Drylands count among the most globally extensive biomes, and while many desert and dry rangeland ecosystems are under threat, genetic structures of dryland species are still rarely studied.
Artemisia ...frigida
is one of the most widely distributed plant species in the temperate rangelands of Eurasia and North America, and it also dominates in many habitats of Mongolia due to its tolerance to low temperatures, drought and disturbance. Local environmental conditions and grazing pressure can influence species performance and affect spatial patterns of genetic diversity in contrasting ways, and our study set out to evaluate such effects on the genetic diversity and structure of
A. frigida
. We first developed new species-specific Simple Sequence Repeats (SSRs) markers using whole genome sequencing. We then analysed 11 populations of
A. frigida
that had been sampled along a large climatic gradient in Mongolia, which were sub-structured according to three levels of grazing intensity. Estimates of genetic diversity at the population level were high (H
O
= 0.56, H
E
= 0.73) and tended to increase with higher precipitation and soil nutrient availability. Grazing had no effect on genetic diversity, however, a high number of grazing-specific indicator alleles was found at grazed sites. Genetic differentiation among populations was extremely low (global G
ST
= 0.034). Analysis of Molecular Variance revealed 5% variance between populations along the climatic gradient, with 3% of the variance being partitioned among different grazing intensity levels. We found no relationship between geographic and genetic distances, and thus no isolation by distance in this widely distributed species. The relatively low genetic structuring suggests that considerable gene flow exists among
A. frigida
populations across the rangelands of Mongolia, in spite of the pervasive grazing in the region.
The Irano‐Turanian (IT) floristic region is considered an important center of origin for many taxa. However, there is a lack of studies dealing with typical IT genera that also occur in neighboring ...areas. The species‐rich monocot genus Gagea Salisb. shows a center of diversity in IT region and a distribution in adjacent regions, therefore representing a good study object to investigate spatial and temporal relationships among IT region and its neighboring areas (East Asia, Euro‐Siberia, Himalaya, and Mediterranean). We aimed at (a) testing the origin of the genus and of its major lineages in the IT region, (b) reconstructing divergence times, and (c) reconstructing colonization events. To address these problems, sequences of the ribosomal DNA internal transcribed spacer (ITS) region of 418 individuals and chloroplast intergenic spacers sequences (psbA‐trnH, trnL‐trnF) of 497 individuals, representing 116 species from all sections of the genus and nearly its entire distribution area were analyzed. Divergence times were estimated under a random molecular clock based on nrITS phylogeny, which was the most complete data set regarding the representation of species and distribution areas. Ancestral distribution ranges were estimated for the nrITS data set as well as for a combined data set, revealing that Gagea most likely originated in southwestern Asia. This genus first diversified there starting in the Early Miocene. In the Middle Miocene, Gagea migrated to the Mediterranean and to East Asia, while migration into Euro‐Siberia took place in the Late Miocene. During the Pleistocene, the Arctic was colonized and Gagea serotina, the most widespread species, reached North America. The Mediterranean basin was colonized multiple times from southwestern Asia or Euro‐Siberia. Most of the currently existing species originated during the last 3 Ma.
Divergence time estimation and ancestral range reconstructions were carried out for the species‐rich monocot genus Gagea (Liliaceae). Our study could demonstrate that the species‐rich Irano‐Turanian (IT) floristic region, a current centre of Gagea species diversity, is also the origin of the genus and of its major linages. Colonisation of adjacent areas started from the IT floristic region and benefit from periods of climatic changes creating dry habits. Therefore, our study supports that the IT region is an important source of taxa for adjacent areas of Euro‐Siberia.
Saffron crocus (
) is a male-sterile, triploid flower crop, and source of the spice and colorant saffron. For over three millennia, it was cultivated across the Mediterranean, including ancient ...Greece, Persia, and other cultures, later spreading all over the world. Despite saffron crocus' early omnipresence, its origin has been the matter of a century-old debate, in terms of area and time as well as parental species contribution. While remnants of the ancient arts, crafts, and texts still provide hints on its origin, modern genetics has the potential to efficiently follow these leads, thus shedding light on new possible lines of descent. In this review, we follow ancient arts and recent genetics to trace the evolutionary origin of saffron crocus. We focus on the place and time of saffron domestication and cultivation, and address its presumed autopolyploid origin involving cytotypes of wild
. Both ancient arts from Greece, Iran, and Mesopotamia as well as recent cytogenetic and comparative next-generation sequencing approaches point to saffron's emergence and domestication in ancient Greece, showing how both disciplines converge in tracing its origin.
