Genetic Consequences Research Articles

Genomes of Galápagos Mockingbirds Reveal the Impact of Island Size and Past Demography on Inbreeding and Genetic Load in Contemporary Populations.

Restricted range size brings about noteworthy genetic consequences that may affect the viability of a population and eventually its extinction. Particularly, the question if an increase in inbreeding can avert the accumulation of genetic load via purging is hotly debated in the conservation genetic field. Insular populations with limited range sizes represent an ideal setup for relating range size to these genetic factors. Leveraging a set of eight differently sized populations of Galápagos mockingbirds (Mimus), we investigated how island size shaped effective population size (Ne), inbreeding and genetic load. We assembled a genome of M. melanotis and genotyped three individuals per population by whole-genome resequencing. Demographic inference showed that the Ne of most populations remained high after the colonisation of the archipelago 1-2 Mya. Ne decline in M. parvulus happened only 10-20 Kya, whereas the critically endangered M. trifasciatus showed a longer history of reduced Ne. Despite these historical fluctuations, the current island size determines Ne in a linear fashion. In contrast, significant inbreeding coefficients, derived from runs of homozygosity, were identified only in the four smallest populations. The index of additive genetic load suggested purging in M. parvulus, where the smallest populations showed the lowest load. By contrast, M. trifasciatus carried the highest genetic load, possibly due to a recent rapid bottleneck. Overall, our study demonstrates a complex effect of demography on inbreeding and genetic load, providing implications in conservation genetics in general and in a conservation project of M.trifasciatus in particular.

Temporal Changes in Tasmanian Devil Genetic Diversity at Sites With and Without Supplementation.

Management interventions for threatened species are well documented with genetic data now playing a pivotal role in informing their outcomes. However, insitu actions like supplementations (releasing individuals into an existing population) are often restricted to a singular site. Considerable research and management effort have been dedicated to conserving the Tasmanian devil (Sarcophilus harrisii), offering a unique opportunity to investigate the temporal genetic consequences of supplementation at multiple sites, in comparison to outcomes observed in the absence of management interventions. Using 1,778 genome-wide SNPs across 1,546 individuals, we compared four wild-supplemented sites to four monitoring-only sites (not supplemented; control sites) over 9 years (2014-2022). At the study completion, genetic differentiation among supplemented sites had significantly decreased compared to among not-supplemented sites. We found statistically significant variation in genetic change over time between sites using linear mixed-effects modelling with random slopes. Investigating this among-site variation showed that three of the supplemented sites conformed to predictions that supplementations would have a positive impact on the genetic diversity of devils at these sites. We predicted no change over time at our fourth site due to the observed relatively high gene flow, however, this site did not align with predictions, instead showing decreased genetic diversity and increased relatedness. Amongst not supplemented sites, there was no consistent pattern of temporal genetic change, suggesting devil sites across Tasmania are highly heterogeneous, likely reflecting variation in site connectivity and genetic drift. Our study demonstrates that long-term concurrent monitoring of multiple sites, including controls, is necessary to contextualise the influence of management interventions on natural species fluctuations.

Bayesian phylodynamic inference of population dynamics with dormancy.

Many organisms employ reversible dormancy, or seedbank, in response to environmental fluctuations. This life-history strategy alters fundamental eco-evolutionary forces, leading to distinct patterns of genetic diversity. Two models of dormancy have been proposed based on the average duration of dormancy relative to coalescent timescales: weak seedbank, induced by scheduled seasonality (e.g., plants, invertebrates), and strong seedbank, where individuals stochastically switch between active and dormant states (e.g., bacteria, fungi). The weak seedbank coalescent is statistically equivalent to Kingman's coalescent with a scaled mutation rate, allowing the use of existing inference methods. In contrast, the strong seedbank coalescent differs fundamentally, as only active lineages can coalesce, while dormant lineages cannot. Additionally, dormant individuals typically mutate at a slower rate than active ones. Despite the significant role of dormancy in the eco-evolutionary dynamics of many organisms, no methods currently exist for inferring population dynamics and associated parameters involving dormancy. We present a Bayesian framework for jointly inferring a latent genealogy, seedbank parameters, and evolutionary parameters from molecular sequence data under the strong seedbank coalescent. We derive the exact probability density of genealogies sampled under the strong seedbank coalescent, characterize the corresponding likelihood function, and present efficient computational algorithms for its evaluation based on our theoretical framework. We develop a tailored Markov chain Monte Carlo sampler and implement our inference framework as a package SeedbankTree within BEAST2. Our work provides both a theoretical foundation and practical inference framework for studying the population genetic and genealogical consequences of dormancy.

