flowers even harder to explain. More information is needed on the genetic basis of cleistogamy to resolve this conundrum. [ABSTRACT FROM AUTHOR]

To improve our understanding of the selfing of G. lingzhi basidiospore monokaryons and increase the efficiency of breeding excellent strains, 52 basidiospore monokaryons were isolated from a commercial G. lingzhi strain (laboratory number P). A severe partial segregation was observed using the chi-square test, the growth rate of the monokaryotic strains was normally distributed, and colonies exhibited 5 forms. The genetic diversity of the monokaryotic strains was further demonstrated by intersimple sequence repeat (ISSR) analysis, and the similarity coefficient was in the range of 0.49–1, which was consistent with the genotype classification results. In total, 14 AxBx monokaryotic strains were randomly selected for selfing with the 1 AyBy strain when the similarity coefficient was 0.76, and a total of 14 offspring were obtained via selfing, all of which were incompatible with their parents. The traits of the selfing progenies were diverse. The mycelial growth rate, fruiting body yield, and polysaccharide, triterpene, and sterol contents were the main indices. According to the membership function value, 71.43% of the selfing progeny were super parent, and the A88 strain with the best comprehensive traits was selected. These findings prove that ISSR molecular marker-assisted breeding reduces blindness, greatly reduces workload, and improves work efficiency.

The use of open-pollinated seeds from seed orchards is a common strategy for the deployment of genetically improved eucalypts, including Eucalyptus globulus, an important pulpwood tree in many temperate climate areas. However, seed quality can be affected by the rate of selfing and to a lesser extent by contamination from pollen outside the orchard. Inbreeding between related parents and especially from self-crosses is known to cause diminished growth and developmental abnormalities in the resulting progeny. This study looks at the magnitude and variation in selfing and the impact in inbreeding depression across several E. globulus families collected over the years in a seed orchard. The effects on growth and development of outcrossed and selfed progeny were studied across five progeny trials, after pedigree reconstruction of the open pollinated progeny based on SSR genotyping. An additive genetic mixed linear model was fitted to the data to evaluate the impact of inbreeding on height growth. The results showed a significant inbreeding depression, with a height growth reduction of 15% in selfed progeny, when compared with crosses from unrelated parents. These inbreeding depression values varied among families, ranging between 7% and 24%, evidencing the importance of genetic background. Contamination rates were on average 10% suggesting long distance pollen dispersal was present. A small number of abnormal phenotypes (less than 10%) was observed in the field. This was associated with specific, unrelated, crosses and not to high inbreeding rates such as found among selfed progeny. The relevance of these results for orchard management and parent selection is discussed.

Abstract Background Gastropod snails remain strongly understudied, despite their important role in transmitting parasitic diseases. Knowledge of their distribution and population dynamics increases our understanding of the processes driving disease transmission. We report the first study to use high-throughput sequencing (HTS) to elucidate the population genetic structure of the hermaphroditic snail Bulinus truncatus (Gastropoda, Heterobranchia) on a regional (17–150 km) and inter-regional (1000–5400 km) scale. This snail species acts as an intermediate host of Schistosoma haematobium and Schistosoma bovis, which cause human and animal schistosomiasis respectively. Methods Bulinus truncatus snails were collected in Senegal, Cameroon, Egypt and France and identified through DNA barcoding. A single-end genotyping-by-sequencing (GBS) library, comprising 87 snail specimens from the respective countries, was built and sequenced on an Illumina HiSeq 2000 platform. Reads were mapped against S. bovis and S. haematobium reference genomes to identify schistosome infections, and single nucleotide polymorphisms (SNPs) were scored using the Stacks pipeline. These SNPs were used to estimate genetic diversity, assess population structure and construct phylogenetic trees of B. truncatus. Results A total of 10,750 SNPs were scored and used in downstream analyses. The phylogenetic analysis identified five clades, each consisting of snails from a single country but with two distinct clades within Senegal. Genetic diversity was low in all populations, reflecting high selfing rates, but varied between locations due to habitat variability. Significant genetic differentiation and isolation by distance patterns were observed at both spatial scales, indicating that gene flow is not strong enough to counteract the effects of population bottlenecks, high selfing rates and genetic drift. Remarkably, the population genetic differentiation on a regional scale (i.e. within Senegal) was as large as that between populations on an inter-regional scale. The blind GBS technique was able to pick up parasite DNA in snail tissue, demonstrating the potential of HTS techniques to further elucidate the role of snail species in parasite transmission. Conclusions HTS techniques offer a valuable toolbox to further investigate the population genetic patterns of intermediate schistosome host snails and the role of snail species in parasite transmission. Graphical Abstract