Spring crocuses, the eleven species within
series
(Iridaceae), consist of di- and tetraploid cytotypes. Among them is a group of polyploids from southeastern Europe with yet-unclear taxonomic ...affiliation. Crocuses are generally characterized by complex dysploid chromosome number changes, preventing a clear correlation between these numbers and ploidy levels. To reconstruct the evolutionary history of series
and particularly its polyploid lineages associated with
, we used an approach combining phylogenetic analyses of two chloroplast regions, 14 nuclear single-copy genes plus rDNA spacers, genome-wide genotyping-by-sequencing (GBS) data, and morphometry with ploidy estimations through genome size measurements, analysis of genomic heterozygosity frequencies and co-ancestry, and chromosome number counts. Chromosome numbers varied widely in diploids with 2
= 8, 10, 12, 14, 16, and 28 and tetraploid species or cytotypes with 2
= 16, 18, 20, and 22 chromosomes.
, the diploid with the highest chromosome number, possesses the smallest genome (2C = 3.21 pg), while the largest diploid genomes are in a range of 2C = 7-8 pg. Tetraploid genomes have 2C values between 10.88 pg and 12.84 pg. Heterozygosity distribution correlates strongly with genome size classes and allows discernment of di- and tetraploid cytotypes. Our phylogenetic analyses showed that polyploids in the
group are allotetraploids derived from multiple and partly reciprocal crosses involving different genotypes of diploid
(2
= 10) and
(2
= 8). Dysploid karyotype changes after polyploidization resulted in the tetraploid cytotypes with 20 and 22 chromosomes. The multi-data approach we used here for series
, combining evidence from nuclear and chloroplast phylogenies, genome sizes, chromosome numbers, and genomic heterozygosity for ploidy estimations, provides a way to disentangle the evolution of plant taxa with complex karyotype changes that can be used for the analysis of other groups within
and beyond. Comparing these results with morphometric analysis results in characters that can discern the different taxa currently subsumed under
Cistanthe longiscapa is an endemic annual herb and characteristic element of the Chilean Atacama Desert. Principal threats are the destruction of its seed deposits by human activities and reduced ...germination rates due to the decreasing occurrence of precipitation events. To enable population genetic and phylogeographic analyses in this species we performed paired-end shotgun sequencing (2x100 bp) of genomic DNA on the Illumina HiSeq platform and identified microsatellite (SSR) loci in the resulting sequences. From 29 million quality-filtered read pairs we obtained 549,174 contigs (average length 614 bp; N50 = 904). Searching for SSRs revealed 10,336 loci with microsatellite motifs. Initially, we designed primers for 96 loci, which were tested for PCR amplification on three C. longiscapa individuals. Successfully amplifying loci were further tested on eight individuals to screen for length variation in the resulting amplicons, and the alleles were exemplarily sequenced to infer the basis for the observed length variation. Finally we arrived at 26 validated SSR loci for population studies in C. longiscapa, which resulted in 146 bi-allelic SSR markers in our test sample of eight individuals. The genomic sequences were also used to assemble the plastid genome of C. longiscapa, which provides an additional set of maternally inherited genetic markers.
The
Crocus gargaricus
complex (Iridaceae) is known from a handful of scattered populations and three taxa from Turkey. The relationship between these taxa and their taxonomic state, however, has ...remained controversial for the past 200 years.
Crocus gargaricus
was described from Mount Ida in 1841 and later a geographically distant population was discovered at Göktepe, Muğla. The closely related
C. thirkeanus
, which was considered a synonym for about 40 years until 1984 when it was elevated to subspecies level as
C. gargaricus
subsp.
herbertii,
was known only from Uludağ. The latest molecular methods have now shown
C. thirkeanus
and
C. gargaricus
to be distinct species. However, one major limitation of previous studies was their heavy reliance on cultivated material. This study examines all known populations of the
C. gargaricus
complex, collected from their type locations, as well as two more recently discovered populations (Kütahya and İzmir). We combine morpho-anatomical measurements, statistical data analyses and molecular phylogeny to help resolve the relationships between these taxa across their known ranges. Our analysis revealed a clear division of the six populations into three taxa:
C. gargaricus
,
C. thirkeanus
and
C. cigdemiae
, a new species described herein.