Genetic features and pharmacological rescue of novel Kv7.2 variants in patients with epilepsy

BackgroundIncreasing evidence indicates a robust correlation between epilepsy and variants of the Kv7.2 (KCNQ2) channel, which is critically involved in directing M-currents and regulating neuronal excitability within the nervous system....

Abnormalities in Chromosomes 5 and 7 in Myelodysplastic Syndrome and Acute Myeloid Leukemia.

Chromosomes 5 and 7 are large chromosomes that contain close to 1,000 genes each. Deletions of the long arms or loss of the entire chromosome (monosomy) are common defects in myeloid disorders, particularly MDS and AML. Loss of material from either chromosome 5 or 7 results in haploinsufficiency of multiple genes, with some implicated in leukemogenesis. Abnormalities of one or both occur in up to 15% of MDS and AML cases and co-segregate in half of these. Generally, these chromosomal abnormalities are harbingers of adverse risk in both myeloid disorders. A notable exception is del(5q) in 5q- syndrome, a subtype of MDS. In this review, we describe the pathogenesis and genetic consequences of deletions in chromosomes 5 and 7. Furthermore, we provide an overview of current testing methodologies used in the assessment of these chromosomal defects in hematological malignancies and describe the disease associations and prognostic implications of aberrations in chromosomes 5 and 7 in both MDS and AML.

Species-Specific Traits Shape Genetic Diversity During an Expansion-Contraction Cycle and Bias Demographic History Reconstruction.

Species ranges are dynamic, experiencing expansions, contractions or shifts in response to habitat changes driven by extrinsic factors such as climate change or human activities. While existing research examines the genetic consequences of spatial processes, few studies integrate species-specific traits to analyse how habitat changes affect co-existing species. In this study, we address this gap by investigating how genetic diversity patterns vary among species with different traits (such as generation length, population density and dispersal) experiencing similar habitat changes. Using spatial simulations and a simpler panmictic population model, we investigate the temporal genetic diversity in refugium populations undergoing range expansion of their habitat, followed by stationary and contraction periods. By varying habitat contraction speed and species traits, we identified three distinct temporal dynamics of genetic diversity during contraction: (i) a decrease in genetic diversity, (ii) an initial increase followed by a decrease and (iii) a continuous increase throughout the contraction period. We show that genetic diversity trajectories during population decline can be predicted by comparing sampled population diversity to equilibrium values expected under expanded and contracted habitat ranges. Our study also challenges the belief that high genetic diversity in a refugium population is due to a recent and rapid habitat loss. Instead, we found contrasting effects of contraction speed on genetic diversity depending on the interaction between species-specific traits and the dynamics of habitat change. Finally, using simulated genetic data, we found that demographic histories inferred from effective population size estimates may vary across species, even when they experience similar habitat changes.

Diverged Populations Admixture Bolsters Genetic Diversity of a New Island Dibbler (Parantechinus apicalis) Population, but Does Not Prevent Subsequent Loss of Genetic Variation.

Translocating individuals from multiple source populations is one way to bolster genetic variation and avoid inbreeding in newly established populations. However, mixing isolated populations, especially from islands, can potentially lead to outbreeding depression and/or assortative mating, which may limit interbreeding between source populations. Here, we investigated genetic consequences of mixing individuals from two island populations of the dibbler (Parantechinus apicalis) in an island translocation. Despite a high level of genetic divergence between the source populations (F ST ranges 0.33-0.64), and significant differences in body size, individuals with different ancestries were able to successfully interbreed in captivity and in the wild. However, the genetic contributions from each source population were unequal initially despite each of the source populations contributing an equal number of founders. Mating success of captive animals based on the pedigree suggests that this bias toward one source population was due to founder mortality and the mating success of younger and heavier animals. Nevertheless, genetic contributions in the translocated population became equal over time with no parental purebreds, suggesting an extreme excess of hybrids across multiple years. While genetic variation in the translocated population was comparable or higher than the source populations, the increase was short-lived. Genetic composition of captive animals may not reflect what happens in the wild. These changes post-translocation highlight the need for continued genetic monitoring.

Sociodemographic Factors and Awareness of Consanguineous Marriages in Rural Northern Karnataka: A Cross-Sectional Study.

