Erosion Of Genetic Diversity Research Articles

Why biodiversity matters in agriculture and food systems.

Imagine a world where the variety of food sources we rely on is reduced to a mere handful of species. This is not a dystopian future. It's the path we are on right now, and it's happening silently in fields, farms, and forests across the globe. Biodiversity-the lifeblood of our ecosystems and food systems-is under siege. Driven by climate change, habitat destruction, and the relentless march of agricultural expansion, we are witnessing an unprecedented erosion of genetic diversity. This loss is more than just a scientific or environmental concern; it's a direct threat to global food security, and by extension, human survival.

Unraveling the Genetic Legacy of Commercial Whaling and Population Dynamics in Arctic Bowhead Whales and Narwhals.

Assessing genetic structure and diversity in wildlife is particularly important in the context of climate change. The Arctic is rapidly warming, and endemic species must adapt quickly or face significant threats to persistence. Bowhead whales (Balaena mysticetus) and narwhals (Monodon monoceros) are two long-lived Arctic species with similar habitat requirements and are often seen together in the Canadian Arctic. Although their ranges overlap extensively, bowhead whales experienced significantly greater commercial whaling mortality than narwhals over several centuries. The similar habitat requirements but different harvest histories of these two species provide an opportunity to examine present-day genetic diversity and the demographic and genetic consequences of commercial whaling. We whole-genome resequenced contemporary Canadian Arctic bowhead whales and narwhals to delineate population structure and reconstruct demographic history. We found higher genetic diversity in bowhead whales compared to narwhals. However, bowhead whale effective population size sharply declined contemporaneously with the intense commercial whaling period. Narwhals, in contrast, exhibited recent growth in effective population size, likely reflecting exposure to limited opportunistic commercial harvest. Bowhead whales will likely continue to experience significant genetic drift in the future, leading to the erosion of genetic diversity. In contrast, narwhals do not seem to be at imminent risk of losing their current levels of genetic variation due to their long-term low effective population size and lack of evidence for a recent decline. This work highlights the importance of considering population trajectories in addition to genetic diversity when assessing the genetics of populations for conservation and management purposes.

Preservation of Biodiversity and Sustainability of Ecosystem

Sustainable agriculture and biodiversity have a significant impact on human well-being, ecological resilience, and food security. They are closely related aspects of the future of our planet.It promotes the stability and functioning of ecosystems, providing numerous ecosystem services vital for agriculture, including pollination, pest control, nutrient cycling, and genetic resources for crop breeding. Biodiversity provides ecosystem services strengthening agricultural productivity and resilience. For instance, pollinators like bees and butterflies facilitate the reproduction of many crops, while natural predators help control pest populations, reducing the need for chemical pesticides. Sustainable agriculture, on the other hand, seeks to meet current food needs without compromising the ability of future generations to do the same. However, modern agricultural practices have often led to the degradation of ecosystems, loss of biodiversity, and the erosion of genetic diversity in crops and livestock. These problems have been exacerbated by deforestation, overuse of agrochemicals, and monocropping. In the long term these practices harm the environment and endanger food security by reducing the system's ability to adapt to changing conditions. Sustainable agricultural practices, by enhancing farming methods such as crop rotation, agroforestry, and organic farming, can support and enhance biodiversity by preserving habitat diversity. Conservation of native species, implementation of agro-ecological practices, and support for small-scale farmers are important steps towards achieving a harmonious coexistence between agriculture and biodiversity. There is a need of collaboration across all sections of society from intergovernmental agreements down to local community action for tackling the biodiversity catastrophe. People may learn more about local ecosystems and develop a greater regard and appreciation for them by reestablishing a connection with nature and inspiring others to do the same. UNDP sustainable development goal-15 aims to protect the biodiversity by sustainable use of terrestrial ecosystem.