To investigate the deflection, maximum stress, maximum strain, and failure of pavement joints of conventional and remix concrete pavement models. Nine model pavement slab specimens has been cast and statically loaded using hydraulic jack, load cell on loading frame assembly. Two concrete mix design grades and three concrete remixing procedures were chosen and fixed. This work checks the effect of remix concrete on rigid pavements, taking into account time lag (t in hr.) of Concrete (THC) and the blend ratio (r). The methods were a regular mixed with traditional procedures and a remix mixture with selfing and crossing methods. The results of a 3D finite element analysis with ANSYS simulation are compared to experimental trials. By adding a higher graded fresh concrete to the old and partially set concrete, there is improvement in the compressive strength, quality of the concrete, and modulus subgrade reaction, according to this study. [ABSTRACT FROM AUTHOR]

To adapt to high-altitude habitats, many alpine plants develop self-compatible breeding systems from outcrossing. The genetic bases for this shift and the resulting demographic consequences remain largely unexplored. Here, we present a high-quality, chromosome-level genome assembly of the monotypic and endangered alpine perennial Przewalskia tangutica (Solanaceae) occurring on the Qinghai–Tibet Plateau (QTP). Our assembled genome is approximately 3 Gb, with a contig N50 size of 17 Mb, and we identified one lineage-specific whole-genome duplication. We found that the gametophytic self-incompatibility (GSI) syntenic locus to the other obligate outcrossing Solanaceae species was broken by the inserted the long terminal repeats, and changes in the flower-specific expression of the homologous genes, and the linked GSI genes in this species. Such changes may have led to its self-compatibility. We identified three deeply diverged lineages in the central distribution of this species, and the gene flow between them was weak but continuous. All three lineages diverged and decreased their population sizes since the largest glaciations occurred in the QTP approximately 720–500 thousand years ago. In addition, we identified one obvious hybrid population between two lineages, suggesting that genetic exchanges between and within lineages still occur. Our results provide insights into evolutionary adaptation through facultative self-pollination and demographic consequences of this alpine rare species in arid habitats. [ABSTRACT FROM AUTHOR]

Premise of research. Inbreeding depression is well known to contribute to the maintenance of outcrossing in flowering plants because of its direct negative impacts on germination, survival, and fertility. Yet inbreeding depression could also impact fitness indirectly by affecting traits that govern biotic interactions. Relatively little is known about inbreeding depression on traits related to pollination success. Although often associated with pollinator attraction or reward, pollination success is also determined by floral longevity. Inbreeding depression in floral longevity has not been studied but has the potential to compound pollination disadvantages confronting inbred plants. Methodology. We investigated inbreeding depression for traits related to pollination success in the mixed-mating biennial Sabatia angularis L. (Pursh) (Gentianaceae). Under controlled, pollinator-free conditions, we performed crosses to create families of selfed and outcross seed and raised these plants to flower. We compared selfed and outcrossed individuals for the following traits: flower number, flower size, corolla longevity, stigma longevity, and plant height. We also considered whether inbreeding depression was influenced by flower number–longevity trade-offs or plant size. Pivotal results. Selfed plants produced significantly smaller flowers that lived for a significantly shorter amount of time than flowers of outcrossed plants, based on corolla and stigma longevity. Consistent with prior work, we found trade-offs between floral longevity and flower number and positive relationships between longevity and plant height. However, we did not detect inbreeding depression for flower number or plant size. Conclusions. We find novel evidence that inbreeding reduces both floral longevity and flower size. Although moderate, inbreeding depression for these traits could leave selfed plants at a disadvantage in pollen-limited environments, especially where rates of pollen export outpace deposition such that plants are forced to rely on pollinators for seed production. Our work contributes to our understanding of how inbreeding depression can alter plant-pollinator interaction outcomes and raises questions about its influence on reproductive allocation. [ABSTRACT FROM AUTHOR]