Background Consanguineous marriages, defined as unions between closely related individuals, are influenced by a complex interplay of cultural, social, economic, religious, and demographic factors. These marriages are prevalent among communities such as Hindus, Muslims, Jews, Buddhists, Christians, and Parsis in Southern and Western Asia, with significant regional variations within India. There is a lack of appropriate decision-making among women in consanguineous unions, particularly those with a low level of educational attainment, which leads to an increase in the prevalence of consanguineous marriages. This needs to be addressed through more studies and educational campaigns. Therefore, the primary objective of this study is to assess knowledge about the consequences of consanguinity and the sociodemographic factors related to consanguinity. Methodology A cross-sectional study was conducted in Unnat Bharat Abhiyan villages (Ukkali, Donur, Yambatnal, Hegadihal, Deginal) enrolled under Shri B. M. Patil Medical College, Hospital and Research Centre, BLDE (Deemed to be University), Vijayapura, India, which was selected using a lottery method. The houses were selected randomly, focusing on ever-married females aged 15-49 within the reproductive age group. Data on sociodemographic profile, marital status, and awareness status of the participants were collected from March 2023 to April 2024 using an interview technique with a pretested, semi-structured questionnaire. Results The study involved the enrollment of a total of 108 participants (Donur - 24, Yembatnal - 32, Ukkali - 27, Deginal - 10, Hegadihal - 15). Among the respondents, only 37 participants (34%) know the specific health and genetic consequences of consanguinity, such as increased risk of genetic disorders (stillbirth, milestone delay, cerebral palsy). The study highlights a significant association between respondents' knowledge of the consequences of consanguineous marriage, their literacy level, and socioeconomic status. Conclusion The study concludes that literacy levels are inversely related to the prevalence of consanguineous marriages, suggesting that education holds the key to reducing this practice. The results of this study highlight the necessity of tackling this problem through a multifaceted strategy. This strategy should include culturally sensitive educational programs, economic empowerment initiatives for women, and religious discourse that promotes genetic diversity, offering the potential for change and progress.

The Genetic Consequences of Range Expansion and Its Influence on Diploidization in Polyploids

The Genetic Consequences of Range Expansion and Its Influence on Diploidization in Polyploids

Phenotypic upregulation of hexocylceramides and ether-linked phosphocholines as markers of human extreme longevity.

Centenarians and their relatives possess a notable survival advantage, with higher longevity and reduced susceptibility to major age-related diseases. To date, characteristic omics profiles of centenarians have been described, demonstrating that these individuals with exceptional longevity regulate their metabolism to adapt and incorporate more resilient biomolecules into their cells. Among these adaptations, the lipidomic profile stands out. However, it has not yet been determined whether this lipidomic profile is specific to centenarians or is the consequence of extreme longevity genetics and is also present in centenarians' offspring. This distinction is crucial for defining potential therapeutic targets that could help delay the aging process and associated pathologies. We applied mass-spectrometry-based techniques to quantify 569 lipid species in plasma samples from 39 centenarians, 63 centenarians' offspring, and 69 noncentenarians' offspring without familial connections. Based on this profile, we calculated different indexes to characterize the functional and structural properties of plasma lipidome. Our findings demonstrate that extreme longevity genetics (centenarians and centenarians' offspring) determines a specific lipidomic signature characterized by (i) an enrichment of hexosylceramides, (ii) a decrease of specific species of ceramides and sulfatides, (iii) a global increase of ether-PC and ether-LPC, and (iv) changes in the fluidity and diversity of specific lipid classes. We point out the conversion of ceramides to hexosylceramides and the maintenance of the levels of the ether-linked PC as a phenotypic trait to guarantee extreme longevity. We propose that this molecular signature is the result of an intrinsic adaptive program that preserves protective mechanisms and cellular identity.

Recent Crop-To-Weed Adaptive Introgression Has Reshaped the Genomic Composition and Geographical Structure of US Weedy Rice (Oryza spp.).

Weedy rice is a close relative of cultivated rice (Oryza sativa) that infests rice fields worldwide and drastically reduces yields. To combat this agricultural pest, rice farmers in the southern US began to grow herbicide-resistant (HR) rice cultivars in the early 2000s, which permitted the application of herbicides that selectively targeted weedy rice without harming the crop. The widespread adoption of HR rice coincided with increased reliance on hybrid rice cultivars in place of traditional inbred varieties. Although both cultivated and weedy rice are predominantly self-fertilising, the combined introductions of HR and hybrid rice dramatically altered the opportunities and selective pressure for crop-weed hybridization and adaptive introgression. In this study, we generated genotyping-by-sequencing data for 178 weedy rice samples collected from across the rice growing region of the southern US; these were analysed together with previously published rice and weedy rice genome sequences to determine the recent genomic and population genetic consequences of adaptive introgression and selection for herbicide resistance in US weedy rice populations. We find a reshaped geographical structure of southern US weedy rice as well as purging of crop-derived alleles in some weed strains of crop-weed hybrid origin. Furthermore, we uncover evidence that related weedy rice strains have made use of different genetic mechanisms to respond to selection. Lastly, we identify widespread presence of HR alleles in both hybrid-derived and nonadmixed samples, which further supports an overall picture of weedy rice evolution and adaptation through diverse genetic mechanisms.

