Asexual Reproduction Research Articles

Genetic diversity, asexual reproduction and conservation of the edible fruit tree Spondias purpurea L. (Anacardiaceae) in the Costa Rican tropical dry forest.

The term circa situm has been used to describe different conservation strategies within agricultural landscapes. Circa situm conserves planted or remnant species in farmlands, where natural vegetation has been modified through anthropogenic intervention. It has been proposed that trees planted or retained under circa situm conditions may contribute to maintaining genetic diversity, however information on the role of this strategy in preserving genetic diversity is scarce. The aim of this study was to determine the levels of genetic diversity and structure, and mating patterns in planted and unmanaged stands of the tropical fruit tree Spondias purpurea L. in north western Costa Rica. In three localities, we used seven polymorphic microsatellite loci and genotyped 201 adults and 648 seeds from planted and wild stands. We found no differences in genetic diversity among planted and wild stands. Genetic structure analysis revealed that gene flow occurs among planted and wild stands within localities. Clones were present and their diversity and evenness were both high and similar between planted and wild stands. The number of pollen donors per progeny array was low (Nep = 1.01) which resulted in high levels of correlated paternity (rp = 0.9). Asexual seeds were found in 4.6% of the progeny arrays, which had multilocus genotypes that were identical to the maternal trees. Our results show that although planted stands under circa situm conditions can maintain similar levels of genetic diversity than wild stands, the low number of sires and asexual seed formation could threaten the long term persistence of populations.

A review of reproduction in the seaweed genus Fucus (Ochrophyta, Fucales): Background for renewed consideration as a model organism

The genusFucusdominates the intertidal and shallow subtidal rocky reefs of the North Atlantic and also is commonly found in the intertidal of the North Pacific. It likely diversified 12.2-2.7 mya into two genetically distinct lineages: Lineage 1 with one species in the North Pacific and two in the North Atlantic; and Lineage 2 found only in the North Atlantic (one species recently introduced into the North Pacific). With 10 accepted species,Fucusspp. (and the Fucales) are unique among algae in having a diplontic life cycle, whereby the only haploid stage is the single-celled gamete. Further,Fucusspp. produce eight eggs in each oogonium; have hermaphroditic and dioecious species in each lineage; display sperm:egg ratios differing by more than one order of magnitude; have synchronized and predictable release of gametes; are capable of self- and/or cross- fertilization and asexual (fragmentationviaadventitious branching) reproduction; readily hybridize in culture, as well as the field; and form ecads (free-living individuals with morphological variability linked to habitat) by hybridization or polyploidy. Consequently, the genus is an excellent model for a variety of studies in reproductive biology, employing laboratory and field manipulations as well as detailed genetic studies using the molecular ‘omics’. We review here the relevant literature in order to fully understand and appreciate the unique opportunities thatFucusspp. provide as model organisms for future studies of reproduction.

Reproductive cycles of the oviparous sponges Cinachyrella apion (Spirophorida) and Tethya maza (Tethyida) in a tropical intertidal environment

AbstractEnvironmental factors are constantly changing in the intertidal region. Consequently, the various benthic organisms that densely colonize this ocean area had to adapt to these constant changes. Reproductive strategy might be considered one of these adaptations. However, knowledge about this aspect of the biology of marine invertebrates is still contentious for some groups, especially with regard to sponges (Porifera). Here, we investigated the effects of different environmental factors on the timing and effort of sexual and asexual reproduction in Cinachyrella apion and Tethya maza, two oviparous demosponges in Salvador, Bahia, Brazil. We analyzed the influence of humidity, atmospheric temperature, seawater temperature, photoperiod, rainfall, height of low tides, and chlorophyll‐a concentration on the density and size of oocytes and buds of these sponges. Both species reproduced aperiodically. Cinachyrella apion had a maximum 2.8 ± 4.04 oocytes/mm2 and 0.73 ± 0.15 buds/mm2, whereas T. maza had a maximum 6.0 ± 12.21 oocytes/mm2 and 0.31 ± 0.13 buds/mm2. The density of oocytes in C. apion was positively influenced by chlorophyll‐a concentration, whereas that of T. maza was negatively modulated by relative humidity. We did not observe any relationship between the environmental factors and bud density in C. apion, but bud density variation in T. maza was positively related to chlorophyll‐a concentration and to seawater temperature. It seems that individuals of both species alternated between the production of sexual and asexual propagules, suggesting a trade‐off between reproductive modes. Therefore, asexual and sexual reproduction seems to impact population growth and reproduction of both species, likely contributing to the recruitment of new sponges. In tropical intertidal regions, multiple environmental factors seem to contribute more to determining the quantity of sexual and asexual reproductive elements rather than the species' reproductive period.