Species-specific erosion of genetic diversity in grassland butterflies depends on landscape land cover

Changes in land cover, particularly agricultural intensification, are a primary cause of pollinator decline. Decline and isolation can reduce genetic diversity, reducing adaptive potential and unmasking genetic load. Maintenance of functional connectivity in changing landscapes is necessary to ensure persistence, but how land cover impacts genetic diversity and functional connectivity in butterflies remains poorly understood. We assess to which extent land cover functionally isolates grassland butterfly populations and what consequences isolation has for genetic diversity using whole genome and land cover data. We assess species-specific patterns across three butterfly species that vary in habitat specialization and mobility - Polyommatus icarus, Plebejus argus and Cyaniris semiargus - using samples from 6 to 11 populations across a ~25,000 km2 area in southern Sweden. We find that while generalist Po. icarus is nearly panmictic and heathland specialist Pl. argus maintains modest functional connectivity, grassland specialist C. semiargus exists in largely isolated populations. Genetic diversity in all species is positively related to grassland extent in the surrounding landscape. Arable and forest extent are positively and negatively related to genetic diversity in Po. icarus, while the inverse is true in C. semiargus. Lower functional connectivity in C. semiargus is coupled with higher rates of inbreeding, suggesting more urgent need of conservation action aimed at restoring functional connectivity in this species, illustrating how genetic data can reveal threats that may go unnoticed with abundance data alone. We conclude that specialist butterfly genetic diversity relies upon preservation of well-connected semi-natural grasslands to maintain functional connectivity at longer distances.

Conservation Mitonuclear Replacement: Facilitated mitochondrial adaptation for a changing world.

Most species will not be able to migrate fast enough to cope with climate change, nor evolve quickly enough with current levels of genetic variation. Exacerbating the problem are anthropogenic influences on adaptive potential, including the prevention of gene flow through habitat fragmentation and the erosion of genetic diversity in small, bottlenecked populations. Facilitated adaptation, or assisted evolution, offers a way to augment adaptive genetic variation via artificial selection, induced hybridization, or genetic engineering. One key source of genetic variation, particularly for climatic adaptation, are the core metabolic genes encoded by the mitochondrial genome. These genes influence environmental tolerance to heat, drought, and hypoxia, but must interact intimately and co-evolve with a suite of important nuclear genes. These coadapted mitonuclear genes form some of the important reproductive barriers between species. Mitochondrial genomes can and do introgress between species in an adaptive manner, and they may co-introgress with nuclear genes important for maintaining mitonuclear compatibility. Managers should consider the relevance of mitonuclear genetic variability in conservation decision-making, including as a tool for facilitating adaptation. I propose a novel technique dubbed Conservation Mitonuclear Replacement (CmNR), which entails replacing the core metabolic machinery of a threatened species-the mitochondrial genome and key nuclear loci-with those from a closely related species or a divergent population, which may be better-adapted to climatic changes or carry a lower genetic load. The most feasible route to CmNR is to combine CRISPR-based nuclear genetic editing with mitochondrial replacement and assisted reproductive technologies. This method preserves much of an organism's phenotype and could allow populations to persist in the wild when no other suitable conservation options exist. The technique could be particularly important on mountaintops, where rising temperatures threaten an alarming number of species with almost certain extinction in the next century.

Conservation genetics of the white-bellied pangolin in West Africa: A story of lineage admixture, declining demography, and wide sourcing by urban bushmeat markets.

During the last 40 years, the volumes of African pangolins feeding the illegal wildlife trade have dramatically increased. We conducted a conservation genetics survey of the most traded African species, the white bellied pangolin (WBP; Phataginus tricuspis), across three West African countries including Guinea, Côte d'Ivoire, and Ghana. Our study combining mitochondrial DNA sequencing and microsatellite genotyping is the first to reveal a wide pattern of admixture between two of the six mitochondrial lineages as previously delimited within WBP. We found a signature of isolation by distance but a lack of population genetic structuring, supporting the idea that WBP may have underestimated dispersal abilities. Levels of genetic diversity were low in West African lineages (WAfr and Gha) compared to Central Africa, reinforcing the picture of genetic pauperization shared by West African WBP. We observed a 85%-98% decline in the effective population size of WBP occurring c. 3200 to 400 ya, with current numbers (520-590) at the lower end of the conservative thresholds for minimum viable population size. The microsatellite markers were powerful enough to differentiate between individuals and identify replicated samples, confirming the utility of this approach in tracing the pangolin trade. Genetic diversity estimates confirmed that Yopougon, the main bushmeat market from Abidjan (Côte d'Ivoire), was fed by a large trade network as confirmed by vendors reporting 10 different sources situated 62-459 km away from the market. We conclude that WBP distributed in the Upper Guinean Block should be considered a single management unit of high conservation concern, as impacted by genetic diversity erosion, drastic decline in effective population size, and wide range sourcing for feeding urban bushmeat markets. Given the genetic admixture pattern detected within WBP from West Africa, we advocate for a multi-locus strategy to trace the international trade of the species.

