New insights into the polyploid complex Cenchrus ciliaris L. (Poaceae) show its capacity for gene flow and recombination processes despite its apomictic nature

2011 ◽  
Vol 59 (6) ◽  
pp. 543 ◽  
Author(s):  
Amina Kharrat-Souissi ◽  
Alex Baumel ◽  
Franck Torre ◽  
Marianick Juin ◽  
Sonja Siljak-Yakovlev ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Perennial Grass ◽  
Common Garden ◽  
Aflp Markers ◽  
Phenotypic Traits ◽  
Cenchrus Ciliaris ◽  
Ploidy Levels ◽  
Recombination Processes

Cenchrus ciliaris L. is a C4 perennial grass of arid lands which is under the focus of different ecological issues such as response to desertification, quality of forage grass and impacts of invasions. Here, molecular and morphological analyses of the genetic diversity of several Tunisian provenances of C. ciliaris were performed to better understand the phenotypic polymorphism of this agamospermous and polyploid grass. Ten phenotypic traits associated with productivity were measured in a common garden environment. Amplified Fragment Length Polymorphism (AFLP) markers were developed to investigate the structure of genetic diversity among and within provenances and between the three ploidy levels. Heritable phenotypic traits showed considerable differences within provenances. Surprisingly, AFLP markers revealed the existence of genotypic variations between individuals of the same sibship and a high G/N value (0.55). A neighbour-joining tree based on AFLP markers revealed three major groups; tetraploid, pentaploid and a mix of pentaploid and hexaploids. These groups do not correspond completely to the geographical origin of samples. The results underline the possibility of sexual reproduction, recombination and gene flow within and between populations of C. ciliaris. In respect with the well known dynamic nature of polyploid genomes, these results should have strong consequences for the future management of this grass for both conservation and invasion issues.

scholarly journals Genetic Diversity and Population Structure of Bermudagrass [Cynodon dactylon (L.) Pers.] along Latitudinal Gradients and the Relationship with Polyploidy Level

Diversity ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 135 ◽  
Author(s):  
Jingxue Zhang ◽  
Miaoli Wang ◽  
Zhipeng Guo ◽  
Yongzhuo Guan ◽  
Jianyu Liu ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Population Genetic ◽  
Cynodon Dactylon ◽  
Latitudinal Gradients ◽  
Wind Pollination ◽  
Ploidy Levels ◽  
Sexual And Asexual Reproduction ◽  
Genetic Pattern

Understanding the population genetic pattern and process of gene flow requires a detailed knowledge of how landscape characteristics structure populations. Although Cynodon dactylon (L.) Pers. (common bermudagrass) is widely distributed in the world, information on its genetic pattern and population structure along latitudinal gradients is limited. We tried to estimate the genetic diversity and genetic structure of C. dactylon along a latitudinal gradient across China. Genetic diversity among different ploidy levels was also compared in the study. The material used consisted of 296 C. dactylon individuals sampled from 16 geographic sites from 22°35′ N to 36°18′ N. Genetic diversity was estimated using 153 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. Higher within-population genetic diversity appeared at low-latitude, as well as having positive correlation with temperature and precipitation. The genetic diversity increased with the ploidy level of C. dactylon, suggesting polyploidy creates higher genetic diversity. No isolation by distance and notable admixture structure existed among populations along latitudes. Both seed dispersal (or vegetative organs) and extrinsic pollen played important roles for gene flow in shaping the spatial admixture population structure of C. dactylon along latitudes. In addition, populations were separated into three clusters according to ploidy levels. C. dactylon has many such biological characters of perennial growth, wind-pollination, polyploidy, low genetic differentiation among populations, sexual and asexual reproduction leading to higher genetic diversity, which gives it strong adaptability with its genetic patterns being very complex across all the sampled latitudes. The findings of this study are related to landscape population evolution, polyploidy speciation, preservation, and use of bermudagrass breeding.