FaSmi1 Is Essential for the Vegetative Development, Asexual Reproduction, DON Production and Virulence of Fusarium asiaticum.

Smi1 is a protein required for cell cycle progression, morphogenesis, stress response and life span of Saccharomyces cerevisiae. FaSmi1 was identified as a Smi1 homolog in a wheat scab pathogenic fungus Fusarium asiaticum strain 2021. The deletion of FaSmi1 leads to defects in mycelial growth, asexual reproduction, and virulence. The FaSmi1 deletion mutant also exhibited increased sensitivity to osmotic stresses generated by NaCl and KCl, but increased tolerance to oxidative stresses and cell wall integrity inhibitors. All of these defects were restored by genetic complementation of the mutant with the whole parental FaSmi1 gene. Interestingly, the antioxidant system-associated genes exhibit a lower expression level and the mycotoxins' DON content was decreased in the FaSmi1 deletion mutant compared with the parental strain 2021. These results indicate that FaSmi1 plays a critical role in the vegetative development, asexual reproduction, DON production and virulence of F. asiaticum.

Using individual-based modelling to investigate a pluralistic explanation for the prevalence of sexual reproduction in animal species

Attempts to resolve the paradox of sexual reproduction in animal species have typically involved single factor explanations, including but not limited to sexual species being better able to cope with fluctuating resources, being better able to evade pathogens and predators and sex facilitating the elimination of deleterious alleles. Only a handful of studies have investigated two potentially interacting factors, which most commonly involve the ability to evade pathogens and predators and mutation load; only two simulation studies by the same authors have examined the potential interaction of 3 factors.. Our study is the first three-factor study to examine the potential interaction between purifying selection, the ability to avoid predators and the ability to cope with fluctuating resources. Therefore, we addressed a number of open eco-evolutionary questions in our study: First, what is the effect of these three factors on the prevalence of sexual reproduction in animals? Second, do these factors act integratively, antagonistically or independently in determining the prevalence of sexual reproduction The ‘controls’ were our three prior studies where we investigated each of these factors individually. Our aim was to determine if the effect sizes in our individual studies were integratively enhanced by the interaction with the remaining two factors. What we found is that purifying selection purging deleterious alleles in sexual species was integratively enhanced by the two additional factors of increased predation and fluctuating resources. On the other hand, the effect of purifying selection and increased predation had an antagonistic effect on the levels of sexual reproduction and asexual reproduction in facultative species where there were fluctuating resources. Finally, the presence of an intermediate intensity deleterious allele and fluctuating resources had no discernable effect on the extinction levels of sexual and asexual species where there is increased predation. These results are not surprising, as there is no a priori reason to assume that multiple factors will have a greater impact on mode of reproduction than any of these factors acting independently. Our results suggest that multiple factors can act intergratively, antagonistically and non-reductively all at the same time, which is a significant contribution to the open question in the biological literature regarding the effect of multiple factors on the prevalence of sexual reproduction.

Synthesis of aglycones, structure-activity relationships, and mode of action of lycosides as inhibitors of the asexual reproduction of Phytophthora.