How density dependence, genetic erosion and the extinction vortex impact evolutionary rescue.

Following severe environmental change that reduces mean population fitness below replacement, populations must adapt to avoid eventual extinction, a process called evolutionary rescue. Models of evolutionary rescue demonstrate that initial size, genetic variation and degree of maladaptation influence population fates. However, many models feature populations that grow without negative density dependence or with constant genetic diversity despite precipitous population decline, assumptions likely to be violated in conservation settings. We examined the simultaneous influences of density-dependent growth and erosion of genetic diversity on populations adapting to novel environmental change using stochastic, individual-based simulations. Density dependence decreased the probability of rescue and increased the probability of extinction, especially in large and initially well-adapted populations that previously have been predicted to be at low risk. Increased extinction occurred shortly following environmental change, as populations under density dependence experienced more rapid decline and reached smaller sizes. Populations that experienced evolutionary rescue lost genetic diversity through drift and adaptation, particularly under density dependence. Populations that declined to extinction entered an extinction vortex, where small size increased drift, loss of genetic diversity and the fixation of maladaptive alleles, hindered adaptation and kept populations at small densities where they were vulnerable to extinction via demographic stochasticity.

Genetic imprints of grafting in wild iron walnut populations in southwestern China

BackgroundAnthropogenic activities are causing unprecedented loss of genetic diversity in many species. However, the effects on genetic diversity from large-scale grafting onto wild plants of crop species are largely undetermined. Iron walnut (Juglans sigillata Dode) is a deciduous nut tree crop endemic to southwestern China with a long history of cultivation. Due to the rapid expansion of the walnut industry, many natural populations are now being replaced by cultivars grafted onto wild rootstocks. However, little is known about the potential genetic consequences of such action on natural populations.ResultsWe sampled the scion and the rootstock from each of 149 grafted individuals within nine wild populations of J. sigillata from Yunnan Province which is the center of walnut diversity and cultivation in China, and examined their genetic diversity and population structure using 31 microsatellite loci. Scions had lower genetic diversity than rootstocks, and this pattern was repeated in seven of the nine examined populations. Among those seven populations, AMOVA and clustering analyses showed a clear genetic separation between all rootstocks and all scions. However, the two remaining populations, both from northern Yunnan, showed genetic similarity between scions and rootstocks, possibly indicating that wild populations here are derived from feralized local cultivars. Moreover, our data indicated probable crop-to-wild gene flow between scions and rootstocks, across all populations.ConclusionsOur results indicate that large-scale grafting has been causing genetic diversity erosion and genetic structure breakdown in the wild material of J. sigillata within Yunnan. To mitigate these effects, we caution against the overuse of grafting in wild populations of iron walnut and other crop species and recommend the preservation of natural genotypes through in situ and ex situ conservation.

Rhizobium as Biotechnological Tools for Green Solutions: An Environment-Friendly Approach for Sustainable Crop Production in the Modern Era of Climate Change.

Modern and industrialized agriculture enhanced farm output during the last few decades, but it became possible at the cost of agricultural sustainability. Industrialized agriculture focussed only on the increase in crop productivity and the technologies involved were supply-driven, where enough synthetic chemicals were applied and natural resources were overexploited with the erosion of genetic diversity and biodiversity. Nitrogen is an essential nutrient required for plant growth and development. Even though nitrogen is available in large quantities in the atmosphere, it cannot be utilized by plants directly with the only exception of legumes which have the unique ability to fix atmospheric nitrogen and the process is known as biological nitrogen fixation (BNF). Rhizobium, a group of gram-negative soil bacteria, helps in the formation of root nodules in legumes and takes part in the BNF. The BNF has great significance in agriculture as it acts as a fertility restorer in soil. Continuous cereal-cereal cropping system, which is predominant in a major part of the world, often results in a decline in soil fertility, while legumes add nitrogen and improve the availability of other nutrients too. In the present context of the declining trend of the yield of some important crops and cropping systems, it is the need of the hour for enriching soil health to achieve agricultural sustainability, where Rhizobium can play a magnificent role. Though the role of Rhizobium in biological nitrogen fixation is well documented, their behaviour and performance in different agricultural environments need to be studied further for a better understanding. In the article, an attempt has been made to give an insight into the behaviour, performance and mode of action of different Rhizobium species and strains under versatile conditions.