scholarly journals Non-linear genetic diversity and notable population differentiation caused by low gene flow of bermudagrass [Cynodon dactylon (L.) Pers.] along longitude gradients

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11953
Author(s):  
Jing-Xue Zhang ◽  
Miaoli Wang ◽  
Jibiao Fan ◽  
Zhi-Peng Guo ◽  
Yongzhuo Guan ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Gene Flow ◽  
Genetic Distance ◽  
Ploidy Level ◽  
Population Genetic ◽  
Annual Precipitation ◽  
Mean Annual Precipitation ◽  
Ploidy Levels ◽  
Population Genetic Diversity

Background Environmental variation related to ecological habitat is the main driver of plant adaptive divergence. Longitude plays an important role in the formation of plant population structure, indicating that environmental differentiation can significantly shape population structure. Methods Genetic diversity and population genetic structure were estimated using 105 expressed sequence tag-derived simple sequence repeat (EST-SSR) loci. A total of 249 C. dactylon (L.) Pers. (common bermudagrass) individuals were sampled from 13 geographic sites along the longitude (105°57′34″–119°27′06″E). Results There was no obvious linear trend of intra-population genetic diversity along longitude and the intra-population genetic diversity was not related to climate in this study. Low gene flow (Nm = 0.7701) meant a rich genetic differentiation among populations of C. dactylon along longitude gradients. Significantly positive Mantel correlation (r = 0.438, P = 0.001) was found between genetic distance and geographical interval while no significant partial Mantel correlation after controlling the effect of mean annual precipitation, which indicated geographic distance correlated with mean annual precipitation affect genetic distance. The genetic diversity of C. dactylon with higher ploidy level was higher than that with lower ploidy level and groups of individuals with higher ploidy level were separated further away by genetic distance from the lower ploidy levels. Understanding the different genetic bases of local adaptation comparatively between latitude and longitude is one of the core findings in the adaptive evolution of plants.

scholarly journals Anthropogenic disturbance drives dispersal syndromes, demography, and gene flow in spatially structured amphibian populations

2019 ◽  
Author(s):  
Hugo Cayuela ◽  
Aurélien Besnard ◽  
Julien Cote ◽  
Martin Laporte ◽  
Eric Bonnaire ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Common Garden ◽  
Structured Populations ◽  
Habitat Patch ◽  
Dispersal Syndromes ◽  
Spatially Structured Populations ◽  
Capture Recapture ◽  
Common Garden Experiments ◽  
Dispersal Evolution

AbstractThere is growing evidence that anthropogenic landscapes can strongly influence the evolution of dispersal, particularly through fragmentation, and may drive organisms into an evolutionary trap by suppressing dispersal. However, the influence on dispersal evolution of anthropogenic variation in habitat patch turnover has so far been largely overlooked. In this study, we examined how human-driven variation in patch persistence affects dispersal rates and distances, determines dispersal-related phenotypic specialization, and drives neutral genetic structure in spatially structured populations. We addressed this issue in an amphibian, Bombina variegata, using an integrative approach combining capture–recapture modeling, demographic simulation, common garden experiments, and population genetics. B. variegata reproduces in small ponds that occur either in habitat patches that are persistent (i.e. several decades or more), located in riverine environments with negligible human activity, or in patches that are highly temporary (i.e. a few years), created by logging operations in intensively harvested woodland. Our capture–recapture models revealed that natal and breeding dispersal rates and distances were drastically higher in spatially structured populations (SSPs) in logging environments than in riverine SSPs. Population simulations additionally showed that dispersal costs and benefits drive the fate of logging SSPs, which cannot persist without dispersal. The common garden experiments revealed that toadlets reared in laboratory conditions have morphological and behavioral specialization that depends on their habitat of origin. Toadlets from logging SSPs were found to have higher boldness and exploration propensity than those from riverine SSPs, indicating transgenerationally transmitted dispersal syndromes. We also found contrasting patterns of neutral genetic diversity and gene flow in riverine and logging SSPs, with genetic diversity and effective population size considerably higher in logging than in riverine SSPs. In parallel, intra-patch inbreeding and relatedness levels were lower in logging SSPs. Controlling for the effect of genetic drift and landscape connectivity, gene flow was found to be higher in logging than in riverine SSPs. Taken together, these results indicate that anthropogenic variation in habitat patch turnover may have an effect at least as important as landscape fragmentation on dispersal evolution and the long-term viability and genetic structure of wild populations.