Phytophthora are plant pathogens that damage agricultural products. Lycosides (1a-d), found in vegetable juice, have the potential to curb the rapid outbreak and crop damage caused by the asexual reproduction of Phytophthora. Here, aglycones 2a, b with slightly higher activity than lycosides were synthesized as a diastereomeric mixture (mix-2) possessing activity (IC50=4.1 µm) comparable with that of lycosides. The importance of the cyclohexanone structure and side-chain length was demonstrated via structure-activity relationship analysis using synthetic intermediates. In addition, the action mechanism of lycosides was investigated using transcriptome analysis, which revealed a contribution to proline biosynthesis inhibition, a process crucial for the asexual reproduction of Phytophthora. These findings indicate that lycosides (and aglycone) are environmentally benign agents that can be used for protecting agricultural products from Phytophthora pathogens.

Clonal Propagation of Walnuts (Juglans spp.): A Review on Evolution from Traditional Techniques to Application of Biotechnology.

Walnuts (Juglans sp.) are allogamous species. Seed-derived plants are not always superior to the selected parent. Clonal propagation of selected stock plants is an essential requirement for the clonal fidelity of the descendants and to maintain their genetic structure. Selection of the desired plant is realized only after reaching maturity, and characterizing and evaluating the performance of adult trees require a long time. Clonal propagation methods ensure proper transmission of characters to descendants and can be used effectively in breeding programs. The commercialization of a cultivar or rootstock depends on the success of vegetative propagation. Walnuts, like other tree species, are recalcitrant to conventional vegetative propagation methods and even non-conventional in vitro culture (micropropagation). Elucidation of factors determining the success of cloning of desired plants would contribute to understanding current limitations for most genotypes of Juglans. We outline the role of grafting and cuttings and stool layering, as well as in vitro culture on walnut multiplication. These techniques are, in practice, entirely different; nevertheless, they are affected by common factors. The incompatibility of stock-scion and the reduced ability of stem cuttings to root are the main bottlenecks for grafting and cutting, respectively. Genotype, age, and physiological status, reinvigoration or rejuvenation-treatment of donor plant, period of harvesting and processing of explants critically affect the results of methods followed. The in vitro culture technology is the most suitable for walnut cloning. This also has constraints that affect commercial propagation of most desired genotypes. We describe comprehensive results and synthesis in this review on the asexual reproduction of walnuts, providing a better comprehension of the limiting factors and the ways to overcome them, with direct implications on commercial propagation and the releasing of outstanding genotypes.

Can resin extraction have an effect on the reproductive biology in burseraceae species?: A global analysis

Plant reproductive biology encompasses the study of sexual and asexual reproduction, as well as morphological, physiological, ecological, and genetic aspects influencing these processes. Management can influence reproduction of plants and associated attributes. For economically and culturally important species, it is known that exudates affect biomass of reproductive parts, but limited information is available on how reproductive biology is affected by harvest of exudates. This study reviews the effects of resins extraction in economic and culturally important species of Burseraceae. We conducted a systematic review on studies of floral biology, management, propagation and germination, resource allocation and pollination, hypothesizing that the extraction of exudates negatively impacts the reproductive biology of these plants by altering their mating system, pollination, and reproductive success as a consequence of resource reallocation. We identified that dioecy is the most frequent mating system in Burseraceae plants, and the extraction of exudates negatively affects the reproductive success of the species utilized, since it is related to a decrease in the number of flowers, fruits, and seeds, as well as in the percentage of viability and seed germination. Our review suggests the relevance of conducting studies on the ecophysiological effects of management on resiniferous species. Furthermore, it highlights the difficulty of detecting clear patterns, specific studies should be carried out to corroborate the hypothesis derived from this review. We propose specific strategies that better explore the effect of human management and exudate extraction techniques on vital processes such as germination, development, growth, reproduction, and pollination, in species that are used for this purpose.