Multigenerational hybridisation results in heterosis and facilitates adaptive introgression, with no evidence of outbreeding depression in a pair of marine gastropods.

Anthropogenic environmental changes continue to threaten species globally. For example, translocation of species has caused unintentional hybridisation, which has contributed to species declines. On the other hand, hybridisation can be used to increase the evolutionary potential of species vulnerable to rapid environmental change, although the benefits of mixing genetically divergent lineages do not come without risks to individual fitness and the long-term viability of populations. Here, we use a combination of genome-wide Single Nucleotide Polymorphism (SNP) markers, mitochondrial DNA sequencing and measurements of growth rate to determine the genetic consequences of hybridisation between two congeneric marine gastropods across 27 years (~18 generations). Multigeneration hybridisation resulted from the introduction of the intertidal periwinkle Bembicium vittatum (a direct developer) into the native range of its congener Bembicium auratum (a species with planktotrophic larval dispersal). Despite significant genetic divergence between the species, we found no direct evidence of outbreeding depression in the admixed population. Instead, we found evidence for heterosis, which dissipated over time. After an initial lag, the frequency of introduced B. vittatum alleles declined dramatically in the hybrid population. However, a few B. vittatum alleles (3.18%) increased significantly in frequency against the overall trend, providing evidence of adaptive introgression. In the context of hybridisation as a conservation management tool, our results provide some evidence of the potential benefits that can be gained, and suggest that the costs due to outbreeding depression can be small.

Functional and pathogenic insights into CNNM4 variants in Jalili syndrome

Jalili syndrome, an autosomal recessive disorder causing cone-rod dystrophy and amelogenesis imperfecta, is a rare genetic disorder impacting visual and dental development. Missense variants (c.1474G > T and c.1475G > A) previously identified in patients with Jalili syndrome have been linked to functional impairment of CNNM4, however, the biological consequences of these pathogenic variants remain largely unexplored. In this study, we investigated the functional implications of these CNNM4 missense variants, which correspond to p.(Gly492Cys) and p.(Gly492Asp) substitutions within the CBS domain of the CNNM4 protein. Our findings demonstrated that these variants exhibit significantly reduced protein stability and increased mRNA decay rates compared with wild type. Despite exhibiting normal Mg2+ localization, the mutant proteins demonstrated significantly reduced Mg²⁺ extrusion activity. This suggests that the pathogenic mechanism underlying Jalili syndrome associated with these variants likely involves decreased mRNA and/or protein stability, rather than mislocalization. Our study provides valuable insights into the interplay between genetic variations, molecular stability, and functional consequences in the context of CNNM4-related disorders, highlighting the importance of CNNM4-mediated Mg²⁺ transport in Jalili syndrome. Further investigation into the mechanisms regulating CNNM4 expression and protein stability may reveal potential therapeutic avenues.

Investigation of introgressive hybridization in endangered Sinohyriopsis mussels (Mollusca: Unionidae) using genome-wide data in Japan

Anthropogenic hybridization is a global phenomenon and a major concern in conservation biology. Sinohyriopsis schlegelii (Mollusca: Bivalvia: Unionidae), native to Lake Biwa in Japan, is considered endangered because of its hybridization with an introduced Chinese species, S. cumingii. Although previous research suggested hybridization among Sinohyriopsis mussels, the research has failed to (1) evaluate the prevalence of hybrids, (2) predict the genetic consequences for populations containing hybrids, and (3) genetically assess a population devoid of hybrids. This study aimed to fill the knowledge gaps. We collected samples from all persistent populations in Lake Biwa, Lake Kasumigaura, and Lake Anenuma (the latter two populations were introduced from Lake Biwa) and analyzed genome-wide single nucleotide polymorphisms (SNPs) data. Our findings demonstrate that hybrids are prevalent in Lake Biwa and Lake Kasumigaura but absent in Lake Anenuma. The proportion of S. cumingii ancestry increased over the past 20 years, indicating that the genetic material of S. schlegelii may diminish further in the future. Moreover, the S. schlegelii population in Lake Anenuma shared genetic similarities with the pre-hybridization population of Lake Biwa. Although the Lake Anenuma population exhibited lower genetic diversity, no signs of inbreeding were observed. Overall, the Lake Anenuma population remains the only genetically pure S. schlegelii population, but its low genetic diversity indicates a reduced adaptive potential to environmental changes. This study provides valuable insights into the current genetic status of S. schlegelii, ultimately informing conservation efforts for this critically endangered species.