Genetic drift is expected to remove polymorphism from populations over long periods of time, with the rate of polymorphism loss being accelerated when species experience strong reductions in population size. Adaptive forces that maintain genetic variation in populations, or balancing selection, might counteract this process. To understand the extent to which natural selection can drive the retention of genetic diversity, we document genomic variability after two parallel species-wide bottlenecks in the genus Capsella. We find that ancestral variation preferentially persists at immunity related loci, and that the same collection of alleles has been maintained in different lineages that have been separated for several million years. By reconstructing the evolution of the disease-related locus MLO2b, we find that divergence between ancient haplotypes can be obscured by referenced based re-sequencing methods, and that trans-specific alleles can encode substantially diverged protein sequences. Our data point to long-term balancing selection as an important factor shaping the genetics of immune systems in plants and as the predominant driver of genomic variability after a population bottleneck.

Summary: Under the mentor effect, compatible heterospecific pollen transfer induces self‐pollen germination in otherwise self‐incompatible plants. The mentor effect could be considered a novel mode of reproductive interference if it negatively impacts fitness. Yet to date, this phenomenon has predominately been investigated under experimental conditions rather than in situ. We address this gap in natural populations of the self‐incompatible native dandelion, Taraxacum ceratophorum, where selfing only occurs in association with hybridization from exotic Taraxacum officinale.We tested whether self‐fertilization rate increases in the hybrid zone, as predicted due to the mentor effect. Using results from these investigations, we created an exponential growth model to estimate the potential demographic impacts of the mentor effect on T. ceratophorum population growth.Our results demonstrate that the strength of the mentor effect in Taraxacum depends on the prevalence of pollinator‐mediated outcross pollen deposition rather than self‐pollination. Demographic models suggest that reduced outcrossing in T. ceratophorum under exotic invasion could negatively impact population growth through inbreeding depression.We demonstrate the mentor effect is rare in natural populations of T. ceratophorum due to masking by early life cycle inbreeding depression, prevalent outcrossing, and ovule usurpation by heterospecific pollen. [ABSTRACT FROM AUTHOR]

Much theory has focused on how a population's selfing rate affects the ability of natural selection to remove deleterious mutations from a population. However, most such theory has focused on mutations of a given dominance and fitness effect in isolation. It remains unclear how selfing affects the purging of deleterious mutations in a genome-wide context where mutations with different selection and dominance coefficients co-segregate. Here, we use individual-based forward simulations and analytical models to investigate how mutation, selection and recombination interact with selfing rate to shape genome-wide patterns of mutation accumulation and fitness. In addition to recovering previously described results for how selfing affects the efficacy of selection against mutations of a given dominance class, we find that the interaction of purifying selection against mutations of different dominance classes changes with selfing and recombination rates. In particular, when recombination is low and recessive deleterious mutations are common, outcrossing populations transition from purifying selection to pseudo-overdominance, dramatically reducing the efficacy of selection. At these parameter combinations, the efficacy of selection remains low until populations hit a threshold selfing rate, above which it increases. In contrast, selection is more effective in outcrossing than (partial) selfing populations when recombination rates are moderate to high and recessive deleterious mutations are rare. [ABSTRACT FROM AUTHOR]

Macroevolutionary studies have estimated higher extinction rates of self-compatible lineages than self-incompatible ones. A leading explanation is that selfing may prevent adaptation, since models show that selfing can inhibit the fixation of adaptive alleles at a single locus (1-step adaptation). However, adaptation often involves changes at multiple loci (multi-step adaption), but the effects of selfing remain unclear because selfing increases homozygosity, which affects selection intensity, the effective population size, and the effective recombination rate. By modeling using population genetic models, I investigate the effects of selfing on adaption requiring fixation of 2 adaptive alleles, I show that intermediate selfing rates generally promote adaption, by increasing the fixation probability of the double-mutant haplotype once it is generated. In constant-sized populations, selfing increases the rate of adaptation through the fixation of new mutations even when both alleles are dominant. In demographically declining populations, the rescue probability rises sharply as the selfing rate increases from zero, but quickly drops to be low when it approaches 1.0. These findings are at odds with the hypothesis that higher extinction rates of self-compatible lineages result from reduced adaptive potential but may help explain why some studies have failed to detect relaxation of selection in selfers and also the prevalence of mixed-mating systems. [ABSTRACT FROM AUTHOR]