Synthetic apomixis enables stable transgenerational transmission of heterotic phenotypes in hybrid rice

In hybrid plants, heterosis often produces large, vigorous plants with high yields; however, hybrid seeds are generated by costly and laborious crosses of inbred parents. Apomixis, in which a plant produces a clone of itself via asexual reproduction through seeds, may produce another revolution in plant biology. Recently, synthetic apomixis enabled clonal reproduction of F1 hybrids through seeds in rice (Oryza sativa), but the inheritance of the synthetic apomixis trait and superior heterotic phenotypes across generations remained unclear. Here, we propagated clonal plants to the T4 generation and investigated their genetic and molecular stability at each generation. By analyzing agronomic traits, as well as the genome, methylome, transcriptome, and allele-specific transcriptome, we showed that the descendant clonal plants remained stable. Unexpectedly, in addition to normal clonal seeds, the plants also produced a few aneuploids that had eliminated large genomic segments in each generation. Despite the identification of rare aneuploids, the observation that the synthetic apomixis trait is stably transmitted through multiple generations helps confirm the feasibility of using apomixis in the future.

Symbiont genotype influences holobiont response to increased temperature

As coral reefs face warming oceans and increased coral bleaching, a whitening of the coral due to loss of microalgal endosymbionts, the possibility of evolutionary rescue offers some hope for reef persistence. In tightly linked mutualisms, evolutionary rescue may occur through evolution of the host and/or endosymbionts. Many obligate mutualisms are composed of relatively small, fast-growing symbionts with greater potential to evolve on ecologically relevant time scales than their relatively large, slower growing hosts. Numerous jellyfish species harbor closely related endosymbiont taxa to other cnidarian species such as coral, and are commonly used as a model system for investigating cnidarian mutualisms. We examined the potential for adaptation of the upside-down jellyfish Cassiopea xamachana to increased temperature via evolution of its microalgal endosymbiont, Symbiodinium microadriaticum. We quantified trait variation among five algal genotypes in response to three temperatures (26 °C, 30 °C, and 32 °C) and fitness of hosts infected with each genotype. All genotypes showed positive growth rates at each temperature, but rates of respiration and photosynthesis decreased with increased temperature. Responses varied among genotypes but were unrelated to genetic similarity. The effect of temperature on asexual reproduction and the timing of development in the host also depended on the genotype of the symbiont. Natural selection could favor different algal genotypes at different temperatures, affecting host fitness. This eco-evolutionary interaction may be a critical component of understanding species resilience in increasingly stressful environments.

Annual rhythmicity in the switching of reproductive mode in planarians

Species of planarians include both asexually reproducing individuals (reproduce through fission and regeneration) and sexually reproducing individuals (hermaphrodites that mate to produce cocoons). While some individuals can switch between the asexual and sexual modes of reproduction. In this study, we examined the reproductive modes and ploidy of Dugesia japonica and Dugesia ryukyuensis from three spring wells in Okinawa (Japan) during two consecutive years. D. japonica are mostly asexual and triploid. In contrast, only 40 % of D. ryukyuensis are asexual and triploid; the remaining are sexual, and diploid or triploid. The sexually reproductive season of D. ryukyuensis is winter. In July, the reproductive organs disappear, and the individuals start asexual reproduction through fission and regeneration. In January of the following year, the individuals develop ovaries and necessary reproductive organs and start sexual reproduction. When these species were lab-reared for a longer period, the reproductive cycles in three strains were repeated for three years. These results confirm that D. ryukyuensis population in Okinawa switches between reproductive modes on an annual cycle, even when kept under constant temperature and no light/dark cycle.

Trichoderma atroviride hyphal regeneration and conidiation depend on cell-signaling processes regulated by a microRNA-like RNA.