Premise
Microsatellite markers were developed for Xerophyta dasylirioides (Velloziaceae), a species endemic to the Malagasy inselbergs, to explore the impact of its island‐like distribution on ...genetic diversity and gene flow.
Methods and Results
A total of 7110 perfect microsatellite loci were recovered by shotgun sequencing on an Illumina MiSeq platform. Primer pairs were designed for 40 arbitrarily selected loci. Fifteen primer pairs that generated distinct PCR products were used to genotype 80 individuals of X. dasylirioides from three inselberg populations. All markers were polymorphic, revealing two to 17 alleles in the overall sampling. Levels of observed and expected heterozygosity per locus ranged from zero to 1.000 and from zero to 0.850, respectively. Success rates of cross‐amplification in 10 additional species of Xerophyta (X. croatii, X. decaryi, X. isaloensis, X. labatii, X. lewisiae, X. pinifolia, X. retinervis, X. setosa, X. spekei, X. tulearensis) ranged from zero to 70%.
Conclusions
Fifteen newly developed microsatellite markers provide a toolkit for assessing population genetic parameters of X. dasylirioides in its unique island‐like habitats.
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•GBS data infer an autotriploid origin of saffron derived from Crocus cartwrightianus.•Saffron evolved and was domesticated in Attica (Greece).•New saffron types might be synthesized ...from different C. cartwrightianus genotypes.
Crocus sativus, the saffron crocus, is the source of saffron, which is made from the dried stigmas of the plant. It is a male-sterile triploid lineage that ever since its origin has been propagated vegetatively. Its mode of evolution and area of origin are matters of long-lasting debates. Here we analyzed chloroplast genomes and genome-wide DNA polymorphisms obtained through genotyping-by-sequencing (GBS) to infer the parent and area of origin of C. sativus. These data were complemented by genome size measurements and analyses of nuclear single-copy genes. We could place 99.3% of saffron GBS alleles in Crocus cartwrightianus, a species occurring in southeastern mainland Greece and on Aegean islands, identifying it as the sole progenitor of the saffron crocus. Phylogenetic and population assignment analyses together with chloroplast polymorphisms indicated the C. cartwrightianus population in the vicinity of Athens as most similar to C. sativus. We conclude that the crop is an autotriploid that evolved in Attica by combining two different genotypes of C. cartwrightianus. Triploid sterility and vegetative propagation prevented afterwards segregation of the favorable traits of saffron, resulting in worldwide cultivation of a unique clonal lineage.
Epiarenic (sand-growing) Tillandsia vegetation in the hyperarid and arid region of the Chilean-Peruvian Atacama Desert represents an extreme case of adaptation in plant species-poor ecosystems. The ...involved species exist at the limit of terrestrial life and form mono/oligo-specific and very characteristic structures within the landscape. Covering thousands of square kilometers they represent the major carbon sink in the hyperarid Atacama core. The various Tillandsia species and respective vegetation may have evolved and adapted independently to this extreme environment. The most abundant vicariant diploid species are T. landbeckii in Chile and T. purpurea in Peru. Spatio-temporally varying distribution range overlaps may have caused potentially adaptive gene flow between different species leading to present day gene pools. Using species distribution modelling we explored the idea that from Last Glacial Maximum (LGM) onwards both species shifted their distribution ranges, which resulted in the formation of varying suture zones from Peru towards northern Chile. We further explored genetic data from a Tillandsia loma vegetation in Southern Peru with three sympatrically growing species exemplifying inter-species gene flow crossing even ploidy levels. This mechanism highlights a strategy to evolve and adapt more rapidly to environmental changes in extreme arid and hyperarid habitats and provides an opportunity for Tillandsia populations to efficiently conserve new genotypes via subsequent clonal propagation.
•Range shifts of Tillandsia in the Atacama Desert fostered sympatric occurrence and gene flow for the last 22,000 years.•Gene flow across species boundaries increase the adaptive capacity at the limits of plant life.•Aneuploid genotypes can be captured and secured serving as a frozen gene pool in a hyperarid landscape.
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