Agricultural losses brought about by insect herbivores can be reduced by understanding the strategies that plants use against insect herbivores. The two main strategies that plants use against herbivory are resistance and tolerance. They are, however, predicted to be mutually exclusive, yet numerous populations have them both (hence a mixed defense strategy). This has been explained, among other alternatives, by the non-linear behavior of the costs and benefits of resistance and tolerance and their interaction with plants' mating system. Here, we studied how non-linearity and mating system affect the evolutionary stability of mixed defense strategies by means of agent-based model simulations. The simulations work on a novel model that was built upon previous ones. It incorporates resistance and tolerance costs and benefits, inbreeding depression, and a continuously scalable non-linearity. The factors that promoted the evolutionary stability of mixed defense strategies include a multiplicative allocation of costs and benefits of resistance and tolerance, a concave non-linearity, non-heritable selfing, and high tolerance costs. We also found new mechanisms, enabled by the mating system, that are worth considering for empirical studies. One was a double trade-off between resistance and tolerance, predicted as a consequence of costs duplication and the inducibility of tolerance, and the other was named the resistance-cost-of-selfing, a term coined by us, and was derived from the duplication of costs that homozygous individuals conveyed when a single resistance allele provided full protection. [ABSTRACT FROM AUTHOR]

Plant mating systems shape patterns of genetic diversity and impact the long-term success of populations. As such, they are relevant to the design of seed collections aiming to maximise genetic diversity (e.g., germplasm conservation, ecological restoration). However, for most species, little is known empirically about how variation in mating systems and genetic diversity is distributed. We investigated the relationship between genetic diversity and mating systems in two functionally similar, co-occurring species of Hakea (Proteaceae), and evaluated the extent to which genetic diversity was captured in seeds. We genotyped hundreds of seedlings and mother plants via DArTseq, and developed novel implementations of two approaches to inferring the mating system from SNP data. A striking contrast in patterns of genetic diversity between H. sericea and H. teretifolia was revealed, consistent with a contrast in their mating systems. While both species had mixed mating systems, H. sericea was found to be habitually selfing, while H. teretifolia more evenly employed both selfing and outcrossing. In both species, seed collection schemes maximised genetic diversity by increasing the number of maternal lines and sites sampled, but twice as many sites were needed for the selfing species to capture equivalent levels of genetic variation at a regional scale. [ABSTRACT FROM AUTHOR]

The repeated transition from outcrossing to selfing is a key topic in evolutionary biology. However, the molecular basis of such shifts has been rarely examined due to lack of knowledge of the genes controlling these transitions. A classic example of mating system transition is the repeated shift from heterostyly to homostyly. Occurring in 28 angiosperm families, heterostyly is characterized by the reciprocal position of male and female sexual organs in two (or three) distinct, usually self‐incompatible floral morphs. Conversely, homostyly is characterized by a single, self‐compatible floral morph with reduced separation of male and female organs, facilitating selfing. Here, we investigate the origins of homostyly in Primula vulgaris and its microevolutionary consequences by integrating surveys of the frequency of homostyles in natural populations, DNA sequence analyses of the gene controlling the position of female sexual organs (CYPᵀ), and microsatellite genotyping of both progeny arrays and natural populations characterized by varying frequencies of homostyles. As expected, we found that homostyles displace short‐styled individuals, but long‐style morphs are maintained at low frequencies within populations. We also demonstrated that homostyles repeatedly evolved from short‐styled individuals in association with different types of loss‐of‐function mutations in CYPᵀ. Additionally, homostyly triggers a shift to selfing, promoting increased inbreeding within and genetic differentiation among populations. Our results elucidate the causes and consequences of repeated transitions to homostyly within species, and the putative mechanisms precluding its fixation in P. vulgaris. This study represents a benchmark for future analyses of losses of heterostyly in other angiosperms. see also the Perspective by Deborah Charlesworth [ABSTRACT FROM AUTHOR]