Orofacial Cleft and Its Association with Consanguineous Marriage and Other Risk Factors: A Case-control Study from a Tertiary Care Hospital in Jammu Province.

Orofacial cleft is among the most common craniofacial malformations. It presents a complex and multifactorial etiology that involves genetic and environmental factors. One of the etiological factors is consanguinity (marriage between blood relatives). Multiple environmental risk factors, such as advanced maternal age, parity, maternal smoking, radiation, alcohol consumption, diabetes mellitus, and maternal use of drugs (i.e., anticonvulsants), folic acid deficiency, etc., have also been linked to the development of cleft lip and/or palate (CL/P). There is a dearth of literature reporting the occurrence of cleft due to consanguinity and other risk factors. The aim of this study is to describe the orofacial cleft demographics and to determine the influence of parental consanguinity and other associated risk factors on the occurrence of orofacial clefts (OFC) at a tertiary healthcare hospital in Jammu Province. This was a hospital-based case-control study. In the present study, data collection was specifically done regarding demographic features, history of consanguinity, degree of consanguinity, and other associated maternal risk factors in both the cleft and control groups. This study elucidates a significant association between parental consanguinity, degree of consanguinity, and other associated risk factors (i.e., maternal age ≥30 years, birth order ≥3, maternal smoking, alcohol consumption, and lack of folic acid consumption) with the occurrence of OFC. Prevention is better than cure. Awareness programs and appropriate counseling should be conducted to educate the community about the risk factors and the anticipated genetic consequences of consanguinity to prevent the development of cleft anomalies in such populations. Gupta A, Kaul B, Gulbar S, et al. Orofacial Cleft and Its Association with Consanguineous Marriage and Other Risk Factors: A Case-control Study from a Tertiary Care Hospital in Jammu Province. Int J Clin Pediatr Dent 2024;17(11):1258-1264.

Restricted inclusion of wild broodstock at a large hatchery does not result in detectable genetic differentiation in a supplemented coho salmon (Oncorhynchus kisutch) population

Hatchery production is common in salmonid management for harvest and conservation. Many hatcheries employ integrated broodstock programs, where wild-origin fish are included as broodstock and uni- or bi-directional gene flow between wild and hatchery components of the population is encouraged. Such approaches often assume that opportunistically obtained wild fish meet the genetic goals of minimizing hatchery–wild differentiation and maintaining genetic diversity. This may be incorrect if fine-scale spatial genetic structure exists. Here we investigate the population genetic consequences of such hatchery operations in coho salmon ( Oncorhynchus kisutch) in a small river system featuring a large integrated broodstock program. We do so using 11 082 SNPs scored in wild-origin and hatchery-origin fish collected throughout the system. We found no evidence for genetic differentiation between hatchery-origin and wild-origin fish, no evidence of lowered genetic diversity in hatchery-origin fish, and no evidence for genetic differentiation among fish sampled throughout the river system. In addition, we did not detect inbreeding. Collectively, these results are consistent with current practices meeting integrated hatchery program goals of adequately sampling the genetic diversity present in wild-origin fish, although they may slightly reduce the effective population size of the combined population.

Conservation: Corals in an extinction vortex

Population declines threaten many marine ecosystems, but their genetic consequences remain largely unknown. A new study shows how a Caribbean coral finds itself trapped in an extinction vortex and vulnerable to the interplay of climate change, habitat degradation, small population size, low genetic diversity and reduced dispersal.