Indirect estimates reveal the potential of transgene flow in the crop–wild–weed Sorghum bicolor complex in its centre of origin, Ethiopia

2016 ◽  
Vol 15 (6) ◽  
pp. 496-505
Author(s):  
Asfaw Adugna ◽  
Endashaw Bekele
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Phenotypic Traits ◽  
Wild Populations ◽  
Centre Of Origin ◽  
Transgene Flow ◽  
Potential Risks ◽  
Cultivated Populations ◽  
Simple Sequence

AbstractA study was carried out between 2008 and 2011 to investigate the potential risks of gene flow and its consequences in the crop–wild–weed S. bicolor complex in Ethiopia to aid efforts to conserve genetic diversity. Morphological measurements and genomic DNA samples were taken in situ from 30 wild and eight cultivated populations representing a total of 760 samples from five regions. Genetic diversity, gene flow, population structure and outcrossing rates of wild populations were computed using phenotypic measurements and/or polymorphic simple sequence repeat (SSR) markers. Moreover, morphological analyses of fitness of crop–wild hybrids were studied. High diversity was observed among the wild/weedy sorghum populations for phenotypic traits and SSRs. SSR diversity was high in both wild and cultivated populations, but the magnitude was greater in the former. Gene flow between the wild and the cultivated sorghum was observed to be higher than that within either pool. Wild sorghums exhibited variation in the multilocus outcrossing rate (range = 0.31–0.65) and fitness was not compromised in most wild × crop hybrids. The study indicated that crop-to-wild gene flow is possible in Ethiopia. Thus, genes from transgenic sorghum are expected to enter into the wild and non-transgenic cultivated populations and may spread and persist, if transgenic sorghum is deployed in Ethiopia and in other countries of Africa, which may pose risk of introduction of unwanted effects, which in turn may lead to loss of genetic diversity.

scholarly journals A perfect storm: ploidy and preadaptation facilitate Saccharum spontaneum escape and invasion in the Republic of Panama

2020 ◽  
Author(s):  
Kristin Saltonstall ◽  
Graham D. Bonnett ◽  
Karen S. Aitken
Keyword(s):  
Genetic Diversity ◽  
Perennial Grass ◽  
Germplasm Collection ◽  
High Survival ◽  
Saccharum Spontaneum ◽  
Local Conditions ◽  
Ploidy Levels ◽  
Germplasm Collections ◽  
High Ploidy ◽  
Sugarcane Germplasm

AbstractPolyploidy may contribute to invasive ability as it can lead to high survival and fitness during establishment and enhance the processes of adaptation to novel environments by increasing genetic diversity in invading propagules. Many grasses are polyploid and many are aggressive invaders, making them persistent problems in disturbed environments worldwide. Today, vast areas of central Panama are dominated by Saccharum spontaneum, a perennial grass that originates from Asia. While widely regarded as invasive, it is not known when or how it arrived in Panama. We explore hypotheses regarding the timing and origins of this invasion through literature review and comparisons of genetic diversity in Panama with accessions from available sugarcane germplasm collections, highlighting historical accessions that were likely brought to Panama in 1939 as part of a USDA sugarcane germplasm collection. Samples were haplotyped at two chloroplast loci and genotyped using eight microsatellite markers. All sequenced individuals from Panama belong to a single chloroplast lineage which is common worldwide and was common in the Historic germplasm collection. Although genotypic diversity was extremely high in all samples due to high ploidy, samples from Panama had reduced diversity and clustered with several accessions in the Historic collection which had the same haplotype and high ploidy levels. Our results suggest that accidental escape from the historical sugarcane germplasm collection is the likely origin of the S. spontaneum invasion in Panama. Intraspecific hybridization among several historical accessions and pre-adaptation to local conditions may have facilitated its rapid spread and persistence. We discuss the implications of our findings for biosecurity of germplasm collections.