Utilizing Genomics to Characterize the Common Oat Gene Pool—The Story of More Than a Century of Polish Breeding

This study was undertaken to investigate the diversity and population structure of 487 oat accessions, including breeding lines from the ongoing programs of the three largest Polish breeding companies, along with modern and historical Polish and foreign cultivars. The analysis was based on 7411 DArTseq-derived SNPs distributed among three sub-genomes (A, C, and D). The heterogeneity of the studied material was very low, as only cultivars and advanced breeding lines were examined. Principal component analysis (PCA), principal coordinate analysis (PCoA), and cluster and STRUCTURE analyses found congruent results, which show that most of the examined cultivars and materials from Polish breeding programs formed major gene pools, that only some accessions derived from Strzelce Plant Breeding, and that foreign cultivars were outside of the main group. During the 120 year oat breeding process, only 67 alleles from the old gene pool were lost and replaced by 67 new alleles. The obtained results indicate that no erosion of genetic diversity was observed within the Polish native oat gene pool. Moreover, current oat breeding programs have introduced 673 new alleles into the gene pool relative to historical cultivars. The analysis also showed that most of the changes in relation to historical cultivars occurred within the A sub-genome with emphasis on chromosome 6A. The targeted changes were the rarest in the C sub-genome. This study showed that Polish oat breeding based mainly on traditional breeding methods-although focused on improving traits typical to this crop, i.e., enhancing the grain yield and quality and improving adaptability-did not significantly narrow the oat gene pool and in fact produced cultivars that are not only competitive in the European market but are also reservoirs of new alleles that were not found in the analyzed foreign materials.

Pedigree and genome-based patterns of homozygosity in the South African Ayrshire, Holstein, and Jersey breeds.

The erosion of genetic diversity limits long-term genetic gain and impedes the sustainability of livestock production. In the South African (SA) dairy industry, the major commercial dairy breeds have been applying estimated breeding values (EBVs) and/or have been participating in Multiple Across Country Evaluations (MACE). The transition to genomic estimated breeding values (GEBVs) in selection strategies requires monitoring of the genetic diversity and inbreeding of current genotyped animals, especially considering the comparatively small population sizes of global dairy breeds in SA. This study aimed to perform a homozygosity-based evaluation of the SA Ayrshire (AYR), Holstein (HST), and Jersey (JER) dairy cattle breeds. Three sources of information, namely 1) single nucleotide polymorphism (SNP) genotypes (3,199 animals genotyped for 35,572 SNPs) 2) pedigree records (7,885 AYR; 28,391 HST; 18,755 JER), and 3) identified runs of homozygosity (ROH) segments were used to quantify inbreeding related parameters. The lowest pedigree completeness was for the HST population reducing from a value of 0.990 to 0.186 for generation depths of one to six. Across all breeds, 46.7% of the detected ROH were between 4 megabase pairs (Mb) and 8Mb in length. Two conserved homozygous haplotypes were identified in more than 70% of the JER population on Bos taurus autosome (BTA) 7. The JER breed displayed the highest level of inbreeding across all inbreeding coefficients. The mean (± standard deviation) pedigree-based inbreeding coefficient (FPED) ranged from 0.051 (±0.020) for AYR to 0.062 (±0.027) for JER, whereas SNP-based inbreeding coefficients (FSNP) ranged from 0.020 (HST) to 0.190 (JER) and ROH-based inbreeding coefficients, considering all ROH segment coverage (FROH), ranged from 0.053 (AYR) to 0.085 (JER). Within-breed Spearman correlations between pedigree-based and genome-based estimates ranged from weak (AYR: 0.132 between FPED and FROH calculated for ROH <4Mb in size) to moderate (HST: 0.584 between FPED and FSNP). Correlations strengthened between FPED and FROH as the ROH length category was considered lengthened, suggesting a dependency on breed-specific pedigree depth. The genomic homozygosity-based parameters studied proved useful in investigating the current inbreeding status of reference populations genotyped to implement genomic selection in the three most prominent South African dairy cattle breeds.