The ability to respond to injury is essential for the survival of an organism and involves analogous mechanisms in animals and plants. Such mechanisms integrate coordinated genetic and metabolic reprogramming events requiring regulation by small RNAs for adequate healing of the wounded area. We have previously reported that the response to injury of the filamentous fungus Trichoderma atroviride involves molecular mechanisms closely resembling those of plants and animals that lead to the formation of new hyphae (regeneration) and the development of asexual reproduction structures (conidiophores). However, the involvement of microRNAs in this process has not been investigated in fungi. In this work, we explore the participation of microRNA-like RNAs (milRNAs) molecules by sequencing messenger and small RNAs during the injury response of the WT strain and RNAi mutants. We found that Dcr2 appears to play an important role in hyphal regeneration and is required to produce the majority of sRNAs in T. atroviride. We also determined that the three main milRNAs produced via Dcr2 are induced during the damage-triggered developmental process. Importantly, elimination of a single milRNA phenocopied the main defects observed in the dcr2 mutant. Our results demonstrate the essential role of milRNAs in hyphal regeneration and asexual development by post-transcriptionally regulating cellular signalling processes involving phosphorylation events. These observations allow us to conclude that fungi, like plants and animals, in response to damage activate fine-tuning regulatory mechanisms.

Physiological and ecological characteristics and reproductive responses of Phragmites australis to dry-wet conditions in inland saline marshes of Northeast China.

Inland saline marshes in northeastern China have unique soil characteristics and population distribution features. Hydrological change is a critical environmental factor causing wetland degradation and soil salinization in this region. The growth and reproductive responses of typical wetland plants to dry-wet alternations are essential for restoring inland saline marshes. A pot experiment was conducted to study the growth and reproductive responses of Phragmites australis populations to three hydrological treatments simulating drought degradation (drought), permanent inundation restoration (flooding), and seasonal inundation restoration (dry-wet). The species showed different growth and reproductive responses to the three treatments. After 120 d, the drought conditions induced a lower biomass, root length and root surface area of P. australis, but with higher root diameter, soluble sugar, and Na+ ion contents. Flooding and alternating dry-wet treatments induced the opposite responses. Alternating dry-wet treatments can be considered a better solution to effectively conserve water and meet the water needs of P. australis in the current growing season. The biomass under the alternating wet and dry treatment was the same as that under flooding, but the number of rhizome shoots was lower. The alternating dry-wet treatments was able to recover the growth of P. australis in the current season, but the potential for asexual reproduction of the species was insufficient.

Dimorphism and microcycle conidiation of Pseudocercospora pseudostigmina‐platani conidia from American sycamore

AbstractIn this study, the micromorphology and surface details of Pseudocercospora pseudostigmina‐platani conidia were investigated on American sycamore (Platanus occidentalis) leaves. Sooty films were collected from diseased leaves for fungal DNA extraction and observed using light and field‐emission scanning electron microscopy. Two types of conidia were present on the leaves: (i) hyaline and curved Cercostigmina‐like conidia and (ii) brown and straight Stigmina‐like conidia. The fungal pathogen was identified as P. pseudostigmina‐platani based on morphological characteristics and internal transcribed spacer region sequences. Some non‐glandular trichomes were found near the centre of the conidial masses on the abaxial surface of the naturally infected leaves. Leaf ultrasonication to dislodge conidia revealed sporodochia erupting through the stomata. Hyphae from sporodochia grew on the leaf surface and entered host tissues through the stomata. Conidiogenous cells had terminal rings and tapered towards the flat region where a conidium was attached. The conidia produced secondary conidia directly without hyphae. After dislodging the conidia by ultrasonication, scars were observed. These results indicate that the fungus has dimorphic conidia and microcycle conidiation for simple and rapid asexual reproduction.

The competition of ecological resonances in the quantum metabolic model of cancer: Potential energetic interventions

Cancer (a) represents an atavistic reversion to attempted asexual reproduction; (b) metastasizes to absorber “soil” tissues based upon temporal, ontogenetic commonalities; (c) cycles/precesses with competitive immunological surveillance and self-competition within the ecological environment of the body; and (d) is potentially manageable via quantum information qubit phase transitions and universal principles of thermodynamic hysteresis and resonant driving forces . We use retro-recognition of evidence-based cancer anomalies to make these arguments, which in sum position cancer as an ecological quantum information problem. The findings reposition the quantum metabolic model of cancer and presents a research approach aimed at applied treatments: Tertiary Lymphoid Structure ecological competition with cellular transmembrane quantum energy boosting using VDAC and other voltage gated ion channels.