Fungi have a large potential for flexibility in their mode of sexual reproduction, resulting in mating systems ranging from haploid selfing to outcrossing. However, we know little about which mating strategies are used in nature, and why, even in well‐studied model organisms. Here, we explored the fitness consequences of alternative mating strategies in the ascomycete fungus Podospora anserina. We measured and compared fitness proxies of nine genotypes in either diploid selfing or outcrossing events, over two generations, and with or without environmental stress. We showed that fitness was consistently lower in outcrossing events, irrespective of the environment. The cost of outcrossing was partly attributed to non‐self recognition genes with pleiotropic effects on fertility. We then predicted that when presented with options to either self or outcross, individuals would perform mate choice in favour of the reproductive strategy that yields higher fitness. Contrary to our prediction, individuals did not seem to avoid outcrossing when a choice was offered, in spite of the fitness cost incurred. Our results suggest that, although functionally diploid, P. anserina does not benefit from outcrossing in most cases. We outline different explanations for the apparent lack of mate choice in face of high fitness costs associated with outcrossing, including a new perspective on the pleiotropic effect of non‐self recognition genes. [ABSTRACT FROM AUTHOR]

Tillandsia subgenera Diaphoranthema and Phytarrhiza s.s. are closely related epiphytic and epilithic plants adapted to xeric habitats in the Americas. Several studies suggested that subgenus Diaphoranthema and the xerophytic species of subgenus Phytarrhiza should not be segregated into different subgenera. In recent phylogenetic analyses of Tillandsioideae, subgenus Phytarrhiza s.l. is revealed as highly polyphyletic, showing a xerophytic lineage closely related to subgenus Diaphoranthema. Moreover, the evolution of neotenic traits, a selfing breeding system and polyembryony have yet to be fully investigated in a phylogenetic context. Infrageneric classifications and phylogenetic relationships were inferred using the plastid matK - trnK and nuclear ETS markers and morphology. Phylogenetic analyses of individual and combined molecular data sets were performed under parsimony and Bayesian inference. Our results confirm subgenus Diaphoranthema as monophyletic if three xeric species of subgenus Phytarrhiza are included. In subgenus Diaphoranthema, aggregates Loliacea and Rectangula were recovered as monophyletic, whereas Myosura was paraphyletic and Caliginosa, Capillaris and Recurvata were polyphyletic. Alternative groupings and morphological trends are discussed. Analysis of morphological characters associated with heterochrony indicates that neoteny may not be the only paedomorphic process in the evolution of this group. Furthermore, paedomorphosis would occur in some vegetative structures, inflorescences and flowers, whereas some fruit and seed traits could be modified by peramorphosis. [ABSTRACT FROM AUTHOR]

The breeding system of Anacyclus linearilobus, an annual and endemic species restricted to dune ecosystems of the Algerian coast were assessed through the effect of self-fertilization and intra- and inter-population artificial crosses on the probability of producing viable seeds in 20 individuals from two populations in a common garden. The breeding system was determined for each individual by the self-incompatibility index (ISI). These results were compared with those published for other species of the genus, A. clavatus, A. homogamos and A. valentinus. Results of experimental crosses showed that there was high variation in the female reproductive success between individuals of A. linearilobus, like that found in its sister species, A. valentinus. Unlike the other species in the genus that are self-incompatible, A. linearilobus showed a mixed mating system, with a majority of self-incompatible individuals, others partially self-incompatible and some self-compatible. We argue that this strategy may be related to reproductive assurance in this endemic, annual species whose effective population size has been reduced probably due to individual mating incompatibilities.