Molecular genetics and phenotypic assessment of foxtail millet (Setaria italica (L.) P. Beauv.) landraces revealed remarkable variability of morpho-physiological, yield, and yield-related traits.

Foxtail millet (Setaria italica (L.) P. Beauv.) is highly valued for nutritional traits, stress tolerance and sustainability in resource-poor dryland agriculture. However, the low productivity of this crop in semi-arid regions of Southern India, is further threatened by climate stress. Landraces are valuable genetic resources, regionally adapted in form of novel alleles that are responsible for cope up the adverse conditions used by local farmers. In recent years, there is an erosion of genetic diversity. We have hypothesized that plant genetic resources collected from the semi-arid climatic zone would serve as a source of novel alleles for the development of climate resilience foxtail millet lines with enhanced yield. Keeping in view, there is an urgent need for conservation of genetic resources. To explore the genetic diversity, to identify superior genotypes and novel alleles, we collected a heterogeneous mixture of foxtail millet landraces from farmer fields. In an extensive multi-year study, we developed twenty genetically fixed foxtail millet landraces by single seed descent method. These landraces characterized along with four released cultivars with agro-morphological, physiological, yield and yield-related traits assessed genetic diversity and population structure. The landraces showed significant diversity in all the studied traits. We identified landraces S3G5, Red, Black and S1C1 that showed outstanding grain yield with earlier flowering, and maturity as compared to released cultivars. Diversity analysis using 67 simple sequence repeat microsatellite and other markers detected 127 alleles including 11 rare alleles, averaging 1.89 alleles per locus, expected heterozygosity of 0.26 and an average polymorphism information content of 0.23, collectively indicating a moderate genetic diversity in the landrace populations. Euclidean Ward's clustering, based on the molecular markers, principal coordinate analysis and structure analysis concordantly distinguished the genotypes into two to three sub-populations. A significant phenotypic and genotypic diversity observed in the landraces indicates a diverse gene pool that can be utilized for sustainable foxtail millet crop improvement.

Assessing plant translocation success: common metrics mask high levels of inbreeding in a recently established Banksia brownii (Proteaceae) population

Context As threatening processes continue to impact rare plant populations, the use of translocations is becoming increasingly frequent. The ultimate success of translocation, attaining long-term persistence, is determined by species’ ability to reproduce, recruit, and maintain levels of genetic diversity that permits the capacity to adapt to environmental change. Aims This study aimed to assess translocation success of Banksia brownii. Methods We compared genetic diversity, reproductive output and aspects of the mating system of a translocated population with four reference wild populations. Key results We found that the use of multiple source populations for the translocation resulted in levels of genetic diversity comparable to reference populations of high diversity. Reproductive output was highest in the translocated population and a positive relationship between plant size and number of flowers across all populations was evident. However, mating system analysis revealed a large difference in outcrossing rates between populations in different habitats despite common pollinators, with the translocated population having the highest rates of selfing. Conclusion Whilst genetic diversity and reproductive output were comparable or higher in the translocated population than in the reference populations, assessing translocation outcomes by these measures alone can potentially mask the longer-term erosion of genetic diversity through unfavourable patterns of mating. Implications We recommend using multiple metrics of reproductive, recruitment and genetic diversity to properly assess plant translocation success.

Epigenetics for crop adaptation to climate change

Epigenetics for crop adaptation to climate change

Induced pluripotent stem cells and cerebral organoids from the critically endangered Sumatran rhinoceros

Less than 80 Sumatran rhinos (SR, Dicerorhinus sumatrensis) are left on earth. Habitat loss and limited breeding possibilities are the greatest threats to the species and lead to a continuous population decline. To stop the erosion of genetic diversity, reintroduction of genetic material is indispensable. However, as the propagation rate of captive breeding is far too low, innovative technologies have to be developed. Induced pluripotent stem cells (iPSCs) are a powerful tool to fight extinction. They give rise to each cell within the body including gametes and provide a unique modality to preserve genetic material across time. Additionally, they enable studying species-specific developmental processes. Here, we generate iPSCs from the last male Malaysian SR Kertam, who died in2019, and characterize them comprehensively. Differentiation in cells of thethree germ layers and cerebral organoids demonstrate their high quality and great potential for supporting the rescue of this critically endangered species.