High level of somatic mutations detected in a diploid banana wild relative Musa basjoo.

Plants are thought to lack an early segregating germline and often retain both asexual and sexual reproduction, both of which may allow somatic mutations to enter the gametes or clonal progeny, and thereby impact plant evolution. It is yet unclear how often these somatic mutations occur during plant development and what proportion is transmitted to their sexual or cloned offspring. Asexual "seedless" propagation has contributed greatly to the breeding in many fruit crops, such as citrus, grapes and bananas. Whether plants in these lineages experience substantial somatic mutation accumulation is unknown. To estimate the somatic mutation accumulation and inheritance among a clonal population of plant, here we assess somatic mutation accumulation in Musa basjoo, a diploid banana wild relative, using 30 whole-genome resequenced samples collected from five structures, including leaves, sheaths, panicle, roots and underground rhizome connecting three clonal individuals. We observed 18.5 high proportion de novo somatic mutations on average between each two adjacent clonal suckers, equivalent to ~ 2.48 × 10-8 per site per asexual generation, higher than the per site per sexual generation rates (< 1 × 10-8) reported in Arabidopsis and peach. Interestingly, most of these inter-ramet somatic mutations were shared simultaneously in different tissues of the same individual with a high level of variant allele fractions, suggesting that these somatic mutations arise early in ramet development and that each individual may develop only from a few apical stem cells. These results thus suggest substantial mutation accumulation in a wild relative of banana. Our work reveals the significance of somatic mutation in Musa basjoo genetics variations and contribute to the trait improvement breeding of bananas and other asexual clonal crops.

Machine Learning Deciphers Genotype and Ammonium as Key Factors for the Micropropagation of Bryophyllum sp. Medicinal Plants

Bryophyllum constitutes a subgenus of succulent plants that have been widely employed worldwide in traditional medicine. Micropropagation is required to optimize their growth and reproduction for biotechnological purposes. The mineral composition of culture media is usually an underestimated factor in the design of the in vitro culture protocols of medicinal plants. Universal and highly cited media mineral formulations, such as the Murashige and Skoog (MS) medium, are generally employed in plant tissue culture studies, although they cause physiological disorders due to their imbalanced mineral composition. In this work, neurofuzzy logic is proposed as a machine-learning-based tool to decipher the key factors (genotype, number of subcultures, and macronutrients) that are involved in the establishment of the Bryophyllum sp. in vitro culture. The results show that genotype played a key role, as it impacts both vegetative growth and asexual reproduction in all of the species that were studied. In addition, ammonium was identified as a significant factor, as concentrations above 15 mM promote a negative effect on vegetative growth and reproduction. These findings should be considered as the starting point for optimizing the establishment of the in vitro culture of Bryophyllum species, with large-scale applications as biofactories of health-promoting compounds, such as polyphenols and bufadienolides.

Symbiotic and toxinogenic Rhizopus spp. isolated from soils of different papaya producing regions in Mexico.