Background: Gastropod snails remain strongly understudied, despite their important role in transmitting parasitic diseases. Knowledge of their distribution and population dynamics increases our understanding of the processes driving disease transmission. We report the first study to use high-throughput sequencing (HTS) to elucidate the population genetic structure of the hermaphroditic snail Bulinus truncatus (Gastropoda, Heterobranchia) on a regional (17–150 km) and inter-regional (1000–5400 km) scale. This snail species acts as an intermediate host of Schistosoma haematobium and Schistosoma bovis, which cause human and animal schistosomiasis respectively. Methods: Bulinus truncatus snails were collected in Senegal, Cameroon, Egypt and France and identified through DNA barcoding. A single-end genotyping-by-sequencing (GBS) library, comprising 87 snail specimens from the respective countries, was built and sequenced on an Illumina HiSeq 2000 platform. Reads were mapped against S. bovis and S. haematobium reference genomes to identify schistosome infections, and single nucleotide polymorphisms (SNPs) were scored using the Stacks pipeline. These SNPs were used to estimate genetic diversity, assess population structure and construct phylogenetic trees of B. truncatus. Results: A total of 10,750 SNPs were scored and used in downstream analyses. The phylogenetic analysis identified five clades, each consisting of snails from a single country but with two distinct clades within Senegal. Genetic diversity was low in all populations, reflecting high selfing rates, but varied between locations due to habitat variability. Significant genetic differentiation and isolation by distance patterns were observed at both spatial scales, indicating that gene flow is not strong enough to counteract the effects of population bottlenecks, high selfing rates and genetic drift. Remarkably, the population genetic differentiation on a regional scale (i.e. within Senegal) was as large as that between populations on an inter-regional scale. The blind GBS technique was able to pick up parasite DNA in snail tissue, demonstrating the potential of HTS techniques to further elucidate the role of snail species in parasite transmission. Conclusions: HTS techniques offer a valuable toolbox to further investigate the population genetic patterns of intermediate schistosome host snails and the role of snail species in parasite transmission. [ABSTRACT FROM AUTHOR]

We use extensive geographical sampling and surveys of nuclear microsatellite and mitochondrial DNA loci to investigate the phylogeographic structure of the only recognized self-fertilizing vertebrates, the mangrove killifishes, currently thought to comprise two cryptic species, Kryptolebias marmoratus and Kryptolebias hermaphroditus. All genetic markers revealed three concordant main clades. The Northern clade includes populations from Florida, northern Cuba, Bahamas, Belize and Honduras and corresponds to K. marmoratus. The Southern clade encompasses populations from Brazil and corresponds to K. hermaphroditus. This species was considered endemic to southeastern Brazil, but molecular data corroborate its occurrence in northeastern Brazil. The Central clade, not previously resolved with genetic data, includes populations from Panama and Antilles. Despite the geographic proximity of the Northern and Central clades, the latter is genetically closer to the Southern clade. The discovery of the Central clade raises some taxonomic issues - it can either be considered a distinct species or united with the Southern clade into a single species with two subspecies. Another possible taxonomic solution is a single selfing species, K. marmoratus, with three subspecies. We show that the Central and Southern clades are highly selfing (97-100%), whereas selfing rates of the Northern clade populations vary geographically (39-99%). Genetic patterns indicate that populations in SE Brazil are recent, contrary to expectations based on the known distributions of related species.

Empirical evidence suggests that co-flowering species can facilitate each other through shared pollinators. However, the extent to which one co-flowering species can relieve pollination limitation of another while simultaneously competing for abiotic resource has rarely been examined. Using a deterministic model we explored the demographic outcome for one ("focal") species of its co-occurrence with a species that shares pollinators and competes for both pollinator visitation and abiotic resources. In this paper we showed how the overall impact can be positive or negative, depending on the balance between enhanced fertilization versus increased competition. Our model could predict the density of co-flowering species that will maximize the pollination rate of the focal species by attracting pollinators. Because that density will also give rise to competitive effects, a lower density of co-flowering species is required for optimizing the trade-off between enhanced fertilization and competition so as to give the maximum possible facilitation of reproduction in the focal species. Results were qualitatively different when we considered attractiveness of the co-flowering species, as opposed to its density, because attractiveness, unlike density, had no effect on competition for abiotic resources. Whereas unattractive neighbours would not bring in pollinators, very attractive neighbours would captivate pollinators, not sharing them with the focal species. Thus optimal benefit to the focal species came at intermediate levels of attractiveness in the co-flowering species. This intermediate level of attractiveness in co-flowering species simultaneously maximized pollination and overall facilitation of reproduction for the focal species. The likelihood of facilitation was predicted to decline with the selfing rate of the focal species, revealing an indirect cost for an inbreeding mating system. Whether a co-flowering species can be facilitative depends on the way pollinators respond to the plant density: only a Type III functional response for visitation rate can result in facilitation. Our model provided both a conceptual framework and precise quantitative measures for determining the impacts of a neighbouring co-flowering species on reproduction.