Elevated inbreeding in Heliconia tortuosa is determined by tropical forest stand age, isolation and loss of hummingbird functional diversity.

Forest conversion and habitat loss are major threats to biological diversity. Forest regeneration can mitigate the negative effects of old-growth forest loss on species diversity, but less is known about the extent to which forest loss reduces genetic diversity in remnant populations and whether secondary forests play a role in the maintenance of genetic diversity. We quantified genetic diversity in a tropical hummingbird-pollinated understorey herb, Heliconia tortuosa, across a landscape mosaic of primary and secondary forest regrowth. Using microsatellite genotypes from >850 adult and juvenile plants within 33 forest patches and extensive bird surveys, we examined the effect of contemporary and historical landscape features including forest age (primary vs. secondary forest), stand isolation and pollinator assemblages on genetic diversity and levels of inbreeding in H. tortuosa. We found that inbreeding was up to three times higher in secondary forest, and this effect was amplified with reductions in primary forest in the surrounding landscape through reduced observed heterozygosity in isolated fragments. Inbreeding in forest patches was negatively correlated with the local frequency of specialist long-distance foraging traplining hummingbirds. Traplining hummingbirds therefore appear to facilitate mating among unrelated plants-an inference we tested using empirically parameterized simulations. Higher levels of inbreeding in H. tortuosa are therefore associated with reduced functional diversity of hummingbirds in secondary forests and forest patches isolated from primary forests. Our findings suggest a cryptic consequence of primary forest loss and secondary forest regeneration through the disruption of mutualistic interactions resulting in the erosion of genetic diversity in a common understorey plant.

DIVERSITY ANALYSIS IN UPLAND COTTON GENOTYPES FOR FIBRE QUALITY, DISEASE REACTION AND YIELD-RELATED TRAITS

Erosion of genetic diversity is a side effect of widely used selection-based plant breeding schemes which ultimately ensued to cultivars bearing a narrow genetic base. The present study was carried out at Cotton Research Station, Vehari, Pakistan during the year 2020-21. The aim was to explore the genetic diversity present in the studied genotypes. Principal component analysis (PCA), correlation study, K- mean clustering, and biplot analysis techniques were applied to 102 upland cotton genotypes. Sowing was completed by following a randomized complete block design (RCBD) with three replications. The first three principal components (PC) depicted eigenvalue &gt;1 and enfolded with 53.159% of aggregate variability. Seed cotton yield, ginning out turn (GOT), staple length, and micronaire value (MV) were loaded to PC-1. The plant stature was loaded to PC-2, while the plant population indicated relatedness to PC-3. The MV revealed a positive correlation (0.341) with GOT, while negative bonding (-0.204) with staple length (p&lt;0.05). Cluster analysis classified the studied genotypes into 7 clusters. The highest Mahalanobis distance (16828) was noted between genotypes located in clusters 2 and 6. Biplot analysis demonstrated the unique scatter behaviour of GP-1, GP-8, GP-21, GP-38, GP-39 and VH-259 (check) genotypes being located at the vertex of the polygon. The genotypes in clusters 2 and 6 might be used as parents in future gene pyramiding schemes to breed cotton cultivars with a broad genetic base. Such imminent cultivars will be able to combat incipient stress factors due to climate change.