Comprehensive Exploration of CRISPR and Gene Editing Technologies: Applications, Ethical Considerations, and Future Implications in Genetic Research

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) and other gene-editing technologies have revolutionized genetic research by enabling precise, targeted modifications of DNA sequences. This paper provides a comprehensive exploration of CRISPR technology, detailing its development, mechanism of action, and versatility in diverse applications. From advancements in medicine, including therapeutic interventions for genetic disorders, to innovations in agriculture aimed at enhancing crop resilience and yield, CRISPR's transformative potential is vast. However, the rapid evolution of gene editing presents significant ethical and societal challenges, particularly concerning human germline editing, ecological impacts, and issues of accessibility and equity. This paper examines these ethical considerations, emphasizing the need for robust regulatory frameworks and responsible scientific practices. It also projects the future trajectory of gene editing technologies, speculating on emerging trends, possible breakthroughs, and the global implications of CRISPR in fields such as personalized medicine, synthetic biology, and biotechnology. By critically analyzing current applications and addressing ethical concerns, this study aims to provide a balanced perspective on CRISPR's potential to reshape genetic research while advocating for ethical governance and public engagement in its ongoing development. CRISPR’s ability to target specific genes with high accuracy has made it an invaluable tool not only in research laboratories but also in clinical settings, where it shows promise in treating previously incurable diseases. Recent advancements have extended CRISPR’s applications beyond simple gene knockout, allowing for base editing, prime editing, and epigenetic modifications that expand the possibilities for genetic correction and enhancement. As scientists explore using CRISPR in complex organisms, the precision and control required for safe and effective treatments become a key focus, particularly in addressing off-target effects that could lead to unintended genetic consequences.

Incomplete barriers to heterospecific mating among Somatochlora species (Odonata: Corduliidae) as revealed in multi-gene phylogenies.

Mating between species occurs within many insect orders. The result of heterospecific mating depends upon the effectiveness of pre- and post-reproductive barriers. Incomplete reproductive barriers lead to introgression of DNA into one species or both. Intricate genital morphology among dragonflies provides little assurance of species specificity given that heterospecific mating or mating attempts have been observed among many species. The genetic consequence is unknown for many heterospecific matings. For example, Somatochlora species mating and genetic exchange have been hypothesized based on observational records and individuals with hybrid morphology. We investigate the potential of heterospecific mating between North American Somatochlora species as inferred from multi-gene phylogenies. We used mitochondrial genes (COI and ND3) and nuclear genes (EF1-α and ITS2) to construct phylogenies using maximum parsimony. Observation of non-monophyletic mtDNA lineages but monophyletic nDNA lineages between Somatochlora sister-species would indicate mtDNA introgression and suggest heterospecific matings. Our results highlighted three instances of non-monophyly of mtDNA clades in the following groups: (i) S. hineana + S. tenebrosa; (ii) S. kennedyi + S. forcipata + S. franklini; and (iii) S. calverti + S. provocans + S. filosa. Analysis of partitioned Bremer support indicates that mtDNA COI largely contributed to the non-monophyly of these species, thus suggesting mtDNA introgression resulting from heterospecific matings. Additionally, the topology resulting from the combined data analysis was concordant with previous taxonomic understanding of Somatochlora species groups. These multi-gene phylogenies of North American Somatochlora are the first, providing a foundation for future ecological and evolution studies and knowledge for effective decision-making and public policy, which is especially important for the endangered species, S. hineana.

Population genetics of the freshwater red alga Batrachospermum gelatinosum (Rhodophyta) I: Frequent intragametophytic selfing in a monoicous, haploid-diploid species.

Life cycles with a prolonged haploid phase are thought to be correlated with greater rates of selfing and asexual reproduction. In red algae, recent population genetic studies have aimed to test this prediction but have mostly focused on marine species with separate sexes. We characterized the reproductive system of the obligately monoicous (i.e., hermaphroditic) freshwater red alga Batrachospermum gelatinosum and predicted that we would find genetic signatures of uniparental reproduction because of its haploid-diploid life cycle. We sampled 18 sites and genotyped 311 gametophytes with 10 polymorphic microsatellite loci to describe the reproductive system. Genotypic richness was low (<0.5) and pareto β values (describing clonal membership) were <0.7 for most sites. In taxa with separate sexes, these patterns are typically indicative of asexual reproduction. However, the genetic consequences of selfing in monoicous gametophytes are indistinguishable from those caused by asexual processes. Since we sampled gametophytes and have not yet genotyped the chantransia (i.e., the diploid phase), we interpretedlow diversity as a signature of intragametophytic selfing. Additionally, to understand the factors that drive selfing, we tested latitude and several other environmental variables, but none was significantly correlated with the genetic variation we observed. Nevertheless, future studies should genotype the chantransia to measure observed heterozygosity among other summary statistics to disentangle the effects of selfing versus asexual reproduction. Together, these data, coupled with further characterization of abiotic factors that influence population genetic patterns, will allow us to test potential drivers of reproductive system evolution.