scholarly journals The polyploid nature of Cenchrus ciliaris L. (Poaceae) has been overlooked: new insights for the conservation and invasion biology of this species – a review

2014 ◽  
Vol 36 (1) ◽  
pp. 11 ◽  
Author(s):  
Amina Kharrat-Souissi ◽  
Sonja Siljak-Yakovlev ◽  
Spencer C. Brown ◽  
Alex Baumel ◽  
Franck Torre ◽  
...  
Keyword(s):  
Perennial Grass ◽  
Invasion Biology ◽  
Molecular Data ◽  
Grazing Pressure ◽  
Arid Ecosystems ◽  
Evolutionary Development ◽  
Cenchrus Ciliaris ◽  
Ploidy Levels ◽  
Western Asia ◽  
Genetic Mechanisms

Climate change, associated with increased aridity, and high grazing pressure by livestock results in the scarcity and loss of perennial Poaceae in arid ecosystems. The species threatened by this include Cenchrus ciliaris L., a native perennial grass of the tropical and sub-tropical arid rangelands of Africa and Western Asia and now introduced in Central and South America, and Australia. This species reproduces predominantly through aposporous apomixis although sexual individuals have been occasionally identified. Cenchrus ciliaris is characterised by a significant, heritable, phenotypic polymorphism and three ploidy levels including tetraploids (2n = 4x = 36), pentaploids (2n = 5x = 45) and hexaploids (2n = 6x = 54). Under water-deficit conditions, C. ciliaris shows plasticity in growth characteristics and aboveground biomass. This phenotypic plasticity has led to the identification of genotypic-associated responses conferring more productivity. This underlines the importance of conserving the genetic diversity of C. ciliaris in order to ensure the persistence of the vegetation cover in the arid ecosystems in which it occurs. Observations from cytogenetic and molecular data converge to underline the possibility of sexual reproduction, recombination and gene flow within and between populations of C. ciliaris. Genetic mechanisms, such as polyploidy, hybridisation between ploidy levels and apomixes, are generating and then maintaining the diversity of C. ciliaris. This review emphasises the role of polyploidy in the evolutionary development of C. ciliaris and how it may be a crucial factor for its conservation in some countries and its weedy nature in others.

Genetic diversity within a population of Microlaena stipoides, as revealed by AFLP markers

2014 ◽  
Vol 62 (7) ◽  
pp. 580 ◽  
Author(s):  
M. L. Mitchell ◽  
B. J. Stodart ◽  
J. M. Virgona
Keyword(s):  
Genetic Diversity ◽  
Perennial Grass ◽  
Aflp Markers ◽  
Annual Rainfall ◽  
Sexual And Asexual Reproduction ◽  
Eastern Australia ◽  
Microlaena Stipoides ◽  
Native Pastures ◽  
Clonal Spread ◽  
Vegetative Spread

Microlaena stipoides (Labill.) R.Br. (microlaena), a C3 perennial grass, is common within grazed native pastures in the high-rainfall zone (>550 mm average annual rainfall) of south-eastern Australia. It has the ability to spread via seed production or vegetatively, using both rhizomes and stolons. This experiment aimed to determine how variable a microlaena population was within a single area, with the aim of determining whether microlaena relied on seed or vegetative spread to sustain populations. Leaf samples of microlaena were collected from 85 locations, sampling two transects, within a pasture at Chiltern, in north-eastern Victoria (36°12ʹS, 146°35ʹE). The genetic diversity among samples was analysed using amplified fragment length polymorphism (AFLP) markers. We obtained 1612 fragments, using 10 primers combinations. Polymorphism for the markers ranged from 47% to 65%. These results indicated that the populations of microlaena that exist within the pasture at Chiltern are likely to have undergone some degree of outcrossing (Fst = 0.0219). It is likely that recruitment is occurring from sexual reproduction as well as via clonal spread within the microlaena population examined. This ability to use vegetative spread as well as both sexual and asexual reproduction may make populations of microlaena more resilient in the longer term.