Assessment of the Population Status of Allium Oschaninii O. Fedtsch. In the Mountains of Uzbekistan

Abstract Currently, the genetic resources of plants are on the verge of gradual disappearance, called genetic erosion. The erosion of genetic diversity implies the loss of diverse genes in individual plant species. Therefore, special attention should be paid to the collection and conservation of genetic resources of endangered plants for future use. The aim of this study is to research the natural coenopopulation of the ancestral species of cultivated plant, Allium oschaninii in the mountains of Uzbekistan. Field studies were conducted in nine coenopopulations in the Turkestan, Gissar, and Alai ranges. For each coenopopulation, a phytocoenotic characteristic given on the sites of 100 m2. When determining the structure of A. oschaninii and the characteristics of the coenopopulation, transects from 10 to 30 sites of 1 m2 were established. The condition of the coenopopulation was assessed by the age structure of A. oschaninii and using a demographic indicator. We found that the condition of the coenopopulation is normal, but incomplete. The condition of the coenopopulations 1, 8, 9 is under threat due to anthropogenic load (overgrazing) and unfavorable factors of the ecotype. The ontogenetic spectrum is centered with a peak on average generative individuals and does not coincide with the characteristic one. Coenopopulations with a left-sided type, with a predominance of juvenile individuals, are formed on stony-gravelly, fine-grained gravel, and soft-soil mountain plains. By biological nature, the ontogenetic spectrum of A. oschaninii is left- sided, with an absolute maximum on one of the pregenerative groups. According to the demographic indicators, in diverse communities and in low-mountain and medium-category habitats and in a static substrate with grazing, the coenopopulation is young, mature, and in a transitional state.

Improvement and Re-Evolution of Tetraploid Wheat for Global Environmental Challenge and Diversity Consumption Demand.

Allotetraploid durum wheat is the second most widely cultivated wheat, following hexaploid bread wheat, and is one of the major protein and calorie sources of the human diet. However, durum wheat is encountered with a severe grain yield bottleneck due to the erosion of genetic diversity stemming from long-term domestication and especially modern breeding programs. The improvement of yield and grain quality of durum wheat is crucial when confronted with the increasing global population, changing climate environments, and the non-ignorable increasing incidence of wheat-related disorders. This review summarized the domestication and evolution process and discussed the durum wheat re-evolution attempts performed by global researchers using diploid einkorn, tetraploid emmer wheat, hexaploid wheat (particularly the D-subgenome), etc. In addition, the re-evolution of durum wheat would be promoted by the genetic enrichment process, which could diversify allelic combinations through enhancing chromosome recombination (pentaploid hybridization or pairing of homologous chromosomes gene Ph mutant line induced homoeologous recombination) and environmental adaptability via alien introgressive genes (wide cross or distant hybridization followed by embryo rescue), and modifying target genes or traits by molecular approaches, such as CRISPR/Cas9 or RNA interference (RNAi). A brief discussion of the future perspectives for exploring germplasm for the modern improvement and re-evolution of durum wheat is included.

Detection of Cryptic Sex in Automictic Populations: Theoretical Expectations and a Case Study in Cataglyphis Desert Ants

Reproductive strategies are diverse and a whole continuum of mixed systems lies between strict sexuality and strict clonality (apomixis), including automixis, a parthenogenetic mode of reproduction involving a meiosis and increasing homozygosity over generations. These various systems impact the genetic structure of populations, which can therefore be used to infer reproductive strategies in natural populations. Here, we first develop a mathematical model, validated by simulations, to predict heterozygosity and inbreeding in mixed sexual-automictic populations. It highlights the predominant role of the rate of heterozygosity loss experienced during automixis (γ), which is locus dependent. Whenγis low, mixed populations behave like purely sexual ones until sex becomes rare. In contrast, whenγis high, the erosion of genetic diversity is tightly correlated to the rate of sex, so that the individual inbreeding coefficient can inform on the ratio of sexual/asexual reproduction. In the second part of this study, we used our model to test the presence of cryptic sex in a hybridogeneticCataglyphisant where new queens are produced parthenogenetically, leaving males with an apparent null fitness while they are essential to colony development as sperm is required to produce workers. Occasional sexual production of queens could resolve this paradox by providing males some fertile progeny. To determine whether this occurs in natural populations, we simulated genotypic datasets in a population under various regimes of sexual vs. asexual reproduction for queen production and compared the distribution of inbreeding, expected heterozygosity and inter-individual relatedness coefficients with those observed in a natural population ofCataglyphis mauritanicausing microsatellites. Our simulations show that the distribution of inter-individual relatedness coefficients was particularly informative to assess the relative rate of sexual/asexual reproduction, and our dataset was compatible with pure parthenogenesis but also with up to 2% sexual reproduction. Our approach, implemented in an R script, should be useful to assess reproductive strategies in other biological models.