Mucoralean fungi from the genus Rhizopus are common inhabitants of terrestrial ecosystems, being some pathogens of animals and plants. In this study, we analyzed the symbiotic and toxinogenic potential of Rhizopus species derived from agricultural soils dedicated to the production of papaya (Carica papaya L.) in Mexico. Four representative strains of soil-derived Rhizopus spp. were analyzed employing molecular, microscopic, and metabolic methods. The ITS phylogenies identified the fungi as Rhizopus microsporus HP499, Rhizopus delemar HP475 and HP479, and Rhizopus homothallicus HP487. We discovered that R. microsporus HP499 and R. delemar HP475 harbor similar endofungal bacterial symbionts that belong to the genus Mycetohabitans (Burkholderia sensu lato) and that none of the four fungi were associated with Narnavirus RmNV-20S and RmNV-23S. Intriguingly, the interaction between R. delemar - Mycetohabitans showed different phenotypes from known R. microsporus - Mycetohabitans symbioses. Elimination of bacteria in R. delemar HP475 did not cause a detrimental effect on fungal growth or asexual reproduction. Moreover, metabolic and molecular analyses confirmed that, unlike symbiotic R. microsporus HP499, R. delemar HP475 does not produce rhizoxin, one of the best-characterized toxins produced by Mycetohabitans spp. The rhizoxin (rhi) biosynthetic gene cluster seems absent in this symbiotic bacterium. Our study highlights that the symbioses between Rhizopus and Mycetohabitans are more diverse than anticipated. Our findings contribute to expanding our understanding of the role bacterial symbionts have in the pathogenicity, biology and evolution of Mucorales.

Effects of highland environments on clonal diversity in aquatic plants: An interspecific comparison study on the Qinghai-Tibetan Plateau.

Clonal reproduction is one of the most distinctive characteristics of plants and is common and diverse in aquatic macrophytes. The balance between sexual and asexual reproduction is affected by various conditions, especially adverse environments. However, we know little about clonal diversity of aquatic plants under suboptimal conditions, such as at high altitudes, and having this information would help us understand how environmental gradients influence patterns of clonal and genetic variation in freshwater species. The microsatellite data of four aquatic taxa in our previous studies were revisited to estimate clonal and genetic diversity on the Qinghai-Tibetan Plateau. Clonal diversity among different genetic groups was compared. Local environmental features were surveyed. Beta regressions were used to identify the environmental factors that significantly explained clonal diversity for relative taxon. The level of clonal diversity from high to low was Stuckenia filiformis > Hippuris vulgaris > Myriophyllum species > Ranunculus section Batrachium species. A positive correlation between clonal and genetic diversity was identified for all taxa, except H. vulgaris. Clonal diversity was affected by climate in S. filiformis and by the local environment in H. vulgaris. For Myriophyllum spp., low elevation and high sediment nutrition were significant for sexual recruitment. The environmental effects on clonal diversity were not significant in R. sect. Batrachium spp. Clonal diversity of aquatic plants is moderate to high and varies greatly in highlands. The effects of breeding systems and environmental factors on the patterns of clonal variation were identified. Elevational gradients, climates and local conditions play different roles in clonal diversity among relative taxon. Our results highlight the importance of sexual recruitment in alpine aquatic plant populations and the influence of environmental factors on the genetic patterns in freshwater species at local and regional scales.

Genomic consequences and selection efficacy in sympatric sexual versus asexual kelps

Genetic diversity can influence resilience and adaptative capacity of organisms to environmental change. Genetic diversity within populations is largely structured by reproduction, with the prevalence of asexual versus sexual reproduction often underpinning important diversity metrics that determine selection efficacy. Asexual or clonal reproduction is expected to reduce genotypic diversity and slow down adaptation through reduced selection efficacy, yet the evolutionary consequences of clonal reproduction remain unclear for many natural populations. Here, we examine the genomic consequences of sympatric sexual (haplodiplontic) and clonal morphs of the kelp Ecklonia radiata that occur interspersed on reefs in Hamelin Bay, Western Australia. Using genome-wide single nucleotide polymorphisms, we confirm significant asexual reproduction for the clonal populations, indicated by a significantly lower number of multi-locus lineages and higher intra-individual diversity patterns (individual multi-locus heterozygosity, MLH). Nevertheless, co-ancestry analysis and breeding experiments confirmed that sexual reproduction by the clonal morph and interbreeding between the two morphs is still possible, but varies among populations. One clonal population with long-term asexuality showed trends of decreased selection efficacy (increased ratio non- vs. synonymous gene diversities). Yet, all clonal populations showed distinct patterns of putative local adaptation relative to the sexual morph, possibly indicating maladaptation to local environmental conditions and high vulnerability of this unique clonal morph to environmental stress.