Genetic Diversity of 118 Sugarcane Germplasm Using AFLP Markers

2014 ◽  
Vol 40 (10) ◽  
pp. 1877
Author(s):  
Feng-Gang ZAN ◽  
Cai-Wen WU ◽  
Xue-Kuan CHEN ◽  
Pei-Fang ZHAO ◽  
Jun ZHAO ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Aflp Markers ◽  
Sugarcane Germplasm

Genetic rescue by augmenting gene flow

2017 ◽  
Author(s):  
Richard Frankham ◽  
Jonathan D. Ballou ◽  
Katherine Ralls ◽  
Mark D. B. Eldridge ◽  
Michele R. Dudash ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
Inbreeding Coefficient ◽  
Outbreeding Depression ◽  
Genetic Rescue ◽  
Evolutionary Potential ◽  
Beneficial Effects ◽  
The Difference ◽  
Inbred Populations ◽  
Harmful Effects

Inbreeding is reduced and genetic diversity enhanced when a small isolated inbred population is crossed to another unrelated population. Crossing can have beneficial or harmful effects on fitness, but beneficial effects predominate, and the risks of harmful ones (outbreeding depression) can be predicted and avoided. For crosses with a low risk of outbreeding depression, there are large and consistent benefits on fitness that persist across generations in outbreeding species. Benefits are greater in species that naturally outbreed than those that inbreed, and increase with the difference in inbreeding coefficient between crossed and inbred populations in mothers and zygotes. However, benefits are similar across invertebrates, vertebrates and plants. There are also important benefits for evolutionary potential of crossing between populations.

scholarly journals Mitogenomics of the endangered Mediterranean monk seal (Monachus monachus) reveals dramatic loss of diversity and supports historical gene-flow between Atlantic and eastern Mediterranean populations

2020 ◽  
Author(s):  
Alba Rey-Iglesia ◽  
Philippe Gaubert ◽  
Gonçalo Espregueira Themudo ◽  
Rosa Pires ◽  
Constanza De La Fuente ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Gene Flow ◽  
North Atlantic ◽  
Marine Mammals ◽  
Eastern Mediterranean ◽  
The Black Sea ◽  
Mediterranean Populations ◽  
Geographic Ranges ◽  
Western Sahara ◽  
The Mediterranean

Abstract The Mediterranean monk seal Monachus monachus is one of the most threatened marine mammals, with only 600–700 individuals restricted to three populations off the coast of Western Sahara and Madeira (North Atlantic) and between Greece and Turkey (eastern Mediterranean). Its original range was from the Black Sea (eastern Mediterranean) to Gambia (western African coast), but was drastically reduced by commercial hunting and human persecution since the early stages of marine exploitation. We here analyse 42 mitogenomes of Mediterranean monk seals, from across their present and historical geographic ranges to assess the species population dynamics over time. Our data show a decrease in genetic diversity in the last 200 years. Extant individuals presented an almost four-fold reduction in genetic diversity when compared to historical specimens. We also detect, for the first time, a clear segregation between the two North Atlantic populations, Madeira and Cabo Blanco, regardless of their geographical proximity. Moreover, we show the presence of historical gene-flow between the two water basins, the Atlantic Ocean and the Mediterranean Sea, and the presence of at least one extinct maternal lineage in the Mediterranean. Our work demonstrates the advantages of using full mitogenomes in phylogeographic and conservation genomic studies of threatened species.

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